<?php

declare(strict_types=1);

namespace Grav\Plugin\Api\Controllers;

use Grav\Common\Page\Interfaces\PageInterface;
use Grav\Common\Yaml;
use Grav\Framework\Psr7\Response;
use Grav\Plugin\Api\Exceptions\NotFoundException;
use Grav\Plugin\Api\Exceptions\ValidationException;
use Grav\Plugin\Api\Response\ApiResponse;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;

class MediaController extends AbstractApiController
{
    use HandlesMediaUploads;

    /**
     * Per-folder sidecar holding a manual ordering of site media. Mirrors the
     * page-media `header.media_order` concept for folders that have no page to
     * hang the order on. Lives inside the folder it orders and is excluded from
     * media listings.
     */
    private const MEDIA_ORDER_FILE = 'media_order.yaml';

    /**
     * Sidecar suffix Grav uses for per-file metadata: `photo.jpg.meta.yaml`
     * sits next to `photo.jpg`.
     */
    private const META_SUFFIX = '.meta.yaml';

    /**
     * Keys the metadata editor may never write. These are owned by Grav core
     * (intrinsic file properties it derives, and the `upload` block it persists
     * from a FormFlash upload). Blocking them stops a misconfigured field — or a
     * crafted payload — from overwriting dimensions/mime and breaking rendering.
     * Any such keys already in a sidecar are still preserved untouched on save.
     */
    private const RESERVED_META_KEYS = [
        'width', 'height', 'mime', 'size', 'filesize', 'modified', 'upload', 'type',
    ];

    /** Fallback field set when no `media_metadata.fields` is configured. */
    private const DEFAULT_META_FIELDS = [
        ['key' => 'alt', 'label' => 'Alt Text', 'type' => 'text'],
        ['key' => 'title', 'label' => 'Title', 'type' => 'text'],
        ['key' => 'caption', 'label' => 'Caption', 'type' => 'textarea'],
        ['key' => 'description', 'label' => 'Description', 'type' => 'textarea'],
        ['key' => 'tags', 'label' => 'Tags', 'type' => 'tags'],
    ];

    /** Maximum number of entries kept in a `tags` (list) field. */
    private const MAX_TAGS = 50;

    /**
     * Maximum number of repeatable `?filter=` clauses accepted on a media list
     * request. Bounds the per-request query work, mirroring the `batch.max_items`
     * cap on writes.
     */
    private const MAX_FILTER_CLAUSES = 10;

    /**
     * GET /pages/{route}/media - List all media for a page.
     */
    public function pageMedia(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.read');

        $page = $this->findPageOrFail($request, 'read');
        $pagePath = $page->path();

        // Create fresh Media object to avoid stale page cache
        $media = new \Grav\Common\Page\Media($pagePath);

        // Optional metadata filter/sort, bound to the configured schema.
        $collection = $this->applyMediaQuery($media, $request);

        $serialized = $this->getSerializer()->serializeCollection($collection);

        return ApiResponse::create($serialized);
    }

    /**
     * POST /pages/{route}/media - Upload file(s) to a page.
     */
    public function uploadPageMedia(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $page = $this->findPageOrFail($request, 'update');
        $pagePath = $page->path();

        if (!$pagePath || !is_dir($pagePath)) {
            throw new NotFoundException('Page directory does not exist on disk.');
        }

        $uploadedFiles = $this->flattenUploadedFiles($request->getUploadedFiles());

        if ($uploadedFiles === []) {
            throw new ValidationException('No files were uploaded.');
        }

        // Honor per-field upload settings (random_name, accept, ...) when the
        // file field forwards them; absent, this is an inert no-op.
        $settings = $this->parseUploadFieldSettings($request);

        $uploadedNames = [];
        foreach ($uploadedFiles as $file) {
            // Fire before event — plugins can throw to reject specific files
            $this->fireEvent('onApiBeforeMediaUpload', [
                'page' => $page,
                'filename' => $file->getClientFilename(),
                'type' => $file->getClientMediaType(),
                'size' => $file->getSize(),
            ]);

            $uploadedNames[] = $this->processUploadedFile($file, $pagePath, $settings);
        }

        // Create fresh Media object to pick up newly uploaded files
        $media = new \Grav\Common\Page\Media($pagePath);
        $serialized = $this->getSerializer()->serializeCollection($media->all());

        $this->fireAdminEvent('onAdminAfterAddMedia', ['object' => $page, 'page' => $page]);
        $this->fireEvent('onApiMediaUploaded', [
            'page' => $page,
            'filenames' => $uploadedNames,
        ]);

        $baseUrl = $this->getApiBaseUrl();
        $route = $this->getRouteParam($request, 'route') ?? '';
        $location = "{$baseUrl}/pages/{$route}/media";

        return ApiResponse::created(
            $serialized,
            $location,
            $this->invalidationHeaders([
                'media:update:pages/' . $route,
                'pages:update:/' . $route,
            ]),
        );
    }

    /**
     * DELETE /pages/{route}/media/{filename} - Delete a media file from a page.
     */
    public function deletePageMedia(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $page = $this->findPageOrFail($request, 'update');
        $filename = $this->getSafeFilename($request);
        $pagePath = $page->path();

        if (!$pagePath) {
            throw new NotFoundException('Page directory does not exist on disk.');
        }

        // Collect every physical file backing this medium: the base file, its
        // retina `@Nx` variants, and any `.meta.yaml` siblings. A migrated
        // image stored only as `photo@2x.jpg` (no base `photo.jpg`) is listed
        // by Grav under the synthesized base name `photo.jpg`, which has no file
        // on disk — so a plain `file_exists(photo.jpg)` check 404'd it (admin2#68).
        // Sweeping the variants also stops a deleted base from leaving an orphan
        // `@2x` behind (which would reappear as a ghost base in the listing).
        $targets = $this->mediaFileVariants($pagePath, $filename);
        if ($targets === []) {
            throw new NotFoundException("Media file '{$filename}' not found on this page.");
        }

        $this->fireEvent('onApiBeforeMediaDelete', ['page' => $page, 'filename' => $filename]);

        foreach ($targets as $target) {
            if (is_file($target)) {
                unlink($target);
            }
        }

        // Build fresh media object for admin event compatibility
        $media = new \Grav\Common\Page\Media($pagePath);
        $this->fireAdminEvent('onAdminAfterDelMedia', [
            'object' => $page, 'page' => $page,
            'media' => $media, 'filename' => $filename,
        ]);
        $this->fireEvent('onApiMediaDeleted', ['page' => $page, 'filename' => $filename]);

        $route = $this->getRouteParam($request, 'route') ?? '';
        return ApiResponse::noContent(
            $this->invalidationHeaders([
                'media:delete:pages/' . $route . '/' . $filename,
                'media:update:pages/' . $route,
                'pages:update:/' . $route,
            ]),
        );
    }

    /**
     * GET /pages/{route}/media/{filename}/meta - Read a page media file's
     * editable metadata (the `<filename>.meta.yaml` sidecar).
     */
    public function getPageMediaMeta(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.read');

        $page = $this->findPageOrFail($request, 'read');
        $filename = $this->getSafeFilename($request);
        $filePath = $this->requirePageMediaFile($page->path(), $filename);

        return ApiResponse::create($this->buildMetaResponse($filePath, $filename));
    }

    /**
     * PUT /pages/{route}/media/{filename}/meta - Save a page media file's
     * editable metadata. Only configured fields present in the body are written;
     * every other key in the sidecar (EXIF, dimensions, upload info) is kept.
     */
    public function savePageMediaMeta(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $page = $this->findPageOrFail($request, 'update');
        $filename = $this->getSafeFilename($request);
        $filePath = $this->requirePageMediaFile($page->path(), $filename);

        $this->applyMetaWrite($filePath, $this->extractMetaInput($request));

        $this->fireEvent('onApiMediaMetadataUpdated', ['page' => $page, 'filename' => $filename]);

        $route = $this->getRouteParam($request, 'route') ?? '';
        return ApiResponse::create(
            $this->buildMetaResponse($filePath, $filename),
            200,
            $this->invalidationHeaders([
                'media:update:pages/' . $route,
                'pages:update:/' . $route,
            ]),
        );
    }

    /**
     * DELETE /pages/{route}/media/{filename}/meta - Clear a page media file's
     * editable metadata. Reserved/technical keys are preserved; the sidecar is
     * removed only if nothing else remains in it.
     */
    public function deletePageMediaMeta(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $page = $this->findPageOrFail($request, 'update');
        $filename = $this->getSafeFilename($request);
        $filePath = $this->requirePageMediaFile($page->path(), $filename);

        $this->clearMetaFields($filePath);

