"""Git tools for auto-swe-agent. All commands run inside the Docker sandbox."""

import re
from typing import List, Optional

from langchain_core.tools import tool


def _run_in_sandbox(command: str, workspace_dir: str = "./") -> tuple[int, str]:
    """Run a shell command in the Docker sandbox, return (exit_code, output)."""
    # Import here to avoid circular imports with agent.py
    from agent import get_sandbox

    container = get_sandbox(workspace_dir)
    result = container.exec_run(
        ["bash", "-c", command], workdir="/workspace", demux=False
    )
    output = (result.output or b"").decode().strip()
    return result.exit_code, output


@tool
def create_branch(branch_name: str, workspace_dir: str = "./") -> str:
    """Create and checkout a new git branch in the Docker sandbox.
    Branch name must be lowercase with hyphens only (no spaces or special chars).
    """
    # Validate branch name
    if not re.match(r"^[a-z0-9/][a-z0-9\-/]*$", branch_name):
        return f"Error: invalid branch name '{branch_name}'. Use lowercase letters, numbers, hyphens, and forward slashes only."

    exit_code, output = _run_in_sandbox(f"git checkout -b {branch_name}", workspace_dir)
    if exit_code != 0:
        return f"Error creating branch: {output}"
    return f"Created and checked out branch: {branch_name}"


@tool
def commit_changes(
    message: str, workspace_dir: str = "./", files: Optional[List[str]] = None
) -> str:
    """Stage and commit changes in the Docker sandbox.
    If files is provided, only those files are staged; otherwise all changes are staged.
    Commit message is auto-prefixed with 'auto-swe: ' if not already present.
    """
    if not message.startswith("auto-swe:"):
        message = f"auto-swe: {message}"

    # Configure git identity inside container (required for commits)
    _run_in_sandbox(
        'git config user.email "agent@auto-swe-agent" && git config user.name "auto-swe-agent"',
        workspace_dir,
    )

    if files:
        file_list = " ".join(f'"{f}"' for f in files)
        add_cmd = f"git add {file_list}"
    else:
        add_cmd = "git add -A"

    exit_code, output = _run_in_sandbox(add_cmd, workspace_dir)
    if exit_code != 0:
        return f"Error staging files: {output}"

    exit_code, output = _run_in_sandbox(f'git commit -m "{message}"', workspace_dir)
    if exit_code != 0:
        return f"Error committing: {output}"

    # Extract commit hash from output
    commit_hash = ""
    for line in output.splitlines():
        if line.startswith("["):
            # e.g. "[main abc1234] auto-swe: fix something"
            parts = line.split()
            if len(parts) >= 2:
                commit_hash = parts[1].rstrip("]")
            break

    return f"Committed: {message}\nHash: {commit_hash}\n{output}"


@tool
def generate_pr_description(workspace_dir: str = "./") -> str:
    """Generate a pull request description based on the latest git diff.
    Uses git diff HEAD~1 if commits exist, otherwise git diff for staged changes.
    """
    # Try diff against previous commit first
    exit_code, diff = _run_in_sandbox(
        "git diff HEAD~1 --stat 2>/dev/null || git diff --stat", workspace_dir
    )
    _, full_diff = _run_in_sandbox(
        "git diff HEAD~1 2>/dev/null || git diff", workspace_dir
    )

    # Truncate diff for context window
    if len(full_diff) > 3000:
        full_diff = full_diff[:3000] + "\n... [diff truncated]"

    # Parse changed files from stat output
    changed_files = []
    for line in diff.splitlines():
        line = line.strip()
        if "|" in line and not line.startswith("---"):
            fname = line.split("|")[0].strip()
            if fname:
                changed_files.append(fname)

    files_section = (
        "\n".join(f"- `{f}`" for f in changed_files)
        if changed_files
        else "- (see diff)"
    )

    pr_description = f"""## Changes

{files_section}

## Testing

- pytest passed ✓

## Diff Summary

```
{full_diff}
```

---
*Generated by auto-swe-agent*"""

    return pr_description