From af0f0a4f6cd86e464b59a23532d8ef33a831c9f7 Mon Sep 17 00:00:00 2001
From: Dion Moult <dion@thinkmoult.com>
Date: Sat, 10 Jul 2021 11:43:01 +1000
Subject: [PATCH] Implement support for removing styles. See #1557.

---
 .../blenderbim/bim/module/style/__init__.py   |  1 +
 .../blenderbim/bim/module/style/operator.py   | 25 ++++++++++++++--
 .../blenderbim/bim/module/style/ui.py         |  2 ++
 .../ifcopenshell/api/style/remove_style.py    | 30 +++++++++++++++++++
 4 files changed, 55 insertions(+), 3 deletions(-)
 create mode 100644 src/ifcopenshell-python/ifcopenshell/api/style/remove_style.py

diff --git a/src/blenderbim/blenderbim/bim/module/style/__init__.py b/src/blenderbim/blenderbim/bim/module/style/__init__.py
index 590bb7d66e..e9d7bf9e4b 100644
--- a/src/blenderbim/blenderbim/bim/module/style/__init__.py
+++ b/src/blenderbim/blenderbim/bim/module/style/__init__.py
@@ -4,6 +4,7 @@ from . import ui, operator
 classes = (
     operator.AddStyle,
     operator.EditStyle,
+    operator.RemoveStyle,
     operator.UnlinkStyle,
     ui.BIM_PT_style,
 )
diff --git a/src/blenderbim/blenderbim/bim/module/style/operator.py b/src/blenderbim/blenderbim/bim/module/style/operator.py
index 06b33c8a21..0e53ab57bb 100644
--- a/src/blenderbim/blenderbim/bim/module/style/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/style/operator.py
@@ -29,13 +29,32 @@ class EditStyle(bpy.types.Operator):
 
     def _execute(self, context):
         self.file = IfcStore.get_file()
-        material = bpy.data.objects.get(self.material) if self.material else bpy.context.active_object.active_material
+        material = bpy.data.materials.get(self.material) if self.material else bpy.context.active_object.active_material
         settings = get_colour_settings(material)
         settings["style"] = self.file.by_id(material.BIMMaterialProperties.ifc_style_id)
         ifcopenshell.api.run("style.edit_style", self.file, **settings)
         return {"FINISHED"}
 
 
+class RemoveStyle(bpy.types.Operator):
+    bl_idname = "bim.remove_style"
+    bl_label = "Remove Style"
+    bl_options = {"REGISTER", "UNDO"}
+    material: bpy.props.StringProperty()
+
+    def execute(self, context):
+        return IfcStore.execute_ifc_operator(self, context)
+
+    def _execute(self, context):
+        self.file = IfcStore.get_file()
+        material = bpy.data.materials.get(self.material) if self.material else bpy.context.active_object.active_material
+        ifcopenshell.api.run(
+            "style.remove_style", self.file, style=self.file.by_id(material.BIMMaterialProperties.ifc_style_id)
+        )
+        material.BIMMaterialProperties.ifc_style_id = 0
+        return {"FINISHED"}
+
+
 class AddStyle(bpy.types.Operator):
     bl_idname = "bim.add_style"
     bl_label = "Add Style"
@@ -50,9 +69,9 @@ class AddStyle(bpy.types.Operator):
         material = bpy.data.materials.get(self.material) if self.material else bpy.context.active_object.active_material
         settings = get_colour_settings(material)
         settings["name"] = material.name
-        settings["external_definition"] = None # TODO: Implement. See #1222
+        settings["external_definition"] = None  # TODO: Implement. See #1222
         style = ifcopenshell.api.run("style.add_style", self.file, **settings)
-        material.BIMMaterialProperties.ifc_style_id = int(style.id())
+        material.BIMMaterialProperties.ifc_style_id = style.id()
         return {"FINISHED"}
 
 
diff --git a/src/blenderbim/blenderbim/bim/module/style/ui.py b/src/blenderbim/blenderbim/bim/module/style/ui.py
index b34f4595fb..a56705a751 100644
--- a/src/blenderbim/blenderbim/bim/module/style/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/style/ui.py
@@ -24,5 +24,7 @@ class BIM_PT_style(Panel):
             row.operator("bim.edit_style", icon="GREASEPENCIL")
             op = row.operator("bim.unlink_style", icon="UNLINKED", text="")
             op.material = context.active_object.active_material.name
+            op = row.operator("bim.remove_style", icon="X", text="")
+            op.material = context.active_object.active_material.name
         else:
             row.operator("bim.add_style", icon="ADD")
diff --git a/src/ifcopenshell-python/ifcopenshell/api/style/remove_style.py b/src/ifcopenshell-python/ifcopenshell/api/style/remove_style.py
new file mode 100644
index 0000000000..fa2f9de046
--- /dev/null
+++ b/src/ifcopenshell-python/ifcopenshell/api/style/remove_style.py
@@ -0,0 +1,30 @@
+import ifcopenshell.util.element
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"style": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        self.purge_styled_items(self.settings["style"])
+        ifcopenshell.util.element.remove_deep(self.file, self.settings["style"])
+
+    def purge_styled_items(self, style):
+        for inverse in self.file.get_inverse(style):
+            if inverse.is_a("IfcStyledItem") and len(inverse.Styles) == 1:
+                self.purge_styled_representations(inverse)
+                self.file.remove(inverse)
+
+    def purge_styled_representations(self, styled_item):
+        for inverse in self.file.get_inverse(styled_item):
+            if inverse.is_a("IfcStyledRepresentation") and len(inverse.Items) == 1:
+                self.purge_material_definition_representations(inverse)
+                self.file.remove(inverse)
+
+    def purge_material_definition_representations(self, styled_representation):
+        for inverse in self.file.get_inverse(styled_representation):
+            if inverse.is_a("IfcMaterialDefinitionRepresentation") and len(inverse.Representations) == 1:
+                self.file.remove(inverse)