        $this->fireEvent('onApiMediaMetadataDeleted', ['page' => $page, 'filename' => $filename]);

        $route = $this->getRouteParam($request, 'route') ?? '';
        return ApiResponse::noContent(
            $this->invalidationHeaders([
                'media:update:pages/' . $route,
                'pages:update:/' . $route,
            ]),
        );
    }

    /**
     * Absolute paths of every file backing a medium in $dir: the base file
     * `<stem>.<ext>`, its retina variants `<stem>@<N>x.<ext>`, and the
     * `.meta.yaml` sidecar of each. Used by deletion so retina-only images
     * (no physical base) are still removed and no `@Nx` orphans are left
     * behind (admin2#68). Only files that exist are returned.
     *
     * @return list<string>
     */
    private function mediaFileVariants(string $dir, string $filename): array
    {
        $stem = pathinfo($filename, PATHINFO_FILENAME);
        $ext = pathinfo($filename, PATHINFO_EXTENSION);
        // <stem>@2x.<ext>, <stem>@3x.<ext>, … (case-insensitive extension)
        $variantRe = '/^' . preg_quote($stem, '/') . '@\d+x\.' . preg_quote($ext, '/') . '$/i';

        $files = [];
        foreach (scandir($dir) ?: [] as $entry) {
            if ($entry === '.' || $entry === '..') {
                continue;
            }
            if ($entry !== $filename && !preg_match($variantRe, $entry)) {
                continue;
            }
            $path = $dir . '/' . $entry;
            if (is_file($path)) {
                $files[] = $path;
            }
            $meta = $path . '.meta.yaml';
            if (is_file($meta)) {
                $files[] = $meta;
            }
        }

        return $files;
    }

    /**
     * GET /media - List site-level media with folder browsing, search, and type filter.
     */
    public function siteMedia(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.read');

        $mediaPath = $this->getSiteMediaPath();
        $queryParams = $request->getQueryParams();

        // Validate optional path parameter
        $relativePath = '';
        if (!empty($queryParams['path'])) {
            $relativePath = $this->validateRelativePath($queryParams['path'], $mediaPath);
        }

        $currentPath = $relativePath !== '' ? $mediaPath . '/' . $relativePath : $mediaPath;

        // Is a metadata filter/sort query requested? (mirrors page media, #4210)
        $hasMetaQuery = isset($queryParams['filter'])
            || (isset($queryParams['sort']) && $queryParams['sort'] !== '');

        // Search is a recursive filename scan; metadata filter/sort is a
        // per-folder collection query. Combining them has no coherent meaning,
        // so reject it rather than silently ignoring one (#4210).
        if (!empty($queryParams['search']) && $hasMetaQuery) {
            throw new ValidationException('search cannot be combined with filter or sort.');
        }

        // Handle search mode
        if (!empty($queryParams['search'])) {
            return $this->handleMediaSearch($request, $mediaPath, $queryParams);
        }

        // Verify directory exists
        if (!is_dir($currentPath)) {
            // Return empty result for non-existent paths
            $baseUrl = $this->getApiBaseUrl() . '/media';
            return ApiResponse::paginated([], 0, 1, 20, $baseUrl, 200, [], [
                'path' => $relativePath,
                'folders' => [],
            ]);
        }

        $result = $this->scanMediaDirectoryWithFolders($currentPath, $relativePath);
        // Apply the folder's saved manual ordering before filtering/paginating.
        $result['files'] = $this->applySiteMediaOrder($result['files'], $currentPath);
        $pagination = $this->getPagination($request);

        $files = $result['files'];

        // Optional metadata filter/sort, bound to the configured schema and
        // shared with page media (#4210). Only build a real Media collection
        // when a query is actually requested: constructing Media can trigger an
        // EXIF `.meta.yaml` auto-write on GET when `system.media.auto_metadata_exif`
        // is on, so the plain scan path above must stay side-effect-free.
        if ($hasMetaQuery) {
            $media = new \Grav\Common\Page\Media($currentPath);
            // Throws ValidationException on too many clauses / unknown sort
            // field — let it propagate, matching page media.
            $collection = $this->applyMediaQuery($media, $request);

            // The collection is keyed by filename ("<basename>.<ext>"), the same
            // names scanMediaDirectoryWithFolders() produces, so its keys map
            // straight back onto the scanned list.
            $queried = [];
            foreach ($collection as $name => $medium) {
                $queried[] = is_string($name) && $name !== ''
                    ? $name
                    : ($medium->get('filename') ?: basename((string) $medium->path()));
            }

            if (isset($queryParams['sort']) && $queryParams['sort'] !== '') {
                // A sort overrides the manual-order sidecar: the collection's
                // order wins.
                $files = $queried;
            } else {
                // Filter-only: keep the folder's manual order but drop anything
                // the collection filtered out. Files that don't resolve as media
                // simply won't appear — acceptable per #4210.
                $keep = array_flip($queried);
                $files = array_values(array_filter($files, static fn(string $f) => isset($keep[$f])));
            }
        }

        // Apply type filter
        $typeFilter = $queryParams['type'] ?? null;
        if ($typeFilter) {
            $files = array_values(array_filter($files, function (string $file) use ($currentPath, $typeFilter) {
                $mime = mime_content_type($currentPath . '/' . $file) ?: '';
                return match ($typeFilter) {
                    'image' => str_starts_with($mime, 'image/'),
                    'video' => str_starts_with($mime, 'video/'),
                    'audio' => str_starts_with($mime, 'audio/'),
                    'document' => !str_starts_with($mime, 'image/') && !str_starts_with($mime, 'video/') && !str_starts_with($mime, 'audio/'),
                    default => true,
                };
            }));
        }

        $total = count($files);
        $pagedFiles = array_slice($files, $pagination['offset'], $pagination['limit']);

        $serialized = array_map(
            fn(string $file) => $this->serializeSiteFile($currentPath, $file, $relativePath),
            $pagedFiles,
        );

        $baseUrl = $this->getApiBaseUrl() . '/media';

        return ApiResponse::paginated(
            $serialized,
            $total,
            $pagination['page'],
            $pagination['per_page'],
            $baseUrl,
            200,
            [],
            [
                'path' => $relativePath,
                'folders' => $result['folders'],
                'ordered' => is_file($currentPath . '/' . self::MEDIA_ORDER_FILE),
            ],
        );
    }

    /**
     * POST /media - Upload file(s) to the site media folder (with optional subfolder path).
     */
    public function uploadSiteMedia(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $mediaPath = $this->getSiteMediaPath();
        $queryParams = $request->getQueryParams();

        // Validate optional subfolder path
        $relativePath = '';
        if (!empty($queryParams['path'])) {
            $relativePath = $this->validateRelativePath($queryParams['path'], $mediaPath);
        }

        $targetDir = $relativePath !== '' ? $mediaPath . '/' . $relativePath : $mediaPath;

        if (!is_dir($targetDir) && !mkdir($targetDir, 0775, true)) {
            throw new ValidationException('Unable to create upload directory.');
        }

        $uploadedFiles = $this->flattenUploadedFiles($request->getUploadedFiles());

        if ($uploadedFiles === []) {
            throw new ValidationException('No files were uploaded.');
        }

        $settings = $this->parseUploadFieldSettings($request);

        $created = [];
        foreach ($uploadedFiles as $file) {
            $filename = $this->processUploadedFile($file, $targetDir, $settings);
            $created[] = $this->serializeSiteFile($targetDir, $filename, $relativePath);
        }

        $location = $this->getApiBaseUrl() . '/media';

        return ApiResponse::created(
            $created,
            $location,
            $this->invalidationHeaders(['media:update:' . ($relativePath !== '' ? $relativePath : '/'), 'media:list']),
        );
    }

    /**
     * DELETE /media/{filename} - Delete a site media file (supports subfolder paths).
     */
    public function deleteSiteMedia(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $mediaPath = $this->getSiteMediaPath();
        $relativePath = $this->getSafeRelativeFilePath($request, $mediaPath);
        $filePath = $mediaPath . '/' . $relativePath;

        if (!file_exists($filePath)) {
            throw new NotFoundException("Media file not found.");
        }

        unlink($filePath);

        // Also remove any metadata file
        $metaPath = $filePath . '.meta.yaml';
        if (file_exists($metaPath)) {
            unlink($metaPath);
        }

        // Keep the folder's order sidecar coherent.
        $this->removeFromSiteMediaOrder(dirname($filePath), basename($filePath));

        $parentDir = ltrim(dirname($relativePath), '.');
        return ApiResponse::noContent(
            $this->invalidationHeaders([
                'media:delete:' . $relativePath,
                'media:update:' . ($parentDir !== '' ? $parentDir : '/'),
                'media:list',
            ]),
        );
    }

