const getChunkFiles = require('./lib/getChunkFiles.js');
const replaceAssets = require('./lib/replaceAssets.js');
const createAsset = require('./lib/createAsset.js');

/**
 * A webpack plugin which can be used to replace asset names in compiled chunks.
 * It listens to webpack's emit event and it therefore can also be used in watch mode.
 *
 * @param {Object} options - the options for the plugin
 * @param {string[]} options.targets - the target chunks in which the assets should be replaced
 * @constructor
 */
function InjectAssetsPlugin (options = {}) {
    if (!options.hasOwnProperty('targets')) {
        throw Error('targets must be specified');
    }

    this.options = options;
}

InjectAssetsPlugin.prototype = {
    apply (compiler) {
        compiler.plugin('emit', function injectAssets(compilation, callback) {
            const {targets} = this.options;
            const {assets} = compilation;

            targets.forEach(function replaceAssetsForTarget (targetAssetName) {
                const targetAsset = assets[targetAssetName];

                if (!targetAsset) {
                    console.warn(`the target asset '${targetAsset}' was not found in the compilation 
                                  and therefore gets skipped`.replace(/\s+/, ' '));
                    return;
                }

                const chunkFiles = getChunkFiles(compilation);
                const targetSource = targetAsset.source().toString();
                const modifiedTarget = replaceAssets(targetSource, chunkFiles);

                assets[targetAssetName] = modifiedTarget
                    ? createAsset(modifiedTarget, targetAssetName)
                    : assets[targetAsset];
            });

            callback();
        }.bind(this));
    }
};

module.exports = InjectAssetsPlugin;