- Replaced two dot diff with three dot diff. Cleaned up obsolete code linked to double dot diff.

- Moved target_branch_existence assertion to _prepare_repo method
- Renamed branch_name -> target_branch_name
- Simplified get_files method

pr_agent/git_providers/local_git_provider.py

@@ -1,10 +1,9 @@
 import logging
-import uuid
 from collections import Counter
 from pathlib import Path
 from typing import List
 
-from git import GitCommandError, Repo
+from git import Repo
 
 from pr_agent.config_loader import _find_repository_root, settings
 from pr_agent.git_providers.git_provider import EDIT_TYPE, FilePatchInfo, GitProvider
@@ -29,12 +28,11 @@ class LocalGitProvider(GitProvider):
     For the MVP it only supports the /review and /describe capabilities.
     """
 
-    def __init__(self, branch_name, incremental=False):
+    def __init__(self, target_branch_name, incremental=False):
         self.repo_path = _find_repository_root()
         self.repo = Repo(self.repo_path)
         self.head_branch_name = self.repo.head.ref.name
-        self.branch_name = branch_name
-        self.tmp_branch_name = f'pr_agent_{uuid.uuid4()}'
+        self.target_branch_name = target_branch_name
         self._prepare_repo()
         self.diff_files = None
         self.pr = PullRequestMimic(self.get_pr_title(), self.get_diff_files())
@@ -45,20 +43,6 @@ class LocalGitProvider(GitProvider):
         # inline code comments are not supported for local git repositories
         settings.pr_reviewer.inline_code_comments = False
 
-    def __del__(self):
-        logging.debug('Deleting temporary branch...')
-        self.repo.git.checkout(self.head_branch_name)  # switch back to the original branch
-        # delete the temporary branch
-        if self.tmp_branch_name not in self.repo.heads:
-            return
-        try:
-            self.repo.delete_head(self.tmp_branch_name, force=True)
-        except GitCommandError as e:
-            raise ValueError(
-                'Error while trying to delete the temporary branch.'
-                'Ensure the branch exists.'
-            ) from e
-
     def _prepare_repo(self):
         """
         Prepare the repository for PR-mimic generation.
@@ -66,15 +50,8 @@ class LocalGitProvider(GitProvider):
         logging.debug('Preparing repository for PR-mimic generation...')
         if self.repo.is_dirty():
             raise ValueError('The repository is not in a clean state. Please commit or stash pending changes.')
-        if self.tmp_branch_name in self.repo.heads:
-            self.repo.delete_head(self.tmp_branch_name, force=True)
-        self.repo.git.checkout('HEAD', b=self.tmp_branch_name)
-
-        try:
-            logging.debug('Rebasing the temporary branch on the main branch...')
-            self.repo.git.rebase(self.branch_name)
-        except GitCommandError as e:
-            raise ValueError('Error while rebasing. Resolve conflicts before retrying.') from e
+        if self.target_branch_name not in self.repo.heads:
+            raise KeyError(f'Branch: {self.target_branch_name} does not exist')
 
     def is_supported(self, capability: str) -> bool:
         if capability in ['get_issue_comments', 'create_inline_comment', 'publish_inline_comments', 'get_labels']:
@@ -83,7 +60,7 @@ class LocalGitProvider(GitProvider):
 
     def get_diff_files(self) -> list[FilePatchInfo]:
         diffs = self.repo.head.commit.diff(
-            self.repo.branches[self.branch_name].commit,
+            self.repo.merge_base(self.repo.head, self.repo.branches[self.target_branch_name]),
             create_patch=True,
             R=True
         )
@@ -120,13 +97,10 @@ class LocalGitProvider(GitProvider):
         """
         Returns a list of files with changes in the diff.
         """
-        # Assert existence of specific branch
-        branch_names = [ref.name for ref in self.repo.branches]
-        if self.branch_name not in branch_names:
-            raise KeyError(f"Branch: {self.branch_name} does not exist")
-        branch = self.repo.branches[self.branch_name]
-        # Compare the two branches
-        diff_index = self.repo.head.commit.diff(branch.commit)
+        diff_index = self.repo.head.commit.diff(
+            self.repo.merge_base(self.repo.head, self.repo.branches[self.target_branch_name]),
+            R=True
+        )
         # Get the list of changed files
         diff_files = [item.a_path for item in diff_index]
         return diff_files
@@ -183,7 +157,7 @@ class LocalGitProvider(GitProvider):
         return -1  # Not used anywhere for the local provider, but required by the interface
 
     def get_pr_description(self):
-        commits_diff = list(self.repo.iter_commits(self.branch_name + '..HEAD'))
+        commits_diff = list(self.repo.iter_commits(self.target_branch_name + '..HEAD'))
         # Get the commit messages and concatenate
         commit_messages = " ".join([commit.message for commit in commits_diff])
         # TODO Handle the description better - maybe use gpt-3.5 summarisation here?
@@ -193,7 +167,7 @@ class LocalGitProvider(GitProvider):
         """
         Substitutes the branch-name as the PR-mimic title.
         """
-        return self.branch_name
+        return self.target_branch_name
 
     def get_issue_comments(self):
         raise NotImplementedError('Getting issue comments is not implemented for the local git provider')