// file: compressImages.ts

import ffmpeg from 'fluent-ffmpeg';
import { Buffer } from 'buffer';
import * as fs from 'fs/promises';
import * as path from 'path';
import * as os from 'os';
import { Readable } from 'stream';

export interface ImageInput {
  buffer: Buffer;
  contentType: string;
}

export interface Av1CompressOptions {
  framerate?: number;
  crf?: number;
  preset?: number;
  pixFmt?: string;
}

const mimeToExtensionMap: Record<string, string> = {
  'image/png': 'png',
  'image/jpeg': 'jpg',
  'image/jpg': 'jpg',
  'image/webp': 'webp',
  'image/bmp': 'bmp',
};

/**
 * 将一个包含不同类型图片的Buffer数组压缩成一个使用SVT-AV1编码的视频Buffer。
 * (已修复顺序问题和视频截断问题)
 *
 * @param images 包含图片对象（buffer 和 contentType）的数组。
 * @param options 压缩选项。
 * @returns {Promise<Buffer>} 一个Promise，解析后为包含视频数据的Buffer。
 */
export async function compressImagesToAv1Video(
  images: ImageInput[],
  options: Av1CompressOptions = {}
): Promise<Buffer> {
  if (!images || images.length === 0) {
    throw new Error('Input image array cannot be empty.');
  }

  const tempDir = await fs.mkdtemp(path.join(os.tmpdir(), 'ffmpeg-av1-'));

  try {
    const {
      framerate = 25,
      crf = 30,
      preset = 8,
      pixFmt = 'yuv420p',
    } = options;

    // --- 修复点 1: 修正写入和 list.txt 生成的逻辑 ---
    
    // 1. 先生成所有文件名，并并行写入所有文件
    const fileNames: string[] = [];
    const writePromises = images.map(async (image, index) => {
      const extension = mimeToExtensionMap[image.contentType.toLowerCase()];
      if (!extension) {
        throw new Error(`Unsupported content type: ${image.contentType}`);
      }
      const frameNumber = (index + 1).toString().padStart(5, '0');
      const fileName = `frame-${frameNumber}.${extension}`;
      fileNames[index] = fileName; // 按正确顺序填充文件名数组
      const filePath = path.join(tempDir, fileName);
      return fs.writeFile(filePath, image.buffer);
    });
    await Promise.all(writePromises);

    // 2. 所有文件写入成功后，再生成 concat 文件内容
    const concatFileContent = fileNames.map(name => `file '${name}'`).join('\n');
    const concatFilePath = path.join(tempDir, 'list.txt');
    await fs.writeFile(concatFilePath, concatFileContent);

    // --- 修复点 2: 修正 FFmpeg 命令选项 ---
    return new Promise<Buffer>((resolve, reject) => {
      const command = ffmpeg(concatFilePath)
        .inputOptions([
          '-f', 'concat',
          '-safe', '0',
          `-r ${framerate}`, // 关键：将帧率作为输入选项
        ])
        .videoCodec('libsvtav1')
        .outputOptions([
          `-crf ${crf}`,
          `-preset ${preset}`,
          '-movflags frag_keyframe+empty_moov',
        ])
        .toFormat('mp4');
      
      // 添加一个start监听器，方便调试，它会打印出最终执行的命令
      command.on('start', (commandLine) => {
        console.log('Spawning FFmpeg with command: ' + commandLine);
      });

      const outputStream = command.pipe() as Readable;

      const chunks: Buffer[] = [];
      outputStream.on('data', (chunk) => chunks.push(chunk));
      outputStream.on('error', reject);
      outputStream.on('end', () => resolve(Buffer.concat(chunks)));

      command.on('error', (err, stdout, stderr) => {
        reject(new Error(`FFmpeg error: ${err.message}\nStderr: ${stderr}`));
      });
    }).finally(() => {
        //fs.rm(tempDir, { recursive: true, force: true });
    });

  } catch (error) {
    //await fs.rm(tempDir, { recursive: true, force: true }).catch(() => {});
    throw error;
  }
}

// ... 示例代码 main() 函数无需修改，可以正常工作