feat: add tutor-contrib-google-analytics plugin

Duplicates the GoogleAnalyticsLoader from frontend-platform and registers
it for all MFEs via tutor-mfe's EXTERNAL_SCRIPTS hook.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: arbrandes

plugins/tutor-contrib-google-analytics/README.rst

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+Google Analytics plugin for `Tutor <https://docs.tutor.overhang.io>`__
+=======================================================================
+
+This plugin wires a Google Analytics 4 loader into every Open edX MFE that
+is built through ``tutor-mfe``. It duplicates the ``GoogleAnalyticsLoader``
+that used to ship with ``@openedx/frontend-platform``.
+
+The loader reads ``GOOGLE_ANALYTICS_4_ID`` from the MFE runtime configuration
+(or, for the frontend-base site, from ``commonAppConfig``). When that value
+is unset, the loader is a no-op, so the plugin is safe to enable even if
+Google Analytics has not yet been configured for a deployment.
+
+Implementation
+--------------
+
+The plugin declares a single ``GoogleAnalyticsLoader`` JavaScript class and
+inlines it into both build pipelines that tutor-mfe supports:
+
+- Legacy MFEs: the class is injected into ``env.config.jsx`` via the
+  ``mfe-env-config-buildtime-definitions`` patch and registered for all
+  MFEs through ``tutormfe.hooks.EXTERNAL_SCRIPTS``.
+- frontend-base site: the same class is injected into ``customApp.tsx``
+  via the ``mfe-site-custom-app-definitions`` patch and registered through
+  ``tutormfe.hooks.FRONTEND_SCRIPTS``, which attaches it to the site's
+  ``customApp.externalScripts`` at build time.
+
+At runtime, each pipeline instantiates the loader with the relevant app
+configuration. Setting ``GOOGLE_ANALYTICS_4_ID`` in the MFE runtime config
+(for legacy MFEs) or in ``FRONTEND_SITE_CONFIG['commonAppConfig']`` (for
+the frontend-base site) is enough to activate tracking. Without a value,
+the loader is a safe no-op.
+
+Installation
+------------
+
+Install directly from Github::
+
+    pip install git+https://github.com/openedx/openedx-tutor-plugins.git#subdirectory=plugins/tutor-contrib-google-analytics
+
+Alternatively, clone the parent repository locally and install it from the
+checkout::
+
+    git clone https://github.com/openedx/openedx-tutor-plugins.git
+    cd openedx-tutor-plugins/plugins/tutor-contrib-google-analytics
+    pip install -e .
+
+Usage
+-----
+
+Enable the plugin::
+
+    tutor plugins enable google-analytics
+
+Then rebuild the MFE images and restart the environment so the new
+``env.config.jsx`` takes effect::
+
+    tutor images build mfe mfe-dev
+    tutor local launch
+
+Make sure that ``GOOGLE_ANALYTICS_4_ID`` is present in the MFE runtime
+configuration for the deployments where tracking should be active.
+
+Uninstallation
+--------------
+
+To disable the plugin::
+
+    tutor plugins disable google-analytics
+    tutor local stop && tutor local start -d
+
+License
+-------
+
+This software is licensed under the terms of the AGPLv3.

