export class StartTimeRange {
  public static fromMinutes(start: number): StartTimeRange {
    if (start <= 0) {
      throw new Error('start must be greater than 0');
    }
    return new StartTimeRange(`-PT${start}M`);
  }

  public static fromHours(start: number): StartTimeRange {
    if (start <= 0) {
      throw new Error('start must be greater than 0');
    }
    return new StartTimeRange(`-PT${start}H`);
  }

  public static fromDays(start: number): StartTimeRange {
    if (start <= 0) {
      throw new Error('start must be greater than 0');
    }
    return new StartTimeRange(`-P${start}D`);
  }

  public static fromWeeks(start: number): StartTimeRange {
    if (start <= 0) {
      throw new Error('start must be greater than 0');
    }
    return new StartTimeRange(`-P${start}W`);
  }

  public static fromMonths(start: number): StartTimeRange {
    if (start <= 0) {
      throw new Error('start must be greater than 0');
    }
    return new StartTimeRange(`-P${start}M`);
  }

  public static fromDate(start: Date): StartTimeRange {
    return new StartTimeRange(start.toISOString());
  }

  private constructor(public readonly start: string) { }
}

export class EndTimeRange {
  public static fromDate(end: Date): EndTimeRange {
    return new EndTimeRange(end.toISOString());
  }

  private constructor(public readonly end: string) { }
}

export interface StartTimeRangeType {
  unit?: string; // ex. -PT5M, -P3M.
  date?: string; // ISO 8601 format. For example, 2018-12-17T06:00:00.000Z.
}

export class StartTimeRange {
  public static fromMinutes(unit: number): StartTimeRange {
    if (unit <= 0) {
      throw new Error('start must be greater than 0');
    }
    return new StartTimeRange({
      unit: `-PT${unit}M`,
    });
  }

  public static fromHours(unit: number): StartTimeRange {
    if (unit <= 0) {
      throw new Error('start must be greater than 0');
    }
    return new StartTimeRange({
      unit: `-PT${unit}H`,
    });
  }

  public static fromDays(unit: number): StartTimeRange {
    if (unit <= 0) {
      throw new Error('start must be greater than 0');
    }
    return new StartTimeRange({
      unit: `-P${unit}D`,
    });
  }

  public static fromWeeks(unit: number): StartTimeRange {
    if (unit <= 0) {
      throw new Error('start must be greater than 0');
    }
    return new StartTimeRange({
      unit: `-P${unit}W`,
    });
  }

  public static fromMonths(unit: number): StartTimeRange {
    if (unit <= 0) {
      throw new Error('start must be greater than 0');
    }
    return new StartTimeRange({
      unit: `-P${unit}M`,
    });
  }

  public static fromDate(date: Date): StartTimeRange {
    return new StartTimeRange({
      date: date.toISOString(),
    });
  }

  private constructor(public readonly start: StartTimeRangeType) {}
}

export class EndTimeRange {
  public static fromDate(date: Date): EndTimeRange {
    return new EndTimeRange(date.toISOString());
  }

  private constructor(public readonly end: string) { }
}

export class GaugeWidget extends Resource {
  // ...
  // ...
  constructor(scope: Construct, id: string, props: GaugeWidgetProps = {}) {
    // ...
    // ...
    if (props.end !== undefined && props.start === undefined) {
      throw new Error('If you specify a value for end, you must also specify a value for start.');
    }
    if (props.end !== undefined && props.start?.start.date === undefined) {
      throw new Error('If `end` is specified, `start` must be specified by `StartTimeRange.fromDate`.');