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Diffstat (limited to 'toolkit/components/translations/content/translations-document.sys.mjs')
| -rw-r--r-- | toolkit/components/translations/content/translations-document.sys.mjs | 2140 |
1 files changed, 2140 insertions, 0 deletions
diff --git a/toolkit/components/translations/content/translations-document.sys.mjs b/toolkit/components/translations/content/translations-document.sys.mjs new file mode 100644 index 0000000000..7f436575d8 --- /dev/null +++ b/toolkit/components/translations/content/translations-document.sys.mjs @@ -0,0 +1,2140 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +const lazy = {}; + +ChromeUtils.defineESModuleGetters(lazy, { + setTimeout: "resource://gre/modules/Timer.sys.mjs", + clearTimeout: "resource://gre/modules/Timer.sys.mjs", +}); + +ChromeUtils.defineLazyGetter(lazy, "console", () => { + return console.createInstance({ + maxLogLevelPref: "browser.translations.logLevel", + prefix: "Translations", + }); +}); + +/** + * Map the NodeFilter enums that are used by the TreeWalker into enums that make + * sense for determining the status of the nodes for the TranslationsDocument process. + * This aligns the meanings of the filtering for the translations process. + */ +const NodeStatus = { + // This node is ready to translate as is. + READY_TO_TRANSLATE: NodeFilter.FILTER_ACCEPT, + + // This node is a shadow host and needs to be subdivided further. + SHADOW_HOST: NodeFilter.FILTER_ACCEPT, + + // This node contains too many block elements and needs to be subdivided further. + SUBDIVIDE_FURTHER: NodeFilter.FILTER_SKIP, + + // This node should not be considered for translation. + NOT_TRANSLATABLE: NodeFilter.FILTER_REJECT, +}; + +/** + * @typedef {import("../translations").NodeVisibility} NodeVisibility + * @typedef {(message: string) => Promise<string>} TranslationFunction + */ + +/** + * Create a translation cache with a limit. It implements a "least recently used" strategy + * to remove old translations. After `#cacheExpirationMS` the cache will be emptied. + * This cache is owned statically by the TranslationsChild. This means that it will be + * re-used on page reloads if the origin of the site does not change. + */ +export class LRUCache { + /** @type {Map<string, string>} */ + #htmlCache = new Map(); + /** @type {Map<string, string>} */ + #textCache = new Map(); + /** @type {string} */ + #fromLanguage; + /** @type {string} */ + #toLanguage; + + /** + * This limit is used twice, once for Text translations, and once for HTML translations. + */ + #cacheLimit = 5_000; + + /** + * This cache will self-destruct after 10 minutes. + */ + #cacheExpirationMS = 10 * 60_000; + + /** + * @param {string} fromLanguage + * @param {string} toLanguage + */ + constructor(fromLanguage, toLanguage) { + this.#fromLanguage = fromLanguage; + this.#toLanguage = toLanguage; + } + + /** + * @param {boolean} isHTML + * @returns {boolean} + */ + #getCache(isHTML) { + return isHTML ? this.#htmlCache : this.#textCache; + } + + /** + * Get a translation if it exists from the cache, and move it to the end of the cache + * to keep it alive longer. + * + * @param {string} sourceString + * @param {boolean} isHTML + * @returns {string} + */ + get(sourceString, isHTML) { + const cache = this.#getCache(isHTML); + const targetString = cache.get(sourceString); + + if (targetString === undefined) { + return undefined; + } + + // Maps are ordered, move this item to the end of the list so it will stay + // alive longer. + cache.delete(sourceString); + cache.set(sourceString, targetString); + + this.keepAlive(); + + return targetString; + } + + /** + * @param {string} sourceString + * @param {string} targetString + * @param {boolean} isHTML + */ + set(sourceString, targetString, isHTML) { + const cache = this.#getCache(isHTML); + if (cache.size === this.#cacheLimit) { + // If the cache is at the limit, get the least recently used translation and + // remove it. This works since Maps have keys ordered by insertion order. + const key = cache.keys().next().value; + cache.delete(key); + } + cache.set(sourceString, targetString); + this.keepAlive(); + } + + /** + * @param {string} fromLanguage + * @param {string} toLanguage + */ + matches(fromLanguage, toLanguage) { + return ( + this.#fromLanguage === fromLanguage && this.#toLanguage === toLanguage + ); + } + + /** + * @type {number} + */ + #timeoutId = 0; + + #pendingKeepAlive = false; + + /** + * Clear out the cache on a timer. + */ + keepAlive() { + if (this.#timeoutId) { + lazy.clearTimeout(this.#timeoutId); + } + if (!this.#pendingKeepAlive) { + // Rather than continuously creating new functions in a tight loop, only schedule + // one keepAlive timeout on the next tick. + this.#pendingKeepAlive = true; + + lazy.setTimeout(() => { + this.#pendingKeepAlive = false; + this.#timeoutId = lazy.setTimeout(() => { + this.#htmlCache = new Map(); + this.#textCache = new Map(); + }, this.#cacheExpirationMS); + }, 0); + } + } +} + +/** + * How often the DOM is updated with translations, in milliseconds. + */ +const DOM_UPDATE_INTERVAL_MS = 50; + +/** + * These tags are excluded from translation. + */ +const EXCLUDED_TAGS = new Set([ + // The following are elements that semantically should not be translated. + "CODE", + "KBD", + "SAMP", + "VAR", + "ACRONYM", + + // The following are deprecated tags. + "DIR", + "APPLET", + + // The following are embedded elements, and are not supported (yet). + "MATH", + "EMBED", + "OBJECT", + "IFRAME", + + // This is an SVG tag that can contain arbitrary XML, ignore it. + "METADATA", + + // These are elements that are treated as opaque by Firefox which causes their + // innerHTML property to be just the raw text node behind it. Any text that is sent as + // HTML must be valid, and there is no guarantee that the innerHTML is valid. + "NOSCRIPT", + "NOEMBED", + "NOFRAMES", + + // The title is handled separately, and a HEAD tag should not be considered. + "HEAD", + + // These are not user-visible tags. + "STYLE", + "SCRIPT", + "TEMPLATE", + + // Textarea elements contain user content, which should not be translated. + "TEXTAREA", +]); + +/** + * Attributes to be translated + */ +const TRANSLATABLE_ATTRIBUTES = ["title", "placeholder"]; + +/** + * Selector to get all the attributes + * ["[attribute1]", "[attribute2]", ...]; + */ +const TRANSLATABLE_ATTRIBUTES_SELECTOR = TRANSLATABLE_ATTRIBUTES.map( + attribute => "[" + attribute + "]" +); + +/** + * Options used by the mutation observer + */ +const MUTATION_OBSERVER_OPTIONS = { + characterData: true, + childList: true, + subtree: true, + attributes: true, + attributeFilter: TRANSLATABLE_ATTRIBUTES, +}; + +/** + * This class manages the process of translating the DOM from one language to another. + * A translateHTML and a translateText function are injected into the constructor. This + * class is responsible for subdividing a Node into small enough pieces to where it + * contains a reasonable amount of text and inline elements for the translations engine + * to translate. Once a node has been identified as a small enough chunk, its innerHTML + * is read, and sent for translation. The async translation result comes back as an HTML + * string. The DOM node is updated with the new text and potentially changed DOM ordering. + * + * This class also handles mutations of the DOM and will translate nodes