    /**
     * GET /media/meta?path=... - Read a site media file's editable metadata.
     * The file is addressed by `?path=` (relative to the media root) because
     * site media paths contain slashes and would collide with the greedy
     * `/media/{filename:.+}` route.
     */
    public function getSiteMediaMeta(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.read');

        [$relativePath, $filePath] = $this->requireSiteMediaFile($request);

        return ApiResponse::create($this->buildMetaResponse($filePath, basename($relativePath)));
    }

    /**
     * PUT /media/meta?path=... - Save a site media file's editable metadata.
     */
    public function saveSiteMediaMeta(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        [$relativePath, $filePath] = $this->requireSiteMediaFile($request);

        $this->applyMetaWrite($filePath, $this->extractMetaInput($request));

        $this->fireEvent('onApiMediaMetadataUpdated', ['path' => $relativePath, 'filename' => basename($relativePath)]);

        $parentDir = ltrim(dirname($relativePath), '.');
        return ApiResponse::create(
            $this->buildMetaResponse($filePath, basename($relativePath)),
            200,
            $this->invalidationHeaders([
                'media:update:' . ($parentDir !== '' ? $parentDir : '/'),
                'media:list',
            ]),
        );
    }

    /**
     * POST /media/batch/meta - Apply the same metadata fields to several site
     * media files at once. Only the fields present in the body are written to
     * each file; every file keeps its other sidecar values (so a batch that
     * changes just `tags` leaves each file's own `alt`/`title` untouched).
     *
     * Body: `{"files": ["a.jpg", "sub/b.png"], "fields": {"tags": ["hero"]}}`.
     * Files are listed by path (relative to the media root) rather than via
     * `?path=` because a batch targets many files. Each file is validated and
     * written independently; a failure on one is reported without aborting the
     * rest.
     */
    public function batchSiteMediaMeta(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $body = $this->getRequestBody($request);
        $this->requireFields($body, ['files', 'fields']);

        $files = $body['files'];
        $fields = $body['fields'];

        if (!is_array($files) || $files === []) {
            throw new ValidationException("The 'files' field must be a non-empty array of media paths.");
        }
        if (!is_array($fields)) {
            throw new ValidationException("The 'fields' field must be an object of metadata values.");
        }

        $maxBatch = (int) $this->config->get('plugins.api.batch.max_items', 50);
        if (count($files) > $maxBatch) {
            throw new ValidationException("Batch metadata updates are limited to {$maxBatch} files.");
        }

        $mediaPath = $this->getSiteMediaPath();
        $results = [];
        $parents = [];

        foreach ($files as $file) {
            if (!is_string($file) || $file === '') {
                $results[] = ['path' => (string) $file, 'status' => 'error', 'message' => 'Invalid media path.'];
                continue;
            }

            try {
                $relativePath = $this->validateRelativePath($file, $mediaPath);
                $filePath = $mediaPath . '/' . $relativePath;
                if ($relativePath === '' || !is_file($filePath)) {
                    throw new NotFoundException('Media file not found.');
                }

                $this->applyMetaWrite($filePath, $fields);
                $this->fireEvent('onApiMediaMetadataUpdated', ['path' => $relativePath, 'filename' => basename($relativePath)]);

                $results[] = ['path' => $relativePath, 'status' => 'success'];
                $parents[ltrim(dirname($relativePath), '.')] = true;
            } catch (\Throwable $e) {
                $results[] = ['path' => $file, 'status' => 'error', 'message' => $e->getMessage()];
            }
        }

        $tags = ['media:list'];
        foreach (array_keys($parents) as $parentDir) {
            $tags[] = 'media:update:' . ($parentDir !== '' ? $parentDir : '/');
        }

        return ApiResponse::create(
            [
                'results' => $results,
                'total' => count($results),
                'successful' => count(array_filter($results, static fn($r) => $r['status'] === 'success')),
                'failed' => count(array_filter($results, static fn($r) => $r['status'] === 'error')),
            ],
            200,
            $this->invalidationHeaders($tags),
        );
    }

    /**
     * DELETE /media/meta?path=... - Clear a site media file's editable metadata.
     */
    public function deleteSiteMediaMeta(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        [$relativePath, $filePath] = $this->requireSiteMediaFile($request);

        $this->clearMetaFields($filePath);

        $this->fireEvent('onApiMediaMetadataDeleted', ['path' => $relativePath, 'filename' => basename($relativePath)]);

        $parentDir = ltrim(dirname($relativePath), '.');
        return ApiResponse::noContent(
            $this->invalidationHeaders([
                'media:update:' . ($parentDir !== '' ? $parentDir : '/'),
                'media:list',
            ]),
        );
    }

    /**
     * POST /media/folders - Create a new folder.
     */
    public function createFolder(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $mediaPath = $this->getSiteMediaPath();
        $body = json_decode((string) $request->getBody(), true) ?? [];

        if (empty($body['path'])) {
            throw new ValidationException('Folder path is required.');
        }

        $relativePath = $this->validateRelativePath($body['path'], $mediaPath);
        $absolutePath = $mediaPath . '/' . $relativePath;

        if (is_dir($absolutePath)) {
            throw new ValidationException('Folder already exists.');
        }

        if (!mkdir($absolutePath, 0775, true)) {
            throw new ValidationException('Unable to create folder.');
        }

        $name = basename($relativePath);
        $data = [
            'name' => $name,
            'path' => $relativePath,
            'children_count' => 0,
            'file_count' => 0,
        ];

        return ApiResponse::created(
            $data,
            $this->getApiBaseUrl() . '/media?path=' . urlencode($relativePath),
            $this->invalidationHeaders(['media:create:' . $relativePath, 'media:list']),
        );
    }

    /**
     * DELETE /media/folders/{path} - Delete an empty folder.
     */
    public function deleteFolder(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $mediaPath = $this->getSiteMediaPath();
        $path = $this->getRouteParam($request, 'path');

        if ($path === null || $path === '') {
            throw new ValidationException('Folder path is required.');
        }

        $relativePath = $this->validateRelativePath($path, $mediaPath);
        $absolutePath = $mediaPath . '/' . $relativePath;

        if (!is_dir($absolutePath)) {
            throw new NotFoundException('Folder not found.');
        }

        // Check if folder is empty (only . and ..)
        $isEmpty = true;
        foreach (new \DirectoryIterator($absolutePath) as $item) {
            if (!$item->isDot()) {
                $isEmpty = false;
                break;
            }
        }

        if (!$isEmpty) {
            throw new ValidationException('Folder is not empty. Delete all files first.');
        }

        if (!rmdir($absolutePath)) {
            throw new ValidationException('Unable to delete folder.');
        }

        return ApiResponse::noContent(
            $this->invalidationHeaders(['media:delete:' . $relativePath, 'media:list']),
        );
    }

    /**
     * POST /media/rename - Rename or move a media file.
     */
    public function renameFile(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $mediaPath = $this->getSiteMediaPath();
        $body = json_decode((string) $request->getBody(), true) ?? [];

        if (empty($body['from']) || empty($body['to'])) {
            throw new ValidationException("Both 'from' and 'to' paths are required.");
        }

        $from = $this->validateRelativePath($body['from'], $mediaPath);

        // Preserve the source file's extension and clean the requested name so
        // the result is always a valid, URL-safe media filename. A missing
        // extension makes later `media://` links fatal in Grav's Excerpts
        // parser, and spaces / odd characters break the Markdown image URL the
        // editor generates (getgrav/grav-plugin-admin2#77).
        $originalExt = pathinfo($from, PATHINFO_EXTENSION);
        $rawTo = str_replace('\\', '/', (string) $body['to']);
        $toDir = trim(dirname($rawTo), '/.');
        $toName = $this->sanitizeMediaFilename(basename($rawTo), $originalExt);
        $to = $this->validateRelativePath(($toDir !== '' ? $toDir . '/' : '') . $toName, $mediaPath);

        $fromAbsolute = $mediaPath . '/' . $from;
        $toAbsolute = $mediaPath . '/' . $to;

        if (!file_exists($fromAbsolute)) {
            throw new NotFoundException("Source file not found.");
        }

        // Sanitizing can map the requested name back onto the source (e.g. only
        // the extension was dropped) — treat that as a no-op rather than a
        // "destination exists" error.
        if ($fromAbsolute === $toAbsolute) {
            $targetPath = $toDir !== '' ? $mediaPath . '/' . $toDir : $mediaPath;
            return ApiResponse::ok($this->serializeSiteFile($targetPath, $toName, $toDir));
        }

        if (file_exists($toAbsolute)) {
            throw new ValidationException("A file already exists at the destination.");
        }

