export class CronHelper {
  protected static cronStringToCronObject(str: string | null): {
    ranges: Array<Array<number>> | null;
    value: number | null;
    values: Array<any> | null;
  } | null {
    if (!str) {
      return null;
    }

    if (str === '*') {
      return null;
    }

    if (str.includes(',')) {
      return {
        ranges: null,
        value: null,
        values: str.split(',').map((x) => CronHelper.cronStringToCronObject(x)),
      };
    }

    if (str.includes('-')) {
      const strSplitted: Array<string> = str.split('-');

      return {
        ranges: [[parseInt(strSplitted[0]), parseInt(strSplitted[1])]],
        value: null,
        values: null,
      };
    }

    if (str.includes('/')) {
      return null;
    }

    return {
      ranges: null,
      value: parseInt(str),
      values: null,
    };
  }

  public static matchCurrentTimestamp(
    cron: string | null,
    timestamp: number | null
  ): boolean {
    if (!timestamp) {
      return false;
    }

    if (!cron) {
      return false;
    }

    const cronSplitted: Array<string> = cron.split(' ');

    if (cronSplitted.length !== 5) {
      return false;
    }

    // minute hour date month day
    const minute = CronHelper.cronStringToCronObject(cronSplitted[0]);

    const hour = CronHelper.cronStringToCronObject(cronSplitted[1]);

    const date = CronHelper.cronStringToCronObject(cronSplitted[2]);

    const month = CronHelper.cronStringToCronObject(cronSplitted[3]);

    const day = CronHelper.cronStringToCronObject(cronSplitted[4]);

    if (!CronHelper.validCronObject(minute, new Date(timestamp).getMinutes())) {
      return false;
    }

    if (!CronHelper.validCronObject(hour, new Date(timestamp).getHours())) {
      return false;
    }

    if (!CronHelper.validCronObject(date, new Date().getDate())) {
      return false;
    }

    if (!CronHelper.validCronObject(month, new Date(timestamp).getMonth())) {
      return false;
    }

    if (!CronHelper.validCronObject(day, new Date(timestamp).getDay())) {
      return false;
    }

    return true;
  }

  protected static validCronObject(
    obj: {
      ranges: Array<Array<number>> | null;
      value: number | null;
      values: Array<any> | null;
    } | null,
    value: number | null
  ): boolean {
    if (!obj) {
      return true;
    }

    if (
      obj.values &&
      obj.values.filter((x) => CronHelper.validCronObject(x, value)).length ===
        0
    ) {
      return false;
    }

    if (obj.value && obj.value !== value) {
      return false;
    }

    if (obj.ranges) {
      for (const range of obj.ranges) {
        if (value && value >= range[0] && value <= range[1]) {
          return true;
        }
      }

      return false;
    }

    return true;
  }
}