"use strict";

/* ============================================================
   Transmission Manager — frontend
   Vanilla SPA. Auto-refreshes every 3s.
   ============================================================ */

const REFRESH_MS = 3000;
const TRANSMISSION_STATUSES = {
  0: "stopped",
  1: "check-wait",
  2: "checking",
  3: "download-wait",
  4: "downloading",
  5: "seed-wait",
  6: "seeding",
};

const state = {
  torrents: [],
  stats: {},
  filter: "",
  sortKey: "status",
  lastError: null,
};

const $ = (sel) => document.querySelector(sel);

/* ---------- Fetching ---------- */
async function fetchJSON(url) {
  const res = await fetch(url, { cache: "no-store" });
  if (!res.ok) throw new Error(`HTTP ${res.status} for ${url}`);
  return res.json();
}

async function loadTorrents() {
  const data = await fetchJSON("/api/torrents");
  // Transmission returns { torrents: [...] }
  state.torrents = (data && data.torrents) || [];
}

async function loadStats() {
  const data = await fetchJSON("/api/stats");
  state.stats = data || {};
}

async function sync() {
  setSyncing(true);
  try {
    await Promise.all([loadTorrents(), loadStats()]);
    state.lastError = null;
    renderAll();
  } catch (err) {
    state.lastError = err.message || String(err);
    renderError();
  } finally {
    setSyncing(false);
    $("#last-updated").textContent = `updated ${formatTime(new Date())}`;
  }
}

function setSyncing(on) {
  const el = $("#refresh-indicator");
  if (!el) return;
  el.classList.toggle("syncing", on);
  const t = el.querySelector(".refresh-text");
  if (t) t.textContent = on ? "syncing" : "live";
}

/* ---------- Formatting helpers ---------- */
function humanSize(bytes) {
  if (bytes == null || isNaN(bytes) || bytes < 0) return "—";
  if (bytes === 0) return "0 B";
  const units = ["B", "KB", "MB", "GB", "TB", "PB"];
  const i = Math.min(Math.floor(Math.log(bytes) / Math.log(1024)), units.length - 1);
  const v = bytes / Math.pow(1024, i);
  const digits = i === 0 ? 0 : v < 10 ? 2 : v < 100 ? 1 : 0;
  return `${v.toFixed(digits)} ${units[i]}`;
}

function humanSpeed(bytesPerSec) {
  if (!bytesPerSec || bytesPerSec <= 0) return "0 kB/s";
  return humanSize(bytesPerSec) + "/s";
}

function humanRatio(ratio) {
  if (ratio == null || ratio < 0 || isNaN(ratio)) return "—";
  if (ratio === -1) return "∞";
  return ratio.toFixed(2);
}

function humanPct(p) {
  if (p == null || isNaN(p)) return 0;
  if (p < 0) return 0;
  if (p >= 1) return 1;
  return p;
}

function formatETA(sec) {
  if (sec == null || sec < 0 || isNaN(sec)) return "—";
  if (sec === 0) return "—";
  if (sec < 60) return `${sec}s`;
  const m = Math.floor(sec / 60);
  if (m < 60) return `${m}m ${sec % 60}s`;
  const h = Math.floor(m / 60);
  if (h < 24) return `${h}h ${m % 60}m`;
  const d = Math.floor(h / 24);
  return `${d}d ${h % 24}h`;
}

function formatDate(unix) {
  if (!unix || unix <= 0) return "—";
  const d = new Date(unix * 1000);
  if (isNaN(d.getTime())) return "—";
  return d.toLocaleDateString(undefined, {
    year: "numeric", month: "short", day: "numeric",
  });
}

function formatTime(d) {
  return d.toLocaleTimeString(undefined, { hour: "2-digit", minute: "2-digit", second: "2-digit" });
}

function peerStatus(t) {
  const peers = Array.isArray(t.peers) ? t.peers : [];
  const connected = t.peersConnected || peers.length || 0;
  const at100 = peers.filter((p) => p && p.progress === 1.0).length;
  if (connected === 0) return { connected: 0, at100: 0, label: "no peers" };
  return {
    connected,
    at100,
    label: `${at100}/${connected} @ 100%`,
  };
}

