SingleFile/lib/single-file/modules/css-matched-rules.js

/*
 * Copyright 2010-2020 Gildas Lormeau
 * contact : gildas.lormeau <at> gmail.com
 * 
 * This file is part of SingleFile.
 *
 *   The code in this file is free software: you can redistribute it and/or 
 *   modify it under the terms of the GNU Affero General Public License 
 *   (GNU AGPL) as published by the Free Software Foundation, either version 3
 *   of the License, or (at your option) any later version.
 * 
 *   The code in this file is distributed in the hope that it will be useful, 
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of 
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero 
 *   General Public License for more details.
 *
 *   As additional permission under GNU AGPL version 3 section 7, you may 
 *   distribute UNMODIFIED VERSIONS OF THIS file without the copy of the GNU 
 *   AGPL normally required by section 4, provided you include this license 
 *   notice and a URL through which recipients can access the Corresponding 
 *   Source.
 */

this.singlefile.lib.modules.matchedRules = this.singlefile.lib.modules.matchedRules || (() => {

	const singlefile = this.singlefile;

	const MEDIA_ALL = "all";
	const IGNORED_PSEUDO_ELEMENTS = ["after", "before", "first-letter", "first-line", "placeholder", "selection", "part", "marker"];
	const SINGLE_FILE_HIDDEN_CLASS_NAME = "sf-hidden";
	const DISPLAY_STYLE = "display";
	const REGEXP_VENDOR_IDENTIFIER = /-(ms|webkit|moz|o)-/;
	const DEBUG = false;

	class MatchedRules {
		constructor(doc, stylesheets, styles) {
			this.doc = doc;
			this.mediaAllInfo = createMediaInfo(MEDIA_ALL);
			const matchedElementsCache = new Map();
			let sheetIndex = 0;
			const workStyleElement = doc.createElement("style");
			doc.body.appendChild(workStyleElement);
			stylesheets.forEach(stylesheetInfo => {
				if (!stylesheetInfo.scoped) {
					const cssRules = stylesheetInfo.stylesheet.children;
					if (cssRules) {
						if (stylesheetInfo.mediaText && stylesheetInfo.mediaText != MEDIA_ALL) {
							const mediaInfo = createMediaInfo(stylesheetInfo.mediaText);
							this.mediaAllInfo.medias.set("style-" + sheetIndex + "-" + stylesheetInfo.mediaText, mediaInfo);
							getMatchedElementsRules(doc, cssRules, mediaInfo, sheetIndex, styles, matchedElementsCache, workStyleElement);
						} else {
							getMatchedElementsRules(doc, cssRules, this.mediaAllInfo, sheetIndex, styles, matchedElementsCache, workStyleElement);
						}
					}
				}
				sheetIndex++;
			});
			let startTime;
			if (DEBUG) {
				startTime = Date.now();
				log("  -- STARTED sortRules");
			}
			sortRules(this.mediaAllInfo);
			if (DEBUG) {
				log("  -- ENDED sortRules", Date.now() - startTime);
				startTime = Date.now();
				log("  -- STARTED computeCascade");
			}
			computeCascade(this.mediaAllInfo, [], this.mediaAllInfo, workStyleElement);
			workStyleElement.remove();
			if (DEBUG) {
				log("  -- ENDED computeCascade", Date.now() - startTime);
			}
		}

		getMediaAllInfo() {
			return this.mediaAllInfo;
		}
	}

	return {
		getMediaAllInfo
	};

	function getMediaAllInfo(doc, stylesheets, styles) {
		return new MatchedRules(doc, stylesheets, styles).getMediaAllInfo();
	}

	function createMediaInfo(media) {
		const mediaInfo = { media: media, elements: new Map(), medias: new Map(), rules: new Map(), pseudoRules: new Map() };
		if (media == MEDIA_ALL) {
			mediaInfo.matchedStyles = new Map();
		}
		return mediaInfo;
	}

