const STORAGE_KEY = "shelfItems";
const PREFS_KEY = "shelfPrefs";

const shelfEl = document.getElementById("shelf");
const emptyStateEl = document.getElementById("emptyState");
const searchEl = document.getElementById("search");
const sortSelectEl = document.getElementById("sortSelect");
const viewGridBtn = document.getElementById("viewGridBtn");
const viewListBtn = document.getElementById("viewListBtn");
const showArchivedBtn = document.getElementById("showArchivedBtn");
const unreadCountEl = document.getElementById("unreadCount");
const archivedNoteEl = document.getElementById("archivedNote");
const toastEl = document.getElementById("toast");
const settingsBtn = document.getElementById("settingsBtn");
const settingsPanel = document.getElementById("settingsPanel");
const reminderEnabledEl = document.getElementById("reminderEnabled");
const reminderAmountEl = document.getElementById("reminderAmount");
const reminderUnitEl = document.getElementById("reminderUnit");
const themeSelectEl = document.getElementById("themeSelect");
const autoDeleteEnabledEl = document.getElementById("autoDeleteEnabled");
const autoDeleteAmountEl = document.getElementById("autoDeleteAmount");
const autoDeleteUnitEl = document.getElementById("autoDeleteUnit");
const autoDeleteErrorEl = document.getElementById("autoDeleteError");
const spotlightSectionEl = document.getElementById("spotlight");
const spotlightStripEl = document.getElementById("spotlightStrip");
const spotlightEnabledEl = document.getElementById("spotlightEnabled");
const tagsBtn = document.getElementById("tagsBtn");
const tagsPanel = document.getElementById("tagsPanel");
const tagsListEl = document.getElementById("tagsList");
const tagsEmptyHintEl = document.getElementById("tagsEmptyHint");

let items = [];
let prefs = {
  view: "grid",
  sort: "newest",
  showArchived: false,
  reminderEnabled: false,
  reminderAmount: 7,
  reminderUnit: "days",
  theme: "system",
  autoDeleteEnabled: false,
  autoDeleteAmount: 30,
  autoDeleteUnit: "days",
  spotlightEnabled: true,
};
let toastTimer = null;

const SPOTLIGHT_COUNT = 3;
const SPOTLIGHT_COOLDOWN_MS = 60 * 60 * 1000;
const SPOTLIGHT_STATE_KEY = "shelfSpotlightState";
let spotlightState = { lastRunAt: 0, itemIds: [] };

function isDue(item) {
  if (!prefs.reminderEnabled || item.archived) return false;
  const ms = periodMs(prefs.reminderAmount, prefs.reminderUnit);
  if (!ms) return false;
  return Date.now() - item.dateAdded >= ms;
}

// A short, muted palette for the bookshelf "spine" color, chosen per domain
// so the same site always lands on the same color.
const SPINE_COLORS = ["#C47A4A", "#55684B", "#5A6E8C", "#8C5A6E", "#8C7A4A", "#4A7C8C"];

function spineColorFor(domain) {
  let hash = 0;
  for (let i = 0; i < domain.length; i++) hash = (hash * 31 + domain.charCodeAt(i)) >>> 0;
  return SPINE_COLORS[hash % SPINE_COLORS.length];
}

function timeAgo(ts) {
  const diff = Date.now() - ts;
  const min = 60000, hr = 3600000, day = 86400000;
  if (diff < hr) return `${Math.max(1, Math.round(diff / min))}m ago`;
  if (diff < day) return `${Math.round(diff / hr)}h ago`;
  if (diff < day * 30) return `${Math.round(diff / day)}d ago`;
  return new Date(ts).toLocaleDateString(undefined, { month: "short", day: "numeric", year: "numeric" });
}

function normalizeTag(raw) {
  return raw.trim().toLowerCase().replace(/\s+/g, " ");
}

