server/utils/image-optimizer.ts

import sharp from 'sharp';

export interface ImageOptimizationOptions {
  quality?: number;
  format?: 'webp' | 'jpeg' | 'png';
  width?: number;
  height?: number;
  cropToCenter?: boolean;
  cropHeight?: number;
}

export interface ContentImageOptions {
  quality?: number;
  targetWidth?: number;
  targetHeight?: number;
}

export class ImageOptimizer {
  /**
   * データURLをBufferに変換
   */
  static dataUrlToBuffer(dataUrl: string): Buffer {
    const base64Data = dataUrl.replace(/^data:image\/\w+;base64,/, '');
    return Buffer.from(base64Data, 'base64');
  }

  /**
   * BufferをデータURLに変換
   */
  static bufferToDataUrl(buffer: Buffer, mimeType: string = 'image/webp'): string {
    return `data:${mimeType};base64,${buffer.toString('base64')}`;
  }

  /**
   * 画像をWebP形式に圧縮
   */
  static async compressToWebP(input: Buffer | string, quality: number = 65): Promise<Buffer> {
    const buffer = typeof input === 'string' ? this.dataUrlToBuffer(input) : input;

    return await sharp(buffer).webp({ quality }).toBuffer();
  }

  /**
   * FV画像用の最適化（WebP変換のみ）
   */
  static async optimizeFvImage(input: Buffer | string, options: ImageOptimizationOptions = {}): Promise<string> {
    const { quality = 65, format = 'webp' } = options;

    const buffer = typeof input === 'string' ? this.dataUrlToBuffer(input) : input;

    let processedBuffer: Buffer;

    if (format === 'webp') {
      processedBuffer = await sharp(buffer).webp({ quality }).toBuffer();
    } else if (format === 'jpeg') {
      processedBuffer = await sharp(buffer).jpeg({ quality }).toBuffer();
    } else {
      processedBuffer = await sharp(buffer).png({ quality }).toBuffer();
    }

    const mimeType = format === 'webp' ? 'image/webp' : format === 'jpeg' ? 'image/jpeg' : 'image/png';

    return this.bufferToDataUrl(processedBuffer, mimeType);
  }

  /**
   * コンテンツ画像用の最適化（リサイズ + クロップ + WebP変換）
   */
  static async optimizeContentImage(input: Buffer | string, options: ContentImageOptions = {}): Promise<string> {
    const {
      quality = 50, // 圧縮率を50%に変更
      targetWidth = 400, // 幅を400pxに縮小
      targetHeight = 300, // 高さを300pxに縮小
    } = options;

    const buffer = typeof input === 'string' ? this.dataUrlToBuffer(input) : input;

    // まず400x400にリサイズ
    const resizedBuffer = await sharp(buffer)
      .resize(400, 400, {
        fit: 'cover',
        position: 'center',
      })
      .toBuffer();

    // 上下50pxをクロップして400x300に
    const croppedBuffer = await sharp(resizedBuffer)
      .extract({
        left: 0,
        top: 50, // クロップ位置も調整
        width: targetWidth,
        height: targetHeight,
      })
      .webp({ quality })
      .toBuffer();

    return this.bufferToDataUrl(croppedBuffer, 'image/webp');
  }

  /**
   * 汎用的な画像最適化メソッド
   */
  static async optimizeImage(input: Buffer | string, options: ImageOptimizationOptions = {}): Promise<string> {
    const { quality = 65, format = 'webp', width, height, cropToCenter = false, cropHeight } = options;

    const buffer = typeof input === 'string' ? this.dataUrlToBuffer(input) : input;

    let pipeline = sharp(buffer);

    // リサイズが指定されている場合
    if (width || height) {
      pipeline = pipeline.resize(width, height, {
        fit: cropToCenter ? 'cover' : 'inside',
        position: 'center',
      });
    }

    // クロップが指定されている場合
    if (cropToCenter && width && cropHeight) {
      const metadata = await sharp(buffer).metadata();
      const currentHeight = metadata.height || 0;

      if (currentHeight > cropHeight) {
        const topOffset = Math.floor((currentHeight - cropHeight) / 2);
        pipeline = pipeline.extract({
          left: 0,
          top: topOffset,
          width: width,
          height: cropHeight,
        });
      }
    }

    // フォーマット変換
    let processedBuffer: Buffer;
    if (format === 'webp') {
      processedBuffer = await pipeline.webp({ quality }).toBuffer();
    } else if (format === 'jpeg') {
      processedBuffer = await pipeline.jpeg({ quality }).toBuffer();
    } else {
      processedBuffer = await pipeline.png({ quality }).toBuffer();
    }

    const mimeType = format === 'webp' ? 'image/webp' : format === 'jpeg' ? 'image/jpeg' : 'image/png';

    return this.bufferToDataUrl(processedBuffer, mimeType);
  }

  /**
   * 画像のメタデータを取得
   */
  static async getImageMetadata(input: Buffer | string): Promise<sharp.Metadata> {
    const buffer = typeof input === 'string' ? this.dataUrlToBuffer(input) : input;
    return await sharp(buffer).metadata();
  }

  /**
   * 画像サイズの計算（圧縮前後の比較用）
   */
  static calculateDataUrlSize(dataUrl: string): number {
    const base64Data = dataUrl.replace(/^data:image\/\w+;base64,/, '');
    return Buffer.from(base64Data, 'base64').length;
  }

  /**
   * 圧縮率の計算
   */
  static calculateCompressionRatio(originalSize: number, compressedSize: number): number {
    return Math.round((1 - compressedSize / originalSize) * 100);
  }
}