firefox-desktop/browser/components/genai/GenAI.sys.mjs

/**
 * 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 { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";

const lazy = {};
XPCOMUtils.defineLazyPreferenceGetter(
  lazy,
  "chatEnabled",
  "browser.ml.chat.enabled"
);
XPCOMUtils.defineLazyPreferenceGetter(
  lazy,
  "chatOpenSidebarOnProviderChange",
  "browser.ml.chat.openSidebarOnProviderChange",
  true
);
XPCOMUtils.defineLazyPreferenceGetter(
  lazy,
  "chatPromptPrefix",
  "browser.ml.chat.prompt.prefix"
);
XPCOMUtils.defineLazyPreferenceGetter(
  lazy,
  "chatProvider",
  "browser.ml.chat.provider",
  null,
  (_pref, _old, val) => onChatProviderChange(val)
);
XPCOMUtils.defineLazyPreferenceGetter(
  lazy,
  "chatSidebar",
  "browser.ml.chat.sidebar"
);

export const GenAI = {
  chatProviders: new Map(),

  /**
   * Handle startup tasks like telemetry, adding listeners.
   */
  init() {
    // Access this getter for its side effect of observing provider pref change
    lazy.chatProvider;

    // Detect about:preferences to add controls
    Services.obs.addObserver(this, "experimental-pane-loaded");
  },

  /**
   * Build prompts menu to ask chat for context menu or popup.
   *
   * @param {MozMenu} menu Element to update
   * @param {nsContextMenu} context Additional menu context
   */
  buildAskChatMenu(menu, context) {
    if (!lazy.chatEnabled || lazy.chatProvider == "") {
      context.showItem(menu, false);
      return;
    }

    menu.context = context;
    menu.label = "Ask chatbot";
    menu.menupopup?.remove();
    Services.prefs.getChildList("browser.ml.chat.prompts.").forEach(pref => {
      try {
        let prompt = Services.prefs.getStringPref(pref);
        try {
          prompt = JSON.parse(prompt);
        } catch (ex) {}
        menu
          .appendItem(prompt.label ?? prompt, prompt.value ?? "")
          .addEventListener("command", this.handleAskChat.bind(this));
      } catch (ex) {
        console.error("Failed to add menu item for " + pref, ex);
      }
    });
    context.showItem(menu, menu.itemCount > 0);
  },

  /**
   * Build a prompt with context.
   *
   * @param {MozMenuItem} item Use value falling back to label
   * @param {object} context Placeholder keys with values to replace
   * @returns {string} Prompt with placeholders replaced
   */
  buildChatPrompt(item, context = {}) {
    // Combine prompt prefix with the item then replace placeholders from the
    // original prompt (and not from context)
    return (lazy.chatPromptPrefix + (item.value || item.label)).replace(
      // Handle %placeholder% as key|options
      /\%(\w+)(?:\|([^%]+))?\%/g,
      (placeholder, key, options) =>
        // Currently only supporting numeric options for slice with `undefined`
        // resulting in whole string
        context[key]?.slice(0, options) ?? placeholder
    );
  },

  /**
   * Handle selected prompt by opening tab or sidebar.
   *
   * @param {Event} event from menu command
   */
  async handleAskChat({ target }) {
    // TODO bug 1902449 to make this less context-menu specific
    const win = target.ownerGlobal;
    const { gBrowser, SidebarController } = win;
    const { selectedTab } = gBrowser;
    const prompt = this.buildChatPrompt(target, {
      currentTabTitle:
        (selectedTab._labelIsContentTitle && selectedTab.label) || "",
      selection: target.closest("menu").context.selectionInfo.fullText ?? "",
    });

    // Pass the prompt via GET url ?q= param or request header
    const { header } = this.chatProviders.get(lazy.chatProvider) ?? {};
    const url = new URL(lazy.chatProvider);
    const options = {
      inBackground: false,
      relatedToCurrent: true,
      triggeringPrincipal: Services.scriptSecurityManager.createNullPrincipal(
        {}
      ),
    };
    if (header) {
      options.headers = Cc[
        "@mozilla.org/io/string-input-stream;1"
      ].createInstance(Ci.nsIStringInputStream);
      options.headers.data = `${header}: ${encodeURIComponent(prompt)}\r\n`;
    } else {
      url.searchParams.set("q", prompt);
    }

    // Get the desired browser to handle the prompt url request
    let browser;
    if (lazy.chatSidebar) {
      await SidebarController.show("viewGenaiChatSidebar");
      browser = await SidebarController.browser.contentWindow.browserPromise;
    } else {
      browser = gBrowser.addTab("", options).linkedBrowser;
    }
    browser.fixupAndLoadURIString(url, options);
  },

  /**
   * Build preferences for chat such as handling providers.
   *
   * @param {Window} window for about:preferences
   */
  buildPreferences({ document, Preferences }) {
    const providerEl = document.getElementById("genai-chat-provider");
    if (!providerEl) {
      return;
    }

    const enabled = Preferences.get("browser.ml.chat.enabled");
    const onEnabledChange = () => (providerEl.disabled = !enabled.value);
    onEnabledChange();
    enabled.on("change", onEnabledChange);

    // TODO bug 1895433 populate providers
    Preferences.add({ id: "browser.ml.chat.provider", type: "string" });
  },

  // nsIObserver
  observe(window) {
    this.buildPreferences(window);
  },
};

/**
 * Ensure the chat sidebar is shown to reflect changed provider.
 *
 * @param {string} value New pref value
 */
function onChatProviderChange(value) {
  if (value && lazy.chatEnabled && lazy.chatOpenSidebarOnProviderChange) {
    Services.wm
      .getMostRecentWindow("navigator:browser")
      ?.SidebarController.show("viewGenaiChatSidebar");
  }
}