as they are added + * to the page, or the when the node's text is changed by content scripts. + */ +export class TranslationsDocument { + /** + * The BCP 47 language tag that is used on the page. + * + * @type {string} */ + documentLanguage; + + /** + * The timeout between the first translation received and the call to update the DOM + * with translations. + */ + #updateTimeout = null; + #attributeUpdateTimeout = null; + + /** + * The nodes that need translations. They are queued when the document tree is walked, + * and then they are dispatched for translation based on their visibility. The viewport + * nodes are given the highest priority. + * + * @type {Map<Node, NodeVisibility>} + */ + #queuedNodes = new Map(); + + /** + * The nodes that need Attribute translations. They are queued when the document tree is walked, + * and then they are dispatched for translation based on their visibility. The viewport + * nodes are given the highest priority. + * + * @type {Map<Node, { attributeList: string[], visibility: NodeVisibility }>} + */ + #queuedAttributeNodes = new Map(); + + /** + * The count of how many pending translations have been sent to the translations + * engine. + */ + #pendingTranslationsCount = 0; + + /** + * The list of nodes that need updating with the translated HTML. These are batched + * into an update. + * + * @type {Set<{ node: Node, translatedHTML: string }} + */ + #nodesWithTranslatedHTML = new Set(); + + /** + * The list of nodes that need updating with the translated Attribute HTML. These are batched + * into an update. + * + * @type {Set<{ node: Node, translation: string, attribute: string }} + */ + #nodesWithTranslatedAttributes = new Set(); + + /** + * The set of nodes that have been subdivided and processed for translation. They + * should not be submitted again unless their contents have been changed. + * + * @type {WeakSet<Node>} + */ + #processedNodes = new WeakSet(); + + /** + * All root elements we're trying to translate. This should be the `document.body` + * and the the `title` element. + * + * @type {Set<Node>} + */ + #rootNodes = new Set(); + + /** + * This promise gets resolved when the initial viewport translations are done. + * This is a key user-visible performance metric. It represents what the user + * actually sees. + * + * @type {Promise<void> | null} + */ + viewportTranslated = null; + + isDestroyed = false; + + /** + * Construct a new TranslationsDocument. It is tied to a specific Document and cannot + * be re-used. The translation functions are injected since this class shouldn't + * manage the life cycle of the translations engines. + * + * @param {Document} document + * @param {string} documentLanguage - The BCP 47 tag of the source language. + * @param {string} toLanguage - The BCP 47 tag of the destination language. + * @param {number} innerWindowId - This is used for better profiler marker reporting. + * @param {MessagePort} port - The port to the translations engine. + * @param {() => void} requestNewPort - Used when an engine times out and a new + * translation request comes in. + * @param {number} translationsStart + * @param {() => number} now + * @param {LRUCache} translationsCache + */ + constructor( + document, + documentLanguage, + toLanguage, + innerWindowId, + port, + requestNewPort, + translationsStart, + now, + translationsCache + ) { + /** + * The language of the document. If elements are found that do not match this language, + * then they are skipped. + * + * @type {string} + */ + this.documentLanguage = documentLanguage; + if (documentLanguage.length !== 2) { + throw new Error( + "Expected the document language to be a valid 2 letter BCP 47 language tag: " + + documentLanguage + ); + } + if (toLanguage.length !== 2) { + throw new Error( + "Expected the destination language to be a valid 2 letter BCP 47 language tag: " + + toLanguage + ); + } + + /** @type {QueuedTranslator} */ + this.translator = new QueuedTranslator(port, requestNewPort); + + /** @type {number} */ + this.innerWindowId = innerWindowId; + + /** @type {DOMParser} */ + this.domParser = new document.ownerGlobal.DOMParser(); + + /** @type {Document} */ + this.document = document; + + /** @type {LRUCache} */ + this.translationsCache = translationsCache; + + /** + * This selector runs to find child nodes that should be excluded. It should be + * basically the same implementation of `isExcludedNode`, but as a selector. + * + * @type {string} + */ + this.excludedNodeSelector = [ + // Use: [lang|=value] to match language codes. + // + // Per: https://developer.mozilla.org/en-US/docs/Web/CSS/Attribute_selectors + // + // The elements with an attribute name of attr whose value can be exactly + // value or can begin with value immediately followed by a hyphen, - (U+002D). + // It is often used for language subcode matches. + `[lang]:not([lang|="${this.documentLanguage}"])`, + `[translate=no]`, + `.notranslate`, + `[contenteditable="true"]`, + `[contenteditable=""]`, + [...EXCLUDED_TAGS].join(","), + ].join(","); + + this.observer = new document.ownerGlobal.MutationObserver(mutationsList => { + for (const mutation of mutationsList) { + switch (mutation.type) { + case "childList": + for (const node of mutation.addedNodes) { + this.#processedNodes.delete(node); + this.subdivideNodeForTranslations(node); + if (node.nodeType === Node.ELEMENT_NODE) { + this.translateAttributes(node); + } + } + break; + case "characterData": + this.#processedNodes.delete(mutation); + this.subdivideNodeForTranslations(mutation.target); + break; + case "attributes": + this.queueAttributeNodeForTranslation(mutation.target, [ + mutation.attributeName, + ]); + this.dispatchQueuedAttributeTranslations(); + break; + default: + break; + } + } + }); + + this.document.addEventListener( + "visibilitychange", + this.handleVisibilityChange + ); + + this.addRootElement(document.querySelector("title")); + this.addRootElement(document.body, true /* reportWordsInViewport */); + + this.viewportTranslated?.then(() => { + ChromeUtils.addProfilerMarker( + "TranslationsChild", + { innerWindowId, startTime: now() }, + "Viewport translations" + ); + ChromeUtils.addProfilerMarker( + "TranslationsChild", + { innerWindowId, startTime: translationsStart }, + "Time to first translation" + ); + }); + + document.documentElement.lang = toLanguage; + + lazy.console.log( + "Beginning to translate.", + // The defaultView may not be there on tests. + document.defaultView?.location.href + ); + } + + /** + * Queue a node for translation of attributes. + * @param {Node} node + * @param {Array<String>} + */ + queueAttributeNodeForTranslation(node, attributeList) { + /** @type {NodeVisibility} */ + let visibility = "out-of-viewport"; + if (isNodeHidden(node)) { + visibility = "hidden"; + } else if (isNodeInViewport(node)) { + visibility = "in-viewport"; + } + this.#queuedAttributeNodes.set(node, { attributeList, visibility }); + } + + /** + * Start and stop the translator as the page is shown. For instance, this will + * transition into "hidden" when the user tabs away from a document. + */ + handleVisibilityChange = () => { + if (this.document.visibilityState === "visible") { + this.translator.showPage(); + } else { + ChromeUtils.addProfilerMarker( + "Translations", + { innerWindowId: this.innerWindowId }, + "Pausing translations and discarding the port" + ); + this.translator.hidePage(); + } + }; + + /** + * Remove any dangling event handlers. + */ + destroy() { + this.isDestroyed = true; + this.translator.destroy(); + this.stopMutationObserver(); + this.document.removeEventListener( + "visibilitychange", + this.handleVisibilityChange + ); + } + + /** + * Helper function for adding a new root to the mutation + * observer. + * @param {Node} root + */ + observeNewRoot(root) { + this.