/**
 * audio.js — Shared audio engine for ASTvinci.
 *
 * Provides a Salamander grand-piano sampler as the default instrument,
 * with a fallback PolySynth available immediately while samples load.
 * Supports lazy-loading of additional instruments (Casio, Vocal).
 */
(function () {
    'use strict';

    /* ---------------------------------------------------------
       FX chain: instrument → delay → reverb → limiter → destination
       --------------------------------------------------------- */
    const compressor = new Tone.Compressor({
        threshold: -24,
        ratio: 12,
        attack: 0.003,
        release: 0.25
    });
    const limiter = new Tone.Limiter(-1).toDestination();
    const reverb = new Tone.Reverb({ decay: 3, wet: 0 }).connect(compressor);
    compressor.connect(limiter);
    const delay = new Tone.FeedbackDelay('8n', 0.5).connect(reverb);
    delay.wet.value = 0;

    /* ---------------------------------------------------------
       Fallback synth (available immediately)
       --------------------------------------------------------- */
    const synth = new Tone.PolySynth(Tone.Synth, {
        envelope: { attack: 0.05, decay: 0.1, sustain: 0.3, release: 1 }
    }).connect(delay);

    /* ---------------------------------------------------------
       Instrument Definitions & Lazy Loading
       --------------------------------------------------------- */
    const instrumentConfigs = {
        'piano': {
            baseUrl: 'https://tonejs.github.io/audio/salamander/',
            urls: {
                'A0': 'A0.mp3', 'C1': 'C1.mp3', 'D#1': 'Ds1.mp3', 'F#1': 'Fs1.mp3',
                'A1': 'A1.mp3', 'C2': 'C2.mp3', 'D#2': 'Ds2.mp3', 'F#2': 'Fs2.mp3',
                'A2': 'A2.mp3', 'C3': 'C3.mp3', 'D#3': 'Ds3.mp3', 'F#3': 'Fs3.mp3',
                'A3': 'A3.mp3', 'C4': 'C4.mp3', 'D#4': 'Ds4.mp3', 'F#4': 'Fs4.mp3',
                'A4': 'A4.mp3', 'C5': 'C5.mp3', 'D#5': 'Ds5.mp3', 'F#5': 'Fs5.mp3',
                'A5': 'A5.mp3', 'C6': 'C6.mp3', 'D#6': 'Ds6.mp3', 'F#6': 'Fs6.mp3',
                'A6': 'A6.mp3', 'C7': 'C7.mp3', 'D#7': 'Ds7.mp3', 'F#7': 'Fs7.mp3',
                'A7': 'A7.mp3', 'C8': 'C8.mp3'
            }
        },
        'casio': {
            baseUrl: 'https://tonejs.github.io/audio/casio/',
            urls: {
                'A1': 'A1.mp3', 'A2': 'A2.mp3', 'B1': 'B1.mp3', 'C2': 'C2.mp3',
                'D2': 'D2.mp3', 'D#2': 'Ds2.mp3', 'E2': 'E2.mp3', 'F2': 'F2.mp3',
                'F#2': 'Fs2.mp3', 'G2': 'G2.mp3'
            }
        },
        'bass-electric': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/bass-electric/',
            urls: {
                'A#1': 'As1.mp3', 'A#2': 'As2.mp3', 'A#3': 'As3.mp3', 'A#4': 'As4.mp3', 'C#1': 'Cs1.mp3', 'C#2': 'Cs2.mp3',
                'C#3': 'Cs3.mp3', 'C#4': 'Cs4.mp3', 'E1': 'E1.mp3', 'E2': 'E2.mp3', 'E3': 'E3.mp3', 'E4': 'E4.mp3',
                'G1': 'G1.mp3', 'G2': 'G2.mp3', 'G3': 'G3.mp3', 'G4': 'G4.mp3'
            }
        },