// Supports comma-separated entry ("css, research") so one Enter press can add several.
function parseTagInput(raw) {
  return [...new Set(raw.split(",").map(normalizeTag).filter(Boolean))];
}

function allTags() {
  const set = new Set();
  items.forEach((item) => (item.tags || []).forEach((t) => set.add(t)));
  return [...set].sort();
}

function filterByTag(tag) {
  searchEl.value = tag;
  closeTagsPanel();
  render();
}

async function addTagsToItem(id, raw) {
  const it = items.find((i) => i.id === id);
  if (!it) return;
  const toAdd = parseTagInput(raw);
  if (!toAdd.length) return;
  const existing = new Set(it.tags || []);
  toAdd.forEach((t) => existing.add(t));
  it.tags = [...existing];
  it.updatedAt = Date.now();
  items = await reconcileWithSync(items);
  await saveItems();
  render();
}

async function removeTagFromItem(id, tag) {
  const it = items.find((i) => i.id === id);
  if (!it) return;
  it.tags = (it.tags || []).filter((t) => t !== tag);
  it.updatedAt = Date.now();
  items = await reconcileWithSync(items);
  await saveItems();
  render();
}

async function loadAll() {
  const data = await chrome.storage.local.get([STORAGE_KEY, PREFS_KEY]);
  items = data[STORAGE_KEY] || [];
  prefs = { ...prefs, ...(data[PREFS_KEY] || {}) };
  items = await reconcileWithSync(items);
  await saveItems();
}

async function savePrefs() {
  await chrome.storage.local.set({ [PREFS_KEY]: prefs });
}

async function saveItems() {
  await chrome.storage.local.set({ [STORAGE_KEY]: items });
}

// Kept out of shelfPrefs deliberately: this is derived runtime state (which
// items were last shown, and when), not a user-configurable setting.
async function loadSpotlightState() {
  const data = await chrome.storage.local.get(SPOTLIGHT_STATE_KEY);
  return data[SPOTLIGHT_STATE_KEY] || { lastRunAt: 0, itemIds: [] };
}

async function saveSpotlightState(state) {
  await chrome.storage.local.set({ [SPOTLIGHT_STATE_KEY]: state });
}

function showToast(msg, actionLabel, actionFn) {
  clearTimeout(toastTimer);
  toastEl.textContent = msg + " ";
  if (actionLabel && actionFn) {
    const btn = document.createElement("button");
    btn.textContent = actionLabel;
    btn.className = "toast-action";
    btn.onclick = () => {
      actionFn();
      toastEl.hidden = true;
    };
    toastEl.appendChild(btn);
  }
  toastEl.hidden = false;
  toastTimer = setTimeout(() => (toastEl.hidden = true), 5000);
}

function applyViewButtons() {
  document.documentElement.dataset.theme = prefs.theme;
  themeSelectEl.value = prefs.theme;

  const isGrid = prefs.view === "grid";
  shelfEl.dataset.view = prefs.view;
  viewGridBtn.setAttribute("aria-pressed", String(isGrid));
  viewListBtn.setAttribute("aria-pressed", String(!isGrid));
  sortSelectEl.value = prefs.sort;
  showArchivedBtn.textContent = prefs.showArchived ? "Hide archived" : "Show archived";
  showArchivedBtn.classList.toggle("active", prefs.showArchived);

  reminderEnabledEl.checked = prefs.reminderEnabled;
  reminderAmountEl.value = prefs.reminderAmount;
  reminderUnitEl.value = prefs.reminderUnit;
  reminderAmountEl.disabled = !prefs.reminderEnabled;
  reminderUnitEl.disabled = !prefs.reminderEnabled;

  autoDeleteEnabledEl.checked = prefs.autoDeleteEnabled;
  autoDeleteAmountEl.value = prefs.autoDeleteAmount;
  autoDeleteUnitEl.value = prefs.autoDeleteUnit;
  autoDeleteAmountEl.disabled = !prefs.autoDeleteEnabled;
  autoDeleteUnitEl.disabled = !prefs.autoDeleteEnabled;
  const autoDeleteValid = periodMs(prefs.autoDeleteAmount, prefs.autoDeleteUnit) > periodMs(prefs.reminderAmount, prefs.reminderUnit);
  autoDeleteErrorEl.hidden = autoDeleteValid;