#rootNodes.add(root); + this.observer.observe(root, MUTATION_OBSERVER_OPTIONS); + } + + /** + * This function finds all sub shadow trees of node and + * add the ShadowRoot of those subtrees to the mutation + * observer. + */ + addShadowRootsToObserver(node) { + const nodeIterator = node.ownerDocument.createTreeWalker( + node, + NodeFilter.SHOW_ELEMENT, + function (node) { + return node.openOrClosedShadowRoot + ? NodeFilter.FILTER_ACCEPT + : NodeFilter.FILTER_SKIP; + } + ); + let currentNode; + while ((currentNode = nodeIterator.nextNode())) { + // Only shadow hosts are accepted nodes + const shadowRoot = currentNode.openOrClosedShadowRoot; + this.observeNewRoot(shadowRoot); + this.addShadowRootsToObserver(shadowRoot); + } + } + + /** + * Add a new element to start translating. This root is tracked for mutations and + * kept up to date with translations. This will be the body element and title tag + * for the document. + * + * @param {Element} [node] + */ + addRootElement(node) { + if (!node) { + return; + } + + if (node.nodeType !== Node.ELEMENT_NODE) { + // This node is not an element, do not add it. + return; + } + + if (this.#rootNodes.has(node)) { + // Exclude nodes that are already targetted. + return; + } + + this.#rootNodes.add(node); + + let viewportNodeTranslations = this.subdivideNodeForTranslations(node); + let viewportAttributeTranslations = this.translateAttributes(node); + + if (!this.viewportTranslated) { + this.viewportTranslated = Promise.allSettled([ + ...(viewportNodeTranslations ?? []), + ...(viewportAttributeTranslations ?? []), + ]); + } + + this.observer.observe(node, MUTATION_OBSERVER_OPTIONS); + this.addShadowRootsToObserver(node); + } + + /** + * Add qualified nodes to queueNodeForTranslation by recursively walk + * through the DOM tree of node, including elements in Shadow DOM. + * + * @param {Element} [node] + */ + processSubdivide(node) { + const nodeIterator = node.ownerDocument.createTreeWalker( + node, + NodeFilter.SHOW_ELEMENT | NodeFilter.SHOW_TEXT, + this.determineTranslationStatusForUnprocessedNodes + ); + + // This iterator will contain each node that has been subdivided enough to + // be translated. + let currentNode; + while ((currentNode = nodeIterator.nextNode())) { + const shadowRoot = currentNode.openOrClosedShadowRoot; + if (shadowRoot) { + this.processSubdivide(shadowRoot); + } else { + this.queueNodeForTranslation(currentNode); + } + } + } + + /** + * Start walking down through a node's subtree and decide which nodes to queue for + * translation. This first node could be the root nodes of the DOM, such as the + * document body, or the title element, or it could be a mutation target. + * + * The nodes go through a process of subdivision until an appropriate sized chunk + * of inline text can be found. + * + * @param {Node} node + */ + subdivideNodeForTranslations(node) { + if (!this.#rootNodes.has(node)) { + // This is a non-root node, which means it came from a mutation observer. + // This new node could be a host element for shadow tree + const shadowRoot = node.openOrClosedShadowRoot; + if (shadowRoot && !this.#rootNodes.has(shadowRoot)) { + this.observeNewRoot(shadowRoot); + } else { + // Ensure that it is a valid node to translate by checking all of its ancestors. + for (let parent of getAncestorsIterator(node)) { + // Parent is ShadowRoot. We can stop here since this is + // the top ancestor of the shadow tree. + if (parent.containingShadowRoot == parent) { + break; + } + if ( + this.determineTranslationStatus(parent) === + NodeStatus.NOT_TRANSLATABLE + ) { + return; + } + } + } + } + + switch (this.determineTranslationStatusForUnprocessedNodes(node)) { + case NodeStatus.NOT_TRANSLATABLE: + // This node is rejected as it shouldn't be translated. + return; + + // SHADOW_HOST and READY_TO_TRANSLATE both map to FILTER_ACCEPT + case NodeStatus.SHADOW_HOST: + case NodeStatus.READY_TO_TRANSLATE: + const shadowRoot = node.openOrClosedShadowRoot; + if (shadowRoot) { + this.processSubdivide(shadowRoot); + } else { + // This node is ready for translating, and doesn't need to be subdivided. There + // is no reason to run the TreeWalker, it can be directly submitted for + // translation. + this.queueNodeForTranslation(node); + } + break; + + case NodeStatus.SUBDIVIDE_FURTHER: + // This node may be translatable, but it needs to be subdivided into smaller + // pieces. Create a TreeWalker to walk the subtree, and find the subtrees/nodes + // that contain enough inline elements to send to be translated. + this.processSubdivide(node); + break; + } + + if (node.nodeName === "BODY") { + this.reportWordsInViewport(); + } + this.dispatchQueuedTranslations(); + } + + /** + * Get all the nodes which have selected attributes + * from the node/document and queue them. + * Call the translate function on these nodes + * @param {Node} node + * @returns {Array<Promise<void>> | null} + */ + translateAttributes(node) { + const attributeList = getTranslatableAttributes(node); + if (attributeList.length) { + // Queue the root node if it has any attributes + // Because querySelectorAll searches only child nodes. + this.queueAttributeNodeForTranslation(node, attributeList); + } + // Get all attributes in child nodes at once + const nodesWithTranslatableAttributes = node.querySelectorAll( + TRANSLATABLE_ATTRIBUTES_SELECTOR + ); + for (const node of nodesWithTranslatableAttributes) { + const attributeList = getTranslatableAttributes(node); + this.queueAttributeNodeForTranslation(node, attributeList); + } + return this.dispatchQueuedAttributeTranslations(); + } + + /** + * Test whether this is an element we do not want to translate. These are things like + * <code> elements, elements with a different "lang" attribute, and elements that + * have a `translate=no` attribute. + * + * @param {Node} node + */ + isExcludedNode(node) { + // Property access be expensive, so destructure required properties so they are + // not accessed multiple times. + const { nodeType } = node; + + if (nodeType === Node.TEXT_NODE) { + // Text nodes are never excluded. + return false; + } + if (nodeType !== Node.ELEMENT_NODE) { + // Only elements and and text nodes should be considered. + return true; + } + + const { nodeName } = node; + + if ( + EXCLUDED_TAGS.has( + // SVG tags can be lowercased, so ensure everything is uppercased. + nodeName.toUpperCase() + ) + ) { + // This is an excluded tag. + return true; + } + + if (!this.matchesDocumentLanguage(node)) { + // Exclude nodes that don't match the fromLanguage. + return true; + } + + if (node.getAttribute("translate") === "no") { + // This element has a translate="no" attribute. + // https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/translate + return true; + } + + if (node.classList.contains("notranslate")) { + // Google Translate skips translations if the classList contains "notranslate" + // https://cloud.google.com/translate/troubleshooting + return true; + } + + if (node.isContentEditable) { + // This field is editable, and so exclude it similar to the way that form input + // fields are excluded. + return true; + } + + return false; + } + + /** + * Runs `determineTranslationStatus`, but only on unprocessed nodes. + * + * @param {Node} node + * @return {number} - One of the NodeStatus values. + */ + determineTranslationStatusForUnprocessedNodes = node => { + if (this.