	function getMatchedElementsRules(doc, cssRules, mediaInfo, sheetIndex, styles, matchedElementsCache, workStylesheet) {
		const cssTree = singlefile.lib.vendor.cssTree;
		let mediaIndex = 0;
		let ruleIndex = 0;
		let startTime;
		if (DEBUG && cssRules.length > 1) {
			startTime = Date.now();
			log("  -- STARTED getMatchedElementsRules", " index =", sheetIndex, "rules.length =", cssRules.length);
		}
		cssRules.forEach(ruleData => {
			if (ruleData.block && ruleData.block.children && ruleData.prelude && ruleData.prelude.children) {
				if (ruleData.type == "Atrule" && ruleData.name == "media") {
					const mediaText = cssTree.generate(ruleData.prelude);
					const ruleMediaInfo = createMediaInfo(mediaText);
					mediaInfo.medias.set("rule-" + sheetIndex + "-" + mediaIndex + "-" + mediaText, ruleMediaInfo);
					mediaIndex++;
					getMatchedElementsRules(doc, ruleData.block.children, ruleMediaInfo, sheetIndex, styles, matchedElementsCache, workStylesheet);
				} else if (ruleData.type == "Rule") {
					const selectors = ruleData.prelude.children.toArray();
					const selectorsText = ruleData.prelude.children.toArray().map(selector => cssTree.generate(selector));
					const ruleInfo = { ruleData, mediaInfo, ruleIndex, sheetIndex, matchedSelectors: new Set(), declarations: new Set(), selectors, selectorsText };
					if (!invalidSelector(selectorsText.join(","), workStylesheet)) {
						for (let selector = ruleData.prelude.children.head, selectorIndex = 0; selector; selector = selector.next, selectorIndex++) {
							const selectorText = selectorsText[selectorIndex];
							const selectorInfo = { selector, selectorText, ruleInfo };
							getMatchedElementsSelector(doc, selectorInfo, styles, matchedElementsCache);
						}
					}
					ruleIndex++;
				}
			}
		});
		if (DEBUG && cssRules.length > 1) {
			log("  -- ENDED   getMatchedElementsRules", "delay =", Date.now() - startTime);
		}
	}

	function invalidSelector(selectorText, workStylesheet) {
		workStylesheet.textContent = selectorText + "{}";
		return workStylesheet.sheet ? !workStylesheet.sheet.cssRules.length : workStylesheet.sheet;
	}

	function getMatchedElementsSelector(doc, selectorInfo, styles, matchedElementsCache) {
		const filteredSelectorText = getFilteredSelector(selectorInfo.selector, selectorInfo.selectorText);
		const selectorText = filteredSelectorText != selectorInfo.selectorText ? filteredSelectorText : selectorInfo.selectorText;
		const cachedMatchedElements = matchedElementsCache.get(selectorText);
		let matchedElements = cachedMatchedElements;
		if (!matchedElements) {
			try {
				matchedElements = doc.querySelectorAll(selectorText);
				if (selectorText != "." + SINGLE_FILE_HIDDEN_CLASS_NAME) {
					matchedElements = Array.from(doc.querySelectorAll(selectorText)).filter(matchedElement =>
						!matchedElement.classList.contains(SINGLE_FILE_HIDDEN_CLASS_NAME) &&
						(matchedElement.style.getPropertyValue(DISPLAY_STYLE) != "none" || matchedElement.style.getPropertyPriority("display") != "important")
					);
				}
			} catch (error) {
				// ignored				
			}
		}
		if (matchedElements) {
			if (!cachedMatchedElements) {
				matchedElementsCache.set(selectorText, matchedElements);
			}
			if (matchedElements.length) {
				if (filteredSelectorText == selectorInfo.selectorText) {
					matchedElements.forEach(element => addRule(element, selectorInfo, styles));
				} else {
					let pseudoSelectors = selectorInfo.ruleInfo.mediaInfo.pseudoRules.get(selectorInfo.ruleInfo.ruleData);
					if (!pseudoSelectors) {
						pseudoSelectors = new Set();
						selectorInfo.ruleInfo.mediaInfo.pseudoRules.set(selectorInfo.ruleInfo.ruleData, pseudoSelectors);
					}
					pseudoSelectors.add(selectorInfo.selectorText);
				}
			}
		}
	}