  spotlightEnabledEl.checked = prefs.spotlightEnabled;

  settingsBtn.classList.toggle(
    "active",
    prefs.reminderEnabled || (prefs.autoDeleteEnabled && autoDeleteValid) || prefs.spotlightEnabled
  );
}

function faviconOrInitial(item) {
  if (item.favicon) {
    const img = document.createElement("img");
    img.src = item.favicon;
    img.alt = "";
    img.style.cssText = "width:20px;height:20px;object-fit:contain;";
    img.onerror = () => { img.replaceWith(initialBadge(item)); };
    return img;
  }
  return initialBadge(item);
}

function initialBadge(item) {
  const span = document.createElement("span");
  span.className = "favicon-fallback";
  span.textContent = (item.domain || item.title || "?").charAt(0).toUpperCase();
  return span;
}

function buildCard(item, view = prefs.view) {
  const card = document.createElement("div");
  card.className = "card";
  if (isDue(item)) card.classList.add("card-due");
  card.dataset.id = item.id;

  if (view === "list") {
    const spine = document.createElement("div");
    spine.className = "spine";
    spine.style.background = spineColorFor(item.domain);
    card.appendChild(spine);
  }

  const thumb = document.createElement("div");
  thumb.className = "card-thumb";
  if (view === "grid" && !item.image) {
    thumb.style.background = `linear-gradient(135deg, ${spineColorFor(item.domain)}33, ${spineColorFor(item.domain)}11)`;
  }
  if (item.image) {
    const img = document.createElement("img");
    img.src = item.image;
    img.alt = "";
    thumb.appendChild(img);
  } else {
    thumb.appendChild(faviconOrInitial(item));
  }
  card.appendChild(thumb);

  const perf = document.createElement("div");
  perf.className = "card-perf";

  const body = document.createElement("div");
  body.className = "card-body";

  const title = document.createElement("a");
  title.className = "card-title";
  title.href = item.url;
  title.textContent = item.title || item.url;
  title.title = item.url;
  title.addEventListener("click", () => markOpened(item.id));
  body.appendChild(title);

  const meta = document.createElement("div");
  meta.className = "card-meta";
  const domainSpan = document.createElement("span");
  domainSpan.textContent = item.domain || "";
  meta.appendChild(domainSpan);
  const dateSpan = document.createElement("span");
  dateSpan.textContent = timeAgo(item.dateAdded);
  meta.appendChild(dateSpan);
  if (isDue(item)) {
    const badge = document.createElement("span");
    badge.className = "due-badge";
    badge.textContent = "due";
    meta.appendChild(badge);
  }
  if (item.archived) {
    const badge = document.createElement("span");
    badge.className = "archived-badge";
    badge.textContent = "archived";
    meta.appendChild(badge);
  }
  body.appendChild(meta);

  // Tag editing needs real vertical room, so it's grid-only. List view stays
  // the compact bookshelf-spine row it's meant to be.
  if (view === "grid") {
    body.appendChild(buildTagsRow(item));
  }

  if (view === "grid") {
    const actions = document.createElement("div");
    actions.className = "card-actions";
    actions.appendChild(makeActionBtn(item));
    actions.appendChild(makeDeleteBtn(item));
    body.appendChild(actions);
  }

  perf.appendChild(body);
  card.appendChild(perf);

  if (view === "list") {
    const actions = document.createElement("div");
    actions.className = "card-actions";
    actions.appendChild(makeActionBtn(item));
    actions.appendChild(makeDeleteBtn(item));
    card.querySelector(".card-body").appendChild(actions);
  }

  return card;
}

function buildTagsRow(item) {
  const row = document.createElement("div");
  row.className = "card-tags";

