Machine to handle service request steps on the device

machine.js

const serviceRequestMachine = Machine({
  id: 'service-request',
  initial: 'service',
  context: {
    hasTerms: false,
    hasQuantity: true,
    quantity: 1,
    terms: false,
  },
  states: {
    service: {
      on: {
        REQUEST: 'request',
      }
    },
    request: {
      on: {
        '': [
          {
          target: 'quantity', cond: 'hasQuantity'
        },
         {
          target: 'terms',
          cond: 'hasTerms'
        },
         {
          target: 'phone', cond: 'hasNoQuantityOrNoTerms'
        },
        ]
      }
    },
    quantity: {
      on: {
        NEXT: [
          { target: 'terms', cond: 'hasTerms' },
          { target: 'phone', cond: 'hasNoTerms' },
        ],
        INCREASE: {
          target: 'quantity',
          actions: 'increaseQuantity',
          cond: 'canIncreaseQuantity'
        },
        DECREASE: {
          target: 'quantity',
          actions: 'decreaseQuantity',
          cond: 'canDecreaseQuantity'
        }
      },
    },
    terms: {
      on: {
        ACCEPT: {
          target: 'phone',
          actions: 'acceptTerms'
        }
      }
    },
    phone: {
      on: {
        SEND: 'confirmation'
      }
    },
    confirmation: {
      after: {
        5000: 'success'
      },
      on: {
        DONE: 'success'
      }
    },
    success: {
      type: 'final'
    }
  }
}, {
  actions: {
    increaseQuantity: assign({ quantity: ({ quantity }) => quantity + 1 }),
    decreaseQuantity: assign({ quantity: ({ quantity }) => quantity - 1 }),
    acceptTerms: assign({ terms: () => true })
  },
  guards: {
    canDecreaseQuantity: ({ quantity }) => quantity > 1,
    canIncreaseQuantity: ({ quantity }) => quantity <= 10,
    hasQuantity: ({ hasQuantity }) => hasQuantity,
    hasTerms: ({ hasTerms }) => hasTerms,
    hasNoQuantityOrNoTerms: ({ hasTerms, hasQuantity }) => !hasQuantity && !hasTerms,
    hasNoTerms: ({ hasTerms }) => !hasTerms,
    didAcceptTerms: ({ terms }) => terms,
  }
})