const fs = require('fs');
const path = require('path');
const ffmpeg = require('fluent-ffmpeg');

// Supported media file extensions
const MEDIA_EXTENSIONS = ['.mp4', '.mkv', '.avi', '.mov', '.flv', '.webm'];

/**
 * Check if a file has a media extension
 * @param {string} filePath - Path to the file
 * @returns {boolean} - True if file is a media file
 */
function isMediaFile(filePath) {
  const ext = path.extname(filePath).toLowerCase();
  return MEDIA_EXTENSIONS.includes(ext);
}

/**
 * Scan a directory for media files
 * @param {string} directoryPath - Path to the directory to scan
 * @returns {Promise<Array>} - Array of media file paths
 */
async function scanDirectory(directoryPath) {
  try {
    const files = fs.readdirSync(directoryPath);
    const mediaFiles = [];
    
    for (const file of files) {
      const filePath = path.join(directoryPath, file);
      try {
        const stat = fs.statSync(filePath);
        
        if (stat.isDirectory()) {
          // Recursively scan subdirectories
          const subDirFiles = await scanDirectory(filePath);
          mediaFiles.push(...subDirFiles);
        } else if (isMediaFile(filePath)) {
          // Extract duration and quality for media files
          let fileData = {
            path: filePath,
            name: file,
            size: stat.size,
            modified: stat.mtime,
            duration: '00:00',
            isProblematic: false,
            quality: 'unknown'
          };
          
          try {
            const durationResult = await extractFileDuration(filePath);
            fileData.duration = durationResult.duration;
            fileData.isProblematic = durationResult.isProblematic;
          } catch (error) {
            console.warn(`Failed to extract duration for ${filePath}:`, error.message);
          }
          
          try {
            const quality = await extractVideoQuality(filePath);
            fileData.quality = quality;
          } catch (error) {
            console.warn(`Failed to extract quality for ${filePath}:`, error.message);
          }
          
          mediaFiles.push(fileData);
        }
      } catch (fileError) {
        // Skip files/directories that cause permission errors
        console.warn(`Skipping file/directory due to permission error: ${filePath}`);
        continue;
      }
    }
    
    return mediaFiles;
  } catch (error) {
    throw new Error(`Failed to scan directory: ${error.message}`);
  }
}

/**
 * Extract file duration using ffmpeg
 * @param {string} filePath - Path to the media file
 * @returns {Promise<string>} - Duration in mm:ss format
 */
async function extractFileDuration(filePath) {
  return new Promise((resolve, reject) => {
    ffmpeg.ffprobe(filePath, (err, metadata) => {
      if (err) {
        console.warn(`ffprobe error for ${filePath}:`, err.message);
        // Try alternative approach - attempt to get duration from file stats or use fallback
        try {
          const fs = require('fs');
          const stats = fs.statSync(filePath);
          console.log(`File size for ${filePath}: ${stats.size} bytes`);
          // For now, return 00:00 as fallback for problematic files
          resolve({ duration: '00:00', isProblematic: true });
        } catch (statsError) {
          console.warn(`Could not get file stats for ${filePath}:`, statsError.message);
          resolve({ duration: '00:00', isProblematic: true });
        }
        return;
      }
      
      const duration = metadata.format.duration;
      if (!duration) {
        resolve({ duration: '00:00', isProblematic: false });
        return;
      }
      
      // Convert seconds to mm:ss format
      const minutes = Math.floor(duration / 60);
      const seconds = Math.floor(duration % 60);
      const formattedDuration = `${minutes.toString().padStart(2, '0')}:${seconds.toString().padStart(2, '0')}`;
      resolve({ duration: formattedDuration, isProblematic: false });
    });
  });
}

/**
 * Extract video quality information using ffmpeg
 * @param {string} filePath - Path to the media file
 * @returns {Promise<string>} - Quality information (e.g., "1080p30fps")
 */
async function extractVideoQuality(filePath) {
  return new Promise((resolve, reject) => {
    ffmpeg.ffprobe(filePath, (err, metadata) => {
      if (err) {
        console.warn(`ffprobe error for quality extraction ${filePath}:`, err.message);
        resolve('unknown');
        return;
      }
      
      try {
        // Find the video stream
        const videoStream = metadata.streams.find(stream => stream.codec_type === 'video');
        
        if (!videoStream) {
          resolve('unknown');
          return;
        }
        
        // Get resolution
        const width = videoStream.width || 0;
        const height = videoStream.height || 0;
        
        // Determine quality based on height
        let quality = 'unknown';
        if (height >= 2160) {
          quality = '4K';
        } else if (height >= 1440) {
          quality = '1440p';
        } else if (height >= 1080) {
          quality = '1080p';
        } else if (height >= 720) {
          quality = '720p';
        } else if (height >= 480) {
          quality = '480p';
        } else {
          quality = 'unknown';
        }
        
        // Get frame rate
        let fps = '';
        if (videoStream.r_frame_rate) {
          // Parse frame rate like "30/1" or "25/1"
          const fpsParts = videoStream.r_frame_rate.split('/');
          if (fpsParts.length === 2) {
            const fpsValue = Math.round(parseInt(fpsParts[0]) / parseInt(fpsParts[1]));
            fps = `${fpsValue}fps`;
          } else {
            const fpsValue = Math.round(parseFloat(videoStream.r_frame_rate));
            fps = `${fpsValue}fps`;
          }
        }
        
        // Format the quality string
        if (quality !== 'unknown' && fps) {
          resolve(`${quality}${fps}`);
        } else if (quality !== 'unknown') {
          resolve(quality);
        } else if (fps) {
          resolve(fps);
        } else {
          resolve('unknown');
        }
      } catch (error) {
        console.warn(`Error extracting quality for ${filePath}:`, error.message);
        resolve('unknown');
      }
    });
  });
}

/**
 * Extract file metadata (duration and quality)
 * @param {string} filePath - Path to the media file
 * @returns {Promise<Object>} - File metadata
 */
async function extractFileMetadata(filePath) {
  // Extract duration and quality using ffmpeg
  let duration = '00:00';
  let quality = 'unknown';
  
  try {
    duration = await extractFileDuration(filePath);
  } catch (error) {
    console.warn(`Failed to extract duration for ${filePath}:`, error.message);
  }
  
  try {
    quality = await extractVideoQuality(filePath);
  } catch (error) {
    console.warn(`Failed to extract quality for ${filePath}:`, error.message);
  }
  
  return {
    duration: duration,
    quality: quality
  };
}

module.exports = {
  scanDirectory,
  extractFileMetadata,
  isMediaFile,
  extractFileDuration,
  extractVideoQuality
};