change create_symlink with type hints and error handling

Refactor create_symlink function to add type hints and enhance error handling for existing symlinks and files.

Author: marvin1099

src/mainutils.py

@@ -5,6 +5,7 @@
 import sys
 import pwd
 import shutil
+import pathlib
 
 from typing import (
     Callable,
@@ -321,8 +322,6 @@ def dereference_links() -> None:
             update_progress(int((i + 1) / total_links * 100))
 
     def find_symlinks(path: str) -> List[List[str]]:
-        import pathlib
-
         links = []
         directory = pathlib.Path(path)
         for item in directory.rglob("*"):
@@ -408,8 +407,6 @@ def copy_folder_with_progress(
     log(f"ignoring: {ignore}\nincluding anyway: {include_override}")
 
     def traverse_folders(path: str) -> List[str]:
-        import pathlib
-
         allf = []
         directory = pathlib.Path(path)
         for item in directory.rglob("*"):
@@ -685,13 +682,29 @@ def flatpakrunner():
     if os.path.isfile(flatpakrunfile):
         os.remove(flatpakrunfile)
 
-# Safe symlink creation function
-# Yeeted from: https://zetcode.com/python/os-symlink/
-def create_symlink(src, dst):
-    try:
-        os.symlink(src, dst)
-    except FileExistsError:
-        if os.path.islink(dst):
-            # Optionally update existing symlink
-            os.remove(dst)
-            os.symlink(src, dst)
+def create_symlink(src: Union[str, pathlib.Path], dst: Union[str, pathlib.Path], replace: Union[bool, None] = True) -> None:
+    # Needs src, dest;  replace can be True (replace all), None (replace only files and symlinks) or False (don't replace anything)
+    src_path = pathlib.Path(src).resolve()
+    dst_path = pathlib.Path(dst)
+
+    if not src_path.exists():
+        raise FileNotFoundError(f"Source does not exist: {src_path}")
+
+    if dst_path.lexists(): # Handle existing destination, still true on broken symlinks
+        if dst_path.is_symlink():
+            if dst_path.resolve() == src_path: # Correct symlink – nothing to do
+                return
+            if replace is False: # Wrong target
+                raise OSError(f"Symlink {dst_path} points to {dst_path.resolve()}, expected {src_path}")
+            dst_path.unlink() # remove incorrect link
+        else:
+            if replace is False:
+                raise OSError(f"{dst_path} exists and is not a symlink")
+            elif dst_path.is_dir() and replace is None:
+                raise OSError(f"{dst_path} exists and is not a file or symlink")
+            if dst_path.is_dir():
+                shutil.rmtree(dst_path) # delete whole directory tree
+            else:
+                dst_path.unlink() # delete regular file
+
+    os.symlink(src_path, dst_path)  # Create link