feat: initial MailOne worker (latest email per recipient, 24h retention)

2026-02-26 09:32:57 +08:00
commit 93dfbc1e61
5 changed files with 182 additions and 0 deletions
--- a/src/index.js
+++ b/src/index.js
@@ -0,0 +1,108 @@
+function json(data, status = 200) {
+  return new Response(JSON.stringify(data, null, 2), {
+    status,
+    headers: {
+      "content-type": "application/json; charset=utf-8",
+      "cache-control": "no-store",
+      "access-control-allow-origin": "*"
+    }
+  });
+}
+
+async function streamToString(stream) {
+  const reader = stream.getReader();
+  const chunks = [];
+  while (true) {
+    const { done, value } = await reader.read();
+    if (done) break;
+    chunks.push(value);
+  }
+  const total = chunks.reduce((n, c) => n + c.length, 0);
+  const merged = new Uint8Array(total);
+  let offset = 0;
+  for (const c of chunks) {
+    merged.set(c, offset);
+    offset += c.length;
+  }
+  return new TextDecoder().decode(merged);
+}
+
+function getHeader(headers, name) {
+  try {
+    return headers.get(name) || "";
+  } catch {
+    return "";
+  }
+}
+
+const ONE_DAY_MS = 24 * 60 * 60 * 1000;
+
+export default {
+  async fetch(request, env) {
+    const url = new URL(request.url);
+
+    if (request.method === "OPTIONS") {
+      return new Response(null, {
+        headers: {
+          "access-control-allow-origin": "*",
+          "access-control-allow-methods": "GET,OPTIONS",
+          "access-control-allow-headers": "content-type"
+        }
+      });
+    }
+
+    const to = (url.searchParams.get("to") || "").trim().toLowerCase();
+    if (!to) return json({ error: "missing query param: to" }, 400);
+
+    const row = await env.DB.prepare(
+      `SELECT recipient, id, sender, nexthop, subject, content, received_at
+       FROM latest_emails
+       WHERE recipient = ?
+       LIMIT 1`
+    ).bind(to).first();
+
+    if (!row) return json(null);
+
+    if (Date.now() - row.received_at > ONE_DAY_MS) {
+      return json(null);
+    }
+
+    return json({
+      id: row.id,
+      recipient: row.recipient,
+      sender: row.sender,
+      nexthop: row.nexthop,
+      subject: row.subject,
+      content: row.content,
+      received_at: row.received_at
+    });
+  },
+
+  async email(message, env) {
+    const recipient = (message.to || "").toLowerCase();
+    const sender = message.from || "";
+    const subject = getHeader(message.headers, "subject");
+    const id = getHeader(message.headers, "message-id") || crypto.randomUUID();
+    const nexthop = recipient.includes("@") ? recipient.split("@")[1] : "";
+    const content = await streamToString(message.raw);
+    const received_at = Date.now();
+
+    await env.DB.prepare(
+      `INSERT INTO latest_emails
+       (recipient, id, sender, nexthop, subject, content, received_at)
+       VALUES (?, ?, ?, ?, ?, ?, ?)
+       ON CONFLICT(recipient) DO UPDATE SET
+         id = excluded.id,
+         sender = excluded.sender,
+         nexthop = excluded.nexthop,
+         subject = excluded.subject,
+         content = excluded.content,
+         received_at = excluded.received_at`
+    ).bind(recipient, id, sender, nexthop, subject, content, received_at).run();
+  },
+
+  async scheduled(_event, env) {
+    const cutoff = Date.now() - ONE_DAY_MS;
+    await env.DB.prepare(`DELETE FROM latest_emails WHERE received_at < ?`).bind(cutoff).run();
+  }
+};