store.ts

// store.ts

import { combineStore, createStore } from 'redux'
import { todosReducer } from './todos'
import { userReducer } from './user'

const store = createStore(
  combineStore({
    user: userReducer,
    todos: todosReducer,
  })
)

export default store

todos.ts

// todos.ts

export interface Todo {
  desc: string
  done: boolean
}

export type TodosState = ReadonlyArray<Todo>

export interface addTodoAction {
  type: 'ADD_TODO'
  payload: Todo
}

export interface updateTodoAction {
  type: 'UPDATE_TODO'
  payload: {
    idx: number
    todo: Todo
  }
}

type TodoActions = addTodoAction | updateTodoAction | removeTodoAction

const initialState: TodosState = []

export interface removeTodoAction {
  type: 'REMOVE_TODO'
  payload: number
}

export function addTodo(desc: string): addTodoAction {
  return {
    type: 'ADD_TODO',
    payload: {
      desc,
      done: false,
    },
  }
}

export function updateTodo(idx: number, todo: Todo): updateTodoAction {
  return {
    type: 'UPDATE_TODO',
    payload: {
      idx,
      todo,
    },
  }
}

export function removeTodo(idx: number): removeTodoAction {
  return {
    type: 'REMOVE_TODO',
    payload: idx,
  }
}

export function todosReducer(state = initialState, action: TodoActions): TodosState {
  switch (action.type) {
    case 'ADD_TODO':
      return state.concat(action.payload)

    case 'UPDATE_TODO':
      return state.map((todo, idx) =>
        idx === action.payload.idx ? { ...todo, ...action.payload.todo } : todo
      )

    case 'REMOVE_TODO':
      return state.filter((_, idx) => idx !== action.payload)

    default:
      return state
  }
}

user.ts

// user.ts

export interface UserState {
  name: string
  age: number
}

export interface setUserNameAction {
  type: 'SET_NAME'
  payload: string
}

export interface setUserAgeAction {
  type: 'SET_AGE'
  payload: number
}

export type UserActions = setUserNameAction | setUserAgeAction

const initialState: UserState = {
  name: '',
  age: 0,
}

export function setUserName(name: string): setUserNameAction {
  return {
    type: 'SET_NAME',
    payload: name,
  }
}

export function setUserAge(age: number): setUserAgeAction {
  return {
    type: 'SET_AGE',
    payload: age,
  }
}

export function userReducer(state = initialState, action: UserActions): UserState {
  switch (action.type) {
    case 'SET_NAME':
      return {
        ...state,
        name: action.payload,
      }

    case 'SET_AGE':
      return {
        ...state,
        age: action.payload,
      }

    default:
      return state
  }
}