import express from "express";
import fetch from "node-fetch";
import { simpleParser } from "mailparser";

const app = express();

const PORT = Number(process.env.PORT || 3334);
const SES_ENDPOINT = process.env.SES_VIEWER_ENDPOINT || "http://localhost:4566/_aws/ses";
const FETCH_TIMEOUT_MS = Number(process.env.SES_VIEWER_FETCH_TIMEOUT_MS || 5000);
const DEFAULT_REFRESH_MS = Number(process.env.SES_VIEWER_REFRESH_MS || 10000);

app.use((req, res, next) => {
  res.set("Cache-Control", "no-store");
  next();
});

app.get("/", (req, res) => {
  res.type("html").send(renderHtml());
});

app.get("/app.js", (req, res) => {
  res.type("application/javascript").send(`(${clientApp.toString()})(${JSON.stringify(getClientConfig())});`);
});

app.get("/health", (req, res) => {
  res.json({
    ok: true,
    endpoint: SES_ENDPOINT,
    port: PORT,
    defaultRefreshMs: DEFAULT_REFRESH_MS
  });
});

app.get("/api/messages", async (req, res) => {
  try {
    res.json(await loadMessages());
  } catch (error) {
    console.error("Error fetching messages:", error);
    res.status(502).json({
      error: "Unable to fetch messages from LocalStack SES",
      details: error.message,
      endpoint: SES_ENDPOINT
    });
  }
});

app.get("/api/messages/:id/raw", async (req, res) => {
  try {
    const message = await findSesMessageById(req.params.id);

    if (!message) {
      res.status(404).type("text/plain").send("Message not found");
      return;
    }

    res.type("text/plain").send(message.RawData || "");
  } catch (error) {
    console.error("Error fetching raw message:", error);
    res.status(502).type("text/plain").send(`Unable to fetch raw message: ${error.message}`);
  }
});

app.get("/api/messages/:id/attachments/:index", async (req, res) => {
  try {
    const attachmentIndex = Number.parseInt(req.params.index, 10);

    if (!Number.isInteger(attachmentIndex) || attachmentIndex < 0) {
      res.status(400).type("text/plain").send("Attachment index must be a non-negative integer");
      return;
    }

    const parsed = await parseSesMessageById(req.params.id);

    if (!parsed) {
      res.status(404).type("text/plain").send("Message not found");
      return;
    }

    const attachment = parsed.attachments?.[attachmentIndex];

    if (!attachment) {
      res.status(404).type("text/plain").send("Attachment not found");
      return;
    }

    const filename = resolveAttachmentFilename(attachment, attachmentIndex);
    const content = Buffer.isBuffer(attachment.content) ? attachment.content : Buffer.from(attachment.content || "");

    res.setHeader("Content-Type", attachment.contentType || "application/octet-stream");
    res.setHeader("Content-Disposition", buildAttachmentDisposition(filename));
    res.setHeader("Content-Length", String(content.length));
    res.send(content);
  } catch (error) {
    console.error("Error downloading attachment:", error);
    res.status(502).type("text/plain").send(`Unable to download attachment: ${error.message}`);
  }
});

async function loadMessages() {
  const startedAt = Date.now();
  const sesMessages = await fetchSesMessages();
  const messages = await Promise.all(sesMessages.map((message, index) => toMessageViewModel(message, index)));

  messages.sort((left, right) => {
    if ((right.timestampMs || 0) !== (left.timestampMs || 0)) {
      return (right.timestampMs || 0) - (left.timestampMs || 0);
    }

    return right.index - left.index;
  });

  return {
    endpoint: SES_ENDPOINT,
    fetchedAt: new Date().toISOString(),
    fetchDurationMs: Date.now() - startedAt,
    totalMessages: messages.length,
    parseErrors: messages.filter((message) => Boolean(message.parseError)).length,
    latestMessageTimestamp: messages[0]?.timestamp || "",
    messages
  };
}

async function fetchSesMessages() {
  const response = await fetch(SES_ENDPOINT, {
    signal: AbortSignal.timeout(FETCH_TIMEOUT_MS)
  });

  if (!response.ok) {
    throw new Error(`SES endpoint responded with ${response.status}`);
  }

  const data = await response.json();
  return Array.isArray(data.messages) ? data.messages : [];
}

async function findSesMessageById(id) {
  const messages = await fetchSesMessages();
  return messages.find((message, index) => resolveMessageId(message, index) === id) || null;
}

async function parseSesMessageById(id) {
  const message = await findSesMessageById(id);

  if (!message) {
    return null;
  }

  return simpleParser(message.RawData || "");
}

async function toMessageViewModel(message, index) {
  const id = resolveMessageId(message, index);

  try {
    const parsed = await simpleParser(message.RawData || "");
    const textContent = normalizeText(parsed.text || "");
    const renderedHtml = buildRenderedHtml(parsed.html || parsed.textAsHtml || "");
    const timestamp = normalizeTimestamp(message.Timestamp || parsed.date);

