// The mini player's lifeline. The mini window is a REMOTE CONTROL, not a
// second brain: it never imports the player store (a second instance would
// double-run the auto-advance and fight this window over the queue — the
// same phantom-instance trap the probe rules exist for). Instead THIS window
// — the only brain, alive while hidden — streams view-state out over three
// channels and executes command intents that come back:
//
//   mini:track  { title, artist, album, artUrl, duration, waveform,
//                 coverage, accent, hover }        on track/waveform change
//   mini:tick   { position, status, volume, muted, shuffle, repeat }
//                                                   throttled ~5/s
//   mini:queue  { rows: [{ title, dur }], index, next: { title, artUrl } }
//                                                   on queue shape change
//   mini:glass  { on }                              on dark-glass flips
//                                                   (applyGlass) + hello
//   mini:cmd    { op, value }                       mini → here
//   mini:hello  {}                                  mini → here, answered
//                                                   with a full snapshot
import { emit } from "@tauri-apps/api/event";
import * as api from "./api.js";
import { glassOn } from "./glass.js";
import {
    player,
    theme,
    togglePlayPause,
    nextTrack,
    prevTrack,
    toggleShuffle,
    cycleRepeat,
    jumpToQueueIndex,
    peekNextIndices,
    engineTime,
    getArt,
    getCatalogArt,
    playerArtSource,
} from "./state.svelte.js";

let started = false;

/** Split the track's sub line ("Artist · Album") the way the bar renders it. */
function meta() {
    const t = player.track;
    if (!t) return { title: null, artist: null, album: null };
    const parts = (t.sub ?? "").split(" · ");
    return { title: t.title ?? null, artist: parts[0] || null, album: parts[1] || null };
}

async function artUrlForCurrent() {
    const item = player.queue?.[player.queueIndex];
    if (!item) return null;
    try {
        if (item.art) return await getArt(item.art);
        if (item.artUrl) return await getCatalogArt(playerArtSource(item));
    } catch {}
    return null;
}

let trackGen = 0;
async function emitTrack() {
    const gen = ++trackGen;
    const m = meta();
    const artUrl = await artUrlForCurrent();
    if (gen !== trackGen) return; // a newer track landed while art resolved
    void emit("mini:track", {
        ...m,
        artUrl,
        duration: player.duration,
        waveform: player.waveform,
        coverage: player.waveformCoverage,
        accent: theme.accentTarget,
        hover: theme.accentHoverTarget,
    });
}

async function emitQueue() {
    const rows = (player.queue ?? []).map((it) => ({
        title: it.title ?? "—",
        dur: it.duration ?? it.duration_secs ?? null,
    }));
    let next = null;
    const [ni] = peekNextIndices(1);
    const nItem = ni != null ? player.queue?.[ni] : null;
    if (nItem) {
        let artUrl = null;
        try {
            if (nItem.art) artUrl = await getArt(nItem.art, 128);
            else if (nItem.artUrl) artUrl = await getCatalogArt(playerArtSource(nItem));
        } catch {}
        next = { title: nItem.title ?? "—", artUrl };
    }
    void emit("mini:queue", { rows, index: player.queueIndex, next });
}

function emitTick() {
    void emit("mini:tick", {
        position: player.position,
        status: player.status,
        volume: player.muted ? 0 : player.volume,
        muted: player.muted,
        shuffle: player.shuffle,
        repeat: player.repeat,
    });
}

export function initMiniBridge() {
    if (started) return;
    started = true;

    // ---- outbound: watch the store, emit on the three channels ----------
    $effect.root(() => {
        // Track identity + waveform arrivals. The waveform array is replaced
        // wholesale by the store, so reference equality is the change signal.
        $effect(() => {
            void player.track?.title;
            void player.track?.sub;
            void player.duration;
            void player.waveform;
            void player.waveformCoverage;
            void emitTrack();
        });
        // Accent: stream the crossfade TARGET, set synchronously when the
        // fade starts, and let the mini run its own CSS fade. Never mirror
        // theme.accent from here — it lerps via rAF in THIS window, which is
        // hidden in mini mode, so it freezes mid-color (and a trailing
        // debounce on it turned the mini's fade into one late snap).
        $effect(() => {
            void theme.accentTarget;
            void theme.accentHoverTarget;
            void emitTrack();
        });
        $effect(() => {
            void player.queue;
            void player.queueIndex;
            void player.shuffle;
            void player.shuffleOrder;
            void player.repeat;
            void emitQueue();
        });
        let tickTimer = null;
        $effect(() => {
            void player.position;
            void player.status;
            void player.volume;
            void player.muted;
            void player.shuffle;
            void player.repeat;
            if (tickTimer) return;
            tickTimer = setTimeout(() => {
                tickTimer = null;
                emitTick();
            }, 180);
        });
    });

    // ---- inbound: the mini's intents, executed by this brain ------------
    api.onEvent("mini:hello", () => {
        void emitTrack();
        void emitQueue();
        emitTick();
        // Frost state rides its own channel: hello answers with the current
        // value, applyGlass pushes flips live (see glass.js).
        void emit("mini:glass", { on: glassOn() });
    });
    api.onEvent("mini:cmd", (p) => {
        const { op, value } = p ?? {};
        if (op === "toggle") togglePlayPause();
        else if (op === "next") nextTrack();
        else if (op === "prev") prevTrack();
        else if (op === "shuffle") toggleShuffle();
        else if (op === "repeat") cycleRepeat();
        else if (op === "jump") jumpToQueueIndex(value);
        else if (op === "seek") api.playerControl("seek", engineTime(value));
        else if (op === "volume") {
            const frac = Math.max(0, Math.min(1, value));
            player.volume = frac;
            player.muted = frac === 0;
            api.playerControl("volume", frac);
        }
    });
}