        // Ensure target directory exists
        $targetDir = dirname($toAbsolute);
        if (!is_dir($targetDir) && !mkdir($targetDir, 0775, true)) {
            throw new ValidationException('Unable to create destination directory.');
        }

        if (!rename($fromAbsolute, $toAbsolute)) {
            throw new ValidationException('Unable to rename file.');
        }

        // Also rename metadata sidecar if it exists
        $fromMeta = $fromAbsolute . '.meta.yaml';
        $toMeta = $toAbsolute . '.meta.yaml';
        if (file_exists($fromMeta)) {
            rename($fromMeta, $toMeta);
        }

        // Keep order sidecars coherent across the rename/move.
        $this->renameInSiteMediaOrder(
            dirname($fromAbsolute),
            basename($fromAbsolute),
            dirname($toAbsolute),
            basename($toAbsolute),
        );

        $toDir = ltrim(dirname($to) === '.' ? '' : dirname($to), '/');
        $toFilename = basename($to);

        $targetPath = $toDir !== '' ? $mediaPath . '/' . $toDir : $mediaPath;

        return ApiResponse::ok(
            $this->serializeSiteFile($targetPath, $toFilename, $toDir),
            $this->invalidationHeaders([
                'media:delete:' . $from,
                'media:create:' . $to,
                'media:list',
            ]),
        );
    }

    /**
     * POST /media/folders/rename - Rename a folder.
     */
    public function renameFolder(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $mediaPath = $this->getSiteMediaPath();
        $body = json_decode((string) $request->getBody(), true) ?? [];

        if (empty($body['from']) || empty($body['to'])) {
            throw new ValidationException("Both 'from' and 'to' paths are required.");
        }

        $from = $this->validateRelativePath($body['from'], $mediaPath);
        $to = $this->validateRelativePath($body['to'], $mediaPath);

        $fromAbsolute = $mediaPath . '/' . $from;
        $toAbsolute = $mediaPath . '/' . $to;

        if (!is_dir($fromAbsolute)) {
            throw new NotFoundException("Source folder not found.");
        }

        if (file_exists($toAbsolute)) {
            throw new ValidationException("A folder already exists at the destination.");
        }

        if (!rename($fromAbsolute, $toAbsolute)) {
            throw new ValidationException('Unable to rename folder.');
        }

        $name = basename($to);
        $data = [
            'name' => $name,
            'path' => $to,
            'children_count' => 0,
            'file_count' => 0,
        ];

        return ApiResponse::ok(
            $data,
            $this->invalidationHeaders([
                'media:delete:' . $from,
                'media:create:' . $to,
                'media:list',
            ]),
        );
    }

    /**
     * POST /media/order - Persist a manual ordering of files in a site media
     * folder. Body: { path?: string, order: string[] }. Writes a per-folder
     * `media_order.yaml` sidecar that `siteMedia` applies when listing.
     */
    public function setSiteMediaOrder(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.write');

        $mediaPath = $this->getSiteMediaPath();
        $body = json_decode((string) $request->getBody(), true) ?? [];

        $relativePath = '';
        if (!empty($body['path'])) {
            $relativePath = $this->validateRelativePath($body['path'], $mediaPath);
        }

        $folderAbs = $relativePath !== '' ? $mediaPath . '/' . $relativePath : $mediaPath;
        if (!is_dir($folderAbs)) {
            throw new NotFoundException('Folder not found.');
        }

        if (!isset($body['order']) || !is_array($body['order'])) {
            throw new ValidationException("An 'order' array of filenames is required.");
        }

        // Reduce to safe basenames; drop blanks and the sidecar itself.
        $order = array_values(array_filter(
            array_map(static fn($n) => is_string($n) ? basename($n) : '', $body['order']),
            static fn(string $n) => $n !== '' && $n !== self::MEDIA_ORDER_FILE,
        ));

        $this->writeSiteMediaOrder($folderAbs, $order);

        return ApiResponse::noContent(
            $this->invalidationHeaders([
                'media:update:' . ($relativePath !== '' ? $relativePath : '/'),
                'media:list',
            ]),
        );
    }

    // -------------------------------------------------------------------------
    // Site media ordering (per-folder media_order.yaml sidecar)
    // -------------------------------------------------------------------------

    /**
     * Read the ordered filename list from a folder's order sidecar.
     *
     * @return string[]
     */
    private function readSiteMediaOrder(string $folderAbs): array
    {
        $file = $folderAbs . '/' . self::MEDIA_ORDER_FILE;
        if (!is_file($file)) {
            return [];
        }

        $data = Yaml::parse((string) file_get_contents($file)) ?: [];
        $order = $data['media_order'] ?? [];

        return is_array($order)
            ? array_values(array_filter($order, 'is_string'))
            : [];
    }

    /**
     * Write (or clear) a folder's order sidecar. An empty order removes it.
     *
     * @param string[] $order
     */
    private function writeSiteMediaOrder(string $folderAbs, array $order): void
    {
        $file = $folderAbs . '/' . self::MEDIA_ORDER_FILE;

        if ($order === []) {
            if (is_file($file)) {
                @unlink($file);
            }
            return;
        }

        file_put_contents($file, Yaml::dump(['media_order' => array_values($order)], 99, 2));
    }

    /**
     * Order a folder's file list by its saved sidecar. Files not listed (e.g.
     * new uploads) keep their incoming order and follow the ordered ones.
     *
     * @param string[] $files
     * @return string[]
     */
    private function applySiteMediaOrder(array $files, string $folderAbs): array
    {
        $order = $this->readSiteMediaOrder($folderAbs);
        if ($order === []) {
            return $files;
        }

        $ordered = [];
        foreach ($order as $name) {
            $idx = array_search($name, $files, true);
            if ($idx !== false) {
                $ordered[] = $files[$idx];
                unset($files[$idx]);
            }
        }
        foreach ($files as $name) {
            $ordered[] = $name;
        }

        return $ordered;
    }

    /**
     * Drop a filename from a folder's order sidecar (best-effort, on delete).
     */
    private function removeFromSiteMediaOrder(string $folderAbs, string $filename): void
    {
        $order = $this->readSiteMediaOrder($folderAbs);
        if ($order === []) {
            return;
        }

        $next = array_values(array_filter($order, static fn(string $n) => $n !== $filename));
        if ($next !== $order) {
            $this->writeSiteMediaOrder($folderAbs, $next);
        }
    }

    /**
     * Keep order sidecars coherent across a rename/move (best-effort). Same
     * folder: rename the entry in place. Cross folder: drop it from the source.
     */
    private function renameInSiteMediaOrder(string $fromFolderAbs, string $fromName, string $toFolderAbs, string $toName): void
    {
        if ($fromFolderAbs === $toFolderAbs) {
            $order = $this->readSiteMediaOrder($fromFolderAbs);
            if ($order === []) {
                return;
            }
            $next = array_map(static fn(string $n) => $n === $fromName ? $toName : $n, $order);
            if ($next !== $order) {
                $this->writeSiteMediaOrder($fromFolderAbs, $next);
            }
            return;
        }

        $this->removeFromSiteMediaOrder($fromFolderAbs, $fromName);
    }

    // -------------------------------------------------------------------------
    // Private helpers
    // -------------------------------------------------------------------------

    /**
     * GET /thumbnails/{hash}.{ext} - Serve a cached thumbnail image.
     */
    public function thumbnail(ServerRequestInterface $request): ResponseInterface
    {
        $file = $this->getRouteParam($request, 'file');
        if (!$file) {
            throw new NotFoundException('Thumbnail not found.');
        }

        $cacheDir = $this->grav['locator']->findResource('cache://') . '/api/thumbnails';
        $cachePath = $cacheDir . '/' . basename($file);

        if (!file_exists($cachePath)) {
            throw new NotFoundException('Thumbnail not found.');
        }

        $mime = mime_content_type($cachePath) ?: 'application/octet-stream';
        $content = file_get_contents($cachePath);

        return new Response(
            200,
            [
                'Content-Type' => $mime,
                'Content-Length' => (string) strlen($content),
                'Cache-Control' => 'public, max-age=31536000, immutable',
            ],
            $content
        );
    }

    /**
     * GET /media/raw/{path} - Byte-serve a site-media file.
     *
     * Only used for files the web server refuses to serve directly (see
     * {@see isWebServable()}); everything else keeps its cheap static URL. It is
     * permission-gated like the rest of the site-media routes, and works as an
     * `<img src>` because the API accepts the site's own session cookie.
     */
    public function rawSiteMedia(ServerRequestInterface $request): ResponseInterface
    {
        $this->requirePermission($request, 'api.media.read');

        $mediaPath = $this->getSiteMediaPath();
        $relative = $this->validateRelativePath((string) $this->getRouteParam($request, 'path'), $mediaPath);