    return {
      id,
      index,
      from: formatAddressList(parsed.from) || message.Source || "Unknown sender",
      to: formatAddressList(parsed.to) || "No To Address",
      replyTo: formatAddressList(parsed.replyTo),
      subject: parsed.subject || "No Subject",
      region: message.Region || "",
      timestamp,
      timestampMs: timestamp ? Date.parse(timestamp) : 0,
      messageId: parsed.messageId || "",
      rawSizeBytes: Buffer.byteLength(message.RawData || "", "utf8"),
      attachmentCount: parsed.attachments.length,
      attachments: parsed.attachments.map((attachment, attachmentIndex) => ({
        index: attachmentIndex,
        filename: resolveAttachmentFilename(attachment, attachmentIndex),
        contentType: attachment.contentType || "application/octet-stream",
        size: attachment.size || 0
      })),
      preview: buildPreview(textContent, renderedHtml),
      textContent,
      renderedHtml,
      hasHtml: Boolean(renderedHtml),
      parseError: ""
    };
  } catch (error) {
    return {
      id,
      index,
      from: message.Source || "Unknown sender",
      to: "Unknown recipient",
      replyTo: "",
      subject: "Unable to parse message",
      region: message.Region || "",
      timestamp: normalizeTimestamp(message.Timestamp),
      timestampMs: message.Timestamp ? Date.parse(message.Timestamp) : 0,
      messageId: "",
      rawSizeBytes: Buffer.byteLength(message.RawData || "", "utf8"),
      attachmentCount: 0,
      attachments: [],
      preview: "This message could not be parsed. Open the raw view to inspect the MIME source.",
      textContent: "",
      renderedHtml: "",
      hasHtml: false,
      parseError: error.message
    };
  }
}

function resolveMessageId(message, index = 0) {
  return message.Id || `${message.Timestamp || "unknown"}-${message.Source || "unknown"}-${index}`;
}

function resolveAttachmentFilename(attachment, index = 0) {
  if (attachment?.filename) {
    return attachment.filename;
  }

  return `attachment-${index + 1}${attachmentExtension(attachment?.contentType)}`;
}

function attachmentExtension(contentType) {
  const normalized = String(contentType || "")
    .split(";")[0]
    .trim()
    .toLowerCase();

  return (
    {
      "application/json": ".json",
      "application/pdf": ".pdf",
      "application/zip": ".zip",
      "image/gif": ".gif",
      "image/jpeg": ".jpg",
      "image/png": ".png",
      "image/webp": ".webp",
      "text/calendar": ".ics",
      "text/csv": ".csv",
      "text/html": ".html",
      "text/plain": ".txt"
    }[normalized] || ""
  );
}

function buildAttachmentDisposition(filename) {
  const fallback = String(filename || "attachment")
    .replace(/[^\x20-\x7e]/g, "_")
    .replace(/["\\]/g, "_");

  return `attachment; filename="${fallback}"; filename*=UTF-8''${encodeURIComponent(filename || "attachment")}`;
}

function normalizeTimestamp(value) {
  if (!value) {
    return "";
  }

  const date = value instanceof Date ? value : new Date(value);
  return Number.isNaN(date.getTime()) ? "" : date.toISOString();
}

function normalizeText(value) {
  return String(value || "")
    .replace(/\r\n/g, "\n")
    .trim();
}

function buildPreview(textContent, renderedHtml) {
  const source = (textContent || stripTags(renderedHtml)).replace(/\s+/g, " ").trim();

  if (!source) {
    return "No message preview available.";
  }

  return source.length > 220 ? `${source.slice(0, 217)}...` : source;
}

function buildRenderedHtml(html) {
  if (!html) {
    return "";
  }

  const value = String(html);
  const hasDocument = /<html[\s>]/i.test(value) || /<!doctype/i.test(value);

  if (hasDocument) {
    return value;
  }

  return `<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <base target="_blank">
    <style>body{margin:0;padding:16px;font-family:Arial,sans-serif;background:#fff;}</style>
  </head>
  <body>${value}</body>
</html>`;
}

function stripTags(value) {
  return String(value || "")
    .replace(/<style[\s\S]*?<\/style>/gi, " ")
    .replace(/<script[\s\S]*?<\/script>/gi, " ")
    .replace(/<[^>]+>/g, " ");
}

function formatAddressList(addresses) {
  if (!addresses?.value?.length) {
    return "";
  }

  return addresses.value
    .map(({ name, address }) => {
      if (name && address) {
        return `${name} <${address}>`;
      }

      return address || name || "";
    })
    .filter(Boolean)
    .join(", ");
}

function getClientConfig() {
  return {
    defaultRefreshMs: DEFAULT_REFRESH_MS,
    endpoint: SES_ENDPOINT
  };
}

