/* 수열을 표시하는 프로그램 */
let digits = '';
for (var i = 0; i < 10; i++) {
  digits += i;
}
console.log(digits); // 0123456789

/* 무작위 알파벳을 표시하는 프로그램 */
let randomChars = '';
for (var i = 0; i < 8; i++) {
  randomChars += String.fromCharCode(Math.floor(Math.random() * 26) + 'a'.charCodeAt(0));
}
console.log(randomChars);

// 고차 함수 joinStrings를 활용해 횡단 관심사 추상화
function joinStrings(n, f) {
  var s = '';
  for (var i = 0; i < n; i++) {
    s += f(i);
  }
  return s;
}

let digits = joinStrings(10, function (i) {
  return i;
});
let randomChars = joinStrings(8, function (i) {
  return String.fromCharCode(Math.floor(Math.random() * 26) + 'a'.charCodeAt(0));
});
console.log(digits); // 0123456789
console.log(randomChars); // mzobequt

class CommentList extends React.Component {
  constructor(props) {
    super(props);
    this.handleChange = this.handleChange.bind(this);
    this.state = {
      comments: DataSource.getComments(),
    };
  }

  componentDidMount() {
    DataSource.addChangeListener(this.handleChange);
  }

  componentWillUnmount() {
    DataSource.removeChangeListener(this.handleChange);
  }

  handleChange() {
    this.setState({
      comments: DataSource.getComments(),
    });
  }

  render() {
    return (
      <div>
        {this.state.comments.map((comment) => (
          <Comment comment={comment} key={comment.id} />
        ))}
      </div>
    );
  }
}

class BlogPost extends React.Component {
  constructor(props) {
    super(props);
    this.handleChange = this.handleChange.bind(this);
    this.state = {
      blogPost: DataSource.getBlogPost(props.id),
    };
  }

  componentDidMount() {
    DataSource.addChangeListener(this.handleChange);
  }

  componentWillUnmount() {
    DataSource.removeChangeListener(this.handleChange);
  }

  handleChange() {
    this.setState({
      blogPost: DataSource.getBlogPost(this.props.id),
    });
  }

  render() {
    return <TextBlock text={this.state.blogPost} />;
  }
}

function withSubscription(WrappedComponent, selectData) {
  return class extends React.Component {
    constructor(props) {
      super(props);
      this.handleChange = this.handleChange.bind(this);
      this.state = {
        data: selectData(DataSource, props),
      };
    }

    componentDidMount() {
      DataSource.addChangeListener(this.handleChange);
    }

    componentWillUnmount() {
      DataSource.removeChangeListener(this.handleChange);
    }

    handleChange() {
      this.setState({
        data: selectData(DataSource, this.props),
      });
    }

    render() {
      // 래핑된 컴포넌트는 새로운 props, data와 함께 컨테이너의 모든 props를 전달받는다.
      return <WrappedComponent data={this.state.data} {...this.props} />;
    }
  };
}

const CommentListWithSubscription = withSubscription(CommentList, (DataSource) =>
  DataSource.getComments()
);

const BlogPostWithSubscription = withSubscription(BlogPost, (DataSource, props) =>
  DataSource.getBlogPost(props.id)
);

function logProps(WrappedComponent) {
  return class extends React.Component {
    componentDidUpdate(prevProps) {
      console.log('Current props: ', this.props);
      console.log('Previous props: ', prevProps);
    }
    render() {
      // 입력 component를 변경하지 않는 container 🤗
      return <WrappedComponent {...this.props} />;
    }
  };
}

render() {
  const { extraProp, ...passThroughProps } = this.props;

  const injectedProp = someStateOrInstanceMethod;

  return (
    <WrappedComponent
      injectedProp={injectedProp}
      {...passThroughProps}
    />
  );
}

const ConnectedComment = connect(commentSelector, commentActions)(CommentList);

// connect는 다른 함수를 반환하는 함수
const enhance = connect(commentListSelector, commentListActions);
// 반환된 함수는 Redux store에 연결된 컴포넌트를 반환하는 고차 함수 컴포넌트
const ConnectedComment = enhance(CommentList);

function withSubscription(WrappedComponent) {
  class WithSubscription extends React.Component {
    /* ... */
  }
  WithSubscription.displayName = `WithSubscription(${getDisplayName(WrappedComponent)})`; // WithSubscription(CommentList)
  return WithSubscription;
}

function getDisplayName(WrappedComponent) {
  return WrappedComponent.displayName || WrappedComponent.name || 'Component';
}