        'bassoon': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/bassoon/',
            urls: {
                'A2': 'A2.mp3', 'A3': 'A3.mp3', 'A4': 'A4.mp3', 'C3': 'C3.mp3', 'C4': 'C4.mp3', 'C5': 'C5.mp3',
                'E4': 'E4.mp3', 'G2': 'G2.mp3', 'G3': 'G3.mp3', 'G4': 'G4.mp3'
            }
        },
        'cello': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/cello/',
            urls: {
                'A#2': 'As2.mp3', 'A#3': 'As3.mp3', 'A2': 'A2.mp3', 'A3': 'A3.mp3', 'A4': 'A4.mp3', 'B2': 'B2.mp3',
                'B3': 'B3.mp3', 'B4': 'B4.mp3', 'C#3': 'Cs3.mp3', 'C#4': 'Cs4.mp3', 'C2': 'C2.mp3', 'C3': 'C3.mp3',
                'C4': 'C4.mp3', 'C5': 'C5.mp3', 'D#2': 'Ds2.mp3', 'D#3': 'Ds3.mp3', 'D#4': 'Ds4.mp3', 'D2': 'D2.mp3',
                'D3': 'D3.mp3', 'D4': 'D4.mp3', 'E2': 'E2.mp3', 'E3': 'E3.mp3', 'E4': 'E4.mp3', 'F#3': 'Fs3.mp3',
                'F#4': 'Fs4.mp3', 'F2': 'F2.mp3', 'F3': 'F3.mp3', 'F4': 'F4.mp3', 'G#2': 'Gs2.mp3', 'G#3': 'Gs3.mp3',
                'G#4': 'Gs4.mp3', 'G2': 'G2.mp3', 'G3': 'G3.mp3', 'G4': 'G4.mp3'
            }
        },
        'clarinet': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/clarinet/',
            urls: {
                'A#3': 'As3.mp3', 'A#4': 'As4.mp3', 'A#5': 'As5.mp3', 'D3': 'D3.mp3', 'D4': 'D4.mp3', 'D5': 'D5.mp3',
                'D6': 'D6.mp3', 'F#6': 'Fs6.mp3', 'F3': 'F3.mp3', 'F4': 'F4.mp3', 'F5': 'F5.mp3'
            }
        },
        'contrabass': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/contrabass/',
            urls: {
                'A#1': 'As1.mp3', 'A2': 'A2.mp3', 'B3': 'B3.mp3', 'C#3': 'Cs3.mp3', 'C2': 'C2.mp3', 'D2': 'D2.mp3',
                'E2': 'E2.mp3', 'E3': 'E3.mp3', 'F#1': 'Fs1.mp3', 'F#2': 'Fs2.mp3', 'G#2': 'Gs2.mp3', 'G#3': 'Gs3.mp3',
                'G1': 'G1.mp3'
            }
        },
        'flute': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/flute/',
            urls: {
                'A4': 'A4.mp3', 'A5': 'A5.mp3', 'A6': 'A6.mp3', 'C4': 'C4.mp3', 'C5': 'C5.mp3', 'C6': 'C6.mp3',
                'C7': 'C7.mp3', 'E4': 'E4.mp3', 'E5': 'E5.mp3', 'E6': 'E6.mp3'
            }
        },
        'french-horn': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/french-horn/',
            urls: {
                'A1': 'A1.mp3', 'A3': 'A3.mp3', 'C2': 'C2.mp3', 'C4': 'C4.mp3', 'D#2': 'Ds2.mp3', 'D3': 'D3.mp3',
                'D5': 'D5.mp3', 'F3': 'F3.mp3', 'F5': 'F5.mp3', 'G2': 'G2.mp3'
            }
        },
        'guitar-acoustic': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/guitar-acoustic/',
            urls: {
                'A#2': 'As2.mp3', 'A#3': 'As3.mp3', 'A#4': 'As4.mp3', 'A2': 'A2.mp3', 'A3': 'A3.mp3', 'A4': 'A4.mp3',
                'B2': 'B2.mp3', 'B3': 'B3.mp3', 'B4': 'B4.mp3', 'C#3': 'Cs3.mp3', 'C#4': 'Cs4.mp3', 'C#5': 'Cs5.mp3',
                'C3': 'C3.mp3', 'C4': 'C4.mp3', 'C5': 'C5.mp3', 'D#2': 'Ds2.mp3', 'D#3': 'Ds3.mp3', 'D#4': 'Ds3.mp3',
                'D2': 'D2.mp3', 'D3': 'D3.mp3', 'D4': 'D4.mp3', 'D5': 'D5.mp3', 'E2': 'E2.mp3', 'E3': 'E3.mp3',
