From dc6131d121ddeefe685c53b35e94b3310c2ac0b4 Mon Sep 17 00:00:00 2001
From: ChrisLR <arzhul@gmail.com>
Date: Sat, 19 Mar 2022 19:10:51 -0400
Subject: [PATCH] Added TagField for components

---
 .../base_systems/components/__init__.py       |  2 +-
 .../base_systems/components/component.py      |  5 +++
 .../base_systems/components/dbfield.py        | 43 +++++++++++++++++++
 .../contrib/base_systems/components/holder.py | 14 ++++++
 4 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/evennia/contrib/base_systems/components/__init__.py b/evennia/contrib/base_systems/components/__init__.py
index 705e9ee411..1aa94a1df1 100644
--- a/evennia/contrib/base_systems/components/__init__.py
+++ b/evennia/contrib/base_systems/components/__init__.py
@@ -9,7 +9,7 @@ See the docs for more information.
 """
 
 from evennia.contrib.base_systems.components.component import Component
-from evennia.contrib.base_systems.components.dbfield import DBField, NDBField
+from evennia.contrib.base_systems.components.dbfield import DBField, NDBField, TagField
 from evennia.contrib.base_systems.components.holder import ComponentHolderMixin, ComponentProperty
 
 
diff --git a/evennia/contrib/base_systems/components/component.py b/evennia/contrib/base_systems/components/component.py
index f260610e54..4b1697da38 100644
--- a/evennia/contrib/base_systems/components/component.py
+++ b/evennia/contrib/base_systems/components/component.py
@@ -144,6 +144,11 @@ class Component:
         ndb_fields = getattr(self, "_ndb_fields", {})
         return ndb_fields.keys()
 
+    @property
+    def tag_field_names(self):
+        tag_fields = getattr(self, "_tag_fields", {})
+        return tag_fields.keys()
+
 
 class ComponentRegisterError(Exception):
     pass
diff --git a/evennia/contrib/base_systems/components/dbfield.py b/evennia/contrib/base_systems/components/dbfield.py
index 8e4f63b5da..c63ab1bebc 100644
--- a/evennia/contrib/base_systems/components/dbfield.py
+++ b/evennia/contrib/base_systems/components/dbfield.py
@@ -52,3 +52,46 @@ class NDBField(NAttributeProperty):
             ndb_fields = {}
             setattr(owner, '_ndb_fields', ndb_fields)
         ndb_fields[name] = self
+
+
+class TagField:
+    """
+    Component Descriptor to add a tag to the host.
+    """
+    def __init__(self, default=None, enforce_single=False):
+        self._category_key = None
+        self._default = default
+        self._enforce_single = enforce_single
+
+    def __set_name__(self, owner, name):
+        """
+        Called when descriptor is first assigned to the class. It is called with
+        the name of the field.
+
+        """
+        self._category_key = f"{owner.name}__{name}"
+        tag_fields = getattr(owner, "_tag_fields", None)
+        if tag_fields is None:
+            tag_fields = {}
+            setattr(owner, '_tag_fields', tag_fields)
+        tag_fields[name] = self
+
+    def __get__(self, instance, owner):
+        tag_value = instance.host.tags.get(
+            default=self._default,
+            category=self._category_key,
+        )
+        return tag_value
+
+    def __set__(self, instance, value):
+        tag_handler = instance.host.tags
+        if self._enforce_single:
+            tag_handler.clear(category=self._category_key)
+
+        tag_handler.add(
+            key=self._key,
+            category=self._category_key,
+        )
+
+    def __delete__(self, instance):
+        instance.host.tags.clear(category=self._category_key)
diff --git a/evennia/contrib/base_systems/components/holder.py b/evennia/contrib/base_systems/components/holder.py
index ef0be1a242..651ae5840a 100644
--- a/evennia/contrib/base_systems/components/holder.py
+++ b/evennia/contrib/base_systems/components/holder.py
@@ -66,6 +66,10 @@ class ComponentHandler:
         self.db_names.append(component.name)
         self.host.tags.add(component.name, category="components")
         component.at_added(self.host)
+        for tag_field_name in component.tag_field_names:
+            default_tag = type(component).__dict__[tag_field_name]._default
+            if default_tag:
+                setattr(component, tag_field_name, default_tag)
 
     def add_default(self, name):
         """
@@ -87,6 +91,10 @@ class ComponentHandler:
         self.db_names.append(name)
         self.host.tags.add(name, category="components")
         new_component.at_added(self.host)
+        for tag_field_name in component.tag_field_names:
+            default_tag = type(component).__dict__[tag_field_name]._default
+            if default_tag:
+                setattr(component, tag_field_name, default_tag)
 
     def remove(self, component):
         """
@@ -103,6 +111,8 @@ class ComponentHandler:
             component.at_removed(self.host)
             self.db_names.remove(component_name)
             self.host.tags.remove(component_name, category="components")
+            for tag_field_name in component.tag_field_names:
+                self.host.tags.remove()
             del self._loaded_components[component_name]
         else:
             message = f"Cannot remove {component_name} from {self.host.name} as it is not registered."
@@ -217,6 +227,10 @@ class ComponentHolderMixin(object):
             component = component_class.create(self, **values)
             component_names.append(component_name)
             self.components._loaded_components[component_name] = component
+            for tag_field_name in component.tag_field_names:
+                default_tag = type(component).__dict__[tag_field_name]._default
+                if default_tag:
+                    setattr(component, tag_field_name, default_tag)
 
         self.db.component_names = component_names