let path = require('path');
let config = require('./config');
let ExtractTextPlugin = require('extract-text-webpack-plugin');

exports.assetsPath = function(_path) {
    let assetsSubDirectory = process.env.NODE_ENV === 'production' ?
    config.build.assetsSubDirectory :
    config.dev.assetsSubDirectory;

    return path.posix.join(assetsSubDirectory, _path);
};

exports.cssLoaders = function(options) {
    options = options || {};

    let cssLoader = {
        loader: 'css-loader',
        options: {
            minimize: process.env.NODE_ENV === 'production',
            sourceMap: options.sourceMap
        }
    };
    let autoprefixerLoader = {
        loader: 'autoprefixer-loader'
    };

  // generate loader string to be used with extract text plugin
    function generateLoaders(loader, loaderOptions) {
        let loaders = [cssLoader, autoprefixerLoader];

        if (loader) {
            loaders.push({
                loader: loader + '-loader',
                options: Object.assign({}, loaderOptions, {
                    sourceMap: options.sourceMap
                })
            });
        }

    // Extract CSS when that option is specified
    // (which is the case during production build)
        if (options.extract) {
            return ExtractTextPlugin.extract({
                use: loaders,
                fallback: 'vue-style-loader'
            });
        } else {
            return ['vue-style-loader'].concat(loaders);
        }
    }

  // https://vue-loader.vuejs.org/en/configurations/extract-css.html
    return {
        css: generateLoaders(),
        scss: generateLoaders('sass'),
    };
};

// Generate loaders for standalone style files (outside of .vue)
exports.styleLoaders = function(options) {
    let output = [];
    let loaders = exports.cssLoaders(options);

    for (let extension in loaders) {
        if (!extension) {
            continue;
        }
        let loader = loaders[extension];

        output.push({
            test: new RegExp('\\.' + extension + '$'),
            use: loader
        });
    }
    return output;
};