Structured content links (#2089)

* Update CSS to JSON converter to generalize the remove-property comment

* Fix navigation not being updated when _clearContent is run

* Add structured content schema for link tags

* Add test links

* Add external-link icon

* Pass Display instance to DisplayContentManager

* Update structured content generation

* Update link styles

3 files changed, 80 insertions, 3 deletions

diff --git a/ext/js/display/display-content-manager.js b/ext/js/display/display-content-manager.js
index 0818f915..0b91b40c 100644
--- a/ext/js/display/display-content-manager.js
+++ b/ext/js/display/display-content-manager.js
@@ -37,11 +37,14 @@
 class DisplayContentManager {
     /**
      * Creates a new instance of the class.
+     * @param {Display} display The display instance that owns this object.
      */
-    constructor() {
+    constructor(display) {
+        this._display = display;
         this._token = {};
         this._mediaCache = new Map();
         this._loadMediaData = [];
+        this._eventListeners = new EventListenerCollection();
     }
 
     /**
@@ -77,6 +80,23 @@ class DisplayContentManager {
         this._mediaCache.clear();
 
         this._token = {};
+
+        this._eventListeners.removeAllEventListeners();
+    }
+
+    /**
+     * Sets up attributes and events for a link element.
+     * @param {Element} element The link element.
+     * @param {string} href The URL.
+     * @param {boolean} internal Whether or not the URL is an internal or external link.
+     */
+    prepareLink(element, href, internal) {
+        element.href = href;
+        if (!internal) {
+            element.target = '_blank';
+            element.rel = 'noreferrer noopener';
+        }
+        this._eventListeners.addEventListener(element, 'click', this._onLinkClick.bind(this));
     }
 
     async _loadMedia(path, dictionary, onLoad, onUnload) {
@@ -127,4 +147,28 @@ class DisplayContentManager {
         }
         return cachedData;
     }
+
+    _onLinkClick(e) {
+        const {href} = e.currentTarget;
+        if (typeof href !== 'string') { return; }
+
+        const baseUrl = new URL(location.href);
+        const url = new URL(href, baseUrl);
+        const internal = (url.protocol === baseUrl.protocol && url.host === baseUrl.host);
+        if (!internal) { return; }
+
+        e.preventDefault();
+
+        const params = {};
+        for (const [key, value] of url.searchParams.entries()) {
+            params[key] = value;
+        }
+        this._display.setContent({
+            historyMode: 'new',
+            focus: false,
+            params,
+            state: null,
+            content: null
+        });
+    }
 }
diff --git a/ext/js/display/display.js b/ext/js/display/display.js
index a89008b4..02d8513f 100644
--- a/ext/js/display/display.js
+++ b/ext/js/display/display.js
@@ -52,7 +52,7 @@ class Display extends EventDispatcher {
         this._styleNode = null;
         this._eventListeners = new EventListenerCollection();
         this._setContentToken = null;
-        this._contentManager = new DisplayContentManager();
+        this._contentManager = new DisplayContentManager(this);
         this._hotkeyHelpController = new HotkeyHelpController();
         this._displayGenerator = new DisplayGenerator({
             japaneseUtil,
@@ -938,7 +938,7 @@ class Display extends EventDispatcher {
 
         this._dictionaryEntries = dictionaryEntries;
 
-        this._updateNavigation(this._history.hasPrevious(), this._history.hasNext());
+        this._updateNavigationAuto();
         this._setNoContentVisible(dictionaryEntries.length === 0 && lookup);
 
         const container = this._container;
@@ -1002,6 +1002,7 @@ class Display extends EventDispatcher {
 
     _clearContent() {
         this._container.textContent = '';
+        this._updateNavigationAuto();
         this._setQuery('', '', 0);
 
         this._triggerContentUpdateStart();
@@ -1058,6 +1059,10 @@ class Display extends EventDispatcher {
         document.title = title;
     }
 
+    _updateNavigationAuto() {
+        this._updateNavigation(this._history.hasPrevious(), this._history.hasNext());
+    }
+
     _updateNavigation(previous, next) {
         const {documentElement} = document;
         if (documentElement !== null) {
diff --git a/ext/js/display/sandbox/structured-content-generator.js b/ext/js/display/sandbox/structured-content-generator.js
index 799da586..eb847d07 100644
--- a/ext/js/display/sandbox/structured-content-generator.js
+++ b/ext/js/display/sandbox/structured-content-generator.js
@@ -59,6 +59,8 @@ class StructuredContentGenerator {
                 return this._createStructuredContentElement(tag, content, dictionary, 'simple', true, true);
             case 'img':
                 return this.createDefinitionImage(content, dictionary);
+            case 'a':
+                return this._createLinkElement(content, dictionary);
         }
         return null;
     }
@@ -253,4 +255,30 @@ class StructuredContentGenerator {
         if (typeof marginRight === 'number') { style.marginRight = `${marginRight}em`; }
         if (typeof marginBottom === 'number') { style.marginBottom = `${marginBottom}em`; }
     }
+
+    _createLinkElement(content, dictionary) {
+        let {href} = content;
+        const internal = href.startsWith('?');
+        if (internal) {
+            href = `${location.protocol}//${location.host}/search.html${href.length > 1 ? href : ''}`;
+        }
+
+        const node = this._createElement('a', 'gloss-link');
+        node.dataset.external = `${!internal}`;
+
+        const text = this._createElement('span', 'gloss-link-text');
+        node.appendChild(text);
+
+        const child = this.createStructuredContent(content.content, dictionary);
+        if (child !== null) { text.appendChild(child); }
+
+        if (!internal) {
+            const icon = this._createElement('span', 'gloss-link-external-icon icon');
+            icon.dataset.icon = 'external-link';
+            node.appendChild(icon);
+        }
+
+        this._contentManager.prepareLink(node, href, internal);
+        return node;
+    }
 }