// AutoTrader Marker — content script
// Attaches a "Not wanted" button to each listing card and stores dismissals in browser.storage.local.
//
// DOM contract (verified against autotrader.co.uk 2026-04):
//   Listing card:  <li data-testid="id-{listingId}">
//   Title:         <a data-testid="search-listing-title">
//   Detail link:   <a href="/car-details/{listingId}?...">
// The `data-testid="id-*"` attribute carries the listing id directly, which is
// more robust than parsing anchor hrefs. Anchor-walk fallback kept for edge
// cases (featured/sponsored slots that render differently).

const api = typeof browser !== "undefined" ? browser : chrome;

const STORAGE_KEY = "dismissedListings";
const SETTINGS_KEY = "settings";

const state = {
  dismissed: {},
  hideDismissed: false,
};

// --- storage ---
//
// Primary: browser.storage.local (per-extension, syncs across tabs via
// storage.onChanged). Secondary: window.localStorage scoped to
// autotrader.co.uk — survives extension reinstall, because it's the site's
// storage, not the extension's. On load, if extension storage is empty but
// the site backup has entries, we re-hydrate. On every write we mirror to the
// site backup so the two stay in lockstep.

const BACKUP_KEY = "atm:dismissedListings:v1";

function readSiteBackup() {
  try {
    const raw = window.localStorage.getItem(BACKUP_KEY);
    return raw ? JSON.parse(raw) : null;
  } catch {
    return null;
  }
}

function writeSiteBackup(dismissed) {
  try {
    window.localStorage.setItem(BACKUP_KEY, JSON.stringify(dismissed));
  } catch {
    // localStorage full/disabled — nothing to do
  }
}

async function loadState() {
  const res = await api.storage.local.get([STORAGE_KEY, SETTINGS_KEY]);
  let dismissed = res[STORAGE_KEY] || {};

  // Re-hydrate from site backup if extension storage lost its entries
  // (e.g. after an unlisted reinstall that didn't upgrade in place).
  const backup = readSiteBackup();
  if (backup && Object.keys(dismissed).length === 0 && Object.keys(backup).length > 0) {
    dismissed = backup;
    await api.storage.local.set({ [STORAGE_KEY]: dismissed });
    console.log("[ATM] restored", Object.keys(dismissed).length, "dismissals from site backup");
  } else if (Object.keys(dismissed).length > 0) {
    // Keep site backup fresh even if we didn't need it this load
    writeSiteBackup(dismissed);
  }

  state.dismissed = dismissed;
  state.hideDismissed = !!(res[SETTINGS_KEY] && res[SETTINGS_KEY].hideDismissed);
  applyHideMode();
}

async function persistDismissed() {
  await api.storage.local.set({ [STORAGE_KEY]: state.dismissed });
  writeSiteBackup(state.dismissed);
}

async function setDismissed(id, title) {
  state.dismissed[id] = { ts: Date.now(), title: title || "" };
  await persistDismissed();
}

async function clearDismissed(id) {
  delete state.dismissed[id];
  await persistDismissed();
}

function applyHideMode() {
  document.documentElement.classList.toggle("atm-hide-dismissed", state.hideDismissed);
}

// --- listing detection ---

function extractIdFromLi(li) {
  // Primary: data-testid="id-202601279443591"
  const testid = li.getAttribute("data-testid") || "";
  const m = testid.match(/^id-(\d+)$/);
  if (m) return m[1];
  // Secondary: the li's own id attribute uses same pattern
  const liId = li.id || "";
  const m2 = liId.match(/^id-(\d+)$/);
  if (m2) return m2[1];
  // Last resort: derive from a /car-details/ anchor inside
  const a = li.querySelector('a[href*="/car-details/"]');
  if (a) {
    const m3 = a.getAttribute("href").match(/\/car-details\/(\d+)/);
    if (m3) return m3[1];
  }
  return null;
}

function extractTitle(card) {
  const t = card.querySelector('[data-testid="search-listing-title"]');
  if (t) return t.textContent.trim().slice(0, 200);
  const h = card.querySelector("h2, h3");
  return h ? h.textContent.trim().slice(0, 200) : "";
}

// A card is "sponsored/featured" if its detail link carries
// journey=FEATURED_LISTING_JOURNEY (AutoTrader's own tagging) or it lives
// inside an explicitly sponsored container.
function isSponsoredCard(card) {
  const anchors = card.querySelectorAll('a[href*="/car-details/"]');
  for (const a of anchors) {
    const href = a.getAttribute("href") || "";
    if (/journey=FEATURED_LISTING_JOURNEY/i.test(href)) return true;
  }
  const testid = (card.getAttribute("data-testid") || "").toLowerCase();
  if (testid.includes("featured") || testid.includes("sponsor") || testid.includes("promoted")) {
    return true;
  }
  // Walk up one level to catch wrapper markers
  const parent = card.parentElement;
  if (parent) {
    const ptid = (parent.getAttribute("data-testid") || "").toLowerCase();
    if (ptid.includes("featured") || ptid.includes("sponsor") || ptid.includes("promoted")) {
      return true;
    }
  }
  return false;
}

function findAllCards() {
  // Primary selector — verified stable on autotrader.co.uk
  const lis = document.querySelectorAll('li[data-testid^="id-"]');
  const cards = new Map();
  for (const li of lis) {
    if (isSponsoredCard(li)) {
      li.classList.add("atm-sponsored");
      continue;
    }
    const id = extractIdFromLi(li);
    if (id) cards.set(li, id);
  }
  return cards;
}

// --- UI injection ---

function decorateCard(card, id) {
  if (card.dataset.atmId === id && card.querySelector(":scope > .atm-btn")) return;
  card.dataset.atmId = id;
  card.classList.add("atm-card");

  // Remove stale button
  const existing = card.querySelector(":scope > .atm-btn");
  if (existing) existing.remove();

  const btn = document.createElement("button");
  btn.type = "button";
  btn.className = "atm-btn";
  btn.addEventListener("click", async (e) => {
    e.preventDefault();
    e.stopPropagation();
    if (state.dismissed[id]) {
      await clearDismissed(id);
    } else {
      await setDismissed(id, extractTitle(card));
    }
    refreshCardState(card, id);
  });

  card.appendChild(btn);
  refreshCardState(card, id);
}

function refreshCardState(card, id) {
  const dismissed = !!state.dismissed[id];
  card.classList.toggle("atm-dismissed", dismissed);
  const btn = card.querySelector(":scope > .atm-btn");
  if (btn) {
    btn.textContent = dismissed ? "✓ Dismissed — undo" : "✗ Not wanted";
    btn.setAttribute("aria-pressed", dismissed ? "true" : "false");
  }
}

function decorateAll() {
  const cards = findAllCards();
  for (const [card, id] of cards) {
    decorateCard(card, id);
  }
  // Also refresh any previously-decorated cards whose state may have changed
  document.querySelectorAll(".atm-card[data-atm-id]").forEach((card) => {
    if (!cards.has(card)) refreshCardState(card, card.dataset.atmId);
  });
}

// --- observers ---

let rafPending = false;
function scheduleDecorate() {
  if (rafPending) return;
  rafPending = true;
  requestAnimationFrame(() => {
    rafPending = false;
    decorateAll();
  });
}

const mo = new MutationObserver(() => scheduleDecorate());

function startObserving() {
  mo.observe(document.body, { childList: true, subtree: true });
}

// --- detail page ---
// URL pattern: /car-details/{digits}. A fixed FAB + optional top banner
// doesn't depend on the page layout, so it's resilient to redesigns.

function getDetailListingId() {
  // Accept /car-details/{id}, /classifieds/advert/{id}, trailing slashes, slugs
  const patterns = [
    /^\/car-details\/(\d+)/i,
    /^\/classifieds\/advert\/(\d+)/i,
    /\/cars?\/[^/]+\/(\d{10,})/i,
  ];
  for (const re of patterns) {
    const m = location.pathname.match(re);
    if (m) return m[1];
  }
  return null;
}

function extractDetailTitle() {
  const h1 = document.querySelector("h1");
  if (h1 && h1.textContent.trim()) return h1.textContent.trim().slice(0, 200);
  return (document.title || "").replace(/\s*\|\s*AutoTrader.*$/i, "").trim().slice(0, 200);
}