/* ---------- Torrent status classification ---------- */
function classify(t) {
  if (t.error && t.error !== 0) {
    return { key: "error", label: "Error", dot: true };
  }
  const tr = TRANSMISSION_STATUSES[t.status];
  switch (tr) {
    case "downloading": return { key: "downloading", label: "Downloading", dot: true };
    case "seeding":     return { key: "seeding", label: "Seeding", dot: true };
    case "stopped":
      if (t.isFinished || (t.percentDone >= 1.0)) return { key: "finished", label: "Finished", dot: false };
      return { key: "paused", label: "Paused", dot: false };
    case "checking":      return { key: "checking", label: "Verifying", dot: true };
    case "check-wait":    return { key: "queued", label: "Queued", dot: true };
    case "download-wait": return { key: "queued", label: "Queued ↓", dot: true };
    case "seed-wait":     return { key: "queued", label: "Queued ↑", dot: true };
    default:
      if (t.isFinished || (t.percentDone >= 1.0)) return { key: "finished", label: "Finished", dot: false };
      return { key: "idle", label: "Idle", dot: false };
  }
}

/* ---------- Sorting ---------- */
const STATUS_RANK = { error: 0, downloading: 1, seeding: 2, queued: 3, checking: 4, finished: 5, paused: 6, idle: 7 };
function sortTorrents(list) {
  const key = state.sortKey;
  const sorted = list.slice();
  sorted.sort((a, b) => {
    switch (key) {
      case "name": return a.name.localeCompare(b.name);
      case "progress": return (b.percentDone || 0) - (a.percentDone || 0);
      case "ratio": return (b.uploadRatio || 0) - (a.uploadRatio || 0);
      case "size": return (b.totalSize || 0) - (a.totalSize || 0);
      case "status": {
        const ra = STATUS_RANK[classify(a).key] ?? 99;
        const rb = STATUS_RANK[classify(b).key] ?? 99;
        if (ra !== rb) return ra - rb;
        return (b.percentDone || 0) - (a.percentDone || 0);
      }
      default: return 0;
    }
  });
  return sorted;
}

/* ---------- Rendering ---------- */
function renderHeader() {
  const s = state.stats || {};
  const torrents = state.torrents || [];
  let dl = 0, ul = 0;
  for (const t of torrents) {
    dl += t.rateDownload || 0;
    ul += t.rateUpload || 0;
  }
  $("#stat-torrents").textContent = String(torrents.length);
  $("#stat-dl").textContent = humanSpeed(dl);
  $("#stat-ul").textContent = humanSpeed(ul);
}

function badgeHTML(cls) {
  return `<span class="badge ${cls.key}"><span class="dotb"></span>${escapeHTML(cls.label)}</span>`;
}

function escapeHTML(s) {
  if (s == null) return "";
  return String(s).replace(/[&<>"']/g, (c) => ({
    "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;",
  })[c]);
}

function initial(name) {
  const n = (name || "").trim();
  if (!n) return "?";
  // try to grab a meaningful token from the filename
  const base = n.replace(/\.[a-z0-9]+$/i, "");
  const m = base.match(/[A-Za-z0-9]/);
  return m ? m[0].toUpperCase() : "?";
}

function renderCard(t) {
  const cls = classify(t);
  const pct = humanPct(t.percentDone);
  const pctText = (pct * 100).toFixed(pct === 1 ? 0 : 1) + "%";
  const isDone = pct >= 1.0;
  const ps = peerStatus(t);

  let barClass = "";
  if (cls.key === "error") barClass = "error";
  else if (isDone) barClass = "done";
  else if (cls.key === "paused" || cls.key === "finished") barClass = "paused";

  const dl = t.rateDownload || 0;
  const ul = t.rateUpload || 0;
  const eta = (dl > 0 && !isDone) ? formatETA(t.eta) : (isDone ? "—" : "∞");

  const hasError = cls.key === "error";

  return `
    <article class="card ${hasError ? "is-error" : ""}" data-id="${t.id}">
      <div class="card-top">
        <div class="favicon">${escapeHTML(initial(t.name))}</div>
        <div class="card-body">
          <div class="card-name" title="${escapeHTML(t.name)}">${escapeHTML(t.name)}</div>
          <div class="card-meta">
            <span class="meta-item"><span class="meta-label">Size</span> ${escapeHTML(humanSize(t.totalSize))}</span>
            <span class="meta-item"><span class="meta-label">Ratio</span> ${escapeHTML(humanRatio(t.uploadRatio))}</span>
            <span class="meta-item"><span class="meta-label">Peers</span> ${escapeHTML(ps.label)}</span>
            ${t.doneDate ? `<span class="meta-item"><span class="meta-label">Done</span> ${escapeHTML(formatDate(t.doneDate))}</span>` : ""}
          </div>
        </div>
        <div class="card-status-col">
          ${badgeHTML(cls)}
          <span class="pct">${escapeHTML(pctText)}</span>
        </div>
      </div>

