<?php
/**
 * get_files.php - Recursively scans media directories and returns file structure as JSON
 */
declare(strict_types=1);

require_once __DIR__ . '/auth.php';
require_once __DIR__ . '/media_cache_lib.php';
require_auth(true);

header('Content-Type: application/json; charset=utf-8');

/**
 * Emit JSON response with cache/timing observability headers.
 */
function fm_emit_response(array $payload, string $type, string $cacheStatus, float $startedAt, bool $forceRefresh, ?string $cacheGeneratedAt = null): void
{
    $elapsedMs = (int)round((microtime(true) - $startedAt) * 1000);

    header('X-Media-Type: ' . $type);
    header('X-Media-Cache: ' . $cacheStatus);
    header('X-Media-Time-Ms: ' . (string)$elapsedMs);
    header('X-Media-Force-Refresh: ' . ($forceRefresh ? '1' : '0'));

    if (is_string($cacheGeneratedAt) && $cacheGeneratedAt !== '') {
        header('X-Media-Cache-Generated-At: ' . $cacheGeneratedAt);
    }

    echo json_encode($payload, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
    exit;
}

$startedAt = microtime(true);

// Media type from query parameter (default: videos)
$type = $_GET['type'] ?? 'videos';
if (!is_string($type)) {
    $type = 'unknown';
}

$forceRefresh = isset($_GET['refresh']) && (string)$_GET['refresh'] === '1';

if (!is_string($type) || !fm_is_valid_type($type)) {
    fm_emit_response(['error' => 'Invalid media type'], $type, 'invalid_type', $startedAt, $forceRefresh);
}

$resolveError = null;
$baseDir = fm_resolve_media_root($resolveError);
if ($baseDir === null) {
    fm_emit_response(['error' => $resolveError ?? 'MEDIA_ROOT base directory not found'], $type, 'error', $startedAt, $forceRefresh);
}

if (!$forceRefresh) {
    $cacheError = null;
    $cached = fm_read_cache_payload($type, $baseDir, $cacheError);
    if (is_array($cached)) {
        $tree = $cached['tree'];
        fm_emit_response(
            empty($tree) ? ['message' => 'No media files found'] : $tree,
            $type,
            'hit',
            $startedAt,
            $forceRefresh,
            isset($cached['generated_at']) && is_string($cached['generated_at']) ? $cached['generated_at'] : null
        );
    }
}

$rebuildError = null;
$tree = fm_rebuild_cache($type, $baseDir, false, $rebuildError);

if (!is_array($tree)) {
    $scanError = null;
    $tree = fm_scan_media_tree($type, $baseDir, $scanError);
    if (!is_array($tree)) {
        fm_emit_response(
            ['error' => $scanError ?? $rebuildError ?? 'Failed to scan media directory'],
            $type,
            'error',
            $startedAt,
            $forceRefresh
        );
    }

    fm_emit_response(
        empty($tree) ? ['message' => 'No media files found'] : $tree,
        $type,
        'fallback_scan',
        $startedAt,
        $forceRefresh
    );
}

fm_emit_response(
    empty($tree) ? ['message' => 'No media files found'] : $tree,
    $type,
    $forceRefresh ? 'rebuild_forced' : 'rebuild',
    $startedAt,
    $forceRefresh
);