  (item.tags || []).forEach((tag) => {
    const chip = document.createElement("span");
    chip.className = "tag-chip";

    const label = document.createElement("span");
    label.className = "tag-chip-label";
    label.textContent = tag;
    label.title = `Filter by "${tag}"`;
    label.addEventListener("click", () => filterByTag(tag));
    chip.appendChild(label);

    const remove = document.createElement("button");
    remove.className = "tag-remove";
    remove.textContent = "×";
    remove.title = `Remove tag "${tag}"`;
    remove.addEventListener("click", (e) => {
      e.preventDefault();
      removeTagFromItem(item.id, tag);
    });
    chip.appendChild(remove);

    row.appendChild(chip);
  });

  const addBtn = document.createElement("button");
  addBtn.className = "tag-add-btn";
  addBtn.textContent = "+ tag";
  addBtn.addEventListener("click", (e) => {
    e.preventDefault();
    addBtn.replaceWith(buildTagInput(item));
  });
  row.appendChild(addBtn);

  return row;
}

function buildTagInput(item) {
  const input = document.createElement("input");
  input.type = "text";
  input.className = "tag-input";
  input.placeholder = "tag, another…";

  // Guards against double-submit: committing rebuilds the shelf (via render()),
  // which removes this input from the DOM, and removing a focused element
  // fires "blur", which would otherwise re-trigger commit() a second time.
  let done = false;
  const commit = () => {
    if (done) return;
    done = true;
    if (input.value.trim()) addTagsToItem(item.id, input.value);
    else render();
  };
  input.addEventListener("keydown", (e) => {
    if (e.key === "Enter") {
      e.preventDefault();
      commit();
    } else if (e.key === "Escape") {
      done = true;
      render();
    }
  });
  input.addEventListener("blur", commit);

  setTimeout(() => input.focus(), 0);
  return input;
}

function makeActionBtn(item) {
  const btn = document.createElement("button");
  btn.className = "icon-btn";
  btn.textContent = item.archived ? "Unarchive" : "Archive";
  btn.addEventListener("click", (e) => {
    e.preventDefault();
    toggleArchive(item.id);
  });
  return btn;
}

function makeDeleteBtn(item) {
  const btn = document.createElement("button");
  btn.className = "icon-btn danger";
  btn.textContent = "Delete";
  btn.addEventListener("click", (e) => {
    e.preventDefault();
    deleteItem(item.id);
  });
  return btn;
}

async function markOpened(id) {
  // Leave the item in place; opening just navigates. No state change needed,
  // but this hook exists in case future versions want "mark as read on open."
}

async function toggleArchive(id) {
  const it = items.find((i) => i.id === id);
  if (!it) return;
  it.archived = !it.archived;
  it.updatedAt = Date.now();
  items = await reconcileWithSync(items);
  await saveItems();
  render();
}

async function deleteItem(id) {
  const idx = items.findIndex((i) => i.id === id);
  if (idx === -1) return;
  const [removed] = items.splice(idx, 1);
  items = await reconcileWithSync(items);
  await saveItems();
  render();
  showToast("Removed from shelf.", "Undo", async () => {
    removed.updatedAt = Date.now();
    items.splice(idx, 0, removed);
    items = await reconcileWithSync(items);
    await saveItems();
    render();
  });
}

// Also run by background.js on an hourly alarm so items get cleaned up even
// when this page isn't open; this copy runs whenever the shelf is open (on
// load, and periodically after) and, unlike the background sweep, surfaces
// a courtesy toast with an Undo, since a human is actually here to see it.
async function runAutoDeleteSweep() {
  if (!prefs.autoDeleteEnabled) return;
  const removed = items.filter((item) => isOverdueForDeletion(item, prefs));
  if (!removed.length) return;

  items = items.filter((item) => !isOverdueForDeletion(item, prefs));
  items = await reconcileWithSync(items);
  await saveItems();
  render();

  const count = removed.length;
  showToast(`Auto-deleted ${count} item${count > 1 ? "s" : ""} you never got back to.`, "Undo", async () => {
    const now = Date.now();
    removed.forEach((item) => { item.updatedAt = now; });
    items.push(...removed);
    items = await reconcileWithSync(items);
    await saveItems();
    render();
  });
}

