const envFlag = require('node-env-flag');
const webpack = require('webpack');
const shouldAnalyze = envFlag(process.env.ANALYZE);
const assetPrefix = process.env.NEXT_ASSET_PREFIX;

module.exports = {
  webpack: config => {
    config.plugins.push(new webpack.EnvironmentPlugin({ BASE_URL: null, LONG_CACHE: null }));

    if (shouldAnalyze) {
      // We don't include webpack-bundle-analyzer in devDependencies, so  load
      // lazily.
      const { BundleAnalyzerPlugin } = require('webpack-bundle-analyzer');
      config.plugins.push(new BundleAnalyzerPlugin({
        analyzerMode: 'server',
        analyzerPort: 8888,
        openAnalyzer: true,
      }));
    }

    config.module.loaders = (config.module.loaders || []).concat({
      test: /\.json$/,
      loader: 'json-loader',
    });

    if (assetPrefix) {
      config.output.publicPath = `${assetPrefix}/${config.output.publicPath}`;
    }

    return config;
  },
  exportPathMap: () => ({
    '/': { page: '/' },
  }),
};

// Avoid setting an `undefined` value. This causes
// `TypeError: Cannot read property 'replace' of undefined` at build time.
if (assetPrefix) {
  module.exports.assetPrefix = assetPrefix;
}