function renderHtml() {
  return `<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>LocalStack Email Viewer</title>
    <style>${renderStyles()}</style>
  </head>
  <body>
    <div class="page">
      <header class="hero">
        <div class="hero-copy">
          <p class="eyebrow">LocalStack SES</p>
          <h1>Email Viewer</h1>
          <p class="lede">Compact inbox for generated emails with live polling, search, and raw MIME inspection.</p>
        </div>
        <div class="hero-controls">
          <div class="row">
            <button id="refreshButton" class="primary" type="button">Refresh</button>
            <label class="chip"><input id="autoToggle" type="checkbox" checked> Live refresh</label>
            <label class="chip">Every
              <select id="intervalSelect">
                <option value="5000">5s</option>
                <option value="10000" selected>10s</option>
                <option value="15000">15s</option>
                <option value="30000">30s</option>
                <option value="60000">60s</option>
              </select>
            </label>
          </div>
          <div class="row">
            <input id="searchInput" class="search" type="search" placeholder="Search subject, sender, preview..." autocomplete="off">
            <button id="clearSearchButton" class="ghost" type="button">Clear</button>
          </div>
          <div class="row">
            <button id="expandAllButton" class="ghost" type="button">Open all</button>
            <button id="collapseAllButton" class="ghost" type="button">Close all</button>
            <span id="statusChip" class="status">Waiting for first refresh...</span>
          </div>
        </div>
      </header>

      <section class="stats">
        <article class="stat"><span>Total</span><strong id="totalStat">0</strong><small id="visibleStat">0 visible</small></article>
        <article class="stat"><span>New</span><strong id="newStat">0</strong><small>New since last refresh</small></article>
        <article class="stat"><span>Newest</span><strong id="newestStat" class="small">No messages</strong><small id="updatedStat">Not refreshed yet</small></article>
        <article class="stat"><span>Fetch</span><strong id="fetchStat" class="small">Idle</strong><small id="fetchDetail">Endpoint: ${escapeHtml(SES_ENDPOINT)}</small></article>
      </section>

      <div id="banner" class="banner" hidden></div>
      <div id="empty" class="empty" hidden></div>
      <section id="list" class="list" aria-live="polite"></section>
    </div>

