Interval generator

generator.js

// TIME_INTERVAL - это те самые интервалы между временем.
// START_TIME - "00:00"
// END_TIME - "23:00"
function getTimesInterval(TIME_INTERVAL, START_TIME, END_TIME) {
  const INT_START_TIME = convert24ToInt(START_TIME, 'START')
  const INT_END_TIME = convert24ToInt(END_TIME, 'END')
  const INT_STEP = TIME_INTERVAL * 100 / 60
  const TIMES_RAGE = generateRange(INT_START_TIME, INT_END_TIME, INT_STEP).map(convertIntTo24)

  function convert24ToInt(TIME, TYPE) {
    let [hours, minutes] = splitTime(TIME)

    if (TYPE === 'END') {
      if (hours === '00') {
        hours = 24.01
      }
    }

    return (hours * 100) + (minutes * 100.0 / 60)
  }

  function splitTime(TIME) {
    return TIME.split(':')
  }

  function convertIntTo24(TIME) {
    function leftPad(NUMBER) {
      return (NUMBER < 10) ? ('0' + NUMBER) : NUMBER
    }

    let hours = Math.round(parseInt(TIME / 100, 10))
    let minutes = Math.round((TIME % 100) * 60 / 100)

    if (hours === 24) {
      hours = 0
    }

    return `${leftPad(hours)}:${leftPad(minutes)}`
  }

  function generateRange(START, STOP, STEP) {
    const OUTPUT = [START]
    let temp = START

    while(temp < STOP) {
      temp += STEP
      OUTPUT.push(temp)
    }

    return OUTPUT
  }

  function generateTimeInterval(TIME_RANGE) {
    const TIME_RANGE_LENGTH = TIME_RANGE.length - 1

    return TIME_RANGE.reduce((ACCUMULATOR, ITEM, INDEX) => {
      const CURRENT_TIMESTAMP = ITEM
      const NEXT_TIMESTAMP = TIME_RANGE[INDEX + 1]

      if (NEXT_TIMESTAMP === undefined) {
        return ACCUMULATOR
      }

      if (TIME_RANGE_LENGTH === INDEX + 1 && NEXT_TIMESTAMP > END_TIME) {
        return ACCUMULATOR
      }


      const [FROM_HOUR, FROM_MINUTE] = splitTime(CURRENT_TIMESTAMP)
      const [TO_HOUR, TO_MINUTE] = splitTime(NEXT_TIMESTAMP)

      ACCUMULATOR.push({
        fullIntervalTime: `${CURRENT_TIMESTAMP}-${NEXT_TIMESTAMP}`,

        from: {
          hour: FROM_HOUR,
          minute: FROM_MINUTE
        },

        to: {
          hour: TO_HOUR,
          minute: TO_MINUTE
        }
      })

      return ACCUMULATOR
    }, [])
  }

  return generateTimeInterval(TIMES_RAGE)
}