/* VV frontend: лента (scroll-snap) + сетка, лайки, теги. Без фреймворков. */
const $ = (s) => document.querySelector(s);
const feed = $("#feed"), grid = $("#grid"), chips = $("#chips");
const state = { tag: "", q: "", sort: "new", page: 1, pages: 1, items: [], tagFor: null,
  loading: false, current: null };

const liked = new Set(JSON.parse(localStorage.getItem("vv_liked") || "[]"));
const saveLiked = () => localStorage.setItem("vv_liked", JSON.stringify([...liked].slice(-500)));

async function api(path, opts) {
  const r = await fetch(path, opts);
  if (!r.ok) throw new Error(await r.text());
  return r.status === 204 ? null : r.json();
}

/* --- теги-чипсы --- */
async function loadTags() {
  const tags = await api("/api/tags").catch(() => []);
  chips.innerHTML = "";
  const all = document.createElement("button");
  all.textContent = "Все";
  all.className = state.tag ? "" : "on";
  all.onclick = () => { state.tag = ""; state.page = 1; loadTags(); reload(); };
  chips.append(all);
  for (const t of tags.slice(0, 40)) {
    const b = document.createElement("button");
    b.textContent = `#${t.name} ${t.count}`;
    b.className = state.tag === t.name ? "on" : "";
    b.onclick = () => { state.tag = t.name; state.page = 1; loadTags(); reload(); };
    chips.append(b);
  }
}

/* --- загрузка списка --- */
async function fetchVideos(append) {
  const p = new URLSearchParams({
    tag: state.tag, q: state.q, sort: state.sort,
    page: state.page, per_page: 20,
  });
  const data = await api("/api/videos?" + p);
  state.pages = data.pages;
  state.items = append ? state.items.concat(data.items) : data.items;
  return data.items;
}

function slideEl(v) {
  const s = document.createElement("section");
  s.className = "slide";
  s.dataset.file = v.file;
  const tags = v.tags.map((t) => `<span class="tag" data-tag="${t}">#${t}</span>`).join(" ");
  s.innerHTML = `
    <video src="${v.url}" loop muted playsinline preload="metadata"></video>
    <div class="hint">❤️</div>
    <div class="meta"><div class="fname">${escapeHtml(v.file)}</div><div>${tags}</div></div>
    <div class="actions">
      <button class="like ${liked.has(v.file) ? "liked" : ""}">❤️<small>${v.likes}</small></button>
      <button class="tagbtn">🏷️</button>
      <a href="${v.url}" download><button type="button">⬇️</button></a>
    </div>`;
  const video = s.querySelector("video");
  s.querySelector(".like").onclick = () => likeVideo(v.file, s);
  s.querySelector(".tagbtn").onclick = () => openTagForm(v.file);
  s.querySelectorAll(".tag").forEach((el) => {
    el.onclick = () => { state.tag = el.dataset.tag; state.page = 1; loadTags(); reload(); };
  });
  // тап по центру = play/pause, даблтап = лайк
  let lastTap = 0;
  video.onclick = () => {
    const now = Date.now();
    if (now - lastTap < 300) likeVideo(v.file, s);
    else if (video.paused) video.play().catch(() => {});
    else video.pause();
    lastTap = now;
  };
  return s;
}

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

async function reload() {
  feed.innerHTML = ""; grid.innerHTML = "";
  state.page = 1; state.current = null;
  state.loading = true;
  const items = await fetchVideos(false).catch(() => []);
  state.loading = false;
  if (!items.length) {
    feed.innerHTML = `<div class="empty">Ничего не найдено 😢</div>`;
    return;
  }
  renderFeed(items);
  renderGrid(items);
  observeSlides();
}

async function loadMore() {
  if (state.loading || state.page >= state.pages) return;
  state.loading = true;
  state.page++;
  const before = state.items.length;
  const items = await fetchVideos(true).catch(() => []);
  state.loading = false;
  const fresh = state.items.slice(before);
  if (!fresh.length) return;
  // убрать старую кнопку "Ещё" перед дорисовкой
  feed.querySelector(".more")?.remove();
  renderFeed(fresh, true);
  renderGrid(fresh, true);
  observeSlides();
  void items;
}

function renderFeed(items, append) {
  if (!append) feed.innerHTML = "";
  for (const v of items) feed.append(slideEl(v));
  if (state.page < state.pages) {
    const b = document.createElement("button");
    b.className = "more"; b.textContent = "Ещё ⬇";
    b.onclick = () => { b.remove(); loadMore(); };
    feed.append(b);
  }
}

function renderGrid(items, append) {
  if (!append) grid.innerHTML = "";
  for (const v of items) {
    const c = document.createElement("div");
    c.className = "card";
    c.innerHTML = `
      <video src="${v.url}#t=0.5" preload="metadata" muted playsinline></video>
      <div class="row"><span>❤️ ${v.likes}</span><span>${escapeHtml(shortName(v.file))}</span></div>
      <a class="open" href="#"></a>`;
    c.querySelector(".open").onclick = (e) => {
      e.preventDefault();
      setMode("feed");
      const el = feed.querySelector(`[data-file="${CSS.escape(v.file)}"]`);
      if (el) el.scrollIntoView();
    };
    grid.append(c);
  }
}

function shortName(f) {
  return f.length > 18 ? f.slice(0, 17) + "…" : f;
}

/* автоплей видимого слайда */
let observer;
function observeSlides() {
  observer && observer.disconnect();
  observer = new IntersectionObserver((entries) => {
    for (const e of entries) {
      const video = e.target.querySelector("video");
      if (!video) continue;
      if (e.intersectionRatio > 0.6) {
        state.current = e.target;
        video.muted = false;
        video.play().catch(() => { video.muted = true; video.play().catch(() => {}); });
        // догружаем следующую страницу заранее
        const slides = [...feed.querySelectorAll(".slide")];
        if (slides.indexOf(e.target) > slides.length - 4) loadMore();
      } else {
        video.pause();
        video.muted = true;
      }
    }
  }, { root: feed, threshold: [0.6] });
  feed.querySelectorAll(".slide").forEach((s) => observer.observe(s));
}

/* --- лайки --- */
async function likeVideo(file, slide) {
  const btn = slide.querySelector(".like");
  const count = btn.querySelector("small");
  const data = await api("/api/videos/" + encodeURIComponent(file) + "/like", { method: "POST" })
    .catch(() => null);
  if (!data) return;
  count.textContent = data.likes;
  liked.add(file); saveLiked();
  btn.classList.add("liked");
  if (!data.already) {
    const hint = slide.querySelector(".hint");
    hint.style.opacity = 1;
    setTimeout(() => (hint.style.opacity = 0), 500);
  }
}

/* --- теги --- */
function openTagForm(file) {
  state.tagFor = file;
  $("#tagform").classList.add("show");
  $("#taginput").value = "";
  $("#taginput").focus();
}
$("#tagform").onsubmit = async (e) => {
  e.preventDefault();
  const tag = $("#taginput").value.trim();
  if (!tag || !state.tagFor) return;
  const data = await api("/api/videos/" + encodeURIComponent(state.tagFor) + "/tags", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ tag }),
  }).catch((err) => { alert("Не вышло: " + err.message); return null; });
  if (!data) return;
  $("#tagform").classList.remove("show");
  loadTags();
  reload();
};

/* --- режимы, поиск, клавиатура --- */
function setMode(m) {
  document.body.classList.toggle("mode-grid", m === "grid");
  $("#btn-feed").classList.toggle("on", m === "feed");
  $("#btn-grid").classList.toggle("on", m === "grid");
}
$("#btn-feed").onclick = () => setMode("feed");
$("#btn-grid").onclick = () => setMode("grid");

let qTimer;
$("#q").oninput = (e) => {
  clearTimeout(qTimer);
  qTimer = setTimeout(() => { state.q = e.target.value.trim(); reload(); }, 400);
};
$("#sort").onchange = (e) => { state.sort = e.target.value; reload(); };

document.addEventListener("keydown", (e) => {
  if (e.target.tagName === "INPUT" || e.target.tagName === "SELECT") return;
  const cur = state.current && document.contains(state.current) ? state.current : $(".slide");
  if (e.key === "ArrowDown" || e.key === "ArrowUp") {
    e.preventDefault();
    const slides = [...feed.querySelectorAll(".slide")];
    const i = slides.indexOf(cur);
    const next = slides[i + (e.key === "ArrowDown" ? 1 : -1)];
    if (next) next.scrollIntoView({ behavior: "smooth" });
  }
  if ((e.key === "l" || e.key === "д" || e.key === "L") && cur) {
    likeVideo(cur.dataset.file, cur);
  }
});

loadTags();
reload();