                'E4': 'E4.mp3', 'F#2': 'Fs2.mp3', 'F#3': 'Fs3.mp3', 'F#4': 'Fs4.mp3', 'F2': 'F2.mp3', 'F3': 'F3.mp3',
                'F4': 'F4.mp3', 'G#2': 'Gs2.mp3', 'G#3': 'Gs3.mp3', 'G#4': 'Gs4.mp3', 'G2': 'G2.mp3', 'G3': 'G3.mp3',
                'G4': 'G4.mp3'
            }
        },
        'guitar-electric': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/guitar-electric/',
            urls: {
                'A2': 'A2.mp3', 'A3': 'A3.mp3', 'A4': 'A4.mp3', 'A5': 'A5.mp3', 'C#2': 'Cs2.mp3', 'C3': 'C3.mp3',
                'C4': 'C4.mp3', 'C5': 'C5.mp3', 'C6': 'C6.mp3', 'D#3': 'Ds3.mp3', 'D#4': 'Ds4.mp3', 'D#5': 'Ds5.mp3',
                'E2': 'E2.mp3', 'F#2': 'Fs2.mp3', 'F#3': 'Fs3.mp3', 'F#4': 'Fs4.mp3', 'F#5': 'Fs5.mp3'
            }
        },
        'guitar-nylon': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/guitar-nylon/',
            urls: {
                'A#5': 'As5.mp3', 'A2': 'A2.mp3', 'A3': 'A3.mp3', 'A4': 'A4.mp3', 'A5': 'A5.mp3', 'B1': 'B1.mp3',
                'B2': 'B2.mp3', 'B3': 'B3.mp3', 'B4': 'B4.mp3', 'C#3': 'Cs3.mp3', 'C#4': 'Cs4.mp3', 'C#5': 'Cs5.mp3',
                'D#4': 'Ds4.mp3', 'D2': 'D2.mp3', 'D3': 'D3.mp3', 'D5': 'D5.mp3', 'E2': 'E2.mp3', 'E3': 'E3.mp3',
                'E4': 'E4.mp3', 'E5': 'E5.mp3', 'F#2': 'Fs2.mp3', 'F#3': 'Fs3.mp3', 'F#4': 'Fs4.mp3', 'F#5': 'Fs5.mp3',
                'G#2': 'Gs2.mp3', 'G#4': 'Gs4.mp3', 'G#5': 'Gs5.mp3', 'G3': 'G3.mp3', 'G5': 'G3.mp3'
            }
        },
        'harmonium': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/harmonium/',
            urls: {
                'A#2': 'As2.mp3', 'A#3': 'As3.mp3', 'A#4': 'As4.mp3', 'A2': 'A2.mp3', 'A3': 'A3.mp3', 'A4': 'A4.mp3',
                'C#2': 'Cs2.mp3', 'C#3': 'Cs3.mp3', 'C#4': 'Cs4.mp3', 'C#5': 'Cs5.mp3', 'C2': 'C2.mp3', 'C3': 'C3.mp3',
                'C4': 'C4.mp3', 'C5': 'C5.mp3', 'D#2': 'Ds2.mp3', 'D#3': 'Ds3.mp3', 'D#4': 'Ds4.mp3', 'D2': 'D2.mp3',
                'D3': 'D3.mp3', 'D4': 'D4.mp3', 'D5': 'D5.mp3', 'E2': 'E2.mp3', 'E3': 'E3.mp3', 'E4': 'E4.mp3',
                'F#2': 'Fs2.mp3', 'F#3': 'Fs3.mp3', 'F2': 'F2.mp3', 'F3': 'F3.mp3', 'F4': 'F4.mp3', 'G#2': 'Gs2.mp3',
                'G#3': 'Gs3.mp3', 'G#4': 'Gs4.mp3', 'G2': 'G2.mp3', 'G3': 'G3.mp3', 'G4': 'G4.mp3'
            }
        },
        'harp': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/harp/',
            urls: {
                'A2': 'A2.mp3', 'A4': 'A4.mp3', 'A6': 'A6.mp3', 'B1': 'B1.mp3', 'B3': 'B3.mp3', 'B5': 'B5.mp3',
                'B6': 'B6.mp3', 'C3': 'C3.mp3', 'C5': 'C5.mp3', 'D2': 'D2.mp3', 'D4': 'D4.mp3', 'D6': 'D6.mp3',
                'D7': 'D7.mp3', 'E1': 'E1.mp3', 'E3': 'E3.mp3', 'E5': 'E5.mp3', 'F2': 'F2.mp3', 'F4': 'F4.mp3',
                'F6': 'F6.mp3', 'F7': 'F7.mp3', 'G1': 'G1.mp3', 'G3': 'G3.mp3', 'G5': 'G5.mp3'
            }
        },
        'organ': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/organ/',
            urls: {
