<?php

/**
 * VideoMetadataExtractor - Extract technical metadata from video files
 *
 * Uses ffprobe to extract:
 * - Duration
 * - Bitrate
 * - Frame dimensions (width/height)
 * - Aspect ratio
 * - Frame rate
 * - Codec info
 */
class VideoMetadataExtractor
{
    /**
     * Extract video metadata using ffprobe
     *
     * @param string $filePath Path to video file
     * @return array Video metadata or empty array if not video/failed
     */
    public function extractVideoMetadata($filePath)
    {
        if (!file_exists($filePath)) {
            error_log("VideoMetadata: File not found: $filePath");
            return [];
        }

        $mimeType = mime_content_type($filePath);
        if (strpos($mimeType, 'video') === false) {
            error_log("VideoMetadata: Not a video file: $mimeType");
            return [];
        }

        // Try ffprobe first (most accurate)
        $metadata = $this->extractWithFfprobe($filePath);

        if (empty($metadata)) {
            // Fallback to basic file info
            error_log("VideoMetadata: ffprobe not available, using basic info");
            $metadata = $this->extractBasicInfo($filePath);
        }

        return $metadata;
    }

    /**
     * Extract metadata using ffprobe
     */
    private function extractWithFfprobe($filePath)
    {
        // Check if ffprobe is available
        exec('which ffprobe 2>&1', $output, $returnCode);
        if ($returnCode !== 0) {
            return [];
        }

        $command = 'ffprobe -v quiet -print_format json -show_format -show_streams ' . escapeshellarg($filePath);
        exec($command, $output, $returnCode);

        if ($returnCode !== 0) {
            return [];
        }

        $json = implode('', $output);
        $data = json_decode($json, true);

        if (!$data) {
            return [];
        }

        // Extract video stream info
        $videoStream = null;
        if (isset($data['streams'])) {
            foreach ($data['streams'] as $stream) {
                if ($stream['codec_type'] === 'video') {
                    $videoStream = $stream;
                    break;
                }
            }
        }

        $format = $data['format'] ?? [];

        $metadata = [
            'width' => $videoStream['width'] ?? -1,
            'height' => $videoStream['height'] ?? -1,
            'duration' => $format['duration'] ?? null,
            'duration_formatted' => null,
            'bitrate' => $format['bit_rate'] ?? null,
            'aspect_ratio' => null,
            'aspect_ratio_formatted' => null,
            'frame_rate' => $videoStream['r_frame_rate'] ?? null,
            'codec' => $videoStream['codec_name'] ?? null
        ];

        // Calculate aspect ratio
        if ($metadata['width'] > 0 && $metadata['height'] > 0) {
            $aspectDecimal = $metadata['width'] / $metadata['height'];
            $metadata['aspect_ratio'] = round($aspectDecimal, 3);

            // Format as ratio (16:9, 4:3, etc.)
            $metadata['aspect_ratio_formatted'] = $this->formatAspectRatio($metadata['width'], $metadata['height']);
        }

        // Format duration as HH:MM:SS:FF (timecode)
        if ($metadata['duration']) {
            $metadata['duration_formatted'] = $this->formatDuration($metadata['duration']);
        }

        error_log("VideoMetadata: Extracted - {$metadata['width']}x{$metadata['height']}, {$metadata['duration']}s, {$metadata['bitrate']} bps");

        return $metadata;
    }

    /**
     * Extract basic info without ffprobe
     */
    private function extractBasicInfo($filePath)
    {
        return [
            'width' => -1,
            'height' => -1,
            'duration' => null,
            'bitrate' => null,
            'aspect_ratio' => null,
            'aspect_ratio_formatted' => null
        ];
    }

    /**
     * Format aspect ratio as standard ratio string (16:9, 4:3, etc.)
     */
    private function formatAspectRatio($width, $height)
    {
        if ($width <= 0 || $height <= 0) {
            return null;
        }

        // Common ratios
        $commonRatios = [
            '16:9' => 1.778,
            '4:3' => 1.333,
            '1:1' => 1.0,
            '21:9' => 2.333,
            '2.35:1' => 2.35,
            '2.39:1' => 2.39
        ];

        $aspectDecimal = $width / $height;

        // Find closest match
        $closest = '16:9';
        $minDiff = abs($aspectDecimal - 1.778);

        foreach ($commonRatios as $ratio => $value) {
            $diff = abs($aspectDecimal - $value);
            if ($diff < $minDiff) {
                $minDiff = $diff;
                $closest = $ratio;
            }
        }

        // If very close to a common ratio, use it
        if ($minDiff < 0.01) {
            return $closest;
        }

        // Otherwise calculate GCD for exact ratio
        $gcd = $this->gcd($width, $height);
        return ($width / $gcd) . ':' . ($height / $gcd);
    }

    /**
     * Greatest common divisor
     */
    private function gcd($a, $b)
    {
        return $b ? $this->gcd($b, $a % $b) : $a;
    }

    /**
     * Format duration in seconds to HH:MM:SS:FF timecode
     */
    private function formatDuration($seconds)
    {
        $hours = floor($seconds / 3600);
        $minutes = floor(($seconds % 3600) / 60);
        $secs = floor($seconds % 60);
        $frames = round(($seconds - floor($seconds)) * 30); // Assume 30fps

        return sprintf('%02d:%02d:%02d:%02d', $hours, $minutes, $secs, $frames);
    }
}