        $filePath = $relative !== '' ? $mediaPath . '/' . $relative : '';
        if ($filePath === '' || !is_file($filePath)) {
            throw new NotFoundException('Media file not found.');
        }

        $mime = mime_content_type($filePath) ?: 'application/octet-stream';

        // Allow-list rather than deny-list: this route steps around the web
        // server's own rules, so anything not recognisably media stays
        // unreachable instead of being handed back as readable source.
        $servable = str_starts_with($mime, 'image/')
            || str_starts_with($mime, 'video/')
            || str_starts_with($mime, 'audio/')
            || str_starts_with($mime, 'font/')
            || $mime === 'application/pdf';

        if (!$servable) {
            throw new NotFoundException('Media file not found.');
        }

        $content = file_get_contents($filePath);
        if ($content === false) {
            throw new NotFoundException('Media file not found.');
        }

        return new Response(
            200,
            [
                'Content-Type' => $mime,
                'Content-Length' => (string) strlen($content),
                'Content-Disposition' => 'inline; filename="' . basename($filePath) . '"',
                // The media folder is user-writable, so an uploaded SVG is a
                // stored-XSS vector the moment it is navigated to directly. The
                // sandbox and null default-src neuter it while leaving it
                // renderable in an <img>; nosniff stops type confusion.
                'Content-Security-Policy' => "default-src 'none'; style-src 'unsafe-inline'; sandbox",
                'X-Content-Type-Options' => 'nosniff',
                'Cache-Control' => 'private, max-age=600',
            ],
            $content
        );
    }

    /**
     * Resolve a page from the route parameter or throw a 404.
     */
    private function findPageOrFail(ServerRequestInterface $request, ?string $pageAction = null): PageInterface
    {
        $route = $this->getRouteParam($request, 'route');

        if ($route === null || $route === '') {
            throw new NotFoundException('Page route is required.');
        }

        $page = $this->resolvePageByRoute($route);

        if (!$page) {
            throw new NotFoundException("Page '/{$route}' not found.");
        }

        // A page's media lives inside the page, so rules in its frontmatter
        // apply here too: a page nobody may edit is a page whose attachments
        // nobody may replace (getgrav/grav-plugin-admin2#150). This only takes
        // authority away — permission to touch media still comes from
        // `api.media.*`, never from a page-level grant.
        if ($pageAction !== null) {
            $this->assertPageNotDenied($request, $page, $pageAction);
        }

        return $page;
    }

    /**
     * Clean a user-supplied media filename into one that is safe on disk and
     * valid inside a Markdown `media://` URL, re-attaching the source file's
     * extension. Spaces (and runs of whitespace) collapse to a single dash, and
     * characters outside unicode letters/digits plus `. _ -` are dropped, so
     * `Test Image` with a `.jpg` source becomes `Test-Image.jpg`. Forcing the
     * original extension also stops an extension-less rename, which otherwise
     * produces a `media://` link that fatals in Grav's Excerpts parser
     * (getgrav/grav-plugin-admin2#77).
     */
    private function sanitizeMediaFilename(string $newName, string $extension): string
    {
        // Work on the stem only; the source extension is re-attached below so a
        // rename can never change (or drop) the file type.
        $stem = pathinfo($newName, PATHINFO_FILENAME);
        $stem = preg_replace('/\s+/u', '-', trim($stem));
        $stem = preg_replace('/[^\p{L}\p{N}._-]+/u', '', (string) $stem);
        $stem = trim((string) preg_replace('/-{2,}/', '-', (string) $stem), '-_.');

        if ($stem === '') {
            throw new ValidationException('The new name must contain at least one letter or number.');
        }

        return $extension !== '' ? $stem . '.' . $extension : $stem;
    }

    /**
     * Validate a relative path is safe and within the media directory.
     * Returns the sanitized relative path.
     */
    private function validateRelativePath(string $path, string $basePath): string
    {
        // Normalize separators
        $path = str_replace('\\', '/', $path);
        $path = trim($path, '/');

        if ($path === '') {
            return '';
        }

        // Check each segment
        foreach (explode('/', $path) as $segment) {
            if (
                $segment === '' ||
                $segment === '.' ||
                $segment === '..' ||
                str_contains($segment, "\0") ||
                str_starts_with($segment, '.')
            ) {
                throw new ValidationException("Invalid path: '{$path}'.");
            }
        }

        // Verify resolved path is within base
        $absolute = $basePath . '/' . $path;

        // For existing paths, use realpath
        if (file_exists($absolute)) {
            $real = realpath($absolute);
            $realBase = realpath($basePath);
            if ($real === false || $realBase === false || !str_starts_with($real, $realBase . '/')) {
                throw new ValidationException("Invalid path: '{$path}'.");
            }
        }

        return $path;
    }

    /**
     * Extract and validate a relative file path from route parameters.
     * Unlike getSafeFilename() which strips directories with basename(),
     * this preserves path components for subfolder support.
     */
    private function getSafeRelativeFilePath(ServerRequestInterface $request, string $basePath): string
    {
        $filename = $this->getRouteParam($request, 'filename');

        if ($filename === null || $filename === '') {
            throw new ValidationException('Filename is required.');
        }

        // Normalize
        $filename = str_replace('\\', '/', $filename);
        $filename = trim($filename, '/');

        // Validate each path segment
        foreach (explode('/', $filename) as $segment) {
            if (
                $segment === '' ||
                $segment === '.' ||
                $segment === '..' ||
                str_contains($segment, "\0") ||
                str_starts_with($segment, '.')
            ) {
                throw new ValidationException('Invalid filename.');
            }
        }

        // Verify resolved path is within base
        $absolute = $basePath . '/' . $filename;
        if (file_exists($absolute)) {
            $real = realpath($absolute);
            $realBase = realpath($basePath);
            if ($real === false || $realBase === false || !str_starts_with($real, $realBase . '/')) {
                throw new ValidationException('Invalid filename.');
            }
        }

        return $filename;
    }

    // -------------------------------------------------------------------------
    // Media metadata (.meta.yaml) helpers
    // -------------------------------------------------------------------------

    /**
     * Resolve and validate a page media file for a metadata operation, returning
     * its absolute path. 404s if the file does not exist on disk.
     */
    private function requirePageMediaFile(?string $pagePath, string $filename): string
    {
        if (!$pagePath) {
            throw new NotFoundException('Page directory does not exist on disk.');
        }

        $filePath = $pagePath . '/' . $filename;
        if (!is_file($filePath)) {
            throw new NotFoundException("Media file '{$filename}' not found on this page.");
        }

        return $filePath;
    }

    /**
     * Resolve and validate a site media file (addressed by `?path=`) for a
     * metadata operation. Returns `[relativePath, absolutePath]`.
     *
     * @return array{0: string, 1: string}
     */
    private function requireSiteMediaFile(ServerRequestInterface $request): array
    {
        $mediaPath = $this->getSiteMediaPath();
        $path = $request->getQueryParams()['path'] ?? '';

        if (!is_string($path) || $path === '') {
            throw new ValidationException("A 'path' query parameter identifying the media file is required.");
        }

        $relativePath = $this->validateRelativePath($path, $mediaPath);
        $filePath = $mediaPath . '/' . $relativePath;

        if ($relativePath === '' || !is_file($filePath)) {
            throw new NotFoundException('Media file not found.');
        }

        return [$relativePath, $filePath];
    }

    /**
     * The configured editable metadata fields, normalized to a list of
     * `['key' => string, 'label' => string, 'type' => 'text'|'textarea']`.
     * Entries with an unsafe/reserved key or an unknown type are dropped; an
     * empty or absent config falls back to the built-in defaults.
     *
     * @return list<array{key: string, label: string, type: string}>
     */
    private function getMetadataFieldDefs(): array
    {
        $configured = $this->config->get('plugins.api.media_metadata.fields');
        $source = is_array($configured) && $configured !== [] ? $configured : self::DEFAULT_META_FIELDS;

        $defs = [];
        $seen = [];
        foreach ($source as $entry) {
            if (!is_array($entry)) {
                continue;
            }
            $key = trim((string) ($entry['key'] ?? ''));
            // Safe, non-reserved key only: letters/digits/dot/dash/underscore.
            if ($key === '' || !preg_match('/^[A-Za-z0-9._-]+$/', $key)) {
                continue;
            }
            if (in_array($key, self::RESERVED_META_KEYS, true) || isset($seen[$key])) {
                continue;
            }
            $type = (string) ($entry['type'] ?? 'text');
            if (!in_array($type, ['text', 'textarea', 'tags'], true)) {
                $type = 'text';
            }
            $label = trim((string) ($entry['label'] ?? '')) ?: $key;