// Picks a fresh "Worth a second look" selection at most once per cooldown
// window, so opening several new tabs in quick succession (normal browsing)
// doesn't get miscounted as repeated views and falsely inflate backoff.
async function refreshSpotlightSelection() {
  if (!prefs.spotlightEnabled) return;

  spotlightState = await loadSpotlightState();
  const now = Date.now();
  if (spotlightState.itemIds.length && now - (spotlightState.lastRunAt || 0) < SPOTLIGHT_COOLDOWN_MS) {
    return;
  }

  const picked = pickSpotlightItems(items, prefs, SPOTLIGHT_COUNT);
  picked.forEach((item) => {
    item.surfaceCount = (item.surfaceCount || 0) + 1;
    item.lastSurfacedAt = now;
    item.updatedAt = now;
  });

  if (picked.length) {
    items = await reconcileWithSync(items);
    await saveItems();
  }

  spotlightState = { lastRunAt: now, itemIds: picked.map((i) => i.id) };
  await saveSpotlightState(spotlightState);
}

// Pure projection of the current selection against live item state. No
// selection logic here, so archiving/deleting a spotlighted card just makes
// it disappear (via the normal render() path) with no replacement sliding
// in until the next cooldown-triggered refresh.
function renderSpotlight() {
  if (!prefs.spotlightEnabled || searchEl.value.trim()) {
    spotlightSectionEl.hidden = true;
    return;
  }

  const visible = spotlightState.itemIds
    .map((id) => items.find((i) => i.id === id))
    .filter((item) => item && !item.archived);

  spotlightStripEl.innerHTML = "";
  visible.forEach((item) => spotlightStripEl.appendChild(buildCard(item, "grid")));
  spotlightSectionEl.hidden = visible.length === 0;
}

function renderTagsPanel() {
  const tags = allTags();
  tagsListEl.innerHTML = "";
  tags.forEach((tag) => {
    const chip = document.createElement("button");
    chip.className = "tag-chip tag-chip-filter";
    chip.textContent = tag;
    chip.addEventListener("click", () => filterByTag(tag));
    tagsListEl.appendChild(chip);
  });
  tagsEmptyHintEl.hidden = tags.length > 0;
}

function getFilteredSorted() {
  const query = searchEl.value.trim().toLowerCase();
  let list = items.filter((i) => (prefs.showArchived ? true : !i.archived));

  if (query) {
    list = list.filter(
      (i) =>
        (i.title || "").toLowerCase().includes(query) ||
        (i.domain || "").toLowerCase().includes(query) ||
        (i.url || "").toLowerCase().includes(query) ||
        (i.tags || []).some((t) => t.includes(query))
    );
  }

  const sorters = {
    newest: (a, b) => b.dateAdded - a.dateAdded,
    oldest: (a, b) => a.dateAdded - b.dateAdded,
    title: (a, b) => (a.title || "").localeCompare(b.title || ""),
    domain: (a, b) => (a.domain || "").localeCompare(b.domain || ""),
  };
  list.sort(sorters[prefs.sort] || sorters.newest);

  if (prefs.reminderEnabled) {
    const due = list.filter(isDue);
    const rest = list.filter((i) => !isDue(i));
    list = [...due, ...rest];
  }

  return list;
}

function render() {
  applyViewButtons();
  const list = getFilteredSorted();

  shelfEl.innerHTML = "";
  list.forEach((item) => shelfEl.appendChild(buildCard(item)));

  const unreadTotal = items.filter((i) => !i.archived).length;
  unreadCountEl.textContent = unreadTotal;
  const archivedTotal = items.length - unreadTotal;
  archivedNoteEl.textContent = archivedTotal > 0 ? ` · ${archivedTotal} archived` : "";

  emptyStateEl.hidden = items.length > 0;
  shelfEl.hidden = items.length === 0;

  renderSpotlight();
  renderTagsPanel();
}

// --- Event wiring ---
searchEl.addEventListener("input", render);

sortSelectEl.addEventListener("change", async () => {
  prefs.sort = sortSelectEl.value;
  await savePrefs();
  render();
});

viewGridBtn.addEventListener("click", async () => {
  prefs.view = "grid";
  await savePrefs();
  render();
});
viewListBtn.addEventListener("click", async () => {
  prefs.view = "list";
  await savePrefs();
  render();
});

