"""Configuration loading utilities."""

import json
import os
import secrets
from pathlib import Path
from typing import Any

from flowly.config.schema import Config


def get_config_path() -> Path:
    """Get the default configuration file path."""
    return Path.home() / ".flowly" / "config.json"


def get_data_dir() -> Path:
    """Get the flowly data directory."""
    from flowly.utils.helpers import get_data_path
    return get_data_path()


def load_config(config_path: Path | None = None) -> Config:
    """
    Load configuration from file or create default.
    
    Args:
        config_path: Optional path to config file. Uses default if not provided.
    
    Returns:
        Loaded configuration object.
    """
    path = config_path or get_config_path()
    
    if path.exists():
        try:
            with open(path, encoding="utf-8") as f:
                data = json.load(f)
            return Config.model_validate(convert_keys(data))
        except (json.JSONDecodeError, ValueError) as e:
            print(f"Warning: Failed to load config from {path}: {e}")
            print("Using default configuration.")
    
    return Config()


def save_config(config: Config, config_path: Path | None = None) -> None:
    """
    Save configuration to file.
    
    Args:
        config: Configuration to save.
        config_path: Optional path to save to. Uses default if not provided.
    """
    path = config_path or get_config_path()
    path.parent.mkdir(parents=True, exist_ok=True)
    
    # Convert to camelCase format
    data = config.model_dump()
    data = convert_to_camel(data)
    
    # Atomic write: write to temp file then rename to prevent corruption
    tmp_path = path.with_suffix(f".tmp.{secrets.token_hex(4)}")
    try:
        tmp_path.write_text(json.dumps(data, indent=2), encoding="utf-8")
        os.replace(str(tmp_path), str(path))
    except Exception:
        tmp_path.unlink(missing_ok=True)
        raise

    # Restrict permissions: owner read/write only (config contains API keys)
    try:
        os.chmod(path, 0o600)
    except OSError:
        pass


def convert_keys(data: Any) -> Any:
    """Convert camelCase keys to snake_case for Pydantic."""
    if isinstance(data, dict):
        return {camel_to_snake(k): convert_keys(v) for k, v in data.items()}
    if isinstance(data, list):
        return [convert_keys(item) for item in data]
    return data


def convert_to_camel(data: Any) -> Any:
    """Convert snake_case keys to camelCase."""
    if isinstance(data, dict):
        return {snake_to_camel(k): convert_to_camel(v) for k, v in data.items()}
    if isinstance(data, list):
        return [convert_to_camel(item) for item in data]
    return data


def camel_to_snake(name: str) -> str:
    """Convert camelCase to snake_case."""
    result = []
    for i, char in enumerate(name):
        if char.isupper() and i > 0:
            result.append("_")
        result.append(char.lower())
    return "".join(result)


def snake_to_camel(name: str) -> str:
    """Convert snake_case to camelCase."""
    components = name.split("_")
    return components[0] + "".join(x.title() for x in components[1:])