plugins/tutor-contrib-google-analytics/setup.py

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+import io
+import os
+from setuptools import setup, find_packages
+
+HERE = os.path.abspath(os.path.dirname(__file__))
+
+
+def load_readme():
+    with io.open(os.path.join(HERE, "README.rst"), "rt", encoding="utf8") as f:
+        return f.read()
+
+
+def load_about():
+    about = {}
+    with io.open(
+        os.path.join(HERE, "tutor_google_analytics", "__about__.py"),
+        "rt",
+        encoding="utf-8",
+    ) as f:
+        exec(f.read(), about)  # pylint: disable=exec-used
+    return about
+
+
+ABOUT = load_about()
+
+
+setup(
+    name="tutor-contrib-google-analytics",
+    version=ABOUT["__version__"],
+    url="https://github.com/openedx/openedx-tutor-plugins",
+    project_urls={
+        "Code": "https://github.com/openedx/openedx-tutor-plugins",
+        "Issue tracker": "https://github.com/openedx/openedx-tutor-plugins/issues",
+    },
+    license="AGPLv3",
+    author="Adolfo R. Brandes",
+    description="Google Analytics plugin for Tutor",
+    long_description=load_readme(),
+    packages=find_packages(exclude=["tests*"]),
+    include_package_data=True,
+    python_requires=">=3.11",
+    install_requires=["tutor>=21.0.0", "tutor-mfe>=21.0.0"],
+    extras_require={"dev": ["tutor[dev]>=21.0.0"]},
+    entry_points={
+        "tutor.plugin.v1": [
+            "google-analytics = tutor_google_analytics.plugin"
+        ]
+    },
+    classifiers=[
+        "Development Status :: 3 - Alpha",
+        "Intended Audience :: Developers",
+        "License :: OSI Approved :: GNU Affero General Public License v3",
+        "Operating System :: OS Independent",
+        "Programming Language :: Python",
+        "Programming Language :: Python :: 3.11",
+        "Programming Language :: Python :: 3.12",
+    ],
+)

plugins/tutor-contrib-google-analytics/tutor_google_analytics/__about__.py

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+__version__ = "0.1.0"

plugins/tutor-contrib-google-analytics/tutor_google_analytics/__init__.py

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+from tutor import hooks
+from tutormfe.hooks import EXTERNAL_SCRIPTS, FRONTEND_SCRIPTS
+
+
+GOOGLE_ANALYTICS_LOADER = """
+class GoogleAnalyticsLoader {
+  constructor({ config }) {
+    this.analyticsId = config.GOOGLE_ANALYTICS_4_ID;
+  }
+
+  loadScript() {
+    if (!this.analyticsId) {
+      return;
+    }
+
+    global.googleAnalytics = global.googleAnalytics || [];
+    const { googleAnalytics } = global;
+
+    // If the snippet was invoked do nothing.
+    if (googleAnalytics.invoked) {
+      return;
+    }
+
+    // Invoked flag, to make sure the snippet
+    // is never invoked twice.
+    googleAnalytics.invoked = true;
+
+    googleAnalytics.load = (key, options) => {
+      const scriptSrc = document.createElement('script');
+      scriptSrc.type = 'text/javascript';
+      scriptSrc.async = true;
+      scriptSrc.src = `https://www.googletagmanager.com/gtag/js?id=${key}`;
+
+      const scriptGtag = document.createElement('script');
+      scriptGtag.innerHTML = `
+        window.dataLayer = window.dataLayer || [];
+        function gtag(){dataLayer.push(arguments);}
+        gtag('js', new Date());
+        gtag('config', '${key}');
+      `;
+
+      // Insert our scripts next to the first script element.
+      const first = document.getElementsByTagName('script')[0];
+      first.parentNode.insertBefore(scriptSrc, first);
+      first.parentNode.insertBefore(scriptGtag, first);
+      googleAnalytics._loadOptions = options; // eslint-disable-line no-underscore-dangle
+    };
+
+    // Load GoogleAnalytics with your key.
+    googleAnalytics.load(this.analyticsId);
+  }
+}
+"""
+
+
+# Legacy MFEs (frontend-platform): inline the loader into env.config.jsx.
+hooks.Filters.ENV_PATCHES.add_item(
+    ("mfe-env-config-buildtime-definitions", GOOGLE_ANALYTICS_LOADER)
+)
+EXTERNAL_SCRIPTS.add_item(("all", "GoogleAnalyticsLoader"))
+
+
+# frontend-base site: inline the loader into customApp and register it.
+hooks.Filters.ENV_PATCHES.add_item(
+    ("mfe-site-custom-app-definitions", GOOGLE_ANALYTICS_LOADER)
+)
+FRONTEND_SCRIPTS.add_item("GoogleAnalyticsLoader")