#processedNodes.has(node)) { + // Skip nodes that have already been processed. + return NodeStatus.NOT_TRANSLATABLE; + } + + return this.determineTranslationStatus(node); + }; + + /** + * Determines if a node should be submitted for translation, not translatable, or if + * it should be subdivided further. It doesn't check if the node has already been + * processed. + * + * The return result works as a TreeWalker NodeFilter as well. + * + * @param {Node} node + * @returns {number} - One of the `NodeStatus` values. See that object + * for documentation. These values match the filters for the TreeWalker. + * These values also work as a `NodeFilter` value. + */ + determineTranslationStatus(node) { + if (node.openOrClosedShadowRoot) { + return NodeStatus.SHADOW_HOST; + } + + if (isNodeQueued(node, this.#queuedNodes)) { + // This node or its parent was already queued, reject it. + return NodeStatus.NOT_TRANSLATABLE; + } + + if (this.isExcludedNode(node)) { + // This is an explicitly excluded node. + return NodeStatus.NOT_TRANSLATABLE; + } + + if (node.textContent.trim().length === 0) { + // Do not use subtrees that are empty of text. This textContent call is fairly + // expensive. + return !node.hasChildNodes() + ? NodeStatus.NOT_TRANSLATABLE + : NodeStatus.SUBDIVIDE_FURTHER; + } + + if (nodeNeedsSubdividing(node)) { + // Skip this node, and dig deeper into its tree to cut off smaller pieces + // to translate. It is presumed to be a wrapper of block elements. + return NodeStatus.SUBDIVIDE_FURTHER; + } + + if ( + containsExcludedNode(node, this.excludedNodeSelector) && + !hasTextNodes(node) + ) { + // Skip this node, and dig deeper into its tree to cut off smaller pieces + // to translate. + return NodeStatus.SUBDIVIDE_FURTHER; + } + + // This node can be treated as entire block to submit for translation. + return NodeStatus.READY_TO_TRANSLATE; + } + + /** + * Queue a node for translation. + * @param {Node} node + */ + queueNodeForTranslation(node) { + /** @type {NodeVisibility} */ + let visibility = "out-of-viewport"; + if (isNodeHidden(node)) { + visibility = "hidden"; + } else if (isNodeInViewport(node)) { + visibility = "in-viewport"; + } + + this.#queuedNodes.set(node, visibility); + } + + /** + * Submit the translations giving priority to nodes in the viewport. + * @returns {Array<Promise<void>> | null} + */ + dispatchQueuedTranslations() { + let inViewportCounts = 0; + let outOfViewportCounts = 0; + let hiddenCounts = 0; + + let inViewportTranslations = null; + if (!this.viewportTranslated) { + inViewportTranslations = []; + } + + for (const [node, visibility] of this.#queuedNodes) { + if (visibility === "in-viewport") { + inViewportCounts++; + const promise = this.submitTranslation(node); + if (inViewportTranslations) { + inViewportTranslations.push(promise); + } + } + } + for (const [node, visibility] of this.#queuedNodes) { + if (visibility === "out-of-viewport") { + outOfViewportCounts++; + this.submitTranslation(node); + } + } + for (const [node, visibility] of this.#queuedNodes) { + if (visibility === "hidden") { + hiddenCounts++; + this.submitTranslation(node); + } + } + + ChromeUtils.addProfilerMarker( + "Translations", + { innerWindowId: this.innerWindowId }, + `Translate ${this.#queuedNodes.size} nodes.\n\n` + + `In viewport: ${inViewportCounts}\n` + + `Out of viewport: ${outOfViewportCounts}\n` + + `Hidden: ${hiddenCounts}\n` + ); + + this.#queuedNodes.clear(); + return inViewportTranslations; + } + + /** + * Submit the Attribute translations giving priority to nodes in the viewport. + * @returns {Array<Promise<void>> | null} + */ + dispatchQueuedAttributeTranslations() { + let inViewportCounts = 0; + let outOfViewportCounts = 0; + let hiddenCounts = 0; + + let inViewportTranslations = null; + if (!this.viewportTranslated) { + inViewportTranslations = []; + } + // Submit the nodes with attrbutes to be translated. + for (const [node, { attributeList, visibility }] of this + .#queuedAttributeNodes) { + if (visibility === "in-viewport") { + inViewportCounts++; + const promise = this.submitAttributeTranslation(node, attributeList); + if (inViewportTranslations) { + inViewportTranslations.push(promise); + } + } + } + for (const [node, { attributeList, visibility }] of this + .#queuedAttributeNodes) { + if (visibility === "out-of-viewport") { + outOfViewportCounts++; + this.submitAttributeTranslation(node, attributeList); + } + } + for (const [node, { attributeList, visibility }] of this + .#queuedAttributeNodes) { + if (visibility === "hidden") { + hiddenCounts++; + this.submitAttributeTranslation(node, attributeList); + } + } + + ChromeUtils.addProfilerMarker( + "Attribute Translations", + { innerWindowId: this.innerWindowId }, + `Attribute Translate ${this.#queuedAttributeNodes.size} nodes.\n\n` + + `In viewport: ${inViewportCounts}\n` + + `Out of viewport: ${outOfViewportCounts}\n` + + `Hidden: ${hiddenCounts}\n` + ); + + this.#queuedAttributeNodes.clear(); + + return inViewportTranslations; + } + + /** + * Submit a node for Attribute translation to the translations engine. + * + * @param {Node} node + * @returns {Promise<void>} + */ + async submitAttributeTranslation(node, attributeList) { + if (node.nodeType === Node.ELEMENT_NODE) { + for (const attribute of attributeList) { + const text = node.getAttribute(attribute); + + if (text.trim().length === 0) { + continue; + } + const translation = await this.maybeTranslate( + node, + text, + false /*isHTML*/ + ); + if (translation != null) { + this.scheduleNodeUpdateWithTranslationAttribute( + node, + translation, + attribute + ); + } + } + } + } + + /** + * Schedule a node to be updated with a translation. + * + * @param {Node} node + * @param {string} translation + */ + scheduleNodeUpdateWithTranslationAttribute(node, translation, attribute) { + // Add the nodes to be populated with the next translation update. + this.#nodesWithTranslatedAttributes.add({ + node, + translation, + attribute, + }); + + if (this.#pendingTranslationsCount === 0) { + // No translations are pending, update the node. + this.updateNodesWithTranslationsAttributes(); + } else if (!this.#attributeUpdateTimeout) { + // Schedule an update. + this.#attributeUpdateTimeout = lazy.setTimeout( + this.updateNodesWithTranslationsAttributes.bind(this), + DOM_UPDATE_INTERVAL_MS + ); + } else { + // An update has been previously scheduled, do nothing here. + } + } + + /** + * This is called every `DOM_UPDATE_INTERVAL_MS` ms with translations + * for attributes in the nodes. + * + * This function is called asynchronously, so nodes may already be dead. Before + * accessing a node make sure and run `Cu.isDeadWrapper` to check that it is alive. + */ + updateNodesWithTranslationsAttributes() { + // Stop the mutations so that the updates won't trigger observations. + + this.pauseMutationObserverAndRun(() => { + for (const { node, translation, attribute } of this + .