            $seen[$key] = true;
            $defs[] = ['key' => $key, 'label' => $label, 'type' => $type];
        }

        return $defs !== [] ? $defs : self::DEFAULT_META_FIELDS;
    }

    /**
     * Apply the optional metadata filter/sort query params to a media
     * collection, returning the (possibly filtered/sorted) collection to
     * serialize. With no query params this is a no-op returning `$media->all()`.
     * Shared by page media (`GET /pages/{route}/media`) and site media
     * (`GET /media`); the parameter is typed to the `AbstractMedia` base both
     * `Page\Media` and `GlobalMedia` extend.
     *
     * The filterable/sortable surface is bound to the configured
     * `media_metadata.fields` schema (via {@see getMetadataFieldDefs()}): only
     * admin-defined keys are accepted and each field's `type` drives which
     * operators are legal. Unknown fields are ignored leniently; malformed
     * clauses and unsupported operators are rejected with a 400. Filtering rides
     * the existing `api.media.read` permission and adds no path or file input.
     *
     * Supported params:
     *  - `filter=field:op:value` or `filter=field:value` (repeatable via
     *    `filter[]=…`). Operators: {@see AbstractMedia::META_OPERATORS}.
     *  - `sort=field` with `order=asc|desc` (`dir=` accepted as an alias).
     *
     * @param \Grav\Common\Page\Medium\AbstractMedia $media
     * @return iterable<\Grav\Common\Media\Interfaces\MediaObjectInterface>
     */
    private function applyMediaQuery(\Grav\Common\Page\Medium\AbstractMedia $media, ServerRequestInterface $request): iterable
    {
        // Guard against a core older than the one that shipped the query
        // methods; degrade to the full unfiltered listing rather than error.
        if (!method_exists($media, 'filterBy')) {
            return $media->all();
        }

        $query = $request->getQueryParams();

        $typeByKey = [];
        foreach ($this->getMetadataFieldDefs() as $def) {
            $typeByKey[$def['key']] = $def['type'];
        }
        $maxLen = $this->getMetadataMaxLength();

        $collection = $media;
        $applied = false;

        // --- filters ---
        $clauses = $this->normalizeFilterParam($query['filter'] ?? null);
        if (count($clauses) > self::MAX_FILTER_CLAUSES) {
            throw new ValidationException(
                sprintf('Too many filter clauses (maximum %d).', self::MAX_FILTER_CLAUSES)
            );
        }
        foreach ($clauses as $clause) {
            $parsed = $this->parseFilterClause($clause, $typeByKey, $maxLen);
            if ($parsed === null) {
                // Unknown/absent field: ignored, never fatal.
                continue;
            }
            [$field, $operator, $value] = $parsed;
            $collection = $collection->filterBy($field, $value, $operator);
            $applied = true;
        }

        // --- sort ---
        $sort = $query['sort'] ?? null;
        if (is_string($sort) && $sort !== '') {
            // Configured metadata keys plus intrinsic keys the list already
            // exposes (so ?sort=filename etc. leaks nothing new).
            $sortable = array_merge(array_keys($typeByKey), ['filename', 'size', 'modified']);
            if (!in_array($sort, $sortable, true)) {
                throw new ValidationException(sprintf("Invalid sort field '%s'.", $sort));
            }
            // Prefer `order` (consistent with the rest of the API); accept `dir`.
            $dir = strtolower((string) ($query['order'] ?? $query['dir'] ?? 'asc'));
            if (!in_array($dir, ['asc', 'desc'], true)) {
                $dir = 'asc';
            }
            $collection = $collection->sortBy($sort, $dir);
            $applied = true;
        }

        // Return the collection object (not ->all(), which would re-order and
        // undo an applied sort); it iterates in filtered/sorted order.
        return $applied ? $collection : $media->all();
    }

    /**
     * Normalize the `filter` query param to a list of clause strings. Accepts a
     * single `filter=…` string or a repeatable `filter[]=…` array.
     *
     * @param mixed $raw
     * @return list<string>
     */
    private function normalizeFilterParam(mixed $raw): array
    {
        if (is_array($raw)) {
            $out = [];
            foreach ($raw as $value) {
                if (is_string($value) && $value !== '') {
                    $out[] = $value;
                }
            }
            return $out;
        }

        return is_string($raw) && $raw !== '' ? [$raw] : [];
    }

    /**
     * Parse and validate one `filter` clause into `[field, operator, value]`,
     * or null if the field is not part of the configured schema (ignored
     * leniently). Throws {@see ValidationException} for a malformed clause,
     * unknown operator, or an operator disallowed for the field's type.
     *
     * @param array<string, string> $typeByKey field key => field type
     * @return array{0: string, 1: string, 2: string|list<string>}|null
     */
    private function parseFilterClause(string $clause, array $typeByKey, int $maxLen): ?array
    {
        $parts = explode(':', $clause, 3);
        $field = trim($parts[0]);

        if ($field === '' || !preg_match('/^[A-Za-z0-9_.-]+$/', $field)) {
            throw new ValidationException(sprintf("Malformed filter field in '%s'.", $clause));
        }

        // Schema-bound: only configured keys are filterable.
        if (!array_key_exists($field, $typeByKey)) {
            return null;
        }
        $type = $typeByKey[$field];

        if (count($parts) === 3) {
            $operator = trim($parts[1]);
            $rawValue = $parts[2];
        } elseif (count($parts) === 2) {
            // `field:value` shorthand — operator inferred from the field type.
            $operator = $type === 'tags' ? 'contains' : '==';
            $rawValue = $parts[1];
        } else {
            throw new ValidationException(
                sprintf("Malformed filter clause '%s'. Use field:value or field:operator:value.", $clause)
            );
        }

        if (!in_array($operator, \Grav\Common\Page\Medium\AbstractMedia::META_OPERATORS, true)) {
            throw new ValidationException(sprintf("Unsupported filter operator '%s'.", $operator));
        }

        // Type-aware policy: a tags (list) field only takes membership operators.
        if ($type === 'tags' && !in_array($operator, ['in', 'contains'], true)) {
            throw new ValidationException(
                sprintf("Field '%s' is a tags field; use the 'in' or 'contains' operator.", $field)
            );
        }

        if ($operator === 'in') {
            $value = array_values(array_filter(
                array_map(fn($v) => $this->sanitizeFilterValue($v, $maxLen), explode(',', $rawValue)),
                static fn($v) => $v !== ''
            ));
        } else {
            $value = $this->sanitizeFilterValue($rawValue, $maxLen);
        }

        return [$field, $operator, $value];
    }

    /**
     * Sanitize a filter value the same way write input is treated: strip tags
     * and control characters, collapse whitespace, and cap the length. Read-only
     * — there is no path, regex, or callable surface here.
     */
    private function sanitizeFilterValue(string $value, int $maxLen): string
    {
        $value = strip_tags($value);
        $value = (string) preg_replace('/[\x00-\x1F\x7F]+/u', ' ', $value);
        $value = trim((string) preg_replace('/\s+/u', ' ', $value));

        if (mb_strlen($value) > $maxLen) {
            $value = mb_substr($value, 0, $maxLen);
        }

        return $value;
    }

    /** Maximum accepted length for a single metadata value. */
    private function getMetadataMaxLength(): int
    {
        return max(1, (int) $this->config->get('plugins.api.media_metadata.max_length', 2000));
    }

    /**
     * Sanitize an incoming metadata value. Metadata renders into `<img>`
     * attributes on the site, so every value is coerced to a scalar string,
     * stripped of HTML tags and control characters, collapsed (single-line
     * fields), and capped at the configured maximum length.
     */
    private function sanitizeMetadataValue(mixed $value, string $type, int $maxLen): string
    {
        if (is_array($value) || is_object($value)) {
            throw new ValidationException('Metadata values must be plain text.');
        }
        if (is_bool($value)) {
            $value = $value ? '1' : '';
        }

        $str = strip_tags((string) $value);

        if ($type === 'textarea') {
            // Keep newlines/tabs; drop other control characters.
            $str = (string) preg_replace('/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/u', '', $str);
            $str = trim($str);
        } else {
            // Single line: control chars and whitespace runs collapse to a space.
            $str = (string) preg_replace('/[\x00-\x1F\x7F]+/u', ' ', $str);
            $str = trim((string) preg_replace('/\s+/u', ' ', $str));
        }

        if (mb_strlen($str) > $maxLen) {
            $str = mb_substr($str, 0, $maxLen);
        }

        return $str;
    }

    /**
     * Sanitize an incoming `tags` value into a clean list of strings. Accepts an
     * array of strings, or a single comma-separated string. Each entry is
     * single-line-sanitized (tags render into attributes/queries just like other
     * metadata), commas are dropped (they delimit entries), blanks and
     * duplicates are removed, and the list is capped at MAX_TAGS.
     *
     * @return list<string>
     */
    private function sanitizeMetadataList(mixed $value, int $maxLen): array
    {
        if (is_string($value)) {
            $value = explode(',', $value);
        }
        if (!is_array($value)) {
            throw new ValidationException('A tags value must be a list of strings.');
        }