                'A1': 'A1.mp3', 'A2': 'A2.mp3', 'A3': 'A3.mp3', 'A4': 'A4.mp3', 'A5': 'A5.mp3', 'C1': 'C1.mp3',
                'C2': 'C2.mp3', 'C3': 'C3.mp3', 'C4': 'C4.mp3', 'C5': 'C5.mp3', 'C6': 'C6.mp3', 'D#1': 'Ds1.mp3',
                'D#2': 'Ds2.mp3', 'D#3': 'Ds3.mp3', 'D#4': 'Ds4.mp3', 'D#5': 'Ds5.mp3', 'F#1': 'Fs1.mp3', 'F#2': 'Fs2.mp3',
                'F#3': 'Fs3.mp3', 'F#4': 'Fs4.mp3', 'F#5': 'Fs5.mp3'
            }
        },
        'saxophone': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/saxophone/',
            urls: {
                'A#3': 'As3.mp3', 'A#4': 'As4.mp3', 'A4': 'A4.mp3', 'A5': 'A5.mp3', 'B3': 'B3.mp3', 'B4': 'B4.mp3',
                'C#3': 'Cs3.mp3', 'C#4': 'Cs4.mp3', 'C#5': 'Cs5.mp3', 'C4': 'C4.mp3', 'C5': 'C5.mp3', 'D#3': 'Ds3.mp3',
                'D#4': 'Ds4.mp3', 'D#5': 'Ds5.mp3', 'D3': 'D3.mp3', 'D4': 'D4.mp3', 'D5': 'D5.mp3', 'E3': 'E3.mp3',
                'E4': 'E4.mp3', 'E5': 'E5.mp3', 'F#3': 'Fs3.mp3', 'F#4': 'Fs4.mp3', 'F#5': 'Fs5.mp3', 'F3': 'F3.mp3',
                'F4': 'F4.mp3', 'F5': 'F5.mp3', 'G#3': 'Gs3.mp3', 'G#4': 'Gs4.mp3', 'G#5': 'Gs5.mp3', 'G3': 'G3.mp3',
                'G4': 'G4.mp3', 'G5': 'G5.mp3'
            }
        },
        'trombone': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/trombone/',
            urls: {
                'A#1': 'As1.mp3', 'A#2': 'As2.mp3', 'A#3': 'As3.mp3', 'C#2': 'Cs2.mp3', 'C#4': 'Cs4.mp3', 'C3': 'C3.mp3',
                'C4': 'C4.mp3', 'D#2': 'Ds2.mp3', 'D#3': 'Ds3.mp3', 'D#4': 'Ds4.mp3', 'D3': 'D3.mp3', 'D4': 'D4.mp3',
                'F2': 'F2.mp3', 'F3': 'F3.mp3', 'F4': 'F4.mp3', 'G#2': 'Gs2.mp3', 'G#3': 'Gs3.mp3'
            }
        },
        'trumpet': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/trumpet/',
            urls: {
                'A#4': 'As4.mp3', 'A3': 'A3.mp3', 'A5': 'A5.mp3', 'C4': 'C4.mp3', 'C6': 'C6.mp3', 'D#4': 'Ds4.mp3',
                'D5': 'D5.mp3', 'F3': 'F3.mp3', 'F4': 'F4.mp3', 'F5': 'F5.mp3', 'G4': 'G4.mp3'
            }
        },
        'tuba': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/tuba/',
            urls: {
                'A#1': 'As1.mp3', 'A#2': 'As2.mp3', 'A#3': 'As3.mp3', 'D#2': 'Ds2.mp3', 'D3': 'D3.mp3', 'D4': 'D4.mp3',
                'F1': 'F1.mp3', 'F2': 'F2.mp3', 'F3': 'F3.mp3'
            }
        },
        'violin': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/violin/',
            urls: {
                'A3': 'A3.mp3', 'A4': 'A4.mp3', 'A5': 'A5.mp3', 'A6': 'A6.mp3', 'C4': 'C4.mp3', 'C5': 'C5.mp3',
                'C6': 'C6.mp3', 'C7': 'C7.mp3', 'E4': 'E4.mp3', 'E5': 'E5.mp3', 'E6': 'E6.mp3', 'G4': 'G4.mp3',
                'G5': 'G5.mp3', 'G6': 'G6.mp3'
            }
        },
        'xylophone': {
            baseUrl: 'https://cdn.jsdelivr.net/gh/nbrosowsky/tonejs-instruments/samples/xylophone/',
            urls: {
                'C5': 'C5.mp3', 'C6': 'C6.mp3', 'C7': 'C7.mp3', 'C8': 'C8.mp3', 'G4': 'G4.mp3', 'G5': 'G5.mp3',
                'G6': 'G6.mp3', 'G7': 'G7.mp3'
            }
        }
    };