#nodesWithTranslatedAttributes) { + if (Cu.isDeadWrapper(node)) { + // The node is no longer alive. + ChromeUtils.addProfilerMarker( + "Translations", + { innerWindowId: this.innerWindowId }, + "Node is no long alive." + ); + continue; + } + // Update the attribute of the node with translated attribute + if (attribute) { + node.setAttribute(attribute, translation); + } + } + this.#nodesWithTranslatedAttributes.clear(); + this.#attributeUpdateTimeout = null; + }); + } + + /** + * Record how many words were in the viewport, as this is the most important + * user-visible translation content. + */ + reportWordsInViewport() { + if ( + // This promise gets created for the first dispatchQueuedTranslations + this.viewportTranslated || + this.#queuedNodes.size === 0 + ) { + return; + } + + // TODO(Bug 1814195) - Add telemetry. + // TODO(Bug 1820618) - This whitespace regex will not work in CJK-like languages. + // This requires a segmenter for a proper implementation. + + const whitespace = /\s+/; + let wordCount = 0; + for (const [node, visibility] of this.#queuedNodes) { + if (visibility === "in-viewport") { + wordCount += node.textContent.trim().split(whitespace).length; + } + } + + const message = wordCount + " words are in the viewport."; + lazy.console.log(message); + ChromeUtils.addProfilerMarker( + "Translations", + { innerWindowId: this.innerWindowId }, + message + ); + } + + /** + * Submit a node for translation to the translations engine. + * + * @param {Node} node + * @returns {Promise<void>} + */ + async submitTranslation(node) { + // Give each element an id that gets passed through the translation so it can be + // reunited later on. + if (node.nodeType === Node.ELEMENT_NODE) { + node.querySelectorAll("*").forEach((el, i) => { + el.dataset.mozTranslationsId = i; + }); + } + + /** @type {string} */ + let text; + /** @type {boolean} */ + let isHTML; + + if (node.nodeType === Node.ELEMENT_NODE) { + text = node.innerHTML; + isHTML = true; + } else { + text = node.textContent; + isHTML = false; + } + + if (text.trim().length === 0) { + return; + } + + // Mark this node as not to be translated again unless the contents are changed + // (which the observer will pick up on) + this.#processedNodes.add(node); + const translatedHTML = await this.maybeTranslate(node, text, isHTML); + if (translatedHTML != null) { + this.scheduleNodeUpdateWithTranslation(node, translatedHTML); + } + } + + /** + * A single function to update pendingTranslationsCount while + * calling the translate function + * @param {Node} node + * @param {string} text + * @prop {boolean} isHTML + * @returns {Promise<string | null>} + */ + async maybeTranslate(node, text, isHTML) { + this.#pendingTranslationsCount++; + try { + let translation = this.translationsCache.get(text, isHTML); + if (translation === undefined) { + translation = await this.translator.translate(node, text, isHTML); + this.translationsCache.set(text, translation, isHTML); + } + + return translation; + } catch (error) { + lazy.console.log("Translation failed", error); + } finally { + this.#pendingTranslationsCount--; + } + return null; + } + + /** + * Start the mutation observer, for instance after applying the translations to the DOM. + */ + startMutationObserver() { + if (Cu.isDeadWrapper(this.observer)) { + // This observer is no longer alive. + return; + } + for (const node of this.#rootNodes) { + if (Cu.isDeadWrapper(node)) { + // This node is no longer alive. + continue; + } + this.observer.observe(node, MUTATION_OBSERVER_OPTIONS); + } + } + + /** + * Stop the mutation observer, for instance to apply the translations to the DOM. + */ + stopMutationObserver() { + // Was the window already destroyed? + if (!Cu.isDeadWrapper(this.observer)) { + this.observer.disconnect(); + } + } + + /** + * This is called every `DOM_UPDATE_INTERVAL_MS` ms with translations for nodes. + * + * This function is called asynchronously, so nodes may already be dead. Before + * accessing a node make sure and run `Cu.isDeadWrapper` to check that it is alive. + */ + updateNodesWithTranslations() { + // Stop the mutations so that the updates won't trigger observations. + this.pauseMutationObserverAndRun(() => { + for (const { node, translatedHTML } of this.#nodesWithTranslatedHTML) { + if (Cu.isDeadWrapper(node)) { + // The node is no longer alive. + ChromeUtils.addProfilerMarker( + "Translations", + { innerWindowId: this.innerWindowId }, + "Node is no long alive." + ); + continue; + } + switch (node.nodeType) { + case Node.TEXT_NODE: { + if (translatedHTML.trim().length !== 0) { + // Only update the node if there is new text. + node.textContent = translatedHTML; + } + break; + } + case Node.ELEMENT_NODE: { + // TODO (Bug 1820625) - This is slow compared to the original implementation + // in the addon which set the innerHTML directly. We can't set the innerHTML + // here, but perhaps there is another way to get back some of the performance. + const translationsDocument = this.domParser.parseFromString( + `<!DOCTYPE html><div>${translatedHTML}</div>`, + "text/html" + ); + updateElement(translationsDocument, node); + break; + } + } + } + + this.#nodesWithTranslatedHTML.clear(); + this.#updateTimeout = null; + }); + } + + /** + * Stop the mutations so that the updates of the translations + * in the nodes won't trigger observations. + * @param {Function} run The function to update translations + */ + pauseMutationObserverAndRun(run) { + this.stopMutationObserver(); + run(); + this.startMutationObserver(); + } + + /** + * Schedule a node to be updated with a translation. + * + * @param {Node} node + * @param {string} translatedHTML + */ + scheduleNodeUpdateWithTranslation(node, translatedHTML) { + // Add the nodes to be populated with the next translation update. + this.#nodesWithTranslatedHTML.add({ node, translatedHTML }); + + if (this.#pendingTranslationsCount === 0) { + // No translations are pending, update the node. + this.updateNodesWithTranslations(); + } else if (!this.#updateTimeout) { + // Schedule an update. + this.#updateTimeout = lazy.setTimeout( + this.updateNodesWithTranslations.bind(this), + DOM_UPDATE_INTERVAL_MS + ); + } else { + // An update has been previously scheduled, do nothing here. + } + } + + /** + * Check to see if a language matches the document language. + * + * @param {Node} node + */ + matchesDocumentLanguage(node) { + if (!node.lang) { + // No `lang` was present, so assume it matches the language. + return true; + } + + // First, cheaply check if language tags match, without canonicalizing. + if (langTagsMatch(this.documentLanguage, node.lang)) { + return true; + } + + try { + // Make sure the local is in the canonical form, and check again. This function + // throws, so don't trust that the language tags are formatting correctly. + const [language] = Intl.getCanonicalLocales(node.lang); + + return langTagsMatch(this.documentLanguage, language); + } catch (_error) { + return false; + } + } +} + +/** + * Get the list of attributes that need to be translated + * in a given node. + * @returns Array<string> + */ +function getTranslatableAttributes(node) { + if (node.nodeType !