// Dev-only mock library data, for exercising the Library UI on a machine
// without a populated music library. Inert unless explicitly enabled by
// setting localStorage.mockLibrary = "1" in the webview (then reload);
// remove the key to go back to real backend data.

const ARTISTS = ["Aphex Twin","Boards of Canada","Caribou","Daft Punk","Eno Brian","Four Tet","Grimes","Holly Herndon","Jon Hopkins","Kraftwerk","LCD Soundsystem","Moderat","Nils Frahm","Oneohtrix","Portishead","Radiohead","Squarepusher","Tycho","Underworld","Vangelis","Wilco","Yello","Zero 7","Air","Bonobo","Burial","Clark","Deadmau5","Emancipator","Floating Points","Gold Panda","Helios","Kiasmos","Lorn","Moby","Nujabes","Ott","Plaid","Rival Consoles","Shpongle"];

// Titles vary by slot so the Library's classifier has something real to file:
// a live set, demos, a remix record and a collection appear per artist cycle,
// and a few rows have NO art_path so the generated artwork can be judged.
const TITLE_SHAPES = [
    (a, j) => `Album ${j + 1} of ${a}`,
    (a) => `Live at the Roundhouse`,
    (a) => `Four-Track Demos`,
    (a) => `Remixes 2001`,
    (a) => `Singles Collection`,
];
const albums = [];
let aid = 1;
for (let i = 0; i < ARTISTS.length; i++) {
    const n = 2 + (i % 4); // 2-5 albums per artist
    for (let j = 0; j < n; j++) {
        const shape = j < 2 ? TITLE_SHAPES[0] : TITLE_SHAPES[(i + j) % TITLE_SHAPES.length];
        albums.push({
            id: aid,
            artist: ARTISTS[i],
            title: shape(ARTISTS[i], j),
            year: 1995 + ((i + j) % 30),
            track_count: j === 2 && i % 5 === 0 ? 3 : 8 + ((i + j) % 7),
            art_path: (i + j) % 4 === 3 ? null : `mock://art/${aid}`,
            artist_art_path: `mock://artist/${i}`,
            added_at: 1700000000 + i * 86400 * 9 + j * 86400 * 40,
            path: `C:\\mock\\${i}\\${j}`,
        });
        aid++;
    }
}

// Per-album file aggregates, the same shape library_album_stats returns.
// Deterministic variety: a third FLAC 16/44.1, a few 24/96, the rest MP3.
function statsFor(a) {
    const kind = a.id % 7;
    const flac = kind === 0 || kind === 3 || kind === 5;
    const hires = kind === 5;
    const perTrack = flac ? (hires ? 120e6 : 38e6) : 9e6;
    return {
        album_id: a.id,
        secs: a.track_count * (170 + (a.id % 90)),
        bytes: Math.round(a.track_count * perTrack),
        avg_kbps: flac ? (hires ? 2400 : 900) + (a.id % 120) : 192 + (a.id % 4) * 32,
        bit_depth: flac ? (hires ? 24 : 16) : null,
        sample_rate: flac ? (hires ? 96000 : 44100) : null,
        formats: [flac ? "flac" : "mp3"],
        last_played_at: a.id % 3 === 0 ? null : 1723000000 - (a.id % 40) * 86400,
    };
}

function svgArt(hue, label) {
    const s =
        `<svg xmlns="http://www.w3.org/2000/svg" width="256" height="256">` +
        `<rect width="256" height="256" fill="hsl(${hue},45%,35%)"/>` +
        `<text x="128" y="140" font-size="90" text-anchor="middle" fill="rgba(255,255,255,.75)" font-family="sans-serif">${label}</text></svg>`;
    return "data:image/svg+xml;base64," + btoa(s);
}

function tracksFor(albumId) {
    const album = albums.find((a) => a.id === albumId);
    const artist = album?.artist ?? "?";
    const s = album ? statsFor(album) : null;
    const ext = s?.formats[0] ?? "mp3";
    const n = album?.track_count ?? 10;
    return Array.from({ length: n }, (_, k) => ({
        id: albumId * 100 + k,
        album_id: albumId,
        title: `Track ${k + 1}`,
        artist,
        track_no: k + 1,
        duration_secs: 120 + ((albumId + k) % 9) * 23,
        bitrate_kbps: s?.avg_kbps ?? 320,
        bit_depth: s?.bit_depth ?? null,
        sample_rate: s?.sample_rate ?? null,
        size: Math.round((s?.bytes ?? 40e6) / n),
        path: `C:\\mock\\t${albumId}-${k}.${ext}`,
    }));
}

const enabled = (() => {
    try {
        return localStorage.getItem("mockLibrary") === "1";
    } catch {
        return false;
    }
})();

/** Returns a Promise for mocked commands, or undefined to pass through. */
export function mockInvoke(cmd, args) {
    if (!enabled) return undefined;
    if (cmd === "library_albums") return Promise.resolve(albums);
    if (cmd === "library_album_stats") return Promise.resolve(albums.map(statsFor));
    if (cmd === "followed_artists") return Promise.resolve([]);
    if (cmd === "recent_albums") return Promise.resolve([]);
    if (cmd === "album_tracks")
        return new Promise((r) => setTimeout(() => r(tracksFor(args.albumId)), 60));
    if (cmd === "album_art") {
        const m = /(\d+)$/.exec(args.path || "");
        const num = m ? +m[1] : 0;
        return Promise.resolve(svgArt((num * 47) % 360, String.fromCharCode(65 + (num % 26))));
    }
    if (cmd === "list_playlists") return Promise.resolve([]);
    return undefined;
}