Change default .stack-pr.cfg location to repo root

stack-info: PR: #104, branch: laszlokindrat/stack/1

Author: Laszlo Kindrat

README.md

@@ -409,7 +409,7 @@ stack-pr config land.style=disable
 stack-pr config land.style=bottom-only
 ```
 
-The config command modifies the config file (`.stack-pr.cfg` by default, or the path specified by `STACKPR_CONFIG` environment variable). If the file doesn't exist, it will be created. If a setting already exists, it will be updated.
+The config command modifies the config file (the `.stack-pr.cfg` file in the repo root by default, or the path specified by `STACKPR_CONFIG` environment variable). If the file doesn't exist, it will be created. If a setting already exists, it will be updated.
 
 ### Config files
 

src/stack_pr/cli.py

@@ -67,6 +67,7 @@
     branch_exists,
     check_gh_installed,
     get_current_branch_name,
+    get_repo_root,
     get_gh_username,
     get_uncommitted_changes,
     is_rebase_in_progress,
@@ -1612,15 +1613,16 @@ def create_argparser(
     return parser
 
 
-def load_config(config_file: str) -> configparser.ConfigParser:
+def load_config(config_file: str | Path) -> configparser.ConfigParser:
     config = configparser.ConfigParser()
     if Path(config_file).is_file():
         config.read(config_file)
     return config
 
 
 def main() -> None:  # noqa: PLR0912
-    config_file = os.getenv("STACKPR_CONFIG", ".stack-pr.cfg")
+    repo_config_file = get_repo_root() / ".stack-pr.cfg"
+    config_file = os.getenv("STACKPR_CONFIG", repo_config_file)
     config = load_config(config_file)
 
     parser = create_argparser(config)

src/stack_pr/git.py

@@ -101,6 +101,27 @@ def get_current_branch_name(repo_dir: Path | None = None) -> str:
         raise
 
 
+def get_repo_root(repo_dir: Path | None = None) -> Path:
+    """Returns the root of the git repository.
+
+    Args:
+        repo_dir: path to the repo. Defaults to the current working directory.
+
+    Returns:
+        The root of the given git repository.
+    """
+    try:
+        return Path(
+            get_command_output(
+                ["git", "rev-parse", "--show-toplevel"], cwd=repo_dir
+            ).strip()
+        )
+    except subprocess.CalledProcessError as e:
+        if e.returncode == GIT_NOT_A_REPO_ERROR:
+            raise GitError("Not inside a valid git repository.") from e
+        raise
+
+
 def get_uncommitted_changes(
     repo_dir: Path | None = None,
 ) -> dict[str, list[str]]: