(() => {
    "use strict";

    const list = document.getElementById("ymHistory");
    const updated = document.getElementById("ymUpdated");
    const refresh = document.getElementById("ymRefresh");
    const tabs = Array.from(document.querySelectorAll(".ym-tab"));
    if (!list || !updated) return;

    const SOURCES = {
        lb: "/api/listenbrainz/recent",
        ym: "/api/ym/history",
    };
    const POLL_MS = 30000;

    let current = "lb";
    let timer = null;
    let busy = false;
    const state = {
        lb: { seen: new Set(), firstLoad: true },
        ym: { seen: new Set(), firstLoad: true },
    };

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

    const dayLabel = (t) => {
        if (t.nowplaying) return "сейчас";
        if (!t.day) return "";
        const today = new Date().toISOString().slice(0, 10);
        const yest = new Date(Date.now() - 86400000).toISOString().slice(0, 10);
        if (t.day === today) return "сегодня";
        if (t.day === yest) return "вчера";
        const [y, m, d] = t.day.split("-");
        return `${d}.${m}.${y}`;
    };

    const render = (tracks) => {
        const st = state[current];
        const fresh = [];
        const html = tracks.map((t) => {
            const key = `${t.id}:${t.album_id || ""}:${t.day || ""}`;
            if (!st.seen.has(key)) {
                st.seen.add(key);
                if (!st.firstLoad) fresh.push(key);
            }
            const isNew = fresh.includes(key);
            const cover = t.cover
                ? `<img class="ym-cover" src="${escapeHtml(t.cover)}" alt="" loading="lazy" width="48" height="48">`
                : `<span class="ym-cover ym-cover-empty" aria-hidden="true">♪</span>`;
            const artists = (t.artists || []).map(escapeHtml).join(", ");
            const context = t.context ? ` <span class="ym-context">· ${escapeHtml(t.context)}</span>` : "";
            const link = t.url
                ? `<a class="ym-link" href="${escapeHtml(t.url)}" target="_blank" rel="noopener">`
                : `<div class="ym-link">`;
            const close = t.url ? "</a>" : "</div>";
            return `<li class="ym-track${isNew ? " ym-new" : ""}${t.nowplaying ? " ym-playing" : ""}">
                ${link}
                    ${cover}
                    <span class="ym-info">
                        <span class="ym-track-title">${escapeHtml(t.title)}</span>
                        <span class="ym-artists">${artists || "—"}${context}</span>
                    </span>
                    <span class="ym-day${t.nowplaying ? " ym-now" : ""}">${dayLabel(t)}</span>
                ${close}
            </li>`;
        }).join("");

        list.innerHTML = html || '<li class="ym-status">Пока нет прослушиваний</li>';
        st.firstLoad = false;
    };

    const setStatus = (msg, isError) => {
        list.innerHTML = `<li class="ym-status${isError ? " ym-error" : ""}">${escapeHtml(msg)}</li>`;
    };

    const tick = async () => {
        if (busy) return;
        busy = true;
        try {
            const res = await fetch(SOURCES[current], { headers: { Accept: "application/json" } });
            const data = await res.json();
            if (!res.ok || !data.ok) {
                setStatus(data.error || `Ошибка ${res.status}`, true);
                return;
            }
            render(data.tracks || []);
            const t = new Date(data.updated_at * 1000);
            updated.textContent = `обновлено ${t.toLocaleTimeString("ru-RU")}${data.stale ? " (кэш)" : ""}`;
        } catch (e) {
            setStatus("Нет связи с сервером", true);
        } finally {
            busy = false;
            if (timer) clearTimeout(timer);
            timer = setTimeout(tick, POLL_MS);
        }
    };

    const poke = () => { if (timer) clearTimeout(timer); tick(); };

    tabs.forEach((tab) => {
        tab.addEventListener("click", () => {
            const source = tab.dataset.source;
            if (!source || source === current) return;
            current = source;
            tabs.forEach((t) => t.classList.toggle("active", t === tab));
            updated.textContent = "подключение…";
            poke();
        });
    });

    if (refresh) refresh.addEventListener("click", poke);
    document.addEventListener("visibilitychange", () => {
        if (!document.hidden) poke();
    });

    tick();
})();