    <script type="module" src="/app.js"></script>
  </body>
</html>`;
}

function renderStyles() {
  return `
    :root{--panel:rgba(255,255,255,.82);--panel-strong:#fff;--card-shell:linear-gradient(180deg,rgba(255,246,236,.98),rgba(255,252,247,.99));--card-body:#fffdf9;--ink:#1f2933;--muted:#607080;--line:rgba(31,41,51,.12);--card-line:rgba(207,109,60,.24);--accent:#cf6d3c;--accent-soft:rgba(207,109,60,.1);--ok:#1f8f65;--warn:#9d5f00;--bad:#b33a3a;--shadow:0 12px 28px rgba(35,43,53,.08);--card-shadow:0 18px 34px rgba(122,78,34,.12);}
    *{box-sizing:border-box}
    html,body{margin:0;min-height:100%}
    body{background:radial-gradient(circle at top left,rgba(207,109,60,.18),transparent 28%),radial-gradient(circle at top right,rgba(31,143,101,.12),transparent 24%),linear-gradient(180deg,#f8f5ef,#efe7da);color:var(--ink);font:15px/1.45 "Aptos","Segoe UI Variable Display","Segoe UI",system-ui,sans-serif}
    button,input,select,textarea{font:inherit}
    button{cursor:pointer}
    .page{max-width:1360px;margin:0 auto;padding:18px}
    .hero{display:grid;grid-template-columns:minmax(0,1.05fr) minmax(320px,.95fr);gap:14px;margin-bottom:14px}
    .hero-copy,.hero-controls,.stat{background:var(--panel);backdrop-filter:blur(14px);border:1px solid var(--line);box-shadow:var(--shadow)}
    .card{background:var(--card-shell);border:1px solid var(--card-line);box-shadow:var(--card-shadow)}
    .hero-copy,.hero-controls{border-radius:18px;padding:18px}
    .eyebrow{margin:0 0 6px;color:var(--accent);font-size:.76rem;font-weight:700;letter-spacing:.16em;text-transform:uppercase}
    h1{margin:0;font-size:clamp(1.9rem,4vw,3.1rem);line-height:.98;letter-spacing:-.05em}
    .lede{margin:10px 0 0;max-width:54ch;color:var(--muted);font-size:.96rem}
    .hero-controls{display:grid;gap:10px}
    .row{display:flex;flex-wrap:wrap;gap:8px;align-items:center}
    .primary,.ghost,.mini,.tab{border-radius:999px;border:1px solid transparent;transition:transform .12s ease,background-color .12s ease,border-color .12s ease}
    .primary,.ghost{min-height:38px;padding:0 14px;font-weight:700}
    .mini,.tab{min-height:30px;padding:0 10px;font-weight:600}
    .primary{background:var(--accent);color:#fff7f2}
    .ghost,.mini{background:rgba(255,255,255,.76);border-color:var(--line);color:var(--ink)}
    .tab{background:transparent;color:var(--muted)}
    .tab.active{background:#fff;border-color:rgba(207,109,60,.18);color:var(--ink)}
    .primary:hover,.ghost:hover,.mini:hover,.tab:hover{transform:translateY(-1px)}
    .chip{display:inline-flex;align-items:center;gap:8px;min-height:38px;padding:0 12px;border-radius:999px;background:rgba(255,255,255,.76);border:1px solid var(--line);font-weight:600;font-size:.92rem}
    .chip input{margin:0;accent-color:var(--accent)}
    .chip select{border:none;background:transparent;outline:none;color:var(--ink)}
    .search{flex:1 1 260px;min-height:40px;padding:0 14px;border-radius:14px;border:1px solid var(--line);background:rgba(255,255,255,.82);color:var(--ink);outline:none}
    .status{display:inline-flex;align-items:center;min-height:34px;padding:0 12px;border-radius:999px;background:rgba(255,255,255,.76);border:1px solid var(--line);color:var(--muted);font-size:.9rem;font-weight:600}
    .status.ok{color:var(--ok);border-color:rgba(31,143,101,.22);background:rgba(31,143,101,.08)}
    .status.warn{color:var(--warn);border-color:rgba(157,95,0,.22);background:rgba(157,95,0,.08)}
    .status.bad{color:var(--bad);border-color:rgba(179,58,58,.22);background:rgba(179,58,58,.08)}
    .stats{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:10px;margin-bottom:12px}
    .stat{border-radius:16px;padding:14px}
    .stat span{display:block;margin-bottom:8px;color:var(--muted);font-size:.74rem;font-weight:700;letter-spacing:.08em;text-transform:uppercase}
    .stat strong{display:block;font-size:clamp(1.6rem,3vw,2rem);line-height:1;letter-spacing:-.05em}
    .stat strong.small{font-size:1.1rem;line-height:1.3;letter-spacing:-.02em}
    .stat small{display:block;margin-top:8px;color:var(--muted);font-size:.85rem}
    .banner,.empty{margin:0 0 12px;padding:12px 14px;border-radius:14px;border:1px solid var(--line);background:rgba(255,255,255,.82)}
    .banner{color:var(--bad);border-color:rgba(179,58,58,.24);background:rgba(179,58,58,.08)}
    .list{display:grid;gap:12px}
    .card{overflow:hidden;border-radius:16px}
    .card.new{border-color:rgba(31,143,101,.3);box-shadow:var(--card-shadow),0 0 0 1px rgba(31,143,101,.12)}
    .summary{list-style:none;display:grid;gap:8px;padding:14px 16px;cursor:pointer;background:linear-gradient(180deg,rgba(255,250,244,.88),rgba(255,246,238,.96))}
    .summary::-webkit-details-marker{display:none}
    .top,.tags,.toolbar,.actions,.attachments{display:flex;flex-wrap:wrap;gap:8px;align-items:center}
    .top{justify-content:space-between}
    .head{min-width:0;flex:1 1 320px}
    .head h2{margin:0;font-size:clamp(1rem,1.6vw,1.22rem);line-height:1.18;letter-spacing:-.03em;word-break:break-word}
    .meta{margin:4px 0 0;color:var(--muted);font-size:.88rem;word-break:break-word}
    .time,.tag{display:inline-flex;align-items:center;min-height:24px;padding:0 10px;border-radius:999px;font-size:.76rem;font-weight:700}
    .time{background:rgba(31,41,51,.06)}
    .tag{background:var(--accent-soft);color:#8d5632}
    .tag.new{background:rgba(31,143,101,.1);color:var(--ok)}
    .tag.bad{background:rgba(179,58,58,.1);color:var(--bad)}
    .preview{margin:0;color:#324150;font-size:.94rem}
    .body{display:grid;gap:12px;padding:12px 16px 16px;border-top:1px solid rgba(207,109,60,.14);background:var(--card-body)}
    .toolbar{justify-content:space-between;align-items:center}
    .tabs{display:inline-flex;gap:4px;padding:4px;border-radius:999px;background:rgba(207,109,60,.08)}
    .grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:8px}
    .metaCard{padding:10px 12px;border-radius:12px;background:rgba(255,255,255,.78);border:1px solid rgba(207,109,60,.12)}
    .metaCard dt{margin:0 0 4px;color:var(--muted);font-size:.72rem;font-weight:700;letter-spacing:.08em;text-transform:uppercase}
    .metaCard dd{margin:0;word-break:break-word}
    .attachments{gap:6px}
    .attachment{display:inline-flex;align-items:center;gap:8px;padding:7px 10px;border-radius:10px;background:rgba(255,248,240,.96);border:1px solid rgba(207,109,60,.12);font-size:.84rem}
    .attachmentLink{color:#8d5632;text-decoration:none;transition:transform .12s ease,background-color .12s ease,border-color .12s ease}
    .attachmentLink:hover{transform:translateY(-1px);background:#fff;border-color:rgba(207,109,60,.28)}
    .panel{overflow:hidden;border-radius:12px;border:1px solid rgba(207,109,60,.14);background:#fff}
    iframe{width:100%;min-height:560px;border:none;background:#fff}
    pre{margin:0;padding:12px;white-space:pre-wrap;word-break:break-word;overflow:auto;font:12.5px/1.45 "Cascadia Code","Consolas",monospace;color:#102030;background:linear-gradient(180deg,rgba(207,109,60,.04),transparent 140px),#fff}
    .placeholder,.inlineError{padding:12px}
    .inlineError{color:var(--bad)}
    @media (max-width:1080px){.hero{grid-template-columns:1fr}.stats{grid-template-columns:repeat(2,minmax(0,1fr))}}
    @media (max-width:720px){.page{padding:12px}.stats{grid-template-columns:1fr}.primary,.ghost,.chip{width:100%;justify-content:center}.toolbar,.row{align-items:stretch}iframe{min-height:420px}}
  `;
}

