1 files changed, 183 insertions, 0 deletions
diff --git a/comm/mail/components/unifiedtoolbar/content/items/mail-go-button.mjs b/comm/mail/components/unifiedtoolbar/content/items/mail-go-button.mjs
new file mode 100644
index 0000000000..df9266d077
--- /dev/null
+++ b/comm/mail/components/unifiedtoolbar/content/items/mail-go-button.mjs
@@ -0,0 +1,183 @@
+/* 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/. */
+
+import { MailTabButton } from "chrome://messenger/content/unifiedtoolbar/mail-tab-button.mjs";
+
+const { MailServices } = ChromeUtils.import(
+  "resource:///modules/MailServices.jsm"
+);
+
+/**
+ * Map from the direction attribute value to the command the button executes on
+ * click.
+ *
+ * @type {{[string]: string}}
+ */
+const COMMAND_FOR_DIRECTION = {
+  forward: "cmd_goForward",
+  back: "cmd_goBack",
+};
+
+/**
+ * Unified toolbar button to add the selected message to a calendar as event or
+ * task.
+ * Attributes:
+ * - direction: "forward" or "back".
+ */
+class MailGoButton extends MailTabButton {
+  /**
+   * @type {?XULPopupElement}
+   */
+  #contextMenu = null;
+
+  connectedCallback() {
+    if (!this.hasConnected) {
+      const command = COMMAND_FOR_DIRECTION[this.getAttribute("direction")];
+      if (!command) {
+        throw new Error(
+          `Unknown direction "${this.getAttribute("direction")}"`
+        );
+      }
+      this.setAttribute("command", command);
+      this.#contextMenu = document.getElementById("messageHistoryPopup");
+      this.addEventListener("contextmenu", this.#handleContextMenu, true);
+    }
+    super.connectedCallback();
+  }
+
+  /**
+   * Build and show the history popup containing a list of messages to navigate
+   * to. Messages that can't be found or that were in folders we can't find are
+   * ignored. The currently displayed message is marked.
+   *
+   * @param {MouseEvent} event - Event triggering the context menu.
+   */
+  #handleContextMenu = event => {
+    event.preventDefault();
+    event.stopPropagation();
+
+    const tabmail = document.getElementById("tabmail");
+    const currentWindow = tabmail.currentTabInfo.chromeBrowser.contentWindow;
+    const { messageHistory } = tabmail.currentAboutMessage;
+    const { entries, currentIndex } = messageHistory.getHistory();
+
+    // For populating the back menu, we want the most recently visited
+    // messages first in the menu. So we go backward from curPos to 0.
+    // For the forward menu, we want to go forward from curPos to the end.
+    const items = [];
+    const relativePositionBase = entries.length - 1 - currentIndex;
+    for (const [index, entry] of entries.reverse().entries()) {
+      const folder = MailServices.folderLookup.getFolderForURL(entry.folderURI);
+      if (!folder) {
+        // Where did the folder go?
+        continue;
+      }
+
+      let menuText = "";
+      let msgHdr;
+      try {
+        msgHdr = MailServices.messageServiceFromURI(
+          entry.messageURI
+        ).messageURIToMsgHdr(entry.messageURI);
+      } catch (ex) {
+        // Let's just ignore this history entry.
+        continue;
+      }
+      const messageSubject = msgHdr.mime2DecodedSubject;
+      const messageAuthor = msgHdr.mime2DecodedAuthor;
+
+      if (!messageAuthor && !messageSubject) {
+        // Avoid empty entries in the menu. The message was most likely (re)moved.
+        continue;
+      }
+
+      // If the message was not being displayed via the current folder, prepend
+      // the folder name.  We do not need to check underlying folders for
+      // virtual folders because 'folder' is the display folder, not the
+      // underlying one.
+      if (folder != currentWindow.gFolder) {
+        menuText = folder.prettyName + " - ";
+      }
+
+      let subject = "";
+      if (msgHdr.flags & Ci.nsMsgMessageFlags.HasRe) {
+        subject = "Re: ";
+      }
+      if (messageSubject) {
+        subject += messageSubject;
+      }
+      if (subject) {
+        menuText += subject + " - ";
+      }
+
+      menuText += messageAuthor;
+      const newMenuItem = document.createXULElement("menuitem");
+      newMenuItem.setAttribute("label", menuText);
+      const relativePosition = relativePositionBase - index;
+      newMenuItem.setAttribute("value", relativePosition);
+      newMenuItem.addEventListener("command", commandEvent => {
+        this.#navigateToUri(commandEvent.target);
+        commandEvent.stopPropagation();
+      });
+      if (relativePosition === 0 && !messageHistory.canPop(0)) {
+        newMenuItem.setAttribute("checked", true);
+        newMenuItem.setAttribute("type", "radio");
+      }
+      items.push(newMenuItem);
+    }
+    this.#contextMenu.replaceChildren(...items);
+
+    this.#contextMenu.openPopupAtScreen(
+      event.screenX,
+      event.screenY,
+      true,
+      event
+    );
+  };
+
+  /**
+   * Select the message in the appropriate folder for the history popup entry.
+   * Finds the message based on the value of the item, which is the relative
+   * index of the item in the message history.
+   *
+   * @param {Element} target
+   */
+  #navigateToUri(target) {
+    const nsMsgViewIndex_None = 0xffffffff;
+    const historyIndex = Number.parseInt(target.getAttribute("value"), 10);
+    const tabmail = document.getElementById("tabmail");
+    const currentWindow = tabmail.currentTabInfo.chromeBrowser.contentWindow;
+    const messageHistory = tabmail.currentAboutMessage.messageHistory;
+    if (!messageHistory || !messageHistory.canPop(historyIndex)) {
+      return;
+    }
+    const item = messageHistory.pop(historyIndex);
+
+    if (
+      currentWindow.displayFolder &&
+      currentWindow.gFolder?.URI !== item.folderURI
+    ) {
+      const folder = MailServices.folderLookup.getFolderForURL(item.folderURI);
+      currentWindow.displayFolder(folder);
+    }
+    const msgHdr = MailServices.messageServiceFromURI(
+      item.messageURI
+    ).messageURIToMsgHdr(item.messageURI);
+    const index = currentWindow.gDBView.findIndexOfMsgHdr(msgHdr, true);
+    if (index != nsMsgViewIndex_None) {
+      if (currentWindow.threadTree) {
+        currentWindow.threadTree.selectedIndex = index;
+        currentWindow.threadTree.table.body.focus();
+      } else {
+        currentWindow.gViewWrapper.dbView.selection.select(index);
+        currentWindow.displayMessage(
+          currentWindow.gViewWrapper.dbView.URIForFirstSelectedMessage
+        );
+      }
+    }
+  }
+}
+customElements.define("mail-go-button", MailGoButton, {
+  extends: "button",
+});