== Node.ELEMENT_NODE) { + return []; + } + return TRANSLATABLE_ATTRIBUTES.filter(attribute => + node.hasAttribute(attribute) + ); +} + +/** + * This function needs to be fairly fast since it's used on many nodes when iterating + * over the DOM to find nodes to translate. + * + * @param {Text | HTMLElement} node + */ +function isNodeHidden(node) { + /** @type {HTMLElement} */ + const element = getElementForStyle(node); + if (!element) { + throw new Error("Unable to find the Element to compute the style for node"); + } + + // This flushes the style, which is a performance cost. + const style = element.ownerGlobal.getComputedStyle(element); + return style.display === "none" || style.visibility === "hidden"; +} + +/** + * This function cheaply checks that language tags match. + * + * @param {string} knownLanguage + * @param {string} otherLanguage + */ +function langTagsMatch(knownLanguage, otherLanguage) { + if (knownLanguage === otherLanguage) { + // A simple direct match. + return true; + } + if (knownLanguage.length !== 2) { + throw new Error("Expected the knownLanguage to be of length 2."); + } + // Check if the language tags part match, e.g. "en" and "en-US". + return ( + knownLanguage[0] === otherLanguage[0] && + knownLanguage[1] === otherLanguage[1] && + otherLanguage[2] === "-" + ); +} + +/** + * This function returns the correct element to determine the + * style of node. + * + * @param {Node} node + * @returns {HTMLElement} */ +function getElementForStyle(node) { + if (node.nodeType != Node.TEXT_NODE) { + return node; + } + + if (node.parentElement) { + return node.parentElement; + } + + // For cases like text node where its parent is ShadowRoot, + // we'd like to use flattenedTreeParentNode + if (node.flattenedTreeParentNode) { + return node.flattenedTreeParentNode; + } + + // If the text node is not connected or doesn't have a frame. + return null; +} + +/** + * This function runs when walking the DOM, which means it is a hot function. It runs + * fairly fast even though it is computing the bounding box. This is all done in a tight + * loop, and it is done on mutations. Care should be taken with reflows caused by + * getBoundingClientRect, as this is a common performance issue. + * + * The following are the counts of how often this is run on a news site: + * + * Given: + * 1573 DOM nodes + * 504 Text nodes + * 1069 Elements + * + * There were: + * 209 calls to get this funcion. + * + * @param {Node} node + */ +function isNodeInViewport(node) { + const window = node.ownerGlobal; + const document = node.ownerDocument; + + /** @type {HTMLElement} */ + const element = getElementForStyle(node); + if (!element) { + throw new Error("Unable to find the Element to compute the style for node"); + } + + const rect = element.getBoundingClientRect(); + return ( + rect.top >= 0 && + rect.left >= 0 && + rect.bottom <= + (window.innerHeight || document.documentElement.clientHeight) && + rect.right <= (window.innerWidth || document.documentElement.clientWidth) + ); +} + +/** + * Actually perform the update of the element with the translated node. This step + * will detach all of the "live" nodes, and match them up in the correct order as provided + * by the translations engine. + * + * @param {Document} translationsDocument + * @param {Element} element + * @returns {void} + */ +function updateElement(translationsDocument, element) { + // This text should have the same layout as the target, but it's not completely + // guaranteed since the content page could change at any time, and the translation process is async. + // + // The document has the following structure: + // + // <html> + // <head> + // <body>{translated content}</body> + // </html> + + const originalHTML = element.innerHTML; + + /** + * The Set of translation IDs for nodes that have been cloned. + * @type {Set<number>} + */ + const clonedNodes = new Set(); + + merge(element, translationsDocument.body.firstChild); + + /** + * Merge the live tree with the translated tree by re-using elements from the live tree. + * + * @param {Node} liveTree + * @param {Node} translatedTree + */ + function merge(liveTree, translatedTree) { + /** @type {Map<number, Element>} */ + const liveElementsById = new Map(); + + /** @type {Array<Text>} */ + const liveTextNodes = []; + + // Remove all the nodes from the liveTree, and categorize them by Text node or + // Element node. + let node; + while ((node = liveTree.firstChild)) { + node.remove(); + + if (node.nodeType === Node.ELEMENT_NODE) { + liveElementsById.set(node.dataset.mozTranslationsId, node); + } else if (node.nodeType === Node.TEXT_NODE) { + liveTextNodes.push(node); + } + } + + // The translated tree dictates the order. + const translatedNodes = [...translatedTree.childNodes]; + for ( + let translatedIndex = 0; + translatedIndex < translatedNodes.length; + translatedIndex++ + ) { + const translatedNode = translatedNodes[translatedIndex]; + + if (translatedNode.nodeType === Node.TEXT_NODE) { + // Copy the translated text to the original Text node and re-append it. + let liveTextNode = liveTextNodes.shift(); + + if (liveTextNode) { + liveTextNode.data = translatedNode.data; + } else { + liveTextNode = translatedNode; + } + + liveTree.appendChild(liveTextNode); + } else if (translatedNode.nodeType === Node.ELEMENT_NODE) { + const translationsId = translatedNode.dataset.mozTranslationsId; + // Element nodes try to use the already existing DOM nodes. + + // Find the element in the live tree that matches the one in the translated tree. + let liveElement = liveElementsById.get(translationsId); + + if (!liveElement) { + lazy.console.warn("Could not find a corresponding live element", { + path: createNodePath(translatedNode, translationsDocument.body), + translationsId, + liveElementsById, + translatedNode, + }); + continue; + } + + // Has this element already been added to the list? Then duplicate it and re-add + // it as a clone. The Translations Engine can sometimes duplicate HTML. + if (liveElement.parentNode) { + liveElement = liveElement.cloneNode(true /* deep clone */); + clonedNodes.add(translationsId); + lazy.console.warn( + "Cloning a node because it was already inserted earlier", + { + path: createNodePath(translatedNode, translationsDocument.body), + translatedNode, + liveElement, + } + ); + } + + if (isNodeTextEmpty(translatedNode)) { + // The original node had text, but the one that came out of translation + // didn't have any text. This scenario might be caused by one of two causes: + // + // 1) The element was duplicated by translation but then not given text + // content. This happens on Wikipedia articles for example. + // + // 2) The translator messed up and could not translate the text. This + // happens on YouTube in the language selector. In that case, having the + // original text is much better than no text at all. + // + // To make sure it is case 1 and not case 2 check whether this is the only occurrence. + for (let i = 0; i < translatedNodes.length; i++) { + if (translatedIndex === i) { + // This is the current node, not a sibling. + continue; + } + const sibling = translatedNodes[i]; + if ( + // Only consider other element nodes. + sibling.nodeType === Node.ELEMENT_NODE && + // If the sibling's translationsId matches, then use the sibling's + // node instead. + translationsId === sibling.dataset.mozTranslationsId + ) { + // This is case 1 from above. Remove this element's original text nodes, + // since a sibling text node now has all of the text nodes. + removeTextNodes(liveElement); + } + } + + // Report this issue to the console. + lazy.console.warn( + "The translated element has no text even though the original did.", + { + path: createNodePath(translatedNode, translationsDocument.body), + translatedNode, + liveElement, + } + ); + } else