export default {
  async fetch(request, env, ctx) {
    const { searchParams } = new URL(request.url);
    const token = searchParams.get("token"); 
    const key = searchParams.get("key");
    const action = searchParams.get("action");
    const isDownload = searchParams.get("download");

    const corsHeaders = {
      "Access-Control-Allow-Origin": "*",
      "Access-Control-Allow-Methods": "GET, POST, DELETE, OPTIONS",
      "Access-Control-Allow-Headers": "Content-Type",
    };

    if (request.method === "OPTIONS") return new Response(null, { headers: corsHeaders });

    // --- 身分驗證邏輯 ---
    let userId = null;
    if (token) {
      userId = await verifyLineToken(token);
      if (!userId) return new Response("身分驗證失敗", { status: 401, headers: corsHeaders });
    }

    // --- 安全刪除邏輯 ---
    if (request.method === "DELETE" || (request.method === "GET" && action === "delete")) {
      if (!userId || !key || !key.startsWith(`${userId}/`)) return new Response("非法操作", { status: 403, headers: corsHeaders });
      
      try {
        const target = await env.DB.prepare("SELECT id FROM files WHERE userId = ? AND fileKey = ? LIMIT 1").bind(userId, key).first();
        if (target) {
          await env.DB.prepare("DELETE FROM files WHERE id = ?").bind(target.id).run();
          const others = await env.DB.prepare("SELECT id FROM files WHERE userId = ? AND fileKey = ? LIMIT 1").bind(userId, key).first();
          if (!others) {
            await env.MY_BUCKET.delete(key);
          }
        }
      } catch (e) { console.error("Delete logic error", e); }
      return new Response(JSON.stringify({ success: true }), { headers: corsHeaders });
    }

    if (request.method === "GET") {
      if (userId && key) {
        if (!key.startsWith(`${userId}/`)) return new Response("非法存取", { status: 403 });
        const object = await env.MY_BUCKET.get(key);
        if (!object) return new Response("找不到檔案", { status: 404 });
        const headers = new Headers();
        object.writeHttpMetadata(headers);
        headers.set("Access-Control-Allow-Origin", "*");
        if (isDownload) {
          headers.set("Content-Disposition", `attachment; filename="${encodeURIComponent(key.split('/').pop())}"`);
        } else {
          headers.set("Content-Disposition", "inline");
        }
        return new Response(object.body, { headers });
      }

      if (userId) {
        const getHeaders = { "Content-Type": "application/json", ...corsHeaders };
        try {
          const { results } = await env.DB.prepare("SELECT * FROM files WHERE userId = ? ORDER BY uploadedAt DESC").bind(userId).all();
          const fileList = results.map(obj => ({
            name: obj.fileName,
            key: obj.fileKey,
            size: obj.fileSize + " MB",
            date: new Date(obj.uploadedAt).toLocaleString('zh-TW', { timeZone: 'Asia/Taipei' })
          }));
          return new Response(JSON.stringify(fileList), { headers: getHeaders });
        } catch (e) {
          const objects = await env.MY_BUCKET.list({ prefix: `${userId}/` });
          const fileList = objects.objects.map(obj => ({
            name: obj.key.split('/').pop(),
            key: obj.key,
            size: (obj.size / (1024 * 1024)).toFixed(2) + " MB",
            date: new Date(obj.uploaded).toLocaleString('zh-TW', { timeZone: 'Asia/Taipei' })
          }));
          return new Response(JSON.stringify(fileList.reverse()), { headers: getHeaders });
        }
      }
      return new Response("Adan API is running.", { status: 200 });
    }

    if (request.method === "POST") {
      try {
        const data = await request.json();
        for (const event of data.events) {
          const replyToken = event.replyToken;
          const uId = event.source.userId;
          if (event.type === "message" && ['image', 'video', 'audio', 'file'].includes(event.message.type)) {
            // [改邏] 背景異步處理，不再阻塞主執行緒
            ctx.waitUntil(handleR2Upload(event, env, uId));
          } else if (event.type === "message" && event.message.type === "text") {
            const userText = event.message.text.trim();
            let replyText = "";
            if (userText === "開啟時光膠囊") {
              replyText = "🚀 【開啟時光膠囊】\n\n報告！回憶都好好地裝在膠囊裡囉！\n🔗 點擊進入查看：\nhttps://liff.line.me/2009633088-LqIEGiJZ";
            } else if (userText === "阿丹幫幫我") {
              replyText = "❓ 【阿丹怎麼用？】\n\n📸 Q1：怎麼存東西？\n直接把想留的照片、影片等檔案「傳送」或「轉傳」給我就好囉！我會自動幫你按日期排整齊喔！\n💾 Q2：要去哪裡看存好的東西？\n點擊選單左邊「開啟我的時光膠囊」大按鈕即可。\n⏳ Q3：檔案會過期嗎？絕對不會！膠囊外殼比 LINE 紀錄還持久，只要阿丹還在，回憶就在！";
            } else if (userText === "資料安全嗎") {
              replyText = "🛡️ 【資料安全嗎？】\n\n阿丹是個有原則的小幫手，你的回憶由我守護：\n✅只有你能存取：檔案鎖在專屬膠囊裡面。\n✅ 加密傳輸：採用安全的加密技術。\n✅ 絕對保密：阿丹只負責搬運，不會偷看你的秘密！\n\n✨ 【核心功能】\n💾 自動儲存：LINE 檔案一鍵轉傳，永久保存不失效。\n👀 隨時查閱：點擊選單左方的大按鈕即可直達你的時光膠囊。\n📦 每位用戶享有 500MB 免費儲存空間，單個檔案的傳送上限是250MB。";
            } else {
              replyText = "收到！✨\n阿丹今天也是活力滿滿喔！如果有檔案想存，直接傳給我就可以囉！";
            }
            await sendLineReply(replyToken, replyText, env);
          }
        }
      } catch (err) { console.error(err); }
      return new Response("OK", { status: 200 });
    }
  }
};

