var webpack = require('webpack');
var path = require('path');
var fs = require('fs');
var _ = require('lodash');
var path = require('path')

var externalModules = [
	'mkfifo',
	'sqlite3',
	'mysql2',
	'pg',
	'mariasql',
	'mssql',
	'mysql',
	'strong-oracle',
	'oracle',
	'oracledb',
	'pg-query-stream'
]

var requiredModules = []
var maybeOptionalModules = []
lookForOptionalDeps = function (sourceDir) {
	// We iterate over the node modules and mark all optional dependencies as external
	var dirs = fs.readdirSync(sourceDir)
	for (let dir of dirs) {
		let packageJson = {};
		let internalNodeModules = path.join(sourceDir, dir, 'node_modules');
		if (fs.existsSync(internalNodeModules)) {
			lookForOptionalDeps(internalNodeModules);
		}
		try {
			packageJson = JSON.parse(fs.readFileSync(path.join(sourceDir, dir, '/package.json')));
		}
		catch (e) {
			continue;
		}
		if (packageJson.optionalDependencies != null){
			maybeOptionalModules = maybeOptionalModules.concat(_.keys(packageJson.optionalDependencies))
		}
		if (packageJson.dependencies != null){
			requiredModules = requiredModules.concat(_.keys(packageJson.dependencies))
		}
	}
}

lookForOptionalDeps('./node_modules')
externalModules.push(new RegExp('^(' + _.reject(maybeOptionalModules, requiredModules).map(_.escapeRegExp).join('|') + ')(/.*)?$'));

console.log('Using the following dependencies as external:', externalModules);

module.exports = {
	entry: './src/app.coffee',
	output: {
		filename: 'app.js',
		path: path.resolve(__dirname, 'dist')
	},
	resolve: {
		extensions: [".js", ".json", ".coffee"]
	},
	target: 'node',
	module: {
		rules: [
			{
				test: /\.js$/,
				use: require.resolve('./remove-hashbang-loader')
			},
			{
				test: /\.coffee$/,
				use: require.resolve('coffee-loader')
			}
		]
	},
	externals: (context, request, callback) => {
		for (let m of externalModules) {
			if ((typeof m === 'string' && m === request) || (m instanceof RegExp && m.test(request))) {
				return callback(null, 'commonjs ' + request);
			} else if (typeof m != 'string' && !(m instanceof RegExp)) {
				throw new Error('Invalid entry in external modules: ' + m);
			}
		}
		return callback()
	},
	plugins: [
		new webpack.DefinePlugin({
			'process.env.NODE_ENV': '"production"',
		})
	]
};