// taken from https://reacttraining.com/react-router/web/guides/code-splitting
import React from "react";
import load from "little-loader";

export class Bundle extends React.Component {
    constructor(props) {
        super(props);
        this.state = { mod: null };
    }

    componentDidMount() {
        this.load(this.props);
    }

    UNSAFE_componentWillReceiveProps(nextProps) {
        if (nextProps.load !== this.props.load) {
            this.load(nextProps);
        }
    }

    load(props) {
        this.setState({
            mod: null,
        });
        Promise.all(
            [props.loader].concat(
                (props.overrides || []).map((src) => loadAsPromise(src)),
            ),
        ).then((m) => {
            const _mod = m[0];
            this.setState({
                mod: function(mod) {
                    if (mod["default"]) {
                        return mod.default;
                    } else if (mod["__esModule"] === true) {
                        return mod[props.symbol] ? mod[props.symbol] : null;
                    } else {
                        return mod;
                    }
                }(_mod),
            });
        }).catch((err) => {
            console.warn(err);
        });
    }

    render() {
        return this.state.mod ? this.props.children(this.state.mod) : null;
    }
}


function loadAsPromise(src) {
    return new Promise((done, error) => {
        load(src, function(err) {
            if (err) {
                error(err);
                return;
            }
            done();
        });
    });
}