/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
"use strict";

const asyncLib = require("async");
const PrefetchDependency = require("./dependencies/PrefetchDependency");
const NormalModule = require("./NormalModule");

class AutomaticPrefetchPlugin {
	apply(compiler) {
		compiler.hooks.compilation.tap("AutomaticPrefetchPlugin", (compilation, {
			normalModuleFactory
		}) => {
			compilation.dependencyFactories.set(PrefetchDependency, normalModuleFactory);
		});
		let lastModules = null;
		compiler.hooks.afterCompile.tap("AutomaticPrefetchPlugin", (compilation) => {
			lastModules = compilation.modules
				.filter(m => m instanceof NormalModule)
				.map(m => ({
					context: m.context,
					request: m.request
				}));
		});
		compiler.hooks.make.tapAsync("AutomaticPrefetchPlugin", (compilation, callback) => {
			if(!lastModules) return callback();
			asyncLib.forEach(lastModules, (m, callback) => {
				compilation.prefetch(m.context || compiler.context, new PrefetchDependency(m.request), callback);
			}, callback);
		});
	}
}
module.exports = AutomaticPrefetchPlugin;