/**
 * Relabi event generator
 */

import * as Tone from "tone";
import RelabiCanvas from "./canvas";

const TWO_PI = 2 * Math.PI;

/**
 * Wave functions
 */
const WAVE_SHAPES = {
  sine: Math.cos,
  triangle: (time) =>
    (4 / TWO_PI) *
      Math.abs(
        ((((time - TWO_PI / 4) % TWO_PI) + TWO_PI) % TWO_PI) - TWO_PI / 2
      ) -
    1,
  square: (time) => (time % TWO_PI < Math.PI ? 1 : -1),
  saw: (time) => ((time % TWO_PI) - Math.PI) / Math.PI,
};

/**
 * Relabi generator
 */
export default class Relabi {
  /**
   * Initialize generator
   */
  constructor({ waves, bounds, parent }) {
    this.updateTime = 1;
    this.steps = 50;
    this.waves = waves || [
      { shape: "triangle", frequency: randrange(0.5, 1.5) },
      { shape: "triangle", frequency: randrange(0.75, 2.25) },
      { shape: "triangle", frequency: randrange(1, 3) },
      { shape: "triangle", frequency: randrange(2, 4) },
    ];
    this.bounds = bounds;
    this.previousValue = null;
    this.canvas = new RelabiCanvas({ relabi: this, parent });
  }

  /**
   * Start the generator
   */
  start() {
    console.log("Start Relabi");
    this.stop();
    this.clock = new Tone.Clock((time) => {
      const values = this.generate(time);
      const notes = this.play(values);
      this.canvas.append(time, values, notes);
    }, this.updateTime);
    this.clock.start();
  }

  /**
   * Stop the generator and reset it
   */
  stop() {
    if (this.clock) {
      this.clock.stop();
      this.clock.dispose();
    }
  }

  /**
   * Generate relabi events
   */
  generate(time) {
    const waveCount = this.waves.length;
    let index;
    let step;
    let value;
    let values = [];

    // Overshoot the line slightly each time
    let stepCount = this.steps + 20;

    // Generate several events per second
    for (step = 0; step < stepCount; step += 1) {
      // Time offset for this event
      const timeOffset = time + (step * this.updateTime) / this.steps;

      // Initialize value
      value = 0;

      // Compute the wave functions for this event
      for (index = 0; index < waveCount; index += 1) {
        const wave = this.waves[index];
        value += WAVE_SHAPES[wave.shape](timeOffset * wave.frequency);
      }

      // Scale to [-1, 1]
      value /= waveCount;

      values.push([timeOffset, value]);
    }

    return values;
  }

  /**
   * Schedule relabi events
   */
  play(values) {
    const boundsCount = this.bounds.length;
    let previousValue = this.previousValue;
    let index;
    let step;
    let noteCount = 0;
    const notes = [];

    for (step = 0; step < this.steps; step += 1) {
      // Get the next value
      const [time, value] = values[step];

      // Compute whether we crossed a boundary, and which direction
      for (index = 0; index < boundsCount; index += 1) {
        const bound = this.bounds[index];
        if (
          value < bound.level &&
          bound.level < previousValue &&
          previousValue !== null
        ) {
          // Going down
          this.trigger(time, bound.sounds[0]);
          notes.push([time, bound.level, true]);
          noteCount += 1;
        } else if (
          value > bound.level &&
          bound.level > previousValue &&
          previousValue !== null
        ) {
          // Going up
          this.trigger(time, bound.sounds[1]);
          notes.push([time, bound.level, false]);
          noteCount += 1;
        }
      }

      // Update the previous value
      previousValue = value;
    }

    // Store the latest value
    this.previousValue = previousValue;

    // Return the notes
    return notes;
  }

  /**
   * Trigger an event
   */
  trigger(time, sound) {
    // console.log("trigger index", index, time);
    sound.instrument.play(time, sound);
  }
}