      <div class="progress-wrap">
        <div class="progress-bar ${barClass}" style="width:${(pct * 100).toFixed(2)}%"></div>
      </div>

      <div class="card-bottom">
        <div class="stat-cell">
          <span class="k">Downloaded</span>
          <span class="v">${escapeHTML(humanSize(t.downloadedEver))}${isDone ? ` <span class="dim">/ ${escapeHTML(humanSize(t.totalSize))}</span>` : ""}</span>
        </div>
        <div class="stat-cell">
          <span class="k">Uploaded</span>
          <span class="v">${escapeHTML(humanSize(t.uploadedEver))}</span>
        </div>
        <div class="stat-cell">
          <span class="k">↓ Speed</span>
          <span class="v ${dl > 0 ? "accent" : "dim"}">${escapeHTML(humanSpeed(dl))}</span>
        </div>
        <div class="stat-cell">
          <span class="k">↑ Speed</span>
          <span class="v ${ul > 0 ? "success" : "dim"}">${escapeHTML(humanSpeed(ul))}</span>
        </div>
        <div class="stat-cell">
          <span class="k">ETA</span>
          <span class="v">${escapeHTML(eta)}</span>
        </div>
        <div class="stat-cell">
          <span class="k">Peers @ 100%</span>
          <span class="v mono">${escapeHTML(`${ps.at100}/${ps.connected}`)}</span>
        </div>
        <div class="stat-cell">
          <span class="k">Finished</span>
          <span class="v">${escapeHTML(formatDate(t.doneDate))}</span>
        </div>
      </div>

      ${hasError && t.errorString ? `<div class="error-string">${escapeHTML(t.errorString)}</div>` : ""}
    </article>
  `;
}

function renderList() {
  const list = $("#torrents");
  const empty = $("#empty-state");
  const errEl = $("#error-state");

  let torrents = sortTorrents(state.torrents || []);

  const f = state.filter.trim().toLowerCase();
  if (f) torrents = torrents.filter((t) => (t.name || "").toLowerCase().includes(f));

  errEl.classList.add("hidden");
  if (state.lastError) {
    list.innerHTML = "";
    empty.classList.add("hidden");
    errEl.classList.remove("hidden");
    $("#error-msg").textContent = state.lastError;
    return;
  }

  if (torrents.length === 0) {
    list.innerHTML = "";
    empty.classList.remove("hidden");
    return;
  }
  empty.classList.add("hidden");
  list.innerHTML = torrents.map(renderCard).join("");
}

function renderError() {
  // keep stats list emptied on error
  $("#torrents").innerHTML = "";
  $("#empty-state").classList.add("hidden");
  const errEl = $("#error-state");
  errEl.classList.remove("hidden");
  $("#error-msg").textContent = state.lastError || "Could not reach the Transmission daemon.";
}

function renderAll() {
  renderHeader();
  renderList();
}

/* ---------- Events ---------- */
function wireEvents() {
  const filterInput = $("#filter");
  filterInput.addEventListener("input", (e) => {
    state.filter = e.target.value;
    renderList();
  });

  document.querySelectorAll(".sort-btn").forEach((btn) => {
    btn.addEventListener("click", () => {
      document.querySelectorAll(".sort-btn").forEach((b) => b.classList.remove("active"));
      btn.classList.add("active");
      state.sortKey = btn.dataset.sort;
      renderList();
    });
  });

  document.addEventListener("visibilitychange", () => {
    if (!document.hidden) {
      // immediate refresh when returning to the tab
      sync();
    }
  });
}

/* ---------- Init ---------- */
function boot() {
  wireEvents();
  sync();
  setInterval(sync, REFRESH_MS);
}

document.addEventListener("DOMContentLoaded", boot);