suaveplan/packages/media/audio-fx/audio-fx-plugin-spessasynth/tests/stub-module.ts

import type {
    SoundBankLike,
    SpessaSynthModuleLike,
    SpessaSynthProcessorLike,
} from "../src/loader/soundfont-loader.js";

interface ActiveStubNote {
    channel: number;
    note: number;
    velocity: number;
    phase: number;
}

export interface StubProcessorObserver {
    notes: ActiveStubNote[];
    programs: Map<number, number>;
    cc: Array<{ channel: number; controller: number; value: number }>;
    pitchBend: Array<{ channel: number; value: number }>;
    channelPressure: Array<{ channel: number; pressure: number }>;
    polyPressure: Array<{
        channel: number;
        note: number;
        pressure: number;
    }>;
    sysex: Array<Uint8Array>;
    destroyed: boolean;
    resetCount: number;
    stopAllCount: number;
}

export interface StubBank extends SoundBankLike {
    readonly stub: true;
}

class StubProcessor implements SpessaSynthProcessorLike {
    public readonly sampleRate: number;
    public readonly observer: StubProcessorObserver = {
        notes: [],
        programs: new Map(),
        cc: [],
        pitchBend: [],
        channelPressure: [],
        polyPressure: [],
        sysex: [],
        destroyed: false,
        resetCount: 0,
        stopAllCount: 0,
    };
    public readonly soundBankManager = {
        addSoundBank: (_font: SoundBankLike, _id: string) => {
            this.bankAdded = true;
        },
    };
    private bankAdded = false;

    public constructor(sampleRate: number) {
        this.sampleRate = sampleRate;
    }

    public get voiceCount(): number {
        return this.observer.notes.length;
    }

    public process(
        left: Float32Array,
        right: Float32Array,
        _startIndex?: number,
        _sampleCount?: number
    ): void {
        const len = left.length;
        for (let i = 0; i < len; i++) {
            let sum = 0;
            for (const v of this.observer.notes) {
                const freq = 440 * 2 ** ((v.note - 69) / 12);
                const phaseInc = (2 * Math.PI * freq) / this.sampleRate;
                v.phase += phaseInc;
                sum += Math.sin(v.phase) * (v.velocity / 127);
            }
            left[i] = sum;
            right[i] = sum;
        }
    }

    public noteOn(channel: number, midiNote: number, velocity: number): void {
        if (velocity === 0) {
            this.noteOff(channel, midiNote);
            return;
        }
        this.observer.notes.push({
            channel,
            note: midiNote,
            velocity,
            phase: 0,
        });
    }

    public noteOff(channel: number, midiNote: number): void {
        for (let i = this.observer.notes.length - 1; i >= 0; i--) {
            const v = this.observer.notes[i]!;
            if (v.channel === channel && v.note === midiNote) {
                this.observer.notes.splice(i, 1);
                return;
            }
        }
    }

    public programChange(channel: number, programNumber: number): void {
        this.observer.programs.set(channel, programNumber);
    }

    public controllerChange(
        channel: number,
        controller: number,
        value: number
    ): void {
        this.observer.cc.push({ channel, controller, value });
        if (controller === 123) {
            for (let i = this.observer.notes.length - 1; i >= 0; i--) {
                if (this.observer.notes[i]!.channel === channel) {
                    this.observer.notes.splice(i, 1);
                }
            }
        }
    }

    public pitchWheel(channel: number, pitch: number): void {
        this.observer.pitchBend.push({ channel, value: pitch });
    }

    public polyPressure(
        channel: number,
        midiNote: number,
        pressure: number
    ): void {
        this.observer.polyPressure.push({ channel, note: midiNote, pressure });
    }

    public channelPressure(channel: number, pressure: number): void {
        this.observer.channelPressure.push({ channel, pressure });
    }

    public systemExclusive(syx: Uint8Array | number[]): void {
        this.observer.sysex.push(
            syx instanceof Uint8Array ? syx : new Uint8Array(syx)
        );
    }

    public stopAllChannels(_force?: boolean): void {
        this.observer.stopAllCount++;
        this.observer.notes.length = 0;
    }

    public reset(): void {
        this.observer.resetCount++;
    }

    public destroySynthProcessor(): void {
        this.observer.destroyed = true;
    }

    public wasBankAdded(): boolean {
        return this.bankAdded;
    }
}

export function makeStubModule(): SpessaSynthModuleLike & {
    lastProcessor?: StubProcessor;
} {
    const mod = {
        SoundBankLoader: {
            fromArrayBuffer(buffer: ArrayBuffer): StubBank {
                if (buffer.byteLength < 12) {
                    throw new Error("stub-parse-fail");
                }
                return { stub: true };
            },
        },
        SpessaSynthProcessor: class extends StubProcessor {
            constructor(sampleRate: number) {
                super(sampleRate);
                (mod as { lastProcessor?: StubProcessor }).lastProcessor = this;
            }
        } as unknown as SpessaSynthModuleLike["SpessaSynthProcessor"],
    } as SpessaSynthModuleLike & { lastProcessor?: StubProcessor };
    return mod;
}

/** Build a minimal valid RIFF/sfbk header so the magic sniff passes. */
export function buildFakeSf2Bytes(payloadSize = 32): Uint8Array {
    const total = 12 + payloadSize;
    const bytes = new Uint8Array(total);
    bytes[0] = 0x52; // R
    bytes[1] = 0x49; // I
    bytes[2] = 0x46; // F
    bytes[3] = 0x46; // F
    // size field at offset 4..7 — ignored by our magic check
    bytes[8] = 0x73; // s
    bytes[9] = 0x66; // f
    bytes[10] = 0x62; // b
    bytes[11] = 0x6b; // k
    return bytes;
}