    const samplers = {}; // Cache of loaded Tone.Sampler instances
    const loadingPromises = {}; // Cache of promises for instruments in flight

    /**
     * Loads an instrument by name if not already loaded.
     * @param {string} name - The key from instrumentConfigs or 'Synthesizer'.
     * @returns {Promise<Tone.Instrument>}
     */
    function getInstrument(name) {
        if (name === 'Synthesizer') return Promise.resolve(synth);
        if (samplers[name]) return Promise.resolve(samplers[name]);
        if (loadingPromises[name]) return loadingPromises[name];

        const config = instrumentConfigs[name];
        //if (!config) return Promise.reject(new Error(`Instrument "${name}" not defined.`));
        if (!config) return Promise.resolve(synth);

        loadingPromises[name] = new Promise((resolve) => {
            console.log(`[ASTAudio] Loading ${name}...`);
            const inst = new Tone.Sampler({
                urls: config.urls,
                baseUrl: config.baseUrl,
                release: 1,
                onload: () => {
                    inst.name = name; // Tag for identification
                    samplers[name] = inst.connect(delay);
                    console.log(`[ASTAudio] ${name} loaded.`);
                    resolve(inst);
                },
                onerror: (err) => {
                    console.error(`[ASTAudio] Error loading ${name}:`, err);
                }
            });
        });

        return loadingPromises[name];
    }

    // Default piano starts loading immediately
    let pianoReady = false;
    const pianoPromise = getInstrument('piano').then(() => {
        pianoReady = true;
    });

    // Tag the fallback synth
    synth.name = 'Synthesizer';

    /* ---------------------------------------------------------
       Public API
       --------------------------------------------------------- */
    window.ASTAudio = {
        synth,
        reverb,
        delay,
        getInstrument,
        /** Returns piano if loaded, else fallback synth. */
        get instrument() { return samplers['piano'] || synth; },
        get piano() { return samplers['piano']; },
        ready: pianoPromise,
        get isReady() { return pianoReady; },
        get available() { return Object.keys(instrumentConfigs); }
    };
})();