/* The phone's resolver: a catalog track or record → a peer's copy, through
   the desktop's own source rules (src/lib/sources.js — one copy, shared).
   The order is the desktop's: the library first, then the remembered source
   if its bytes are still complete in the cache, then the network — the
   query ladder, the candidates, and up to four peers tried in turn.

   A record queues every track from the ONE folder that wins. A song played
   off a record queues the rest of the record behind it as UNRESOLVED
   entries, each finding its own copy when its turn comes (the player calls
   hooks.resolveEntry). Failover lives in the player: an entry carries its
   runner-up peers in `t.alts`, and a stream that has not sent a byte in
   time moves to the next one. */
import * as api from "../lib/api.js";
import {
    resolveSources, songCandidates, albumCandidates, simplifyTitle, albumQueryTitle,
    cachedStreamSourceFor, rememberStreamSource, catalogTrackFor, cleanTrackName,
    hqCover, qualityOf, refreshSourcePrefs, libraryAlbumIn, libraryTrackIn,
} from "../lib/sources.js";
import { player, hooks, playEntries, playAlbum } from "./player.svelte.js";
import { lib, tracksOf } from "./lib.svelte.js";
import { slsk } from "./slsk.svelte.js";
import { yearOf } from "./catalog.svelte.js";

export const resolver = $state({ active: false, label: "", error: "" });

void refreshSourcePrefs();

const online = () => slsk.connection === "online";
const OFFLINE = "Sign in on Community to play from the network.";

/* ── shapes ────────────────────────────────────────────────────────── */
/** The record a streamed entry belongs to, as the player's `album`. No
 *  library id: the catalog id rides in `catalogId`, and the cover URL is the
 *  art key (art.svelte.js routes https through the catalog art proxy). */
function albumMeta(o, artist) {
    return {
        id: null,
        catalogId: o.albumId ?? null,
        title: o.album ?? null,
        artist: o.albumArtist ?? artist,
        year: o.year ?? null,
        art_path: hqCover(o.cover) ?? null,
    };
}
function streamEntry(title, artist, src, o, album) {
    return {
        t: {
            id: o.trackId != null ? "cat:" + o.trackId : "stream:" + src.username + "|" + src.path,
            title,
            artist,
            path: src.path,
            duration_secs: src.duration ?? o.expectSecs ?? null,
            stream: { username: src.username, size: src.size },
            catalog: { trackId: o.trackId ?? null, albumId: o.albumId ?? null, expectSecs: o.expectSecs ?? null },
            alts: [],
        },
        album,
    };
}
/** The rest of a record, unresolved: a path-less entry the player resolves
 *  on arrival. */
function lazyEntries(rest, artist, o, album) {
    return (rest || []).map((ct) => ({
        t: {
            id: "cat:" + ct.id,
            title: ct.title,
            artist: ct.artist || artist,
            path: null,
            duration_secs: ct.duration_secs ?? null,
            stream: null,
            catalog: { trackId: ct.id ?? null, albumId: o.albumId ?? null, expectSecs: ct.duration_secs ?? null },
            alts: [],
        },
        album,
    }));
}
const alt = (c) => ({ username: c.username, path: c.file.path, size: c.file.size, duration: c.file.duration ?? null });
function remember(e, quality) {
    rememberStreamSource({ stream: e.t.stream, path: e.t.path, title: e.t.title, artist: e.t.artist, trackId: e.t.catalog?.trackId ?? null, duration: e.t.duration_secs, quality });
}

/* the bar says what is being looked for while the ladder runs */
function placeholder(title, artist, album) {
    player.track = { id: "resolving", title, artist, path: null, stream: null };
    player.album = album;
    player.position = 0;
    player.duration = null;
    player.status = "buffering";
    player.phase = "loading";
    player.error = "";
}
function fail(msg) {
    resolver.error = msg;
    player.error = msg;
    if (player.track?.id === "resolving") { player.track = null; player.status = "idle"; player.phase = "ready"; }
}

/* ── a song ────────────────────────────────────────────────────────── */
/** Play a catalog track: `o` carries what the row knows — trackId, albumId,
 *  album (title), cover, expectSecs, year, and `rest` (the record's later
 *  tracks, queued behind it). */
export async function streamSong(artist, title, o = {}) {
    if (resolver.active) return;
    const local = await libraryTrackIn(lib.albums, (id) => tracksOf(id), artist, title);
    if (local) {
        await playAlbum(local.album, local.tracks, local.index);
        return;
    }
    const album = albumMeta(o, artist);
    const from = album.title || artist;
    const cached = await cachedStreamSourceFor(o.trackId ?? null, artist, title);
    if (cached) {
        await playEntries([streamEntry(title, artist, cached, o, album), ...lazyEntries(o.rest, artist, o, album)], 0, from);
        return;
    }
    if (!online()) { fail(OFFLINE); return; }
    placeholder(title, artist, album);
    const { responses, artistIncluded } = await resolveSources(
        `${artist} — ${title}`,
        [`${artist} ${simplifyTitle(title)}`, simplifyTitle(title)],
        (rs) => songCandidates(rs, title, true, o.album, o.expectSecs, artist).length,
        artist,
        resolver,
    );
    const cands = songCandidates(responses, title, true, o.album, o.expectSecs, artist, !artistIncluded);
    if (!cands.length) { fail(`No streamable sources found for “${title}”`); return; }
    const [best, ...alts] = cands.slice(0, 4);
    const e = streamEntry(title, artist, alt(best), o, album);
    e.t.alts = alts.map(alt);
    remember(e, qualityOf(best.file));
    await playEntries([e, ...lazyEntries(o.rest, artist, o, album)], 0, from);
}

/* ── a record ──────────────────────────────────────────────────────── */
/** Play a catalog record from track `at`: the library's copy if it holds
 *  one, else the best folder on the network, every track from that one
 *  peer, the runner-up folders as the first track's failover. */
export async function streamCatalogAlbum(album, at = 0) {
    if (resolver.active) return;
    const local = libraryAlbumIn(lib.albums, album.artist, album.title, album.release_date ?? null);
    if (local) {
        const tracks = await tracksOf(local.id).catch(() => []);
        if (tracks.length) { await playAlbum(local, tracks, Math.min(at, tracks.length - 1)); return; }
    }
    if (!online()) { fail(OFFLINE); return; }
    const meta = albumMeta({ albumId: album.id ?? null, album: album.title, cover: album.cover, year: yearOf(album.release_date) }, album.artist);
    placeholder(album.title, album.artist, meta);
    const catalogTracks = album.id
        ? await api.catalogAlbum(album.id).then((p) => p?.tracks ?? null, () => null)
        : null;
    const trackCount = catalogTracks?.length || album.track_count || null;
    if (trackCount === 1) {
        const t = catalogTracks?.[0];
        player.track = null;
        await streamSong(album.artist, t?.title ?? album.title, {
            cover: t?.cover ?? album.cover, trackId: t?.id ?? null, albumId: album.id ?? null,
            album: album.title || null, expectSecs: t?.duration_secs ?? null, year: meta.year,
        });
        return;
    }
    const { responses, artistIncluded } = await resolveSources(
        `${album.artist} — ${album.title}`,
        [`${album.artist} ${albumQueryTitle(album)}`, albumQueryTitle(album)],
        (rs) => albumCandidates(rs, album, true, trackCount).length,
        album.artist,
        resolver,
    );
    const folders = albumCandidates(responses, album, true, trackCount, !artistIncluded);
    if (!folders.length) { fail(`No streamable sources found for “${album.title}”`); return; }
    const c = folders[0];
    const entries = c.audio.map((f, i) => {
        const ct = catalogTrackFor(f, i, c.audio, catalogTracks);
        const o = { trackId: ct?.id ?? null, albumId: album.id ?? null, expectSecs: ct?.duration_secs ?? null };
        const e = streamEntry(ct?.title ?? cleanTrackName(f.name), album.artist, { username: c.username, path: f.path, size: f.size, duration: f.duration ?? null }, o, meta);
        remember(e, qualityOf(f));
        return e;
    });
    const start = Math.min(Math.max(0, at), entries.length - 1);
    entries[start].t.alts = folders.slice(1, 4).map((g) => {
        const f = g.audio[start] || g.audio[0];
        return { username: g.username, path: f.path, size: f.size, duration: f.duration ?? null };
    });
    await playEntries(entries, start, album.title);
}

/* ── saving ────────────────────────────────────────────────────────── */
/** Fetch a record into the library: the best folder by the DOWNLOAD rules
 *  (quality first, a queue is fine), every file in it — the pipeline files
 *  art and logs beside the finished album and says soulseek:library-changed.
 *  Returns { username, files } or false. */
export async function saveCatalogAlbum(album) {
    if (resolver.active) return false;
    if (!online()) { resolver.error = OFFLINE; player.error = OFFLINE; return false; }
    const catalogTracks = album.id
        ? await api.catalogAlbum(album.id).then((p) => p?.tracks ?? null, () => null)
        : null;
    const trackCount = catalogTracks?.length || album.track_count || null;
    if (trackCount === 1) {
        const t = catalogTracks?.[0];
        return saveSong(album.artist, t?.title ?? album.title);
    }
    const { responses, artistIncluded } = await resolveSources(
        `${album.artist} — ${album.title}`,
        [`${album.artist} ${albumQueryTitle(album)}`, albumQueryTitle(album)],
        (rs) => albumCandidates(rs, album, false, trackCount).length,
        album.artist,
        resolver,
    );
    const best = albumCandidates(responses, album, false, trackCount, !artistIncluded)[0];
    if (!best) {
        resolver.error = `No album sources found for “${album.title}”`;
        player.error = resolver.error;
        return false;
    }
    for (const f of best.files) await api.downloadFile(best.username, f.path, f.size);
    return { username: best.username, files: best.files.length };
}
/** One song into the library, by the download rules. */
export async function saveSong(artist, title) {
    if (resolver.active) return false;
    if (!online()) { resolver.error = OFFLINE; player.error = OFFLINE; return false; }
    const { responses, artistIncluded } = await resolveSources(
        `${artist} — ${title}`,
        [`${artist} ${simplifyTitle(title)}`, simplifyTitle(title)],
        (rs) => songCandidates(rs, title, false, null, null, artist).length,
        artist,
        resolver,
    );
    const best = songCandidates(responses, title, false, null, null, artist, !artistIncluded)[0];
    if (!best) {
        resolver.error = `No sources found for “${title}”`;
        player.error = resolver.error;
        return false;
    }
    await api.downloadFile(best.username, best.file.path, best.file.size);
    return { username: best.username, files: 1 };
}

/* ── an entry's turn ───────────────────────────────────────────────── */
/** Fill in a path-less catalog entry when the queue reaches it: the
 *  library, the cache, then a search of its own. Returns whether it can
 *  play. Mutates the entry (a queue proxy) in place. */
async function resolveEntry(e, quiet = false) {
    const { title, artist, catalog } = e.t;
    const local = await libraryTrackIn(lib.albums, (id) => tracksOf(id), artist, title);
    if (local) {
        const t = local.tracks[local.index];
        e.t.path = t.path;
        e.t.duration_secs = t.duration_secs ?? e.t.duration_secs;
        e.t.stream = null;
        return true;
    }
    const cached = await cachedStreamSourceFor(catalog?.trackId ?? null, artist, title);
    if (cached) {
        e.t.path = cached.path;
        e.t.stream = { username: cached.username, size: cached.size };
        e.t.duration_secs = cached.duration ?? e.t.duration_secs;
        return true;
    }
    if (!online()) return false;
    const { responses, artistIncluded } = await resolveSources(
        `${artist} — ${title}`,
        [`${artist} ${simplifyTitle(title)}`, simplifyTitle(title)],
        (rs) => songCandidates(rs, title, true, e.album?.title, catalog?.expectSecs, artist).length,
        artist,
        quiet ? null : resolver,
    );
    const cands = songCandidates(responses, title, true, e.album?.title, catalog?.expectSecs, artist, !artistIncluded);
    if (!cands.length) return false;
    const [best, ...alts] = cands.slice(0, 4);
    const src = alt(best);
    e.t.path = src.path;
    e.t.stream = { username: src.username, size: src.size };
    e.t.duration_secs = src.duration ?? e.t.duration_secs;
    e.t.alts = alts.map(alt);
    remember(e, qualityOf(best.file));
    return true;
}
hooks.resolveEntry = resolveEntry;