        $tags = [];
        $seen = [];
        foreach ($value as $item) {
            if (is_array($item) || is_object($item)) {
                throw new ValidationException('Each tag must be plain text.');
            }
            // Reuse single-line sanitization, then strip commas (the delimiter).
            $tag = str_replace(',', ' ', $this->sanitizeMetadataValue($item, 'text', $maxLen));
            $tag = trim((string) preg_replace('/\s+/u', ' ', $tag));
            if ($tag === '') {
                continue;
            }
            $fold = mb_strtolower($tag);
            if (isset($seen[$fold])) {
                continue;
            }
            $seen[$fold] = true;
            $tags[] = $tag;
            if (count($tags) >= self::MAX_TAGS) {
                break;
            }
        }

        return $tags;
    }

    /**
     * Pull the incoming metadata field map from a save request body. Accepts
     * either `{"fields": {key: value}}` or a bare `{key: value}` map.
     *
     * @return array<string, mixed>
     */
    private function extractMetaInput(ServerRequestInterface $request): array
    {
        $body = $this->getRequestBody($request);
        $fields = array_key_exists('fields', $body) ? $body['fields'] : $body;

        if (!is_array($fields)) {
            throw new ValidationException('Expected a "fields" object of metadata values.');
        }

        return $fields;
    }

    /**
     * Read a media file's `.meta.yaml` sidecar as a raw associative array.
     *
     * @return array<string, mixed>
     */
    private function readMetaSidecar(string $filePath): array
    {
        $metaFile = $filePath . self::META_SUFFIX;
        if (!is_file($metaFile)) {
            return [];
        }

        $data = Yaml::parse((string) file_get_contents($metaFile));

        return is_array($data) ? $data : [];
    }

    /**
     * Build the metadata read response for a media file: the configured fields
     * with their current values, plus any other (read-only) keys present in the
     * sidecar so the UI can show what it won't touch.
     *
     * @return array<string, mixed>
     */
    private function buildMetaResponse(string $filePath, string $filename): array
    {
        $stored = $this->readMetaSidecar($filePath);
        $defs = $this->getMetadataFieldDefs();

        $fields = [];
        $managedKeys = [];
        foreach ($defs as $def) {
            $key = $def['key'];
            $managedKeys[$key] = true;
            $raw = $stored[$key] ?? null;

            if ($def['type'] === 'tags') {
                // Normalize to a clean list of strings for the tag editor.
                $value = is_array($raw)
                    ? array_values(array_filter(array_map(
                        static fn($t) => is_scalar($t) ? (string) $t : '',
                        $raw,
                    ), static fn($t) => $t !== ''))
                    : (is_scalar($raw) && $raw !== '' ? [(string) $raw] : []);
            } else {
                $value = is_scalar($raw) ? (string) $raw : '';
            }

            $fields[] = [
                'key' => $key,
                'label' => $def['label'],
                'type' => $def['type'],
                'value' => $value,
            ];
        }

        // Everything else stays read-only in the UI (EXIF, dimensions, upload…).
        $extra = [];
        foreach ($stored as $key => $value) {
            if (!isset($managedKeys[$key])) {
                $extra[$key] = $value;
            }
        }

        return [
            'filename' => $filename,
            'has_meta' => is_file($filePath . self::META_SUFFIX),
            'fields' => $fields,
            'extra' => $extra,
        ];
    }

    /**
     * Apply an incoming field map to a media file's sidecar. Only configured,
     * non-reserved fields present in the input are changed (empty value clears
     * the key); all other keys are preserved. An emptied sidecar is removed.
     *
     * @param array<string, mixed> $input
     */
    private function applyMetaWrite(string $filePath, array $input): void
    {
        $stored = $this->readMetaSidecar($filePath);
        $maxLen = $this->getMetadataMaxLength();

        foreach ($this->getMetadataFieldDefs() as $def) {
            $key = $def['key'];
            if (!array_key_exists($key, $input) || in_array($key, self::RESERVED_META_KEYS, true)) {
                continue;
            }

            if ($def['type'] === 'tags') {
                $tags = $this->sanitizeMetadataList($input[$key], $maxLen);
                if ($tags === []) {
                    unset($stored[$key]);
                } else {
                    $stored[$key] = $tags;
                }
                continue;
            }

            $value = $this->sanitizeMetadataValue($input[$key], $def['type'], $maxLen);
            if ($value === '') {
                unset($stored[$key]);
            } else {
                $stored[$key] = $value;
            }
        }

        $this->writeMetaSidecar($filePath, $stored);
    }

    /**
     * Clear every configured (managed) field from a media file's sidecar,
     * leaving reserved/technical keys intact. Removes the sidecar if empty.
     */
    private function clearMetaFields(string $filePath): void
    {
        $stored = $this->readMetaSidecar($filePath);
        foreach ($this->getMetadataFieldDefs() as $def) {
            unset($stored[$def['key']]);
        }

        $this->writeMetaSidecar($filePath, $stored);
    }

    /**
     * Persist (or remove, when empty) a media file's `.meta.yaml` sidecar.
     *
     * @param array<string, mixed> $data
     */
    private function writeMetaSidecar(string $filePath, array $data): void
    {
        $metaFile = $filePath . self::META_SUFFIX;

        if ($data === []) {
            if (is_file($metaFile)) {
                @unlink($metaFile);
            }
            return;
        }

        file_put_contents($metaFile, Yaml::dump($data, 99, 2));
    }

    /**
     * Resolve the absolute path to the site-level media directory.
     */
    private function getSiteMediaPath(): string
    {
        /** @var \Grav\Common\Locator $locator */
        $locator = $this->grav['locator'];

        $path = $locator->findResource('user://media', true, true);

        if (!$path) {
            throw new NotFoundException('Site media directory could not be resolved.');
        }

        return $path;
    }

    /**
     * Handle recursive media search across all subfolders.
     */
    private function handleMediaSearch(
        ServerRequestInterface $request,
        string $mediaPath,
        array $queryParams
    ): ResponseInterface {
        $search = strtolower($queryParams['search']);
        $typeFilter = $queryParams['type'] ?? null;
        $pagination = $this->getPagination($request);

        $matches = [];

        if (is_dir($mediaPath)) {
            $iterator = new \RecursiveIteratorIterator(
                new \RecursiveDirectoryIterator($mediaPath, \FilesystemIterator::SKIP_DOTS),
                \RecursiveIteratorIterator::SELF_FIRST
            );

            foreach ($iterator as $item) {
                if ($item->isDir()) {
                    continue;
                }

                $name = $item->getFilename();

                // Skip hidden and metadata files
                if (str_starts_with($name, '.') || str_ends_with($name, '.meta.yaml')) {
                    continue;
                }

                // Match filename
                if (!str_contains(strtolower($name), $search)) {
                    continue;
                }

                // Apply type filter
                if ($typeFilter) {
                    $mime = mime_content_type($item->getPathname()) ?: '';
                    $passesFilter = match ($typeFilter) {
                        'image' => str_starts_with($mime, 'image/'),
                        'video' => str_starts_with($mime, 'video/'),
                        'audio' => str_starts_with($mime, 'audio/'),
                        'document' => !str_starts_with($mime, 'image/') && !str_starts_with($mime, 'video/') && !str_starts_with($mime, 'audio/'),
                        default => true,
                    };
                    if (!$passesFilter) {
                        continue;
                    }
                }

                // Calculate relative path
                $fullPath = $item->getPathname();
                $relDir = ltrim(str_replace($mediaPath, '', dirname($fullPath)), '/');

                $matches[] = ['filename' => $name, 'dir' => $relDir, 'fullPath' => $fullPath];
            }
        }

        // Sort matches
        usort($matches, fn($a, $b) => strnatcasecmp($a['filename'], $b['filename']));

        $total = count($matches);
        $paged = array_slice($matches, $pagination['offset'], $pagination['limit']);

        $serialized = array_map(function (array $match) {
            return $this->serializeSiteFile(dirname($match['fullPath']), $match['filename'], $match['dir']);
        }, $paged);

        $baseUrl = $this->getApiBaseUrl() . '/media';

        return ApiResponse::paginated(
            $serialized,
            $total,
            $pagination['page'],
            $pagination['per_page'],
            $baseUrl,
            200,
            [],
            [
                'path' => '',
                'folders' => [],
                'search' => $queryParams['search'],
            ],
        );
    }

