[Redux] Extracting Container Components -- VisibleTodoList

Code to be refacted:

const TodoList = ({
  todos,
  onTodoClick
}) => (
  <ul>
    {todos.map(todo =>
      <Todo
        key={todo.id}
        {...todo}
        onClick={() => onTodoClick(todo.id)}
      />
    )}
  </ul>
);

let nextTodoId = 0;
const TodoApp = ({
  todos,
  visibilityFilter
}) => (
  <div>
    ...
    ...
    <TodoList
      todos={
        getVisibleTodos(
          todos,
          visibilityFilter
        )
      }
      onTodoClick={id =>
        store.dispatch({
          type: 'TOGGLE_TODO',
          id
        })
      }
    />
    ....
  </div>
);

Currently we pass the 'todos' and 'onTodoClick' from top container component 'TodoApp', all the way down to the 'Todo' component. 

So we want simplfy 'TodoList' Component in TodoApp, create a new container component 'VisibleTodoList'.

In TodoApp:

const TodoApp = ({
  todos,
  visibilityFilter
}) => (
  <div>
    <AddTodo
      onAddClick={text =>
        store.dispatch({
          type: 'ADD_TODO',
          id: nextTodoId++,
          text
        })
      }
    />
    <VisibleTodoList />
    <Footer />
  </div>
);

VisibleTodoList:

class VisibleTodoList extends Component {
  
  componentDidMount() {
    this.unsubscribe = store.subscribe(() =>
      this.forceUpdate()
    );
  }
  
  componentWillUnmount() {
    this.unsubscribe();
  }
  
  render() {
    
    const props = this.props;
    const state = store.getState();
    
    return (
    <TodoList
      todos={
        getVisibleTodos(
          state.todos,
          state.visibilityFilter
        )
      }
      onTodoClick={id =>
        store.dispatch({
          type: 'TOGGLE_TODO',
          id
        })
      }
    />
    );
  }
}

----------------

Code:

const todo = (state, action) => {
  switch (action.type) {
    case 'ADD_TODO':
      return {
        id: action.id,
        text: action.text,
        completed: false
      };
    case 'TOGGLE_TODO':
      if (state.id !== action.id) {
        return state;
      }

      return {
        ...state,
        completed: !state.completed
      };
    default:
      return state;
  }
};

const todos = (state = [], action) => {
  switch (action.type) {
    case 'ADD_TODO':
      return [
        ...state,
        todo(undefined, action)
      ];
    case 'TOGGLE_TODO':
      return state.map(t =>
        todo(t, action)
      );
    default:
      return state;
  }
};

const visibilityFilter = (
  state = 'SHOW_ALL',
  action
) => {
  switch (action.type) {
    case 'SET_VISIBILITY_FILTER':
      return action.filter;
    default:
      return state;
  }
};

const { combineReducers } = Redux;
const todoApp = combineReducers({
  todos,
  visibilityFilter
});

const { createStore } = Redux;
const store = createStore(todoApp);

const { Component } = React;

const Link = ({
  active,
  children,
  onClick
}) => {
  if (active) {
    return <span>{children}</span>;
  }

  return (
    <a href='#'
       onClick={e => {
         e.preventDefault();
         onClick();
       }}
    >
      {children}
    </a>
  );
};

class FilterLink extends Component {
  componentDidMount() {
    this.unsubscribe = store.subscribe(() =>
      this.forceUpdate()
    );
  }
  
  componentWillUnmount() {
    this.unsubscribe();
  }
  
  render() {
    const props = this.props;
    const state = store.getState();
    
    return (
      <Link
        active={
          props.filter ===
          state.visibilityFilter
        }
        onClick={() =>
          store.dispatch({
            type: 'SET_VISIBILITY_FILTER',
            filter: props.filter
          })
        }
      >
        {props.children}
      </Link>
    );
  }
}

const Footer = () => (
  <p>
    Show:
    {' '}
    <FilterLink
      filter='SHOW_ALL'
    >
      All
    </FilterLink>
    {', '}
    <FilterLink
      filter='SHOW_ACTIVE'
    >
      Active
    </FilterLink>
    {', '}
    <FilterLink
      filter='SHOW_COMPLETED'
    >
      Completed
    </FilterLink>
  </p>
);

const Todo = ({
  onClick,
  completed,
  text
}) => (
  <li
    onClick={onClick}
    style={{
      textDecoration:
        completed ?
          'line-through' :
          'none'
    }}
  >
    {text}
  </li>
);

const TodoList = ({
  todos,
  onTodoClick
}) => (
  <ul>
    {todos.map(todo =>
      <Todo
        key={todo.id}
        {...todo}
        onClick={() => onTodoClick(todo.id)}
      />
    )}
  </ul>
);

const AddTodo = ({
  onAddClick
}) => {
  let input;

  return (
    <div>
      <input ref={node => {
        input = node;
      }} />
      <button onClick={() => {
        onAddClick(input.value);
        input.value = '';
      }}>
        Add Todo
      </button>
    </div>
  );
};

const getVisibleTodos = (
  todos,
  filter
) => {
  switch (filter) {
    case 'SHOW_ALL':
      return todos;
    case 'SHOW_COMPLETED':
      return todos.filter(
        t => t.completed
      );
    case 'SHOW_ACTIVE':
      return todos.filter(
        t => !t.completed
      );
  }
}

class VisibleTodoList extends Component {
  
  componentDidMount() {
    this.unsubscribe = store.subscribe(() =>
      this.forceUpdate()
    );
  }
  
  componentWillUnmount() {
    this.unsubscribe();
  }
  
  render() {
    
    const props = this.props;
    const state = store.getState();
    
    return (
    <TodoList
      todos={
        getVisibleTodos(
          state.todos,
          state.visibilityFilter
        )
      }
      onTodoClick={id =>
        store.dispatch({
          type: 'TOGGLE_TODO',
          id
        })
      }
    />
    );
  }
}

let nextTodoId = 0;
const TodoApp = ({
  todos,
  visibilityFilter
}) => (
  <div>
    <AddTodo
      onAddClick={text =>
        store.dispatch({
          type: 'ADD_TODO',
          id: nextTodoId++,
          text
        })
      }
    />
    <VisibleTodoList />
    <Footer />
  </div>
);

const render = () => {
  ReactDOM.render(
    <TodoApp
      {...store.getState()}
    />,
    document.getElementById('root')
  );
};

store.subscribe(render);
render();