import {ListWrapper} from '@angular/facade';
import {OpaqueToken} from '@angular/core/src/di';

import {Validator} from '../validator';
import {MeasureValues} from '../measure_values';

/**
 * A validator that waits for the sample to have a certain size.
 */
export class SizeValidator extends Validator {
  // TODO(tbosch): use static values when our transpiler supports them
  static get PROVIDERS(): any[] { return _PROVIDERS; }
  // TODO(tbosch): use static values when our transpiler supports them
  static get SAMPLE_SIZE() { return _SAMPLE_SIZE; }

  _sampleSize: number;

  constructor(size) {
    super();
    this._sampleSize = size;
  }

  describe(): {[key: string]: any} { return {'sampleSize': this._sampleSize}; }

  validate(completeSample: MeasureValues[]): MeasureValues[] {
    if (completeSample.length >= this._sampleSize) {
      return ListWrapper.slice(completeSample, completeSample.length - this._sampleSize,
                               completeSample.length);
    } else {
      return null;
    }
  }
}

var _SAMPLE_SIZE = new OpaqueToken('SizeValidator.sampleSize');
var _PROVIDERS = [
  {
    provide: SizeValidator,
    useFactory: (size) => new SizeValidator(size),
    deps: [_SAMPLE_SIZE]
  },
  {provide: _SAMPLE_SIZE, useValue: 10}
];