/**
 * File compression utilities for images and videos
 * Compresses files before upload to reduce size
 */

export interface CompressionOptions {
  maxWidth?: number;
  maxHeight?: number;
  quality?: number; // 0-1 for images
  maxSizeMB?: number; // Skip compression if file is smaller than this
}

const DEFAULT_OPTIONS: CompressionOptions = {
  maxWidth: 1200,
  maxHeight: 1080,
  quality: 0.85,
  maxSizeMB: 2
};

/**
 * Compress an image file
 * @param file - The image file to compress
 * @param options - Compression options
 * @returns Compressed file as Blob
 */
export async function compressImage(
  file: File,
  options: CompressionOptions = {}
): Promise<Blob> {
  const opts = { ...DEFAULT_OPTIONS, ...options };
  
  // Skip compression if file is already small enough
  if (opts.maxSizeMB && file.size <= opts.maxSizeMB * 1024 * 1024) {
    return file;
  }

  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = (e) => {
      const img = new Image();
      img.onload = () => {
        const canvas = document.createElement('canvas');
        let width = img.width;
        let height = img.height;

        // Calculate new dimensions
        if (opts.maxWidth && width > opts.maxWidth) {
          height = (height * opts.maxWidth) / width;
          width = opts.maxWidth;
        }
        if (opts.maxHeight && height > opts.maxHeight) {
          width = (width * opts.maxHeight) / height;
          height = opts.maxHeight;
        }

        canvas.width = width;
        canvas.height = height;

        const ctx = canvas.getContext('2d');
        if (!ctx) {
          reject(new Error('Could not get canvas context'));
          return;
        }

        ctx.drawImage(img, 0, 0, width, height);

        canvas.toBlob(
          (blob) => {
            if (blob) {
              resolve(blob);
            } else {
              reject(new Error('Failed to compress image'));
            }
          },
          file.type || 'image/jpeg',
          opts.quality
        );
      };
      img.onerror = () => reject(new Error('Failed to load image'));
      img.src = e.target?.result as string;
    };
    reader.onerror = () => reject(new Error('Failed to read file'));
    reader.readAsDataURL(file);
  });
}

/**
 * Compress a video file (re-encode to reduce size)
 * Note: This is a basic implementation. For better compression, consider using a library like ffmpeg.wasm
 * @param file - The video file to compress
 * @param options - Compression options
 * @returns Compressed file as Blob (or original if compression not supported)
 */
export async function compressVideo(
  file: File,
  options: CompressionOptions = {}
): Promise<Blob> {
  const opts = { ...DEFAULT_OPTIONS, ...options };
  
  // Skip compression if file is already small enough
  if (opts.maxSizeMB && file.size <= opts.maxSizeMB * 1024 * 1024) {
    return file;
  }

  // For now, return original file as browser video compression is complex
  // In the future, could integrate ffmpeg.wasm for client-side video compression
  // For now, we'll rely on server-side compression or accept larger files
  return file;
}

/**
 * Compress a file based on its type
 * @param file - The file to compress
 * @param options - Compression options
 * @returns Compressed file as File object
 */
export async function compressFile(
  file: File,
  options: CompressionOptions = {}
): Promise<File> {
  let compressedBlob: Blob;

  if (file.type.startsWith('image/')) {
    compressedBlob = await compressImage(file, options);
  } else if (file.type.startsWith('video/')) {
    compressedBlob = await compressVideo(file, options);
  } else {
    // No compression for other file types
    return file;
  }

  // Create a new File object from the compressed blob
  return new File([compressedBlob], file.name, {
    type: file.type,
    lastModified: Date.now()
  });
}