showArchivedBtn.addEventListener("click", async () => {
  prefs.showArchived = !prefs.showArchived;
  await savePrefs();
  render();
});

function closeSettingsPanel() {
  settingsPanel.hidden = true;
  settingsBtn.setAttribute("aria-expanded", "false");
}

settingsBtn.addEventListener("click", (e) => {
  e.stopPropagation();
  const isOpen = !settingsPanel.hidden;
  if (isOpen) {
    closeSettingsPanel();
  } else {
    settingsPanel.hidden = false;
    settingsBtn.setAttribute("aria-expanded", "true");
  }
});

function closeTagsPanel() {
  tagsPanel.hidden = true;
  tagsBtn.setAttribute("aria-expanded", "false");
}

tagsBtn.addEventListener("click", (e) => {
  e.stopPropagation();
  const isOpen = !tagsPanel.hidden;
  if (isOpen) {
    closeTagsPanel();
  } else {
    tagsPanel.hidden = false;
    tagsBtn.setAttribute("aria-expanded", "true");
  }
});

document.addEventListener("click", (e) => {
  if (!settingsPanel.hidden && !e.target.closest(".settings-wrap")) closeSettingsPanel();
  if (!tagsPanel.hidden && !e.target.closest(".tags-wrap")) closeTagsPanel();
});

document.addEventListener("keydown", (e) => {
  if (e.key !== "Escape") return;
  if (!settingsPanel.hidden) closeSettingsPanel();
  if (!tagsPanel.hidden) closeTagsPanel();
});

reminderEnabledEl.addEventListener("change", async () => {
  prefs.reminderEnabled = reminderEnabledEl.checked;
  await savePrefs();
  render();
});

reminderAmountEl.addEventListener("change", async () => {
  const val = Math.max(1, parseInt(reminderAmountEl.value, 10) || 1);
  reminderAmountEl.value = val;
  prefs.reminderAmount = val;
  await savePrefs();
  render();
});

reminderUnitEl.addEventListener("change", async () => {
  prefs.reminderUnit = reminderUnitEl.value;
  await savePrefs();
  render();
});

themeSelectEl.addEventListener("change", async () => {
  prefs.theme = themeSelectEl.value;
  await savePrefs();
  render();
});

autoDeleteEnabledEl.addEventListener("change", async () => {
  prefs.autoDeleteEnabled = autoDeleteEnabledEl.checked;
  await savePrefs();
  render();
});

autoDeleteAmountEl.addEventListener("change", async () => {
  const val = Math.max(1, parseInt(autoDeleteAmountEl.value, 10) || 1);
  autoDeleteAmountEl.value = val;
  prefs.autoDeleteAmount = val;
  await savePrefs();
  render();
});

autoDeleteUnitEl.addEventListener("change", async () => {
  prefs.autoDeleteUnit = autoDeleteUnitEl.value;
  await savePrefs();
  render();
});

spotlightEnabledEl.addEventListener("change", async () => {
  prefs.spotlightEnabled = spotlightEnabledEl.checked;
  await savePrefs();
  renderSpotlight();
});

// Live-update if items change from another tab / the background worker.
chrome.storage.onChanged.addListener((changes, area) => {
  if (area !== "local") return;
  if (changes[STORAGE_KEY]) {
    items = changes[STORAGE_KEY].newValue || [];
    render();
  }
});

// Live-update when another device pushes changes via chrome.storage.sync.
let reconcilingSync = false;
chrome.storage.onChanged.addListener(async (changes, area) => {
  if (area !== "sync" || reconcilingSync) return;
  reconcilingSync = true;
  try {
    items = await reconcileWithSync(items);
    await saveItems();
    render();
  } finally {
    reconcilingSync = false;
  }
});

(async function init() {
  await loadAll();
  render();
  await runAutoDeleteSweep();
  await refreshSpotlightSelection();
  renderSpotlight();
  setInterval(runAutoDeleteSweep, 5 * 60 * 1000);
})();