function escapeHtml(value) {
  return String(value ?? "")
    .replace(/&/g, "&amp;")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&#39;");
}

function clientApp(config) {
  const state = {
    messages: [],
    filtered: [],
    search: "",
    auto: true,
    interval: config.defaultRefreshMs,
    loading: false,
    error: "",
    updatedAt: 0,
    source: "initial",
    duration: 0,
    parseErrors: 0,
    newest: "",
    newIds: new Set(),
    knownIds: new Set(),
    openIds: new Set(),
    views: {},
    raw: {},
    listSignature: ""
  };

  const el = {
    refreshButton: document.getElementById("refreshButton"),
    autoToggle: document.getElementById("autoToggle"),
    intervalSelect: document.getElementById("intervalSelect"),
    searchInput: document.getElementById("searchInput"),
    clearSearchButton: document.getElementById("clearSearchButton"),
    expandAllButton: document.getElementById("expandAllButton"),
    collapseAllButton: document.getElementById("collapseAllButton"),
    statusChip: document.getElementById("statusChip"),
    totalStat: document.getElementById("totalStat"),
    visibleStat: document.getElementById("visibleStat"),
    newStat: document.getElementById("newStat"),
    newestStat: document.getElementById("newestStat"),
    updatedStat: document.getElementById("updatedStat"),
    fetchStat: document.getElementById("fetchStat"),
    fetchDetail: document.getElementById("fetchDetail"),
    banner: document.getElementById("banner"),
    empty: document.getElementById("empty"),
    list: document.getElementById("list")
  };

  el.intervalSelect.value = String(config.defaultRefreshMs);
  wire();
  renderAll();
  refreshMessages("initial");
  window.setInterval(renderLiveClock, 1000);

  function wire() {
    el.refreshButton.addEventListener("click", () => refreshMessages("manual"));

    el.autoToggle.addEventListener("change", () => {
      state.auto = el.autoToggle.checked;
      scheduleRefresh();
      renderStatus();
    });

    el.intervalSelect.addEventListener("change", () => {
      state.interval = Number(el.intervalSelect.value) || config.defaultRefreshMs;
      scheduleRefresh();
      renderStatus();
    });

    el.searchInput.addEventListener("input", (event) => {
      state.search = event.target.value;
      applyFilter();
    });

    el.clearSearchButton.addEventListener("click", () => {
      state.search = "";
      el.searchInput.value = "";
      applyFilter();
    });

    el.expandAllButton.addEventListener("click", () => {
      state.filtered.forEach((message) => state.openIds.add(message.id));
      renderList();
    });

    el.collapseAllButton.addEventListener("click", () => {
      state.openIds.clear();
      renderList();
    });

    el.list.addEventListener("click", async (event) => {
      const button = event.target.closest("button[data-action]");

      if (!button) {
        return;
      }

      const id = button.dataset.id;
      const message = getMessage(id);

      if (!message) {
        return;
      }

      if (button.dataset.action === "view") {
        state.views[id] = button.dataset.view;
        renderList();
        return;
      }

      if (button.dataset.action === "load-raw") {
        await loadRaw(id);
        renderList();
        return;
      }

      if (button.dataset.action === "copy-raw") {
        const raw = await loadRaw(id);

        if (raw) {
          await copyText(raw);
          setStatus("Raw message copied to the clipboard.", "ok");
        }
      }
    });

    document.addEventListener("visibilitychange", () => {
      window.clearTimeout(state.timer);

      if (!document.hidden && state.auto) {
        refreshMessages("visibility");
      } else {
        renderStatus();
      }
    });

    window.addEventListener("keydown", (event) => {
      const isField =
        event.target instanceof HTMLElement &&
        (event.target.matches("input,textarea,select") || event.target.isContentEditable);

      if (!isField && event.key.toLowerCase() === "r") {
        event.preventDefault();
        refreshMessages("keyboard");
      }
    });
  }

  async function refreshMessages(source) {
    if (state.loading) {
      return;
    }

    let shouldRenderList = false;

    state.loading = true;
    state.source = source;
    state.error = "";
    renderStatus();
    renderFetch();

    try {
      const response = await fetch("/api/messages", { cache: "no-store" });

      if (!response.ok) {
        const payload = await safeJson(response);
        throw new Error(payload?.details || payload?.error || `Request failed with ${response.status}`);
      }