function ensureDetailUI(id) {
  let fab = document.getElementById("atm-fab");
  if (!fab) {
    fab = document.createElement("button");
    fab.id = "atm-fab";
    fab.type = "button";
    fab.className = "atm-fab";
    fab.addEventListener("click", async (e) => {
      e.preventDefault();
      if (state.dismissed[id]) {
        await clearDismissed(id);
      } else {
        await setDismissed(id, extractDetailTitle());
      }
      refreshDetailUI(id);
    });
    document.body.appendChild(fab);
  }

  let banner = document.getElementById("atm-banner");
  if (!banner) {
    banner = document.createElement("div");
    banner.id = "atm-banner";
    banner.className = "atm-banner";
    const label = document.createElement("span");
    label.className = "atm-banner-label";
    const undo = document.createElement("button");
    undo.type = "button";
    undo.className = "atm-banner-undo";
    undo.textContent = "Undo";
    undo.addEventListener("click", async () => {
      await clearDismissed(id);
      refreshDetailUI(id);
    });
    banner.appendChild(label);
    banner.appendChild(undo);
    document.body.appendChild(banner);
  }

  refreshDetailUI(id);
}

function refreshDetailUI(id) {
  const dismissed = !!state.dismissed[id];
  const fab = document.getElementById("atm-fab");
  if (fab) {
    fab.textContent = dismissed ? "✓ Dismissed — undo" : "✗ Not wanted";
    fab.setAttribute("aria-pressed", dismissed ? "true" : "false");
    fab.classList.toggle("atm-fab-dismissed", dismissed);
  }
  const banner = document.getElementById("atm-banner");
  if (banner) {
    banner.classList.toggle("atm-banner-visible", dismissed);
    const label = banner.querySelector(".atm-banner-label");
    if (label) label.textContent = "You marked this car as not wanted";
  }
}

// --- React to storage changes (popup / other tabs) ---
api.storage.onChanged.addListener((changes, area) => {
  if (area !== "local") return;
  if (changes[STORAGE_KEY]) {
    state.dismissed = changes[STORAGE_KEY].newValue || {};
    writeSiteBackup(state.dismissed); // keep site backup in sync with popup-driven changes
    document.querySelectorAll(".atm-card[data-atm-id]").forEach((card) => {
      refreshCardState(card, card.dataset.atmId);
    });
    const detailId = getDetailListingId();
    if (detailId) refreshDetailUI(detailId);
  }
  if (changes[SETTINGS_KEY]) {
    state.hideDismissed = !!(changes[SETTINGS_KEY].newValue && changes[SETTINGS_KEY].newValue.hideDismissed);
    applyHideMode();
  }
});

// --- bootstrap + SPA navigation ---

function removeDetailUI() {
  document.getElementById("atm-fab")?.remove();
  document.getElementById("atm-banner")?.remove();
}

let currentDetailId = null;
function applyPageMode() {
  const detailId = getDetailListingId();
  if (detailId) {
    currentDetailId = detailId;
    ensureDetailUI(detailId);
  } else {
    if (currentDetailId) {
      removeDetailUI();
      currentDetailId = null;
    }
    decorateAll();
    startObserving();
  }
}

function watchUrlChanges() {
  let lastUrl = location.href;
  const check = () => {
    if (location.href !== lastUrl) {
      lastUrl = location.href;
      applyPageMode();
    }
  };
  // Cover both history API and back/forward
  const wrap = (fn) => function () {
    const ret = fn.apply(this, arguments);
    queueMicrotask(check);
    return ret;
  };
  history.pushState = wrap(history.pushState);
  history.replaceState = wrap(history.replaceState);
  window.addEventListener("popstate", check);
}

(async function init() {
  await loadState();
  const detailId = getDetailListingId();
  // Diagnostic log — open Firefox DevTools console to confirm detection.
  // Prefixed so you can filter with "ATM" in the console.
  console.log("[ATM]", {
    pathname: location.pathname,
    href: location.href,
    detectedDetailId: detailId,
    dismissedCount: Object.keys(state.dismissed).length,
  });
  applyPageMode();
  watchUrlChanges();
})();