React useReducer for complex state logic

                  import { useReducer } from 'react'

interface FormState {
  values: Record<string, any>
  errors: Record<string, string>
  touched: Record<string, boolean>
  isSubmitting: boolean
}

type FormAction =
  | { type: 'CHANGE_FIELD'; field: string; value: any }
  | { type: 'TOUCH_FIELD'; field: string }
  | { type: 'SET_ERRORS'; errors: Record<string, string> }
  | { type: 'SET_SUBMITTING'; isSubmitting: boolean }
  | { type: 'RESET' }

function formReducer(state: FormState, action: FormAction): FormState {
  switch (action.type) {
    case 'CHANGE_FIELD':
      return {
        ...state,
        values: {
          ...state.values,
          [action.field]: action.value,
        },
        errors: {
          ...state.errors,
          [action.field]: '', // Clear error on change
        },
      }

    case 'TOUCH_FIELD':
      return {
        ...state,
        touched: {
          ...state.touched,
          [action.field]: true,
        },
      }

    case 'SET_ERRORS':
      return {
        ...state,
        errors: action.errors,
      }

    case 'SET_SUBMITTING':
      return {
        ...state,
        isSubmitting: action.isSubmitting,
      }

    case 'RESET':
      return initialState

    default:
      return state
  }
}

const initialState: FormState = {
  values: {},
  errors: {},
  touched: {},
  isSubmitting: false,
}

export function useFormReducer() {
  const [state, dispatch] = useReducer(formReducer, initialState)

  return {
      state,
    changeField: (field: string, value: any) =>
      dispatch({ type: 'CHANGE_FIELD', field, value }),
    touchField: (field: string) =>
      dispatch({ type: 'TOUCH_FIELD', field }),
    setErrors: (errors: Record<string, string>) =>
      dispatch({ type: 'SET_ERRORS', errors }),
    setSubmitting: (isSubmitting: boolean) =>
      dispatch({ type: 'SET_SUBMITTING', isSubmitting }),
    reset: () => dispatch({ type: 'RESET' }),
  }
}