import subprocess
import tempfile
import shutil
import os
from typing import Optional, Union, Dict, List, Any


def get_repo_tree_structure(repo_source: str, commit_depth: int = 1) -> Union[Dict[str, Any], str]:
    """
    Returns the tree structure of a git repository at a specific commit.
    
    Args:
        repo_source: Path to the git repository or URL to a remote repository.
                     Function automatically detects if it's a local path or remote URL.
        commit_depth: How many commits back to check (default=1 for the latest commit).
                      For example, 2 would return the tree for the second-to-last commit.
        
    Returns:
        A dictionary representing the repository structure tree or error string if something fails
    """
    temp_dir = None
    try:
        # Determine if repo_source is a remote URL or local path
        is_remote = repo_source.startswith(('http://', 'https://', 'git://', 'ssh://')) or repo_source.endswith('.git')
        
        # If it's a remote repository, clone it to a temporary directory
        if is_remote:
            temp_dir = tempfile.mkdtemp()
            print(f"Cloning remote repository: {repo_source}")
            clone_cmd = ["git", "clone", repo_source, temp_dir]
            subprocess.check_output(clone_cmd)
            repo_path = temp_dir
        else:
            repo_path = repo_source
            
        # Validate commit_depth parameter
        if commit_depth < 1:
            return "Error: commit_depth must be a positive integer"
            
        # Get the commit hash for the specified depth
        if commit_depth == 1:
            # For the latest commit
            commit_ref = "HEAD"
        else:
            # For earlier commits: HEAD~1, HEAD~2, etc. (0-indexed in git, so we subtract 1)
            commit_ref = f"HEAD~{commit_depth-1}"
            
        # Get the commit hash
        commit_cmd = ["git", "-C", repo_path, "rev-parse", commit_ref]
        try:
            commit_hash = subprocess.check_output(commit_cmd).decode('utf-8').strip()
        except subprocess.CalledProcessError:
            return f"Error: Could not find commit at depth {commit_depth}"
        
        # Use git ls-tree recursively to get the repository structure
        ls_tree_cmd = ["git", "-C", repo_path, "ls-tree", "-r", "--name-only", commit_hash]
        file_list = subprocess.check_output(ls_tree_cmd).decode('utf-8').strip().split('\n')
        
        # Build a tree structure from the file paths
        root = {}
        for file_path in file_list:
            if not file_path:  # Skip empty paths
                continue
                
            parts = file_path.split('/')
            current = root
            
            # Navigate through path components, creating nested dictionaries as needed
            for i, part in enumerate(parts):
                if i == len(parts) - 1:  # It's a file (last part of path)
                    current[part] = None  # Files have None value
                else:  # It's a directory
                    if part not in current:
                        current[part] = {}  # Create directory dict if it doesn't exist
                    current = current[part]  # Move into the directory
        
        return root
        
    except subprocess.CalledProcessError as e:
        return f"Error executing git command: {str(e)}"
    except Exception as e:
        return f"Unexpected error: {str(e)}"
    finally:
        # Clean up temporary directory if it was created
        if temp_dir and os.path.exists(temp_dir):
            shutil.rmtree(temp_dir)


# Helper function to print the tree structure in a more readable format
def print_tree(tree, indent=""):
    """
    Print the repository tree structure in a readable format
    
    Args:
        tree: Dictionary representing the repository structure
        indent: Current indentation level string (used in recursion)
    """
    for key, value in sorted(tree.items()):
        if value is None:  # It's a file
            print(f"{indent}├── {key}")
        else:  # It's a directory
            print(f"{indent}├── {key}/")
            print_tree(value, indent + "│   ")


# Example usage
if __name__ == "__main__":
    import sys
    
    if len(sys.argv) < 2:
        print("Usage: python git_tree_utils.py <repo_path_or_url> [commit_depth]")
        print("  repo_path_or_url: Path to local repository or URL to remote repository")
        print("  commit_depth: Optional - How many commits back to check (default=1 for latest commit)")
        sys.exit(1)
        
    repo_source = sys.argv[1]
    commit_depth = 1  # Default to latest commit
    
    # Check if commit_depth was provided
    if len(sys.argv) > 2:
        try:
            commit_depth = int(sys.argv[2])
            if commit_depth < 1:
                print("Error: commit_depth must be a positive integer")
                sys.exit(1)
        except ValueError:
            print("Error: commit_depth must be an integer")
            sys.exit(1)
    
    print(f"Getting repository structure for: {repo_source} (commit depth: {commit_depth})")
    tree = get_repo_tree_structure(repo_source, commit_depth)
    
    if isinstance(tree, dict):
        print("\nRepository Structure:")
        print_tree(tree)
    else:
        print(tree)  # Error message