Operator to run git diff on current ifc file

Short demo - https://imgur.com/a/TvnztNy

src/bonsai/bonsai/bim/module/ifcgit/__init__.py

@@ -38,6 +38,7 @@ classes = (
     operator.RefreshGit,
     operator.SwitchRevision,
     operator.InstallGit,
+    operator.RunGitDiff,
     prop.IfcGitTag,
     prop.IfcGitListItem,
     prop.IfcGitProperties,

src/bonsai/bonsai/bim/module/ifcgit/operator.py

@@ -409,3 +409,25 @@ class InstallGit(bpy.types.Operator):
         core.install_git(tool.IfcGit, self)
         refresh()
         return {"FINISHED"}
+
+
+class RunGitDiff(bpy.types.Operator):
+    """Run `git diff` for the current version of IFC file and the last saved one."""
+
+    bl_label = "Git Diff"
+    bl_idname = "ifcgit.git_diff"
+    bl_options = set()
+
+    @classmethod
+    def poll(cls, context):
+        if not tool.Ifc.get():
+            cls.poll_message_set("No IFC file loaded.")
+            return False
+        if not tool.Ifc.get_path():
+            cls.poll_message_set("Current IFC file was never saved.")
+            return False
+        return True
+
+    def execute(self, context):
+        core.run_git_diff(tool.IfcGit, self)
+        return {"FINISHED"}

src/bonsai/bonsai/bim/module/ifcgit/ui.py

@@ -283,3 +283,5 @@ class IFCGIT_PT_revision_inspector(bpy.types.Panel):
             "ifcgit.object_log",
             icon="TEXT",
         )
+        row = layout.row()
+        row.operator("ifcgit.git_diff")

src/bonsai/bonsai/core/ifcgit.py

@@ -142,3 +142,7 @@ def install_git(ifcgit: tool.IfcGit, operator: bpy.types.Operator) -> None:
         ifcgit.install_git_windows(operator=operator)
     else:
         print("install_git() not implemented")
+
+
+def run_git_diff(ifcgit: tool.IfcGit, operator: bpy.types.Operator) -> None:
+    ifcgit.run_git_diff(operator)

src/bonsai/bonsai/tool/ifcgit.py

@@ -570,6 +570,29 @@ class IfcGit:
         except FileNotFoundError:
             operator.report({"ERROR"}, "Winget is not available. Make sure Windows Package Manager is installed.")
 
+    @classmethod
+    def run_git_diff(cls, operator: bpy.types.Operator) -> None:
+        path = tool.Ifc.get_path()
+        ifc_file = tool.Ifc.get()
+        ifc_str = ifc_file.to_string()
+
+        # Avoid `text=True` as it's causing issues with colorful output.
+        result = subprocess.run(
+            ("git", "diff", "--no-index", "--color=always", "--", path, "-"),
+            input=ifc_str.encode(),
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+        )
+        if result.returncode == 0:
+            operator.report({"INFO"}, "No changes since last save.")
+            return
+        elif result.returncode == 1:
+            print(result.stdout.decode())
+            operator.report({"INFO"}, "See system console for git diff output.")
+            return
+        print(result)
+        raise Exception("Error running git diff, see system console.")
+
 
 class IfcGitRepo:
     repo: git.Repo = None