/**
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at

 * http://www.apache.org/licenses/LICENSE-2.0

 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import type Nullable from './Nullable';
import { requestAnimationFrame } from './utils/compatible';
import { merge } from './utils/typeChecks';

type AnimationDoFrameCallback = (frameTime: number) => void;

interface AnimationOptions {
  duration: number;
  iterationCount: number;
}

export default class Animation {
  private readonly _options = { duration: 500, iterationCount: 1 };

  private _doFrameCallback: Nullable<AnimationDoFrameCallback>;

  private _currentIterationCount = 0;
  private _running = false;

  private _time = 0;

  constructor(options?: Partial<AnimationOptions>) {
    merge(this._options, options);
  }

  _loop(): void {
    this._running = true;
    const step: () => void = () => {
      if (this._running) {
        const diffTime = new Date().getTime() - this._time;
        if (diffTime < this._options.duration) {
          this._doFrameCallback?.(diffTime);
          requestAnimationFrame(step);
        } else {
          this.stop();
          this._currentIterationCount++;
          if (this._currentIterationCount < this._options.iterationCount) {
            this.start();
          }
        }
      }
    };
    requestAnimationFrame(step);
  }

  doFrame(callback: AnimationDoFrameCallback): this {
    this._doFrameCallback = callback;
    return this;
  }

  setDuration(duration: number): this {
    this._options.duration = duration;
    return this;
  }

  setIterationCount(iterationCount: number): this {
    this._options.iterationCount = iterationCount;
    return this;
  }

  start(): void {
    if (!this._running) {
      this._time = new Date().getTime();
      this._loop();
    }
  }

  stop(): void {
    if (this._running) {
      this._doFrameCallback?.(this._options.duration);
    }
    this._running = false;
  }
}