      const payload = await response.json();
      const messages = Array.isArray(payload.messages) ? payload.messages : [];
      const nextIds = new Set(messages.map((message) => message.id));
      const nextSignature = computeListSignature(messages);

      shouldRenderList = nextSignature !== state.listSignature;
      state.newIds =
        state.updatedAt && shouldRenderList
          ? new Set(messages.filter((message) => !state.knownIds.has(message.id)).map((message) => message.id))
          : state.newIds;
      state.knownIds = nextIds;
      state.messages = messages;
      state.duration = payload.fetchDurationMs || 0;
      state.parseErrors = payload.parseErrors || 0;
      state.newest = payload.latestMessageTimestamp || "";
      state.updatedAt = Date.now();
      state.listSignature = nextSignature;

      pruneState();
      applyFilter(shouldRenderList);
      setStatus(`Updated ${messages.length} message${messages.length === 1 ? "" : "s"}.`, "ok");
    } catch (error) {
      state.error = error.message || "Unknown refresh error";
      setStatus(`Refresh failed: ${state.error}`, "bad");
    } finally {
      state.loading = false;
      scheduleRefresh();
      renderAll({ renderList: shouldRenderList });
    }
  }

  function pruneState() {
    const ids = new Set(state.messages.map((message) => message.id));
    state.openIds = new Set([...state.openIds].filter((id) => ids.has(id)));
    state.newIds = new Set([...state.newIds].filter((id) => ids.has(id)));

    Object.keys(state.views).forEach((id) => {
      if (!ids.has(id)) {
        delete state.views[id];
      }
    });

    Object.keys(state.raw).forEach((id) => {
      if (!ids.has(id)) {
        delete state.raw[id];
      }
    });
  }

  function applyFilter(shouldRenderList = true) {
    const search = state.search.trim().toLowerCase();
    state.filtered = !search
      ? [...state.messages]
      : state.messages.filter((message) => haystack(message).includes(search));
    renderAll({ renderList: shouldRenderList });
  }

  function computeListSignature(messages) {
    return messages
      .map((message) =>
        [
          message.id,
          message.timestampMs || 0,
          message.rawSizeBytes || 0,
          message.attachmentCount || 0,
          message.hasHtml ? 1 : 0,
          message.preview || "",
          message.parseError || ""
        ].join("::")
      )
      .join("|");
  }

  function haystack(message) {
    return [
      message.subject,
      message.from,
      message.to,
      message.replyTo,
      message.preview,
      message.textContent,
      message.region,
      ...(message.attachments || []).flatMap((attachment) => [attachment.filename, attachment.contentType])
    ]
      .filter(Boolean)
      .join(" ")
      .toLowerCase();
  }

  function scheduleRefresh() {
    window.clearTimeout(state.timer);

    if (!state.auto || document.hidden || state.loading) {
      return;
    }

    state.timer = window.setTimeout(() => refreshMessages("auto"), state.interval);
  }

  function renderAll(options = {}) {
    const { renderList: shouldRenderList = true } = options;
    renderStats();
    renderFetch();
    renderStatus();
    if (shouldRenderList) {
      renderList();
    }
    renderLiveClock();
  }

  function renderStats() {
    el.totalStat.textContent = String(state.messages.length);
    el.visibleStat.textContent = `${state.filtered.length} visible${state.search ? " after search" : ""}`;
    el.newStat.textContent = String(state.newIds.size);
    el.newestStat.textContent = state.newest ? formatDateTime(state.newest) : "No messages";
  }

  function renderFetch() {
    if (state.loading) {
      el.fetchStat.textContent = "Refreshing...";
      el.fetchDetail.textContent = `Endpoint: ${config.endpoint}`;
      return;
    }

    if (state.error) {
      el.fetchStat.textContent = "Needs attention";
      el.fetchDetail.textContent = state.error;
      return;
    }

    if (!state.updatedAt) {
      el.fetchStat.textContent = "Idle";
      el.fetchDetail.textContent = `Endpoint: ${config.endpoint}`;
      return;
    }

    el.fetchStat.textContent = `${state.duration}ms`;
    el.fetchDetail.textContent = `${state.parseErrors} parse error${state.parseErrors === 1 ? "" : "s"}. Endpoint: ${config.endpoint}`;
  }

  function renderStatus() {
    el.statusChip.className = "status";

    if (state.loading) {
      el.statusChip.classList.add("warn");
      el.statusChip.textContent = "Refreshing messages...";
      return;
    }

    if (state.error) {
      el.statusChip.classList.add("bad");
      el.statusChip.textContent = `Refresh failed: ${state.error}`;
      return;
    }

    if (!state.auto) {
      el.statusChip.textContent = "Live refresh paused";
      return;
    }

    if (document.hidden) {
      el.statusChip.classList.add("warn");
      el.statusChip.textContent = "Tab hidden, live refresh paused";
      return;
    }

    if (!state.updatedAt) {
      el.statusChip.textContent = "Waiting for first refresh...";
      return;
    }

