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

const asyncLib = require("async");
const path = require("path");

const Tapable = require("tapable").Tapable;
const AsyncSeriesWaterfallHook = require("tapable").AsyncSeriesWaterfallHook;
const SyncWaterfallHook = require("tapable").SyncWaterfallHook;
const ContextModule = require("./ContextModule");
const ContextElementDependency = require("./dependencies/ContextElementDependency");

const EMPTY_RESOLVE_OPTIONS = {};

module.exports = class ContextModuleFactory extends Tapable {
	constructor(resolverFactory) {
		super();
		this.hooks = {
			beforeResolve: new AsyncSeriesWaterfallHook(["data"]),
			afterResolve: new AsyncSeriesWaterfallHook(["data"]),
			contextModuleFiles: new SyncWaterfallHook(["files"]),
			alternatives: new AsyncSeriesWaterfallHook(["modules"])
		};
		this._pluginCompat.tap("ContextModuleFactory", options => {
			switch(options.name) {
				case "before-resolve":
				case "after-resolve":
				case "alternatives":
					options.async = true;
					break;
			}
		});
		this.resolverFactory = resolverFactory;
	}

	create(data, callback) {
		const context = data.context;
		const dependencies = data.dependencies;
		const resolveOptions = data.resolveOptions;
		const dependency = dependencies[0];
		this.hooks.beforeResolve.callAsync(Object.assign({
			context: context,
			dependencies: dependencies,
			resolveOptions
		}, dependency.options), (err, beforeResolveResult) => {
			if(err) return callback(err);

			// Ignored
			if(!beforeResolveResult) return callback();

			const context = beforeResolveResult.context;
			const request = beforeResolveResult.request;
			const resolveOptions = beforeResolveResult.resolveOptions;

			let loaders, resource, loadersPrefix = "";
			const idx = request.lastIndexOf("!");
			if(idx >= 0) {
				loaders = request.substr(0, idx + 1);
				let i;
				for(i = 0; i < loaders.length && loaders[i] === "!"; i++) {
					loadersPrefix += "!";
				}
				loaders = loaders.substr(i).replace(/!+$/, "").replace(/!!+/g, "!");
				if(loaders === "") loaders = [];
				else loaders = loaders.split("!");
				resource = request.substr(idx + 1);
			} else {
				loaders = [];
				resource = request;
			}

			const contextResolver = this.resolverFactory.get("context", resolveOptions || EMPTY_RESOLVE_OPTIONS);
			const loaderResolver = this.resolverFactory.get("loader", EMPTY_RESOLVE_OPTIONS);

			asyncLib.parallel([
				callback => {
					contextResolver.resolve({}, context, resource, {}, (err, result) => {
						if(err) return callback(err);
						callback(null, result);
					});
				},
				callback => {
					asyncLib.map(loaders, (loader, callback) => {
						loaderResolver.resolve({}, context, loader, {}, (err, result) => {
							if(err) return callback(err);
							callback(null, result);
						});
					}, callback);
				}
			], (err, result) => {
				if(err) return callback(err);

				this.hooks.afterResolve.callAsync(Object.assign({
					addon: loadersPrefix + result[1].join("!") + (result[1].length > 0 ? "!" : ""),
					resource: result[0],
					resolveDependencies: this.resolveDependencies.bind(this)
				}, beforeResolveResult), (err, result) => {
					if(err) return callback(err);

					// Ignored
					if(!result) return callback();

					return callback(null, new ContextModule(result.resolveDependencies, result));
				});
			});
		});
	}

	resolveDependencies(fs, options, callback) {
		const cmf = this;
		let resource = options.resource;
		let resourceQuery = options.resourceQuery;
		let recursive = options.recursive;
		let regExp = options.regExp;
		let include = options.include;
		let exclude = options.exclude;
		if(!regExp || !resource)
			return callback(null, []);

		const addDirectory = (directory, callback) => {
			fs.readdir(directory, (err, files) => {
				if(err) return callback(err);
				files = cmf.hooks.contextModuleFiles.call(files);
				if(!files || files.length === 0) return callback(null, []);
				asyncLib.map(files.filter(p => p.indexOf(".") !== 0), (seqment, callback) => {

					const subResource = path.join(directory, seqment);

					if(!exclude || !subResource.match(exclude)) {
						fs.stat(subResource, (err, stat) => {
							if(err) {
								if(err.code === "ENOENT") {
									// ENOENT is ok here because the file may have been deleted between
									// the readdir and stat calls.
									return callback();
								} else {
									return callback(err);
								}
							}

							if(stat.isDirectory()) {

								if(!recursive) return callback();
								addDirectory.call(this, subResource, callback);

							} else if(stat.isFile() && (!include || subResource.match(include))) {

								const obj = {
									context: resource,
									request: "." + subResource.substr(resource.length).replace(/\\/g, "/")
								};

								this.hooks.alternatives.callAsync([obj], (err, alternatives) => {
									if(err) return callback(err);
									alternatives = alternatives.filter(obj => regExp.test(obj.request)).map(obj => {
										const dep = new ContextElementDependency(obj.request + resourceQuery, obj.request);
										dep.optional = true;
										return dep;
									});
									callback(null, alternatives);
								});

							} else callback();

						});
					} else callback();
				}, (err, result) => {
					if(err) return callback(err);

					if(!result) return callback(null, []);

					callback(null, result.filter(Boolean).reduce((a, i) => a.concat(i), []));
				});
			});
		};

		addDirectory(resource, callback);
	}
};