/*
cyclist.mjs - event scheduler for a single strudel instance. for multi-instance scheduler, see - see <https://github.com/tidalcycles/strudel/blob/main/packages/core/neocyclist.mjs>
Copyright (C) 2022 Strudel contributors - see <https://github.com/tidalcycles/strudel/blob/main/packages/core/cyclist.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 createClock from './zyklus.mjs';
import { logger } from './logger.mjs';

export class Cyclist {
  constructor({
    interval,
    onTrigger,
    onToggle,
    onError,
    getTime,
    latency = 0.1,
    setInterval,
    clearInterval,
    beforeStart,
  }) {
    this.started = false;
    this.beforeStart = beforeStart;
    this.cps = 0.5;
    this.num_ticks_since_cps_change = 0;
    this.lastTick = 0; // absolute time when last tick (clock callback) happened
    this.lastBegin = 0; // query begin of last tick
    this.lastEnd = 0; // query end of last tick
    this.getTime = getTime; // get absolute time
    this.num_cycles_at_cps_change = 0;
    this.seconds_at_cps_change; // clock phase when cps was changed
    this.onToggle = onToggle;
    this.latency = latency; // fixed trigger time offset
    this.clock = createClock(
      getTime,
      // called slightly before each cycle
      (phase, duration, _, t) => {
        if (this.num_ticks_since_cps_change === 0) {
          this.num_cycles_at_cps_change = this.lastEnd;
          this.seconds_at_cps_change = phase;
        }
        this.num_ticks_since_cps_change++;
        const seconds_since_cps_change = this.num_ticks_since_cps_change * duration;
        const num_cycles_since_cps_change = seconds_since_cps_change * this.cps;

        try {
          const begin = this.lastEnd;
          this.lastBegin = begin;
          const end = this.num_cycles_at_cps_change + num_cycles_since_cps_change;
          this.lastEnd = end;
          this.lastTick = phase;

          if (phase < t) {
            // avoid querying haps that are in the past anyway
            console.log(`skip query: too late`);
            return;
          }

          // query the pattern for events
          const haps = this.pattern.queryArc(begin, end, { _cps: this.cps });

          haps.forEach((hap) => {
            if (hap.hasOnset()) {
              const targetTime =
                (hap.whole.begin - this.num_cycles_at_cps_change) / this.cps + this.seconds_at_cps_change + latency;
              const duration = hap.duration / this.cps;
              // the following line is dumb and only here for backwards compatibility
              // see https://github.com/tidalcycles/strudel/pull/1004
              const deadline = targetTime - phase;
              onTrigger?.(hap, deadline, duration, this.cps, targetTime);
              if (hap.value.cps !== undefined && this.cps != hap.value.cps) {
                this.cps = hap.value.cps;
                this.num_ticks_since_cps_change = 0;
              }
            }
          });
        } catch (e) {
          logger(`[cyclist] error: ${e.message}`);
          onError?.(e);
        }
      },
      interval, // duration of each cycle
      0.1,
      0.1,
      setInterval,
      clearInterval,
    );
  }
  now() {
    if (!this.started) {
      return 0;
    }
    const secondsSinceLastTick = this.getTime() - this.lastTick - this.clock.duration;
    return this.lastBegin + secondsSinceLastTick * this.cps; // + this.clock.minLatency;
  }
  setStarted(v) {
    this.started = v;
    this.onToggle?.(v);
  }
  async start() {
    await this.beforeStart?.();
    this.num_ticks_since_cps_change = 0;
    this.num_cycles_at_cps_change = 0;
    if (!this.pattern) {
      throw new Error('Scheduler: no pattern set! call .setPattern first.');
    }
    logger('[cyclist] start');
    this.clock.start();
    this.setStarted(true);
  }
  pause() {
    logger('[cyclist] pause');
    this.clock.pause();
    this.setStarted(false);
  }
  stop() {
    logger('[cyclist] stop');
    this.clock.stop();
    this.lastEnd = 0;
    this.setStarted(false);
  }
  async setPattern(pat, autostart = false) {
    this.pattern = pat;
    if (autostart && !this.started) {
      await this.start();
    }
  }
  setCps(cps = 0.5) {
    if (this.cps === cps) {
      return;
    }
    this.cps = cps;
    this.num_ticks_since_cps_change = 0;
  }
  log(begin, end, haps) {
    const onsets = haps.filter((h) => h.hasOnset());
    console.log(`${begin.toFixed(4)} - ${end.toFixed(4)} ${Array(onsets.length).fill('I').join('')}`);
  }
}