    const seconds = Math.max(0, Math.ceil((state.updatedAt + state.interval - Date.now()) / 1000));
    el.statusChip.classList.add("ok");
    el.statusChip.textContent = `Live refresh on, next check in ${seconds}s`;
  }

  function renderLiveClock() {
    if (!state.updatedAt) {
      el.updatedStat.textContent = "Not refreshed yet";
      return;
    }

    el.updatedStat.textContent = `Updated ${formatRelative(state.updatedAt)} via ${state.source}`;
    renderStatus();
  }

  function renderList() {
    el.banner.hidden = !state.error;
    el.banner.textContent = state.error ? `Refresh failed: ${state.error}` : "";

    if (!state.filtered.length) {
      el.list.innerHTML = "";
      el.empty.hidden = false;
      el.empty.textContent = state.messages.length
        ? "No messages match the current search."
        : "No emails yet. Send one through LocalStack SES and refresh.";
      return;
    }

    el.empty.hidden = true;
    el.list.innerHTML = state.filtered.map(renderCard).join("");
    bindCardToggles();
    el.list.querySelectorAll(".card[open]").forEach((details) => hydrate(details, getMessage(details.dataset.id)));
  }

  function bindCardToggles() {
    el.list.querySelectorAll(".card").forEach((details) => {
      details.addEventListener("toggle", () => {
        const id = details.dataset.id;

        if (!id) {
          return;
        }

        if (details.open) {
          state.openIds.add(id);
        } else {
          state.openIds.delete(id);
        }

        hydrate(details, getMessage(id));
      });
    });
  }

  function renderCard(message) {
    const open = state.openIds.has(message.id);
    const view = state.views[message.id] || (message.hasHtml ? "rendered" : "text");
    const tags = [];

    if (state.newIds.has(message.id)) {
      tags.push('<span class="tag new">New</span>');
    }

    if (message.attachmentCount) {
      tags.push(
        `<span class="tag">${message.attachmentCount} attachment${message.attachmentCount === 1 ? "" : "s"}</span>`
      );
    }

    tags.push(`<span class="tag">${message.hasHtml ? "HTML" : "Text only"}</span>`);

    if (message.parseError) {
      tags.push('<span class="tag bad">Parse issue</span>');
    }

    return `
      <details class="card ${state.newIds.has(message.id) ? "new" : ""}" data-id="${escapeHtml(message.id)}" ${open ? "open" : ""}>
        <summary class="summary">
          <div class="top">
            <div class="head">
              <h2>${escapeHtml(message.subject)}</h2>
              <p class="meta">${escapeHtml(message.from)} to ${escapeHtml(message.to)}</p>
            </div>
            <span class="time">${escapeHtml(formatDateTime(message.timestamp))}</span>
          </div>
          <div class="tags">${tags.join("")}</div>
          <p class="preview">${escapeHtml(message.preview)}</p>
        </summary>
        <div class="body">
          <div class="toolbar">
            <div class="tabs">
              ${
                message.hasHtml
                  ? `<button class="tab ${view === "rendered" ? "active" : ""}" type="button" data-action="view" data-view="rendered" data-id="${escapeHtml(message.id)}">Rendered</button>`
                  : ""
              }
              <button class="tab ${view === "text" ? "active" : ""}" type="button" data-action="view" data-view="text" data-id="${escapeHtml(message.id)}">Text</button>
              <button class="tab ${view === "raw" ? "active" : ""}" type="button" data-action="view" data-view="raw" data-id="${escapeHtml(message.id)}">Raw</button>
            </div>
            <div class="actions">
              <button class="mini" type="button" data-action="copy-raw" data-id="${escapeHtml(message.id)}">Copy raw</button>
            </div>
          </div>

          <dl class="grid">
            ${metaCard("From", message.from)}
            ${metaCard("To", message.to)}
            ${metaCard("Reply-To", message.replyTo || "None")}
            ${metaCard("Sent", formatDateTime(message.timestamp))}
            ${metaCard("Region", message.region || "Unknown region")}
            ${metaCard("LocalStack Id", message.id)}
            ${metaCard("Message-Id", message.messageId || "Not available")}
            ${metaCard("Raw size", formatBytes(message.rawSizeBytes))}
            ${message.parseError ? metaCard("Parse error", message.parseError) : ""}
          </dl>

          ${
            message.attachments?.length
              ? `<div class="attachments">${message.attachments
                  .map((attachment) => {
                    const size = attachment.size ? `, ${formatBytes(attachment.size)}` : "";
                    return `<a class="attachment attachmentLink" href="/api/messages/${encodeURIComponent(message.id)}/attachments/${attachment.index}" download="${escapeHtml(attachment.filename)}" title="Download ${escapeHtml(attachment.filename)}">${escapeHtml(attachment.filename)} (${escapeHtml(attachment.contentType)}${escapeHtml(size)})</a>`;
                  })
                  .join("")}</div>`
              : ""
          }

