import React from "react";
import { isEqual } from "underscore";

/**
 * HOC for diagnosing unnecessary renders and identifying faulty selectors
 *
 * Adds a logger function to a component that lists all changed props
 * Also checks if changed props are deeply equal
 *
 * Usage: Decorate the component you are investigating with renderDoctor:
 *
 * @renderDoctor
 * export default class FlightGridControl extends _Base { ...component code };
 *
 * @param  {node} ComposedComponent Component to decorate
 * @return {node}                   Component decorated with logger
 */
const renderDoctor = ComposedComponent => class extends React.Component {
  componentWillReceiveProps(nextProps) {
    let propsChange = Object.keys(nextProps).reduce((changedProps, key) => {
      if (nextProps[key] !== this.props[key]) {
        changedProps = {
          ...changedProps,
          [key]: {
            old: this.props[key],
            new: nextProps[key],
            deepEqual: isEqual(this.props[key], nextProps[key])
          }
        };
      }
      return changedProps;
    }, {});

    if (Object.keys(propsChange).length) {
      console.groupCollapsed("%cRender Doctor%c", "color:#AA0000;", "color:#000;");
      console.table(propsChange, ['deepEqual']);
      console.groupEnd("%cRender Doctor%c", "color:#AA0000;", "color:#000;");
    }
  }

  render() {
    return <ComposedComponent {...this.props} />;
  }
};

export default renderDoctor;