From 370e678ae41da49693ad5cfe10c23aba371e87c1 Mon Sep 17 00:00:00 2001
From: Slavek Kabrda <bkabrda@redhat.com>
Date: Nov 05 2018 15:40:20 +0000
Subject: Make it possible to create hooks that don't have DB entries. Fixes #3972


---

diff --git a/pagure/hooks/__init__.py b/pagure/hooks/__init__.py
index 67212ae..cad4c94 100644
--- a/pagure/hooks/__init__.py
+++ b/pagure/hooks/__init__.py
@@ -145,6 +145,7 @@ class BaseHook(object):
     name = None
     form = None
     description = None
+    backref = None
     db_object = None
     # hook_type is not used in hooks that use a Runner class, as those can
     # implement run actions on whatever is useful to them.
@@ -259,6 +260,26 @@ class BaseHook(object):
         if not cls.runner:
             raise ValueError("BaseHook.remove called for runner-less hook")
 
+    @classmethod
+    def is_enabled_for(cls, project):
+        """ Determine if this hook should be run for given project.
+
+        On some Pagure instances, some hooks should be run on all projects
+        that fulfill certain criteria. It is therefore not necessary to keep
+        database objects for them.
+
+        If a hook's backref is set to None, this method is run to determine
+        whether the hook should be run or not. These hooks also won't show
+        up on settings page, since they can't be turned off.
+
+        :arg project: The project to inspect
+        :type project: pagure.lib.model.Project
+        :return: True if this hook should be run on the given project,
+            False otherwise
+
+        """
+        return False
+
 
 def run_project_hooks(
     session,
diff --git a/pagure/lib/plugins.py b/pagure/lib/plugins.py
index 09fb49c..6bd8944 100644
--- a/pagure/lib/plugins.py
+++ b/pagure/lib/plugins.py
@@ -15,8 +15,16 @@ from straight.plugin import load
 from pagure.lib.model_base import BASE
 
 
-def get_plugin_names(blacklist=None):
-    """ Return the list of plugins names. """
+def get_plugin_names(blacklist=None, without_backref=False):
+    """ Return the list of plugins names.
+
+    :arg blacklist: name or list of names to not return
+    :type blacklist: string or list of strings
+    :arg without_backref: whether or not to include hooks that
+        have backref "None"
+    :type without_backref: bool
+    :return: list of plugin names (strings)
+    """
     from pagure.hooks import BaseHook
 
     plugins = load("pagure.hooks", subclasses=BaseHook)
@@ -26,7 +34,8 @@ def get_plugin_names(blacklist=None):
         blacklist = [blacklist]
 
     output = [
-        plugin.name for plugin in plugins if plugin.name not in blacklist
+        plugin.name for plugin in plugins
+        if plugin.name not in blacklist and (plugin.backref or without_backref)
     ]
     # The default hook is not one we show
     if "default" in output:
@@ -69,9 +78,13 @@ def get_enabled_plugins(project, with_default=False):
     for plugin in load("pagure.hooks", subclasses=BaseHook):
         if plugin.name == "default":
             continue
-        plugin.db_object()
-        if hasattr(project, plugin.backref):
-            dbobj = getattr(project, plugin.backref)
-            if dbobj and dbobj.active:
-                enabled.append((plugin, dbobj))
+        if plugin.backref is None:
+            if plugin.is_enabled_for(project):
+                enabled.append((plugin, None))
+        else:
+            plugin.db_object()
+            if hasattr(project, plugin.backref):
+                dbobj = getattr(project, plugin.backref)
+                if dbobj and dbobj.active:
+                    enabled.append((plugin, dbobj))
     return enabled
diff --git a/tests/test_pagure_lib_plugins.py b/tests/test_pagure_lib_plugins.py
new file mode 100644
index 0000000..b6a174b
--- /dev/null
+++ b/tests/test_pagure_lib_plugins.py
@@ -0,0 +1,76 @@
+# coding=utf-8
+"""
+ (c) 2015-2018 - Copyright Red Hat Inc
+
+ Authors:
+   Slavek Kabrda <bkabrda@redhat.com>
+
+"""
+
+from __future__ import unicode_literals
+
+__requires__ = ['SQLAlchemy >= 0.8']
+import pkg_resources
+
+import os
+import sys
+
+from mock import patch
+
+sys.path.insert(0, os.path.join(os.path.dirname(
+    os.path.abspath(__file__)), '..'))
+
+import pagure.hooks
+import pagure.lib.plugins
+import tests
+
+
+class EnabledForAll(pagure.hooks.BaseHook):
+    name = "EnabledForAll"
+
+    @classmethod
+    def is_enabled_for(cls, project):
+        return True
+
+class DisabledForAll(pagure.hooks.BaseHook):
+    name = "DisabledForAll"
+    # disabled for all is the default
+
+class PagureLibtests_plugins(tests.Modeltests):
+    """
+    Test the pagure.lib.plugins module
+    """
+
+    maxDiff = None
+
+    @patch("pagure.lib.plugins.load")
+    def test_plugin_is_enabled_for(self, load):
+        """ Test the is_enabled_for method of plugins is properly
+        handled by pagure.lib.plugins.get_enabled_plugins.
+        """
+        tests.create_projects(self.session)
+        project = pagure.lib.query._get_project(self.session, "test")
+
+        load.return_value = [EnabledForAll]
+        self.assertEqual(
+            pagure.lib.plugins.get_enabled_plugins(project),
+            [(EnabledForAll, None)]
+        )
+
+        load.return_value = [DisabledForAll]
+        self.assertEqual(
+            pagure.lib.plugins.get_enabled_plugins(project),
+            []
+        )
+
+    @patch("pagure.lib.plugins.load")
+    def test_get_plugin_names(self, load):
+        """ Test the get_plugin_names method with plugins that don't
+        have backref.
+        """
+        load.return_value = [EnabledForAll]
+        self.assertEqual(pagure.lib.plugins.get_plugin_names(), [])
+        self.assertEqual(
+            pagure.lib.plugins.get_plugin_names(without_backref=True),
+            ['EnabledForAll']
+        )