/*

neocyclist.mjs - event scheduler like cyclist, except recieves clock pulses from clockworker in order to sync across multiple instances.

Copyright (C) 2022 Strudel contributors - see <https://codeberg.org/uzu/strudel/src/branch/main/packages/core/neocyclist.mjs>

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.

*/

import { logger } from './logger.mjs';

import { ClockCollator, cycleToSeconds } from './util.mjs';

export class NeoCyclist {

  constructor({ onTrigger, onToggle, getTime }) {

    this.started = false;

    this.cps = 0.5;

    this.getTime = getTime; // get absolute time

    this.time_at_last_tick_message = 0;

    // the clock of the worker and the audio context clock can drift apart over time

    // aditionally, the message time of the worker pinging the callback to process haps can be inconsistent.

    // we need to keep a rolling average of the time difference between the worker clock and audio context clock

    // in order to schedule events consistently.

    this.collator = new ClockCollator({ getTargetClockTime: getTime });

    this.onToggle = onToggle;

    this.latency = 0.1; // fixed trigger time offset

    this.cycle = 0;

    this.id = Math.round(Date.now() * Math.random());

    this.worker = new SharedWorker(new URL('./clockworker.js', import.meta.url));

    this.worker.port.start();

    this.channel = new BroadcastChannel('strudeltick');

    const tickCallback = (payload) => {

      const { cps, begin, end, cycle, time } = payload;

      this.cps = cps;

      this.cycle = cycle;

      const currentTime = this.collator.calculateOffset(time) + time;

      processHaps(begin, end, currentTime);

      this.time_at_last_tick_message = currentTime;

    };

    const processHaps = (begin, end, currentTime) => {

      if (this.started === false) {

        return;

      }

      const haps = this.pattern.queryArc(begin, end, { _cps: this.cps, cyclist: 'neocyclist' });

      haps.forEach((hap) => {

        if (hap.hasOnset()) {

          const timeUntilTrigger = cycleToSeconds(hap.whole.begin - this.cycle, this.cps);

          const targetTime = timeUntilTrigger + currentTime + this.latency;

          const duration = cycleToSeconds(hap.duration, this.cps);

          onTrigger?.(hap, 0, duration, this.cps, targetTime);

        }

      });

    };

    // receive messages from worker clock and process them

    this.channel.onmessage = (message) => {

      if (!this.started) {

        return;

      }

      const { payload, type } = message.data;

      switch (type) {

        case 'tick': {

          tickCallback(payload);

        }

      }

    };

  }

  sendMessage(type, payload) {

    this.worker.port.postMessage({ type, payload, id: this.id });

  }

  now() {

    const gap = (this.getTime() - this.time_at_last_tick_message) * this.cps;

    return this.cycle + gap;

  }

  setCps(cps = 1) {

    this.sendMessage('cpschange', { cps });

  }

  setCycle(cycle) {

    this.sendMessage('setcycle', { cycle });

  }

  setStarted(started) {

    this.sendMessage('toggle', { started });

    this.started = started;

    this.onToggle?.(started);

  }

  start() {

    logger('[cyclist] start');

    this.setStarted(true);

  }

  stop() {

    logger('[cyclist] stop');

    this.collator.reset();

    this.setStarted(false);

  }

  setPattern(pat, autostart = false) {

    this.pattern = pat;

    if (autostart && !this.started) {

      this.start();

    }

  }

  log(begin, end, haps) {

    const onsets = haps.filter((h) => h.hasOnset());

    console.log(`${begin.toFixed(4)} - ${end.toFixed(4)} ${Array(onsets.length).fill('I').join('')}`);

  }

}