          <div class="panel">${renderPanel(message, view)}</div>
        </div>
      </details>
    `;
  }

  function renderPanel(message, view) {
    if (view === "rendered" && message.hasHtml) {
      return `<iframe title="${escapeHtml(message.subject)}" data-frame loading="lazy"></iframe>`;
    }

    if (view === "raw") {
      const raw = state.raw[message.id];

      if (!raw) {
        return `<div class="placeholder">Raw MIME source is loaded on demand.<div class="actions" style="margin-top:12px"><button class="mini" type="button" data-action="load-raw" data-id="${escapeHtml(message.id)}">Load raw source</button></div></div>`;
      }

      if (raw.status === "loading") {
        return '<div class="placeholder">Loading raw source...</div>';
      }

      if (raw.status === "error") {
        return `<div class="inlineError">Unable to load raw source: ${escapeHtml(raw.error)}<div class="actions" style="margin-top:12px"><button class="mini" type="button" data-action="load-raw" data-id="${escapeHtml(message.id)}">Retry</button></div></div>`;
      }

      return `<pre>${escapeHtml(raw.value)}</pre>`;
    }

    return `<pre>${escapeHtml(message.textContent || "No plain-text content available for this message.")}</pre>`;
  }

  function metaCard(label, value) {
    return `<div class="metaCard"><dt>${escapeHtml(label)}</dt><dd>${escapeHtml(value)}</dd></div>`;
  }

  function hydrate(details, message) {
    if (!details || !details.open || !message) {
      return;
    }

    const view = state.views[message.id] || (message.hasHtml ? "rendered" : "text");

    if (view !== "rendered" || !message.hasHtml) {
      return;
    }

    const iframe = details.querySelector("[data-frame]");

    if (iframe) {
      iframe.referrerPolicy = "no-referrer";
      iframe.sandbox = "";
      iframe.srcdoc = message.renderedHtml || "";
    }
  }

  function getMessage(id) {
    return state.messages.find((message) => message.id === id);
  }

  async function loadRaw(id) {
    if (state.raw[id]?.status === "loaded") {
      return state.raw[id].value;
    }

    if (state.raw[id]?.status === "loading") {
      return null;
    }

    state.raw[id] = { status: "loading" };
    renderList();

    try {
      const response = await fetch(`/api/messages/${encodeURIComponent(id)}/raw`, { cache: "no-store" });

      if (!response.ok) {
        throw new Error((await response.text()) || `Request failed with ${response.status}`);
      }

      const value = await response.text();
      state.raw[id] = { status: "loaded", value };
      return value;
    } catch (error) {
      state.raw[id] = { status: "error", error: error.message || "Unknown raw load error" };
      setStatus("Could not load the raw message source.", "bad");
      return null;
    } finally {
      renderList();
    }
  }

  async function copyText(value) {
    try {
      await navigator.clipboard.writeText(value);
    } catch {
      const input = document.createElement("textarea");
      input.value = value;
      input.setAttribute("readonly", "");
      input.style.position = "fixed";
      input.style.opacity = "0";
      document.body.appendChild(input);
      input.select();
      document.execCommand("copy");
      document.body.removeChild(input);
    }
  }

  function setStatus(message, tone) {
    el.statusChip.className = "status";

    if (tone) {
      el.statusChip.classList.add(tone);
    }

    el.statusChip.textContent = message;
  }

  function formatDateTime(value) {
    if (!value) {
      return "Unknown time";
    }

    const date = new Date(value);
    return Number.isNaN(date.getTime())
      ? "Unknown time"
      : new Intl.DateTimeFormat(undefined, { dateStyle: "medium", timeStyle: "short" }).format(date);
  }

  function formatRelative(timestampMs) {
    const seconds = Math.max(1, Math.round((Date.now() - timestampMs) / 1000));

    if (seconds < 60) {
      return `${seconds}s ago`;
    }

    const minutes = Math.round(seconds / 60);

    if (minutes < 60) {
      return `${minutes}m ago`;
    }

    const hours = Math.round(minutes / 60);

    if (hours < 24) {
      return `${hours}h ago`;
    }

    return `${Math.round(hours / 24)}d ago`;
  }

  function formatBytes(value) {
    if (!value) {
      return "0 B";
    }

    const units = ["B", "KB", "MB", "GB"];
    let size = value;
    let index = 0;

    while (size >= 1024 && index < units.length - 1) {
      size /= 1024;
      index += 1;
    }

    return `${index === 0 ? size : size.toFixed(1)} ${units[index]}`;
  }

  function escapeHtml(value) {
    return String(value ?? "")
      .replace(/&/g, "&amp;")
      .replace(/</g, "&lt;")
      .replace(/>/g, "&gt;")
      .replace(/"/g, "&quot;")
      .replace(/'/g, "&#39;");
  }

  async function safeJson(response) {
    try {
      return await response.json();
    } catch {
      return null;
    }
  }
}

app.listen(PORT, () => {
  console.log(`Local email viewer is running on http://localhost:${PORT}`);
  console.log(`Watching LocalStack SES endpoint at ${SES_ENDPOINT}`);
});