if (!isNodeTextEmpty(liveElement)) { + // There are still text nodes to find and update, recursively merge. + merge(liveElement, translatedNode); + } + + // Put the live node back in the live branch. But now t has been synced with the + // translated text and order. + liveTree.appendChild(liveElement); + } + } + + const unhandledElements = [...liveElementsById].filter( + ([, element]) => !element.parentNode + ); + + if (unhandledElements.length) { + lazy.console.warn( + `${createNodePath( + translatedTree, + translationsDocument.body + )} Not all nodes unified`, + { + unhandledElements, + clonedNodes, + originalHTML, + translatedHTML: translationsDocument.body.innerHTML, + liveTree: liveTree.outerHTML, + translatedTree: translatedTree.outerHTML, + } + ); + } + } +} + +/** + * For debug purposes, compute a string path to an element. + * + * e.g. "div/div#header/p.bold.string/a" + * + * @param {Node} node + * @param {Node | null} root + */ +function createNodePath(node, root) { + if (root === null) { + root = node.ownerDocument.body; + } + let path = + node.parentNode && node.parentNode !== root + ? createNodePath(node.parentNode) + : ""; + path += `/${node.nodeName}`; + if (node.id) { + path += `#${node.id}`; + } else if (node.className) { + for (const className of node.classList) { + path += "." + className; + } + } + return path; +} + +/** + * @param {Node} node + * @returns {boolean} + */ +function isNodeTextEmpty(node) { + if ("innerText" in node) { + return node.innerText.trim().length === 0; + } + if (node.nodeType === Node.TEXT_NODE && node.nodeValue) { + return node.nodeValue.trim().length === 0; + } + return true; +} + +/** + * @param {Node} node + */ +function removeTextNodes(node) { + for (const child of node.childNodes) { + switch (child.nodeType) { + case Node.TEXT_NODE: + node.removeChild(child); + break; + case Node.ELEMENT_NODE: + removeTextNodes(child); + break; + default: + break; + } + } +} + +/** + * Test whether any of the direct child text nodes of are non-whitespace + * text nodes. + * + * For example: + * - `<p>test</p>`: yes + * - `<p> </p>`: no + * - `<p><b>test</b></p>`: no + * @param {Node} node + * @returns {boolean} + */ +function hasTextNodes(node) { + if (node.nodeType !== Node.ELEMENT_NODE) { + // Only check element nodes. + return false; + } + + for (const child of node.childNodes) { + if (child.nodeType === Node.TEXT_NODE) { + if (child.textContent.trim() === "") { + // This is just whitespace. + continue; + } + // A text node with content was found. + return true; + } + } + + // No text nodes were found. + return false; +} + +/** + * Like `isExcludedNode` but looks at the full subtree. Used to see whether + * we can submit a subtree, or whether we should split it into smaller + * branches first to try to exclude more of the non-translatable content. + * + * @param {Node} node + * @param {string} excludedNodeSelector + * @returns {boolean} + */ +function containsExcludedNode(node, excludedNodeSelector) { + return ( + node.nodeType === Node.ELEMENT_NODE && + node.querySelector(excludedNodeSelector) + ); +} + +/** + * Check if this node has already been queued to be translated. This can be because + * the node is itself is queued, or its parent node is queued. + * + * @param {Node} node + * @param {Map<Node, any>} queuedNodes + * @returns {boolean} + */ +function isNodeQueued(node, queuedNodes) { + if (queuedNodes.has(node)) { + return true; + } + + // If the immediate parent is the body, it is allowed. + if (node.parentNode === node.ownerDocument.body) { + return false; + } + + // Accessing the parentNode is expensive here according to performance profilling. This + // is due to XrayWrappers. Minimize reading attributes by storing a reference to the + // `parentNode` in a named variable, rather than re-accessing it. + let parentNode; + let lastNode = node; + while ((parentNode = lastNode.parentNode)) { + if (queuedNodes.has(parentNode)) { + return parentNode; + } + lastNode = parentNode; + } + + return false; +} + +/** + * Reads the elements computed style and determines if the element is inline or not. + * + * @param {Element} element + */ +function getIsInline(element) { + const win = element.ownerGlobal; + if (element.namespaceURI === "http://www.w3.org/2000/svg") { + // SVG elements will report as inline, but there is no block layout in SVG. + // Treat every SVG element as being block so that every node will be subdivided. + return false; + } + return win.getComputedStyle(element).display === "inline"; +} + +/** + * Determine if this element is an inline element or a block element. Inline elements + * should be sent as a contiguous chunk of text, while block elements should be further + * subdivided before sending them in for translation. + * + * @param {Node} node + * @returns {boolean} + */ +function nodeNeedsSubdividing(node) { + if (node.nodeType === Node.TEXT_NODE) { + // Text nodes are fully subdivided. + return false; + } + + if (getIsInline(node)) { + return false; + } + + for (let child of node.childNodes) { + switch (child.nodeType) { + case Node.TEXT_NODE: + // Keep checking for more inline or text nodes. + continue; + case Node.ELEMENT_NODE: { + if (getIsInline(child)) { + // Keep checking for more inline or text nodes. + continue; + } + // A child element is not inline, so subdivide this node further. + return true; + } + default: + return true; + } + } + return false; +} + +/** + * Returns an iterator of a node's ancestors. + * + * @param {Node} node + * @returns {Generator<ParentNode>} + */ +function* getAncestorsIterator(node) { + const document = node.ownerDocument; + for ( + let parent = node.parentNode; + parent && parent !== document.documentElement; + parent = parent.parentNode + ) { + yield parent; + } +} + +/** + * This contains all of the information needed to perform a translation request. + * + * @typedef {Object} TranslationRequest + * @prop {Node} node + * @prop {string} sourceText + * @prop {boolean} isHTML + * @prop {Function} resolve + * @prop {Function} reject + */ + +/** + * When a page is hidden, mutations may occur in the DOM. It doesn't make sense to + * translate those elements while the page is hidden, especially as it may bring + * a translations engine back to life, which can be quite expensive. Queue those + * messages here. + */ +class QueuedTranslator { + /** + * @type {MessagePort | null} + */ + #port = null; + + /** + * @type {() => void} + */ + #actorRequestNewPort; + + /** + * An id for each message sent. This is used to match up the request and response. + */ + #nextMessageId = 0; + + /** + * Tie together a message id to a resolved response. + * @type {Map<number, TranslationRequest} + */ + #requests = new Map(); + + /** + * If the translations are paused, they are queued here. This Map is ordered by + * from oldest to newest requests with stale requests being removed. + * @type {Map<Node, TranslationRequest>} + */ + #queue = new Map(); + + /** + * @type {"uninitialized" | "ready" | "error" | "closed"} + */ + engineStatus = "uninitialized"; + + /** + * @param {MessagePort} port + * @param {Document} document + * @param {() => void} actorRequestNewPort + */ + constructor(port, actorRequestNewPort) { + this.