	function getFilteredSelector(selector, selectorText) {
		const cssTree = singlefile.lib.vendor.cssTree;
		const removedSelectors = [];
		selector = { data: cssTree.parse(cssTree.generate(selector.data), { context: "selector" }) };
		filterPseudoClasses(selector);
		if (removedSelectors.length) {
			removedSelectors.forEach(({ parentSelector, selector }) => {
				if (parentSelector.data.children.getSize() == 0 || !selector.prev || selector.prev.data.type == "Combinator" || selector.prev.data.type == "WhiteSpace") {
					parentSelector.data.children.replace(selector, cssTree.parse("*", { context: "selector" }).children.head);
				} else {
					parentSelector.data.children.remove(selector);
				}
			});
			selectorText = cssTree.generate(selector.data).trim();
		}
		return selectorText;

		function filterPseudoClasses(selector, parentSelector) {
			if (selector.data.children) {
				for (let childSelector = selector.data.children.head; childSelector; childSelector = childSelector.next) {
					filterPseudoClasses(childSelector, selector);
				}
			}
			if ((selector.data.type == "PseudoClassSelector") ||
				(selector.data.type == "PseudoElementSelector" && (testVendorPseudo(selector) || IGNORED_PSEUDO_ELEMENTS.includes(selector.data.name)))) {
				removedSelectors.push({ parentSelector, selector });
			}
		}

		function testVendorPseudo(selector) {
			const name = selector.data.name;
			return name.startsWith("-") || name.startsWith("\\-");
		}
	}

	function addRule(element, selectorInfo, styles) {
		const mediaInfo = selectorInfo.ruleInfo.mediaInfo;
		const elementStyle = styles.get(element);
		let elementInfo = mediaInfo.elements.get(element);
		if (!elementInfo) {
			elementInfo = [];
			if (elementStyle) {
				elementInfo.push({ styleInfo: { styleData: elementStyle, declarations: new Set() } });
			}
			mediaInfo.elements.set(element, elementInfo);
		}
		const specificity = computeSpecificity(selectorInfo.selector.data);
		specificity.ruleIndex = selectorInfo.ruleInfo.ruleIndex;
		specificity.sheetIndex = selectorInfo.ruleInfo.sheetIndex;
		selectorInfo.specificity = specificity;
		elementInfo.push(selectorInfo);
	}

	function computeCascade(mediaInfo, parentMediaInfo, mediaAllInfo, workStylesheet) {
		mediaInfo.elements.forEach((elementInfo/*, element*/) =>
			getDeclarationsInfo(elementInfo, workStylesheet/*, element*/).forEach((declarationsInfo, property) => {
				if (declarationsInfo.selectorInfo.ruleInfo || mediaInfo == mediaAllInfo) {
					let info;
					if (declarationsInfo.selectorInfo.ruleInfo) {
						info = declarationsInfo.selectorInfo.ruleInfo;
						const ruleData = info.ruleData;
						const ascendantMedia = [mediaInfo, ...parentMediaInfo].find(media => media.rules.get(ruleData)) || mediaInfo;
						ascendantMedia.rules.set(ruleData, info);
						if (ruleData) {
							info.matchedSelectors.add(declarationsInfo.selectorInfo.selectorText);
						}
					} else {
						info = declarationsInfo.selectorInfo.styleInfo;
						const styleData = info.styleData;
						const matchedStyleInfo = mediaAllInfo.matchedStyles.get(styleData);
						if (!matchedStyleInfo) {
							mediaAllInfo.matchedStyles.set(styleData, info);
						}
					}
					if (!info.declarations.has(property)) {
						info.declarations.add(property);
					}
				}
			}));
		delete mediaInfo.elements;
		mediaInfo.medias.forEach(childMediaInfo => computeCascade(childMediaInfo, [mediaInfo, ...parentMediaInfo], mediaAllInfo, workStylesheet));
	}

