topos/src/API/Filters.ts

const _euclidean_cycle = (
    pulses: number,
    length: number,
    rotate: number = 0,
  ): boolean[] => {
    if (pulses == length) return Array.from({ length }, () => true);
    function startsDescent(list: number[], i: number): boolean {
      const length = list.length;
      const nextIndex = (i + 1) % length;
      return list[i] > list[nextIndex] ? true : false;
    }
    if (pulses >= length) return [true];
    const resList = Array.from(
      { length },
      (_, i) => (((pulses * (i - 1)) % length) + length) % length,
    );
    let cycle = resList.map((_, i) => startsDescent(resList, i));
    if (rotate != 0) {
      cycle = cycle.slice(rotate).concat(cycle.slice(0, rotate));
    }
    return cycle;
  }

export const fullseq = () => (sequence: string, duration: number): boolean | Array<boolean> => {
    if (sequence.split("").every((c) => c === "x" || c === "o")) {
        return [...sequence].map((c) => c === "x").beat(duration);
    } else {
        return false;
    }
};

export const seq = (app: any) => (expr: string, duration: number = 0.5): boolean => {
    let len = expr.length * duration;
    let output: number[] = [];

    for (let i = 1; i <= len + 1; i += duration) {
        output.push(Math.floor(i * 10) / 10);
    }
    output.pop();

    output = output.filter((_, idx) => {
        const exprIdx = idx % expr.length;
        return expr[exprIdx] === "x";
    });

    return oncount(app)(output, len);
};

export const beat = (app: any) => (n: number | number[] = 1, nudge: number = 0): boolean => {
    const nArray = Array.isArray(n) ? n : [n];
    const results: boolean[] = nArray.map(
        (value) =>
        (app.clock.pulses_since_origin - Math.floor(nudge * app.ppqn())) %
        Math.floor(value * app.ppqn()) === 0,
    );
    return results.some((value) => value === true);
};

export const bar = (app: any) => (n: number | number[] = 1, nudge: number = 0): boolean => {
    const nArray = Array.isArray(n) ? n : [n];
    const barLength = app.clock.time_signature[1] * app.ppqn();
    const nudgeInPulses = Math.floor(nudge * barLength);
    const results: boolean[] = nArray.map(
        (value) =>
        (app.clock.pulses_since_origin - nudgeInPulses) %
        Math.floor(value * barLength) === 0,
    );
    return results.some((value) => value === true);
};

export const pulse = (app: any) => (n: number | number[] = 1, nudge: number = 0): boolean => {
    const nArray = Array.isArray(n) ? n : [n];
    const results: boolean[] = nArray.map(
        (value) => (app.clock.pulses_since_origin - nudge) % value === 0,
    );
    return results.some((value) => value === true);
};

export const tick = (app: any) => (tick: number | number[], offset: number = 0): boolean => {
    const nArray = Array.isArray(tick) ? tick : [tick];
    const results: boolean[] = nArray.map(
        (value) => app.clock.time_position.pulse === value + offset,
    );
    return results.some((value) => value === true);
};

export const dur = (app: any) => (n: number | number[]): boolean => {
    let nums: number[] = Array.isArray(n) ? n : [n];
    return beat(app)(nums.dur(...nums));
};


export const flip = (app: any) => (chunk: number, ratio: number = 50): boolean => {
    let realChunk = chunk * 2;
    const time_pos = app.clock.pulses_since_origin;
    const full_chunk = Math.floor(realChunk * app.ppqn());
    const threshold = Math.floor((ratio / 100) * full_chunk);
    const pos_within_chunk = time_pos % full_chunk;
    return pos_within_chunk < threshold;
};

export const flipbar = (app: any) => (chunk: number = 1): boolean => {
    let realFlip = chunk;
    const time_pos = app.clock.time_position.bar;
    const current_chunk = Math.floor(time_pos / realFlip);
    return current_chunk % 2 === 0;
};

export const onbar = (app: any) => (
    bars: number[] | number,
    n: number = app.clock.time_signature[0],
): boolean => {
    let current_bar = (app.clock.time_position.bar % n) + 1;
    return typeof bars === "number"
        ? bars === current_bar
        : bars.some((b) => b === current_bar);
};

export const onbeat = (app: any) => (...beat: number[]): boolean => {
    let final_pulses: boolean[] = [];
    beat.forEach((b) => {
        let beatNumber = b % app.nominator() || app.nominator();
        let integral_part = Math.floor(beatNumber);
        integral_part = integral_part === 0 ? app.nominator() : integral_part;
        let decimal_part = Math.floor((beatNumber - integral_part) * app.ppqn() + 1);
        if (decimal_part <= 0)
            decimal_part += app.ppqn() * app.nominator();
        final_pulses.push(
            integral_part === app.cbeat() && app.cpulse() === decimal_part,
        );
    });
    return final_pulses.some((p) => p === true);
};

export const oncount = (app: any) => (beats: number[] | number, count: number): boolean => {
    if (typeof beats === "number") beats = [beats];
    const origin = app.clock.pulses_since_origin;
    let final_pulses: boolean[] = [];
    beats.forEach((b) => {
        b = b < 1 ? 0 : b - 1;
        const beatInTicks = Math.ceil(b * app.ppqn());
        const meterPosition = origin % (app.ppqn() * count);
        final_pulses.push(meterPosition === beatInTicks);
    });
    return final_pulses.some((p) => p === true);
};

export const oneuclid = (app: any) => (pulses: number, length: number, rotate: number = 0): boolean => {
    const cycle = app._euclidean_cycle(pulses, length, rotate);
    const beats = cycle.reduce((acc: number[], x: boolean, i: number) => {
        if (x) acc.push(i + 1);
        return acc;
    }, []);
    return oncount(app)(beats, length);
};

export const euclid = (app: any) => (iterator: number, pulses: number, length: number, rotate: number = 0): boolean => {
    /**
     * Returns a Euclidean cycle of size length, with n pulses, rotated or not.
     */
    return app._euclidean_cycle(pulses, length, rotate)[iterator % length];
};
export const ec = euclid;

export const rhythm = (app: any) => (div: number, pulses: number, length: number, rotate: number = 0): boolean => {
    /**
     * Returns a rhythm based on Euclidean cycle.
     */
    return (
      app.beat(div) && app._euclidean_cycle(pulses, length, rotate).beat(div)
    );
};
export const ry = rhythm;

export const nrhythm = (app: any) => (div: number, pulses: number, length: number, rotate: number = 0): boolean => {
    /**
     * Returns a negated rhythm based on Euclidean cycle.
     */
    let rhythm = app._euclidean_cycle(pulses, length, rotate).map((n: any) => !n);
    return (
      app.beat(div) && rhythm.beat(div)
    );
};
export const nry = nrhythm;

export const bin = () => (iterator: number, n: number): boolean => {
    /**
     * Returns a binary cycle of size n.
     */
    let convert: string = n.toString(2);
    let tobin: boolean[] = convert.split("").map((x: string) => x === "1");
    return tobin[iterator % tobin.length];
};

export const binrhythm = (app: any) => (div: number, n: number): boolean => {
    /**
     * Returns a binary rhythm based on division and binary cycle.
     */
    let convert: string = n.toString(2);
    let tobin: boolean[] = convert.split("").map((x: string) => x === "1");
    return app.beat(div) && tobin.beat(div);
};
export const bry = binrhythm;