/**
 * Sticker Processor Service
 * Converts images to WhatsApp-compatible stickers (512x512 WebP)
 */
import sharp from 'sharp'

// WhatsApp sticker requirements
const STICKER_SIZE = 512
const MAX_STICKER_KB = 100 // WhatsApp limit for static stickers

export interface StickerResult {
  buffer: Buffer
  mimetype: string
}

/**
 * Convert an image buffer to a WhatsApp-compatible sticker
 * Requirements:
 * - WebP format
 * - 512x512 pixels (will resize maintaining aspect ratio and add padding)
 * - Max 100KB for static stickers
 */
export async function convertToSticker(
  inputBuffer: Buffer,
  inputMimetype: string
): Promise<StickerResult> {
  // Validate input is an image
  if (!inputMimetype.startsWith('image/')) {
    throw new Error('Input must be an image')
  }

  // Process with sharp - resize to fit 512x512 with transparent padding
  let quality = 100
  let buffer = await sharp(inputBuffer)
    .resize(STICKER_SIZE, STICKER_SIZE, {
      fit: 'contain',
      background: { r: 0, g: 0, b: 0, alpha: 0 } // Transparent background
    })
    .webp({ quality, lossless: false })
    .toBuffer()

  // If too large, reduce quality iteratively
  while (buffer.length > MAX_STICKER_KB * 1024 && quality > 10) {
    quality -= 10
    buffer = await sharp(inputBuffer)
      .resize(STICKER_SIZE, STICKER_SIZE, {
        fit: 'contain',
        background: { r: 0, g: 0, b: 0, alpha: 0 }
      })
      .webp({ quality, lossless: false })
      .toBuffer()
  }

  // If still too large after quality reduction, try resizing smaller
  if (buffer.length > MAX_STICKER_KB * 1024) {
    let size = STICKER_SIZE
    while (buffer.length > MAX_STICKER_KB * 1024 && size > 128) {
      size -= 64
      buffer = await sharp(inputBuffer)
        .resize(size, size, {
          fit: 'contain',
          background: { r: 0, g: 0, b: 0, alpha: 0 }
        })
        .webp({ quality: 80, lossless: false })
        .toBuffer()
    }
    // Resize back to 512x512 for WhatsApp compatibility
    if (size < STICKER_SIZE) {
      buffer = await sharp(buffer)
        .resize(STICKER_SIZE, STICKER_SIZE, {
          fit: 'contain',
          background: { r: 0, g: 0, b: 0, alpha: 0 }
        })
        .toBuffer()
    }
  }

  return {
    buffer,
    mimetype: 'image/webp'
  }
}

/**
 * Check if an image can be converted to a sticker
 */
export function canConvertToSticker(mimetype: string): boolean {
  const supportedTypes = [
    'image/jpeg',
    'image/png',
    'image/webp',
    'image/gif' // Will take first frame
  ]
  return supportedTypes.includes(mimetype)
}