    /**
     * Scan a directory for media files, returning just the filenames sorted alphabetically.
     *
     * @return string[]
     */
    private function scanMediaDirectory(string $path): array
    {
        if (!is_dir($path)) {
            return [];
        }

        $files = [];

        /** @var \SplFileInfo $item */
        foreach (new \DirectoryIterator($path) as $item) {
            if ($item->isDot() || $item->isDir()) {
                continue;
            }

            // Skip hidden files and metadata files
            $name = $item->getFilename();
            if (str_starts_with($name, '.') || str_ends_with($name, '.meta.yaml')) {
                continue;
            }

            $files[] = $name;
        }

        sort($files, SORT_NATURAL | SORT_FLAG_CASE);

        return $files;
    }

    /**
     * Scan a directory for media files and subdirectories.
     *
     * @return array{files: string[], folders: array<array{name: string, path: string, children_count: int, file_count: int}>}
     */
    private function scanMediaDirectoryWithFolders(string $absolutePath, string $relativePath = ''): array
    {
        $files = [];
        $folders = [];

        if (!is_dir($absolutePath)) {
            return ['files' => $files, 'folders' => $folders];
        }

        foreach (new \DirectoryIterator($absolutePath) as $item) {
            if ($item->isDot()) {
                continue;
            }

            $name = $item->getFilename();

            // Skip hidden files/dirs
            if (str_starts_with($name, '.')) {
                continue;
            }

            if ($item->isDir()) {
                $folderPath = $relativePath !== '' ? $relativePath . '/' . $name : $name;
                $childPath = $absolutePath . '/' . $name;

                // Count immediate children
                $childrenCount = 0;
                $fileCount = 0;
                if (is_dir($childPath)) {
                    foreach (new \DirectoryIterator($childPath) as $child) {
                        if ($child->isDot() || str_starts_with($child->getFilename(), '.')) {
                            continue;
                        }
                        if ($child->isDir()) {
                            $childrenCount++;
                        } elseif (!str_ends_with($child->getFilename(), '.meta.yaml') && $child->getFilename() !== self::MEDIA_ORDER_FILE) {
                            $fileCount++;
                        }
                    }
                }

                $folders[] = [
                    'name' => $name,
                    'path' => $folderPath,
                    'children_count' => $childrenCount,
                    'file_count' => $fileCount,
                ];
            } else {
                // Skip metadata files and the order sidecar
                if (str_ends_with($name, '.meta.yaml') || $name === self::MEDIA_ORDER_FILE) {
                    continue;
                }
                $files[] = $name;
            }
        }

        sort($files, SORT_NATURAL | SORT_FLAG_CASE);
        usort($folders, fn(array $a, array $b) => strnatcasecmp($a['name'], $b['name']));

        return ['files' => $files, 'folders' => $folders];
    }

    /**
     * Build the browser-facing URL for a site-media file already resolved to an
     * absolute filesystem path.
     *
     * `user://media` is a stream, so it does not always land in `user/media`: a
     * multi-site install resolves it per-environment (`user/env/<host>/media`),
     * and a `user/` folder symlinked outside the install is a supported layout.
     * A hardcoded `/user/media/` prefix therefore points at a path with nothing
     * on disk, and every preview 404s (#28).
     *
     * The direct URL is derived the way core's `MediaFileTrait::url()` does it —
     * strip the install root, prefix `base_url` — but only when the result is
     * something the web server will actually hand over. Grav's shipped
     * `.htaccess` and `webserver-configs/nginx.conf` both deny `user/env` and
     * `user/config` whatever the file type, so those fall back to this plugin's
     * own permission-gated byte-serving route instead of a guaranteed 403.
     */
    private function resolvePublicUrl(string $absolutePath, string $mediaRelativePath): string
    {
        $relative = $this->relativeToWebroot($absolutePath);

        if ($relative !== null && $this->isWebServable($relative)) {
            // `base_url` (not `base_url_relative`) is the key core's own media
            // URLs use, so this honours the install's `system.absolute_urls`
            // setting and its subfolder base in exactly the same way.
            $base = rtrim((string) ($this->grav['base_url'] ?? ''), '/');

            return $base . '/' . $relative;
        }

        $encoded = implode('/', array_map('rawurlencode', explode('/', $mediaRelativePath)));

        return $this->getApiBaseUrl() . '/media/raw/' . $encoded;
    }

    /**
     * Express an absolute path as a webroot-relative URL path, or null when it
     * does not sit under a root the site is served from.
     *
     * Both sides are `realpath()`d and compared with a trailing separator: the
     * locator is built on `GRAV_WEBROOT` and can hand back a symlink-resolved
     * path, and a bare prefix compare would let `/var/www/html` swallow
     * `/var/www/html-backup`. Returning null rather than the input path is
     * deliberate — a miss must never put a server filesystem path into an
     * `<img src>`.
     */
    private function relativeToWebroot(string $absolutePath): ?string
    {
        $real = realpath($absolutePath);
        if ($real === false) {
            return null;
        }

        // USER_DIR is listed separately from the install roots because a `user/`
        // folder symlinked outside the install is a supported layout; its files
        // are still served from `/<user-path>/…`, so the prefix is put back.
        $roots = [
            [GRAV_WEBROOT, ''],
            [GRAV_ROOT, ''],
            [USER_DIR, trim(GRAV_USER_PATH, '/') . '/'],
        ];

        foreach ($roots as [$root, $urlPrefix]) {
            $realRoot = realpath($root);
            if ($realRoot === false) {
                continue;
            }

            $realRoot = rtrim($realRoot, DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR;
            if (strncmp($real, $realRoot, strlen($realRoot)) !== 0) {
                continue;
            }

            return $urlPrefix . str_replace(DIRECTORY_SEPARATOR, '/', substr($real, strlen($realRoot)));
        }

        return null;
    }

    /**
     * Whether the web server will serve a webroot-relative path directly.
     *
     * Mirrors the deny rules Grav ships in `.htaccess` and
     * `webserver-configs/nginx.conf`, which block `user/config`, `user/env` and
     * `user/accounts` for every file type. A multi-site `user://media` living
     * inside `user/env/<host>/` is on disk but 403s over HTTP, so its direct URL
     * would be exactly as broken as the hardcoded one it replaces.
     */
    private function isWebServable(string $relative): bool
    {
        $userPath = preg_quote(trim(GRAV_USER_PATH, '/'), '#');

        return !preg_match('#^' . $userPath . '/(config|env|accounts)(/|$)#i', $relative);
    }

    /**
     * Build a serialized array for a raw file in the site media directory.
     * Used when we don't have Grav Medium objects available.
     */
    private function serializeSiteFile(string $basePath, string $filename, string $relativePath = ''): array
    {
        $filePath = $basePath . '/' . $filename;
        $mime = mime_content_type($filePath) ?: 'application/octet-stream';

        $fullRelativePath = $relativePath !== '' ? $relativePath . '/' . $filename : $filename;

        $data = [
            'filename' => $filename,
            'path' => $relativePath,
            'url' => $this->resolvePublicUrl($filePath, $fullRelativePath),
            'type' => $mime,
            'size' => (int) filesize($filePath),
        ];

        // Alt/title from the `.meta.yaml` sidecar so the media panel can insert
        // `![alt](file)` rather than overwriting alt with the filename.
        $meta = $this->readMetaSidecar($filePath);
        if (isset($meta['alt']) && is_scalar($meta['alt']) && (string) $meta['alt'] !== '') {
            $data['alt'] = (string) $meta['alt'];
        }
        if (isset($meta['title']) && is_scalar($meta['title']) && (string) $meta['title'] !== '') {
            $data['title'] = (string) $meta['title'];
        }

        if (str_starts_with($mime, 'image/') && $mime !== 'image/svg+xml') {
            if ($imageSize = @getimagesize($filePath)) {
                $data['dimensions'] = [
                    'width' => $imageSize[0],
                    'height' => $imageSize[1],
                ];
            }

            // Generate thumbnail. The mime is already known, so pass it through
            // to skip the service's own magic-byte sniff.
            try {
                $thumbnailService = $this->getThumbnailService();
                $thumbFilename = $thumbnailService->ensureThumbnail($filePath, $mime);
                if ($thumbFilename) {
                    $data['thumbnail_url'] = $this->getApiBaseUrl() . '/thumbnails/' . $thumbFilename;
                }
            } catch (\Throwable) {
                // Thumbnail generation failed — skip it
            }
        }

        $mtime = filemtime($filePath);
        $data['modified'] = date(\DateTimeInterface::ATOM, $mtime ?: time());

        return $data;
    }
}
