/**
 * Custom Implementation of React Context to manage
 * global application state
 *
 * @author  Sheharyar Naseer (@sheharyarn)
 * @license MIT
 *
 * Normal Usage:
 *
 * ```
 * <AppContext.Consumer>
 *   { (context, setContext) => (/* do something */) }
 * </AppContext.Consumer>
 * ```
 *
 * HOC Usage:
 *
 * ```
 * export default AppContext.withConsumer(MyComponent);
 * ```
 *
 * Links:
 *  - https://reactjs.org/docs/context.html
 *  - https://auth0.com/blog/react-context-api-managing-state-with-ease/
 *  - https://medium.freecodecamp.org/reacts-new-context-api-how-to-toggle-between-local-and-global-state-c6ace81443d0
 */


import React from 'react'



// TODO:
// Have a separate SessionContext ?
const Context = React.createContext({});
const initialContext = {
  env: process.env.NODE_ENV,
  session: {
    signedIn: false,
    user: null,
    token: null,
  }
};



// Custom Provider
class Provider extends React.Component {
  constructor(props) {
    super(props);

    this.state = {
      context:    initialContext,
      setContext: this.handleSetContext.bind(this),
    };
  }

  handleSetContext(context) {
    const newContext = Object.assign(this.state.context, context);
    this.setState(newContext);
  }

  render() {
    const {env} = this.state.context;

    if (env === 'development')
      console.log("Global Context:", this.state.context);

    return (
      <Context.Provider value={this.state}>
        {this.props.children}
      </Context.Provider>
    );
  }
}



// Custom Consumer
class Consumer extends React.Component {
  render() {
    const {children} = this.props;

    return (
      <Context.Consumer>
        { ({context, setContext}) => children(context, setContext) }
      </Context.Consumer>
    );
  }
}



// ContextualComponent HOC
const withConsumer = (Component) => {
  return function ContextualComponent(props) {
    return (
      <Context.Consumer>
        { (consumer) => <Component {...props} consumer={consumer} /> }
      </Context.Consumer>
    );
  };
}



// Export Methods
export default {Provider, Consumer, withConsumer};