#actorRequestNewPort = actorRequestNewPort; + + this.acquirePort(port); + } + + /** + * When an engine gets closed while still in use, a new one will need to be requested. + * + * @type {{ promise: Promise<void>, resolve: Function, reject: Function } | null} + */ + #portRequest = null; + + /** + * Keep track if the page is shown or hidden. When the page is hidden, no translations + * will be posted to the translations engine. + */ + #isPageShown = true; + + /** + * Note when a new port is being requested so we don't re-request it. + */ + showPage() { + this.#isPageShown = true; + if (this.#port) { + throw new Error( + "Attempting to show the page when there is already port available" + ); + } + if (this.#queue.size) { + // There are queued translations, request a new port. After the port is retrieved + // the pending queue will be processed. + this.#requestNewPort(); + } + } + + /** + * Hide the page, and move any outstanding translation requests to a queue. + */ + hidePage() { + this.#isPageShown = false; + this.discardPort(); + + if (this.#requests.size) { + lazy.console.log( + "Pausing translations with pending translation requests." + ); + } + this.#moveRequestsToQueue(); + } + + /** + * Request a new port. The port will come in via `acquirePort`, and then resolved + * through the `this.#portRequest.resolve`. + * @returns {Promise<void>} + */ + #requestNewPort() { + if (this.#portRequest) { + // A port was already requested. + return this.#portRequest.promise; + } + + const portRequest = { promise: null, resolve: null, reject: null }; + portRequest.promise = new Promise((resolve, reject) => { + portRequest.resolve = resolve; + portRequest.reject = reject; + }); + + this.#portRequest = portRequest; + + // Send a request through the actor for a new port. The request response will + // trigger the method `QueuedTranslator.prototype.acquirePort` + this.#actorRequestNewPort(); + + this.#portRequest.promise + .then( + () => { + this.#portRequest = null; + + // Resume the queued translations. + if (this.#queue.size) { + lazy.console.log( + `Resuming ${ + this.#queue.size + } translations from the pending translation queue.` + ); + + const oldQueue = this.#queue; + this.#queue = new Map(); + this.#repostTranslations(oldQueue); + } + }, + error => { + lazy.console.error(error); + } + ) + .finally(() => { + this.#portRequest = null; + }); + + return portRequest.promise; + } + + /** + * Send a request to translate text to the Translations Engine. If it returns `null` + * then the request is stale. A rejection means there was an error in the translation. + * This request may be queued. + * + * @param {node} Node + * @param {string} sourceText + * @param {boolean} isHTML + */ + async translate(node, sourceText, isHTML) { + if (this.#isPageShown && !this.#port) { + try { + await this.#requestNewPort(); + } catch {} + } + + // At this point we don't know if the page is still shown, or if the attempt + // to get a port was successful so check again. + + if (!this.#isPageShown || !this.#port) { + // Queue the request while the page isn't shown. + return new Promise((resolve, reject) => { + const previousRequest = this.#queue.get(node); + if (previousRequest) { + // Previous requests get resolved as null, as this new one will replace it. + previousRequest.resolve(null); + // Delete the entry so that the order of the queue is maintained. The + // new request will be put on the end. + this.#queue.delete(node); + } + + // This Promises's resolve and reject will be chained after the translation + // request. For now add it to the queue along with the other arguments. + this.#queue.set(node, { node, sourceText, isHTML, resolve, reject }); + }); + } + + return this.#postTranslationRequest(node, sourceText, isHTML); + } + + /** + * Posts the translation to the translations engine through the MessagePort. + * + * @param {Node} node + * @param {string} sourceText + * @param {boolean} isHTML + * @return {{ translateText: TranslationFunction, translateHTML: TranslationFunction}} + */ + #postTranslationRequest(node, sourceText, isHTML) { + return new Promise((resolve, reject) => { + const messageId = this.#nextMessageId++; + // Store the "resolve" for the promise. It will be matched back up with the + // `messageId` in #handlePortMessage. + this.#requests.set(messageId, { + node, + sourceText, + isHTML, + resolve, + reject, + }); + this.#port.postMessage({ + type: "TranslationsPort:TranslationRequest", + messageId, + sourceText, + isHTML, + }); + }); + } + + /** + * Close the port and move any pending translations onto a queue. + */ + discardPort() { + if (this.#port) { + this.#port.postMessage({ type: "TranslationsPort:DiscardTranslations" }); + this.#port.close(); + this.#port = null; + } + this.#moveRequestsToQueue(); + this.engineStatus = "uninitialized"; + } + + /** + * Move any unfulfilled requests to the queue so they can be sent again when + * the page is active again. + */ + #moveRequestsToQueue() { + if (this.#requests.size) { + for (const request of this.#requests.values()) { + this.#queue.set(request.node, request); + } + this.#requests = new Map(); + } + } + + /** + * Acquires a port, checks on the engine status, and then starts or resumes + * translations. + * @param {MessagePort} port + */ + acquirePort(port) { + if (this.#port) { + if (this.engineStatus === "ready") { + lazy.console.error( + "Received a new translation port while one already existed." + ); + } + this.discardPort(); + } + + this.#port = port; + + const portRequest = this.#portRequest; + + // Match up a response on the port to message that was sent. + port.onmessage = ({ data }) => { + switch (data.type) { + case "TranslationsPort:TranslationResponse": { + const { targetText, messageId } = data; + // A request may not match match a messageId if there is a race during the pausing + // and discarding of the queue. + this.#requests.get(messageId)?.resolve(targetText); + this.#requests.delete(messageId); + break; + } + case "TranslationsPort:GetEngineStatusResponse": { + if (portRequest) { + const { resolve, reject } = portRequest; + if (data.status === "ready") { + resolve(); + } else { + reject(new Error("The engine failed to load.")); + } + } + this.engineStatus = data.status; + break; + } + case "TranslationsPort:EngineTerminated": { + // The engine was terminated, and if a translation is needed a new port + // will need to be requested. + this.engineStatus = "closed"; + this.discardPort(); + if (this.#queue.size && this.#isPageShown) { + this.#requestNewPort(); + } + break; + } + default: + lazy.console.error("Unknown translations port message: " + data.type); + break; + } + }; + + port.postMessage({ type: "TranslationsPort:GetEngineStatusRequest" }); + } + + /** + * Re-send a list of translation requests. + * + * @param {Map<any, TranslationRequest>} mappedRequests + * This is either the this.#queue or this.#requests. + */ + #repostTranslations(mappedRequests) { + for (const value of mappedRequests.values()) { + const { node, sourceText, isHTML, resolve, reject } = value; + if (Cu.isDeadWrapper(node)) { + // If the node is dead, resolve without any text. Do not reject as that + // will be treated as an error. + resolve(null); + } else { + this.#postTranslationRequest(node, sourceText, isHTML).then( + resolve, + reject + ); + } + } + } + + /** + * Close the port and remove any pending or queued requests. + */ + destroy() { + this.#port.close(); + this.#requests = new Map(); + this.#queue = new Map(); + } +} |