/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
var Tokenizer = require("css-selector-tokenizer");
var postcss = require("postcss");
var loaderUtils = require("loader-utils");
var assign = require("object-assign");
var getLocalIdent = require("./getLocalIdent");

var localByDefault = require("postcss-modules-local-by-default");
var extractImports = require("postcss-modules-extract-imports");
var modulesScope = require("postcss-modules-scope");
var modulesValues = require("postcss-modules-values");
var cssnano = require("cssnano");

var parserPlugin = postcss.plugin("css-loader-parser", function(options) {
	return function(css) {
		var imports = {};
		var exports = {};
		var importItems = [];
		var urlItems = [];

		function replaceImportsInString(str) {
			if(options.import) {
				var tokens = str.split(/(\S+)/);
				tokens = tokens.map(function (token) {
					var importIndex = imports["$" + token];
					if(typeof importIndex === "number") {
						return "___CSS_LOADER_IMPORT___" + importIndex + "___";
					}
					return token;
				});
				return tokens.join("");
			}
			return str;
		}

		if(options.import) {
			css.walkAtRules("import", function(rule) {
				var values = Tokenizer.parseValues(rule.params);
				var url = values.nodes[0].nodes[0];
				if(url.type === "url") {
					url = url.url;
				} else if(url.type === "string") {
					url = url.value;
				} else throw rule.error("Unexpected format" + rule.params);
				values.nodes[0].nodes.shift();
				var mediaQuery = Tokenizer.stringifyValues(values);
				if(loaderUtils.isUrlRequest(url, options.root) && options.mode === "global") {
					url = loaderUtils.urlToRequest(url, options.root);
				}
				importItems.push({
					url: url,
					mediaQuery: mediaQuery
				});
				rule.remove();
			});
		}

		css.walkRules(function(rule) {
			if(rule.selector === ":export") {
				rule.walkDecls(function(decl) {
					exports[decl.prop] = decl.value;
				});
				rule.remove();
			} else if(/^:import\(.+\)$/.test(rule.selector)) {
				var match = /^:import\((.+)\)$/.exec(rule.selector);
				var url = loaderUtils.parseString(match[1]);
				rule.walkDecls(function(decl) {
					imports["$" + decl.prop] = importItems.length;
					importItems.push({
						url: url,
						export: decl.value
					});
				});
				rule.remove();
			}
		});

		Object.keys(exports).forEach(function(exportName) {
			exports[exportName] = replaceImportsInString(exports[exportName]);
		});

		function processNode(item) {
			switch (item.type) {
				case "value":
					item.nodes.forEach(processNode);
					break;
				case "nested-item":
					item.nodes.forEach(processNode);
					break;
				case "item":
					var importIndex = imports["$" + item.name];
					if (typeof importIndex === "number") {
						item.name = "___CSS_LOADER_IMPORT___" + importIndex + "___";
					}
					break;
				case "url":
					if (options.url && !/^#/.test(item.url) && loaderUtils.isUrlRequest(item.url, options.root)) {
						item.stringType = "";
						delete item.innerSpacingBefore;
						delete item.innerSpacingAfter;
						var url = item.url;
						item.url = "___CSS_LOADER_URL___" + urlItems.length + "___";
						urlItems.push({
							url: url
						});
					}
					break;
			}
		}

		css.walkDecls(function(decl) {
			var values = Tokenizer.parseValues(decl.value);
			values.nodes.forEach(function(value) {
				value.nodes.forEach(processNode);
			});
			decl.value = Tokenizer.stringifyValues(values);
		});
		css.walkAtRules(function(atrule) {
			if(typeof atrule.params === "string") {
				atrule.params = replaceImportsInString(atrule.params);
			}
		});

		options.importItems = importItems;
		options.urlItems = urlItems;
		options.exports = exports;
	};
});

module.exports = function processCss(inputSource, inputMap, options, callback) {

	var query = options.query;
	var root = query.root;
	var context = query.context;
	var localIdentName = query.localIdentName || "[hash:base64]";
	var localIdentRegExp = query.localIdentRegExp;
	var forceMinimize = query.minimize;
	var minimize = typeof forceMinimize !== "undefined" ? !!forceMinimize : options.minimize;

	var parserOptions = {
		root: root,
		mode: options.mode,
		url: query.url !== false,
		import: query.import !== false
	};

	var pipeline = postcss([
		localByDefault({
			mode: options.mode,
			rewriteUrl: function(global, url) {
				if(parserOptions.url){
					if(!loaderUtils.isUrlRequest(url, root)) {
						return url;
					}
					if(global) {
						return loaderUtils.urlToRequest(url, root);
					}
				}
				return url;
			}
		}),
		extractImports(),
		modulesValues,
		modulesScope({
			generateScopedName: function(exportName) {
				return getLocalIdent(options.loaderContext, localIdentName, exportName, {
					regExp: localIdentRegExp,
					hashPrefix: query.hashPrefix || "",
					context: context
				});
			}
		}),
		parserPlugin(parserOptions)
	]);

	if(minimize) {
		var minimizeOptions = assign({}, query);
		["zindex", "normalizeUrl", "discardUnused", "mergeIdents", "reduceIdents"].forEach(function(name) {
			if(typeof minimizeOptions[name] === "undefined")
				minimizeOptions[name] = false;
		});
		pipeline.use(cssnano(minimizeOptions));
	}

	pipeline.process(inputSource, {
		// we need a prefix to avoid path rewriting of PostCSS
		from: "/css-loader!" + options.from,
		to: options.to,
		map: {
			prev: inputMap,
			sourcesContent: true,
			inline: false,
			annotation: false
		}
	}).then(function(result) {
		callback(null, {
			source: result.css,
			map: result.map && result.map.toJSON(),
			exports: parserOptions.exports,
			importItems: parserOptions.importItems,
			importItemRegExpG: /___CSS_LOADER_IMPORT___([0-9]+)___/g,
			importItemRegExp: /___CSS_LOADER_IMPORT___([0-9]+)___/,
			urlItems: parserOptions.urlItems,
			urlItemRegExpG: /___CSS_LOADER_URL___([0-9]+)___/g,
			urlItemRegExp: /___CSS_LOADER_URL___([0-9]+)___/
		});
	}).catch(function(err) {
		callback(err);
	});
};