	function getDeclarationsInfo(elementInfo, workStylesheet/*, element*/) {
		const declarationsInfo = new Map();
		const processedProperties = new Set();
		elementInfo.forEach(selectorInfo => {
			let declarations;
			if (selectorInfo.styleInfo) {
				declarations = selectorInfo.styleInfo.styleData.children;
			} else {
				declarations = selectorInfo.ruleInfo.ruleData.block.children;
			}
			processDeclarations(declarationsInfo, declarations, selectorInfo, processedProperties, workStylesheet);
		});
		return declarationsInfo;
	}

	function processDeclarations(declarationsInfo, declarations, selectorInfo, processedProperties, workStylesheet) {
		const cssTree = singlefile.lib.vendor.cssTree;
		for (let declaration = declarations.tail; declaration; declaration = declaration.prev) {
			const declarationData = declaration.data;
			const declarationText = cssTree.generate(declarationData);
			if (declarationData.type == "Declaration" &&
				(declarationText.match(REGEXP_VENDOR_IDENTIFIER) || !processedProperties.has(declarationData.property) || declarationData.important) && !invalidDeclaration(declarationText, workStylesheet)) {
				const declarationInfo = declarationsInfo.get(declarationData);
				if (!declarationInfo || (declarationData.important && !declarationInfo.important)) {
					declarationsInfo.set(declarationData, { selectorInfo, important: declarationData.important });
					if (!declarationText.match(REGEXP_VENDOR_IDENTIFIER)) {
						processedProperties.add(declarationData.property);
					}
				}
			}
		}
	}

	function invalidDeclaration(declarationText, workStylesheet) {
		let invalidDeclaration;
		workStylesheet.textContent = "single-file-declaration { " + declarationText + "}";
		if (workStylesheet.sheet && !workStylesheet.sheet.cssRules[0].style.length) {
			if (!declarationText.match(REGEXP_VENDOR_IDENTIFIER)) {
				invalidDeclaration = true;
			}
		}
		return invalidDeclaration;
	}

	function sortRules(media) {
		media.elements.forEach(elementRules => elementRules.sort((ruleInfo1, ruleInfo2) =>
			ruleInfo1.styleInfo && !ruleInfo2.styleInfo ? -1 :
				!ruleInfo1.styleInfo && ruleInfo2.styleInfo ? 1 :
					compareSpecificity(ruleInfo1.specificity, ruleInfo2.specificity)));
		media.medias.forEach(sortRules);
	}

	function computeSpecificity(selector, specificity = { a: 0, b: 0, c: 0 }) {
		if (selector.type == "IdSelector") {
			specificity.a++;
		}
		if (selector.type == "ClassSelector" || selector.type == "AttributeSelector" || (selector.type == "PseudoClassSelector" && selector.name != "not")) {
			specificity.b++;
		}
		if ((selector.type == "TypeSelector" && selector.name != "*") || selector.type == "PseudoElementSelector") {
			specificity.c++;
		}
		if (selector.children) {
			selector.children.forEach(selector => computeSpecificity(selector, specificity));
		}
		return specificity;
	}

	function compareSpecificity(specificity1, specificity2) {
		if (specificity1.a > specificity2.a) {
			return -1;
		} else if (specificity1.a < specificity2.a) {
			return 1;
		} else if (specificity1.b > specificity2.b) {
			return -1;
		} else if (specificity1.b < specificity2.b) {
			return 1;
		} else if (specificity1.c > specificity2.c) {
			return -1;
		} else if (specificity1.c < specificity2.c) {
			return 1;
		} else if (specificity1.sheetIndex > specificity2.sheetIndex) {
			return -1;
		} else if (specificity1.sheetIndex < specificity2.sheetIndex) {
			return 1;
		} else if (specificity1.ruleIndex > specificity2.ruleIndex) {
			return -1;
		} else if (specificity1.ruleIndex < specificity2.ruleIndex) {
			return 1;
		} else {
			return -1;
		}
	}

	function log(...args) {
		console.log("S-File <css-mat>", ...args); // eslint-disable-line no-console
	}

})();