import { AudioDocument } from "@suaveplan/audio-core";

/** Build a synthetic metronome audio document. */
export function makeMetronome(opts: {
    bpm: number;
    durationSeconds: number;
    sampleRate?: number;
    clickSamples?: number;
    clickFreq?: number;
}): AudioDocument {
    const sampleRate = opts.sampleRate ?? 8000;
    const total = Math.floor(opts.durationSeconds * sampleRate);
    const data = new Float32Array(total);
    const beatPeriodSamples = Math.floor((60 / opts.bpm) * sampleRate);
    const clickSamples = opts.clickSamples ?? 200;
    const clickFreq = opts.clickFreq ?? 1000;
    for (let beat = 0; beat * beatPeriodSamples < total; beat++) {
        const start = beat * beatPeriodSamples;
        for (let i = 0; i < clickSamples && start + i < total; i++) {
            const env = Math.exp(-i / (clickSamples / 4));
            data[start + i] =
                env * Math.sin((2 * Math.PI * clickFreq * i) / sampleRate);
        }
    }
    return new AudioDocument({
        sampleRate,
        channels: 1,
        sourceLength: total,
        pages: [{ channelData: [data], startSample: 0 }],
    });
}

/** Build a silent audio document. */
export function makeSilence(opts: {
    durationSeconds: number;
    sampleRate?: number;
}): AudioDocument {
    const sampleRate = opts.sampleRate ?? 8000;
    const total = Math.floor(opts.durationSeconds * sampleRate);
    return new AudioDocument({
        sampleRate,
        channels: 1,
        sourceLength: total,
        pages: [{ channelData: [new Float32Array(total)], startSample: 0 }],
    });
}

/** Empty document. */
export function makeEmpty(): AudioDocument {
    return new AudioDocument({
        sampleRate: 8000,
        channels: 1,
        sourceLength: 0,
        pages: [],
    });
}