Automatically determine base_path and throw error on non-git repos (#121)

# Motivation
<!-- Why is this change necessary? -->

# Content
<!-- Please include a summary of the change -->
# Testing
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# Please check the following before marking your PR as ready for review

- [ ] I have added tests for my changes
- [ ] I have updated the documentation or added new documentation as
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- [ ] I have read and agree to the [Contributor License
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Co-authored-by: codegen-bot <team+codegenbot@codegen.sh>

Author: Edward-Codegen

src/codegen/sdk/core/codebase.py

@@ -74,7 +74,7 @@
 from codegen.sdk.typescript.statements.import_statement import TSImportStatement
 from codegen.sdk.typescript.symbol import TSSymbol
 from codegen.sdk.typescript.type_alias import TSTypeAlias
-from codegen.sdk.utils import determine_project_language
+from codegen.sdk.utils import determine_project_language, split_git_path
 from codegen.shared.decorators.docs import apidoc, noapidoc, py_noapidoc
 from codegen.shared.exceptions.control_flow import MaxAIRequestsError
 from codegen.shared.performance.stopwatch_utils import stopwatch
@@ -148,11 +148,16 @@ def __init__(
 
         # Initialize project with repo_path if projects is None
         if repo_path is not None:
+            # Split repo_path into (git_root, base_path)
             repo_path = os.path.abspath(repo_path)
+            git_root, base_path = split_git_path(repo_path)
+            # Create repo_config
             repo_config = BaseRepoConfig()
+            # Create main project
             main_project = ProjectConfig(
-                repo_operator=LocalRepoOperator(repo_config=repo_config, repo_path=repo_path),
+                repo_operator=LocalRepoOperator(repo_config=repo_config, repo_path=git_root),
                 programming_language=determine_project_language(repo_path),
+                base_path=base_path,
             )
             projects = [main_project]
         else:

src/codegen/sdk/utils.py

@@ -290,6 +290,40 @@ def determine_project_language(folder_path: str):
     return language_counts.most_common(1)[0][0]
 
 
+def split_git_path(filepath: str) -> tuple[str, str | None]:
+    """Split a filepath into (git_root, base_path) tuple by finding .git directory.
+
+    Args:
+        filepath (str): The full path to split
+
+    Returns:
+        tuple: (git_root_path, relative_path)
+
+    Raises:
+        ValueError: If the path is not in a git repository
+    """
+    # Convert to absolute path and resolve any symlinks
+    path = Path(filepath).resolve()
+
+    # Start from the given path and traverse up until we find .git
+    current = path
+    while current != current.parent:
+        if (current / ".git").exists():
+            # Found the git root
+            git_root = str(current)
+            rel_path = str(path.relative_to(current))
+
+            # Handle the case where filepath is the git root itself
+            if rel_path == ".":
+                rel_path = None
+
+            return (git_root, rel_path)
+        current = current.parent
+
+    # If we get here, we didn't find a .git directory
+    raise ValueError(f"Path '{filepath}' is not in a git repository!")
+
+
 def truncate_line(input: str, max_chars: int) -> str:
     input = str(input)
     if len(input) > max_chars: