Magic steps

index.test.ts

import { FlightSearchStep, getNextStep, getPrevStep, SeatType } from './index'

const VALID_STEPS_MAP: {
  [key: string]: {
    [key: string]: {
      prev: FlightSearchStep | undefined
      next: FlightSearchStep | undefined
    }
  }
} = {
  [FlightSearchStep.POINTS]: {
    [SeatType.CHARTER]: {
      prev: undefined,
      next: FlightSearchStep.PLANE_CLASS,
    },
    [SeatType.SEATS]: {
      prev: undefined,
      next: FlightSearchStep.DATES,
    },
  },
  [FlightSearchStep.PLANE_CLASS]: {
    [SeatType.CHARTER]: {
      prev: FlightSearchStep.POINTS,
      next: FlightSearchStep.DATES,
    },
    [SeatType.SEATS]: {
      prev: FlightSearchStep.POINTS,
      next: FlightSearchStep.DATES,
    },
  },
  [FlightSearchStep.DATES]: {
    [SeatType.CHARTER]: {
      prev: FlightSearchStep.PLANE_CLASS,
      next: FlightSearchStep.RESULTS,
    },
    [SeatType.SEATS]: {
      prev: FlightSearchStep.POINTS,
      next: FlightSearchStep.RESULTS,
    },
  },
  [FlightSearchStep.RESULTS]: {
    [SeatType.CHARTER]: {
      prev: FlightSearchStep.DATES,
      next: FlightSearchStep.RESULTS_ITEM,
    },
    [SeatType.SEATS]: {
      prev: FlightSearchStep.DATES,
      next: FlightSearchStep.RESULTS_ITEM,
    },
  },
  [FlightSearchStep.RESULTS_ITEM]: {
    [SeatType.CHARTER]: {
      prev: FlightSearchStep.RESULTS,
      next: undefined,
    },
    [SeatType.SEATS]: {
      prev: FlightSearchStep.RESULTS,
      next: undefined,
    },
  },
}

const getExpectedStep = (currentStep: any, seatType: any, direction: 'prev' | 'next') => {
  return VALID_STEPS_MAP[currentStep]?.[seatType]?.[direction]
}

test('`getPrevStep` should work correctly', () => {
  expect(getPrevStep('', '')).toBeUndefined()
  expect(getPrevStep('4', '1')).toBe(FlightSearchStep.DATES)
  expect(getPrevStep(FlightSearchStep.RESULTS, '1')).toBe(FlightSearchStep.DATES)
  expect(getPrevStep('4', SeatType.CHARTER)).toBe(FlightSearchStep.DATES)

  Object.values(SeatType).forEach(seatType => {
    Object.values(FlightSearchStep).forEach(currentStep => {
      expect(getPrevStep(currentStep, seatType)).toBe(getExpectedStep(currentStep, seatType, 'prev'))
    })
  })
})

test('`getNextStep` should work correctly', () => {
  expect(getNextStep('', '')).toBeUndefined()
  expect(getNextStep('4', '1')).toBe(FlightSearchStep.RESULTS_ITEM)
  expect(getNextStep(FlightSearchStep.RESULTS, '1')).toBe(FlightSearchStep.RESULTS_ITEM)
  expect(getNextStep('4', SeatType.CHARTER)).toBe(FlightSearchStep.RESULTS_ITEM)

  Object.values(SeatType).forEach(seatType => {
    Object.values(FlightSearchStep).forEach(currentStep => {
      expect(getNextStep(currentStep, seatType)).toBe(getExpectedStep(currentStep, seatType, 'next'))
    })
  })
})

index.ts

export enum FlightSearchStep {
  POINTS = 1,
  PLANE_CLASS = 2,
  DATES = 3,
  RESULTS = 4,
  RESULTS_ITEM = 5,
}

export enum SeatType {
  CHARTER = 1,
  SEATS = 2
}

type StepsMap = {
  [key: string]: {
    [key: string]: {
      prev: number | undefined
      next: number | undefined
    }
  }
}

const getValue = (valueIndex: number): FlightSearchStep | undefined => {
  const key = FlightSearchStep[valueIndex] as unknown as number
  return FlightSearchStep[key] as unknown as  FlightSearchStep | undefined
}

const STEPS_MAP = (Object.entries(FlightSearchStep) as [string, string | number][])
  .reduce<StepsMap>((acc, [key, valueIndex]) => {
    if (typeof valueIndex === 'number') {
      const prev = getValue(valueIndex - 1)
      const next = getValue(valueIndex + 1)

      acc[FlightSearchStep[key as unknown as FlightSearchStep]] = {
        [SeatType.CHARTER]: { prev, next },
        [SeatType.SEATS]: {
          prev: key === FlightSearchStep[FlightSearchStep.DATES] ? FlightSearchStep.POINTS : prev,
          next: key === FlightSearchStep[FlightSearchStep.POINTS] ? FlightSearchStep.DATES : next,
        },
      }
    }

    return acc
  }, {})

export const getPrevStep = (
  currentStep: string | FlightSearchStep,
  seatType: string | SeatType,
): FlightSearchStep | undefined => {
  return STEPS_MAP[currentStep]?.[seatType]?.prev
}

export const getNextStep = (
  currentStep: string | FlightSearchStep,
  seatType: string | SeatType,
): FlightSearchStep | undefined => {
  return STEPS_MAP[currentStep]?.[seatType]?.next
}