import json
from pathlib import Path

SYSTEM_PROMPT = (
    "You are a helpful assistant. "
    "When outputting Windows file paths in JSON arguments, you must strictly escape all backslashes "
    "(for example: C:\\\\Users\\\\name\\\\file.txt). "
    "If you need to read a file, emit a tool call with the path field."
)


def read_file(path: str) -> str:
    """Read a file from disk and return its contents."""
    file_path = Path(path)
    try:
        return file_path.read_text(encoding="utf-8")
    except FileNotFoundError:
        return f"ERROR: File not found: {path}"
    except Exception as exc:  # pragma: no cover - demo only
        return f"ERROR: {type(exc).__name__}: {exc}"


def sanitize_tool_arguments(raw_arguments: str):
    """Repair malformed JSON emitted by the model when Windows paths are not escaped."""
    try:
        return json.loads(raw_arguments)
    except json.JSONDecodeError:
        repaired = raw_arguments.replace("\\", "\\\\")
        return json.loads(repaired)


def handle_tool_call(response: dict) -> dict:
    """Detect a tool call in the LLM response and execute it locally."""
    tool_calls = response.get("tool_calls") or response.get("function_call")

    if tool_calls is None:
        return {"status": "final_response", "content": response}

    if isinstance(tool_calls, dict):
        tool_calls = [tool_calls]

    for tool_call in tool_calls:
        function_data = tool_call.get("function", tool_call)
        name = function_data.get("name")
        arguments = function_data.get("arguments", {})

        if isinstance(arguments, str):
            try:
                arguments = json.loads(arguments)
            except json.JSONDecodeError:
                try:
                    arguments = sanitize_tool_arguments(arguments)
                except json.JSONDecodeError:
                    return {
                        "status": "invalid_arguments",
                        "raw_arguments": arguments,
                        "message": "The model emitted malformed JSON. Ensure backslashes are escaped.",
                    }

        if name == "read_file":
            file_path = arguments.get("path")
            content = read_file(file_path)
            return {
                "status": "tool_result",
                "tool_call_id": tool_call.get("id"),
                "content": content,
            }

    return {"status": "unsupported_tool_call", "raw": response}


if __name__ == "__main__":
    # A valid OpenAI-style tool call with a Windows path escaped correctly.
    valid_response = {
        "tool_calls": [
            {
                "id": "call_read_001",
                "type": "function",
                "function": {
                    "name": "read_file",
                    "arguments": '{"path": "c:\\Workspace\\llm-server-setup\\README.md"}',
                },
            }
        ]
    }

    # This reproduces the common bug: malformed Windows path in JSON.
    broken_response = {
        "tool_calls": [
            {
                "id": "call_read_002",
                "type": "function",
                "function": {
                    "name": "read_file",
                    "arguments": '{"path": "c:\Workspace\llm-server-setup\README.md"}',
                },
            }
        ]
    }

    result = handle_tool_call(valid_response)
    print(json.dumps(result, ensure_ascii=False, indent=2))

    print("\n--- malformed-path fallback sample ---")
    fallback = handle_tool_call(broken_response)
    print(json.dumps(fallback, ensure_ascii=False, indent=2))