// =====================================================
// 個人頭像上傳 API
// =====================================================

import { NextRequest, NextResponse } from 'next/server';
import { writeFile, mkdir } from 'fs/promises';
import { join } from 'path';
import { UserService } from '@/lib/services/database-service';
import { generateUniqueFileName, isValidImageType, isValidImageSize } from '@/lib/image-utils';
import sharp from 'sharp';

export async function POST(request: NextRequest) {
  try {
    const formData = await request.formData();
    const file = formData.get('avatar') as File;
    const userId = formData.get('userId') as string;

    if (!file) {
      return NextResponse.json(
        { success: false, error: '請選擇要上傳的圖片' },
        { status: 400 }
      );
    }

    if (!userId) {
      return NextResponse.json(
        { success: false, error: '用戶ID不能為空' },
        { status: 400 }
      );
    }

    // 驗證文件類型
    if (!isValidImageType(file)) {
      return NextResponse.json(
        { success: false, error: '只支援 JPEG、PNG、WebP 格式的圖片' },
        { status: 400 }
      );
    }

    // 驗證文件大小（限制 5MB）
    if (!isValidImageSize(file, 5)) {
      return NextResponse.json(
        { success: false, error: '圖片大小不能超過 5MB' },
        { status: 400 }
      );
    }

    // 創建上傳目錄
    const uploadDir = join(process.cwd(), 'public', 'uploads', 'avatars');
    await mkdir(uploadDir, { recursive: true });

    // 生成唯一文件名
    const fileName = generateUniqueFileName(file.name, userId);
    const filePath = join(uploadDir, fileName);

    // 讀取文件緩衝區
    const bytes = await file.arrayBuffer();
    const buffer = Buffer.from(bytes);

    // 使用 Sharp 優化圖片
    const optimizedBuffer = await sharp(buffer)
      .resize(200, 200, { 
        fit: 'cover',
        position: 'center'
      })
      .jpeg({ quality: 85 })
      .toBuffer();

    // 保存優化後的圖片
    await writeFile(filePath, optimizedBuffer);

    // 生成相對路徑（自動適應不同環境）
    const imageUrl = `/uploads/avatars/${fileName}`;

    // 更新用戶頭像
    const userService = new UserService();
    await userService.update(userId, { avatar: imageUrl });

    console.log(`✅ 用戶 ${userId} 頭像上傳成功: ${imageUrl}`);

    return NextResponse.json({
      success: true,
      message: '頭像上傳成功',
      data: {
        imageUrl,
        fileName,
        fileSize: optimizedBuffer.length,
        originalSize: file.size
      }
    });

  } catch (error) {
    console.error('頭像上傳失敗:', error);
    return NextResponse.json(
      { 
        success: false, 
        error: '頭像上傳失敗',
        details: error instanceof Error ? error.message : '未知錯誤'
      },
      { status: 500 }
    );
  }
}