async function verifyLineToken(accessToken) {
  try {
    const response = await fetch('https://api.line.me/v2/profile', {
      headers: { 'Authorization': `Bearer ${accessToken}` }
    });
    if (!response.ok) return null;
    const data = await response.json();
    return data.userId;
  } catch (e) { return null; }
}

async function handleR2Upload(event, env, userId) {
  const messageId = event.message.id;
  const msgType = event.message.type;
  const MAX_FREE_SPACE_MB = 500;
  
  // [改邏] 移除寫死的單檔 250MB 上限檢查，改由 R2 實際串流結果判斷
  const lineUrl = `https://api-data.line.me/v2/bot/message/${messageId}/content`;
  const response = await fetch(lineUrl, { headers: { 'Authorization': `Bearer ${env.LINE_CHANNEL_ACCESS_TOKEN}` } });

  if (response.ok) {
    const contentLength = response.headers.get("Content-Length");
    const estimatedSizeMB = contentLength ? parseFloat((parseInt(contentLength) / (1024 * 1024)).toFixed(2)) : 0;

    const stats = await env.DB.prepare("SELECT SUM(fileSize) as total FROM files WHERE userId = ?").bind(userId).first();
    const currentUsedMB = (stats.total || 0);

    if (currentUsedMB + estimatedSizeMB > MAX_FREE_SPACE_MB) {
      await sendLineReply(event.replyToken, `⚠️ 報告！時光膠囊已經裝不下了（${MAX_FREE_SPACE_MB}MB）！\n為了騰出空間裝新回憶，請先去刪除一些不再需要的檔案喔！`, env);
      return;
    }

    let originalName = event.message.fileName || "";
    let ext = originalName.split('.').pop().toLowerCase();
    if (!ext) {
      if (msgType === 'image') ext = 'jpg';
      else if (msgType === 'video') ext = 'mp4';
      else if (msgType === 'audio') ext = 'm4a';
      else ext = 'bin';
    }

    const blackList = ['exe', 'bat', 'sh', 'com', 'cmd', 'scr', 'vbs'];
    if (blackList.includes(ext)) {
      await sendLineReply(event.replyToken, "⚠️ 唔...阿丹為了保護膠囊的安全，不支援儲存可執行檔喔。", env);
      return;
    }

    const now = new Date(new Date().getTime() + 8 * 3600 * 1000); 
    const randomSuffix = Math.random().toString(36).substring(2, 7);
    const displayFileName = originalName || `${now.getTime()}_${randomSuffix}.${ext}`;
    const folderType = ['image', 'video', 'audio'].includes(msgType) ? `${msgType}s` : 'files';
    const filePath = `${userId}/${folderType}/${now.getFullYear()}/${now.getMonth()+1}/${displayFileName}`;

    await env.MY_BUCKET.put(filePath, response.body, { 
      httpMetadata: { contentType: response.headers.get("Content-Type") || "application/octet-stream" } 
    });

    const obj = await env.MY_BUCKET.head(filePath);
    const actualSizeMB = parseFloat((obj.size / (1024 * 1024)).toFixed(2));
    const finalName = originalName || `rec_${now.getTime()}.${ext}`;
    
    await env.DB.prepare(`
      INSERT INTO files (userId, fileKey, fileName, fileType, fileSize, fileHash)
      VALUES (?, ?, ?, ?, ?, ?)
    `).bind(userId, filePath, finalName, msgType, actualSizeMB, `streamed_${now.getTime()}`).run();
    
    const totalNow = (currentUsedMB + actualSizeMB).toFixed(2);
    const replyText = `咻！阿丹已經收好了！這份回憶已經安全裝進時光膠囊啦！🎁\n📊 空間狀態：已用 ${totalNow}MB / 剩餘 ${(MAX_FREE_SPACE_MB - totalNow).toFixed(2)}MB`;
    await sendLineReply(event.replyToken, replyText, env);
  }
}

async function sendLineReply(token, text, env) {
  await fetch('https://api.line.me/v2/bot/message/reply', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json', 'Authorization': `Bearer ${env.LINE_CHANNEL_ACCESS_TOKEN}` },
    body: JSON.stringify({ replyToken: token, messages: [{ type: 'text', text: text }] })
  });
}