// いじりやすいようにここに変数を集約させたい
const BLOCKLIST = ["hacker@example.com", "spammer@example.com"];
const FORWARD_TO = "mymail@example.com";
const WEBHOOK_URL = "https://discord.com/api/webhooks/xxx/xxx";
// trendcreate icon
const WEBHOOK_ICON = "https://git.v-sli.me/HidemaruOwO/email-worker/raw/branch/main/assets/webhook_icon.jpg";
// mail letter icon
const AUTHOR_ICON = "https://git.v-sli.me/HidemaruOwO/email-worker/raw/branch/main/assets/email_icon.png";
// cloudflare icon
const FOOTER_ICON = "https://git.v-sli.me/HidemaruOwO/email-worker/raw/branch/main/assets/cloudflare_icon.ico";

export default {
  async email(message, env, ctx) {
    if (BLOCKLIST.includes(message.from)) {
      message.setReject("Address is blocked");
      return;
    }

    try {
      const [text] = await Promise.all([
        getMailText(message),
        message.forward(FORWARD_TO)
      ]);
      
      const result = await notify(message.headers.get("from"), message.headers.get('subject'), text, message.headers.get("date"));
      
      if (!result.ok) {
        console.log(await result.text())
        console.log(await result.json())
        return;
      }
    } catch (err) {
      console.error("処理エラー:", err);
    }
  }
};

async function notify(from, subject, text, date) {
  const payload = {
    username: "contact@trendcreate.net",
    avatar_url: WEBHOOK_ICON,
    content: `**${from}**からお問い合わせメールが届いております。`,
    embeds: [{
      author: {name: from || "名前なし", icon_url: AUTHOR_ICON},
      title: `**${subject || "件名なし"}**`,
      description: text || "本文はありません。",
      timestamp: new Date(date).toISOString(),
      footer: {
		    text: 'Powered by Cloudflare Worker and Email Routing',
        icon_url: FOOTER_ICON
	    }
    }],
    
  };

  // console.log(JSON.stringify(payload))

try {
  const result = await fetch(WEBHOOK_URL, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify(payload)
  });
  return result;
} catch (err) {
  console.log(err)
  throw new Error(err)
}
return;
}

async function getMailText(message) {
  try {
    const buf = await readStream(message.raw);
    if (buf === "NO_CONTENT") {
      return ""
    }
    return parseEmail(buf);
  } catch (err) {
    return `エラー: ${err.message}`;
  }
}

async function readStream(stream) {
  if (typeof stream === "undefined") {
    return "NO_CONTENT"
  }

  const chunks = [];
  const reader = stream.getReader();
  
  while (true) {
    const { done, value } = await reader.read();
    if (done) break;
    chunks.push(value);
  }
  
  const size = chunks.reduce((sum, chunk) => sum + chunk.length, 0);
  const result = new Uint8Array(size);
  
  let pos = 0;
  for (const chunk of chunks) {
    result.set(chunk, pos);
    pos += chunk.length;
  }
  
  return result;
}

function parseEmail(buffer) {
  const text = new TextDecoder().decode(buffer);
  const headerEnd = text.indexOf('\r\n\r\n');
  
  if (headerEnd === -1) return '';
  
  const header = text.substring(0, headerEnd);
  const body = text.substring(headerEnd + 4);
  
  const boundaryMatch = header.match(/boundary="?([^"\r\n]+)"?/i);
  
  if (!boundaryMatch) return body.trim();
  
  const boundary = `--${boundaryMatch[1]}`;
  const parts = body.split(boundary);
  
  for (const part of parts) {
    if (part.includes('Content-Type: text/plain')) {
      const isBase64 = part.includes('Content-Transfer-Encoding: base64');
      const partBody = part.split('\r\n\r\n')[1]?.trim();
      
      if (!partBody) continue;
      
      if (isBase64) {
        try {
          const cleanBase64 = partBody.replace(/[\r\n\s]/g, '');
          return decodeBase64(cleanBase64);
        } catch {
          continue;
        }
      } else {
        return partBody;
      }
    }
  }
  
  return '';
}

function decodeBase64(base64) {
  const binary = atob(base64);
  const bytes = new Uint8Array(binary.length);
  
  for (let i = 0; i < binary.length; i++) {
    bytes[i] = binary.charCodeAt(i);
  }
  
  return new TextDecoder().decode(bytes);
}