import re
import secrets
import sys
from dataclasses import dataclass
from pathlib import Path

try:
    import tomllib
except ImportError:
    try:
        import tomli as tomllib  # type: ignore[no-redef]
    except ImportError:
        print("Error: Python 3.11+ is required (for tomllib), or install tomli: pip install tomli")
        sys.exit(1)

CONFIG_PATH = Path("config.toml")


@dataclass
class AppConfig:
    width: int | None
    height: int | None
    fps: int
    clock_font_path: str
    message_font_path: str
    port: int
    default_duration: float
    api_token: str
    rate_limit: int
    password_hash: str
    session_timeout_hours: int
    config_path: Path

    @classmethod
    def load(cls, path: str | Path = CONFIG_PATH) -> "AppConfig":
        p = Path(path)
        if not p.exists():
            print(f"Error: Config file not found: {p}")
            print("Copy config.toml to your working directory and edit it.")
            sys.exit(1)

        with open(p, "rb") as f:
            raw = tomllib.load(f)

        display = raw.get("display", {})
        server = raw.get("server", {})
        api = raw.get("api", {})
        rate = raw.get("rate_limit", {})
        dashboard = raw.get("dashboard", {})

        token = api.get("token", "").strip()
        if not token:
            token = secrets.token_hex(32)
            _update_config_field(p, "token", token)
            print(f"\n[KH-clock] Generated API bearer token (saved to config.toml):")
            print(f"  {token}\n")

        return cls(
            width=display.get("width"),
            height=display.get("height"),
            fps=display.get("fps", 10),
            clock_font_path=display.get("clock_font_path", "").strip(),
            message_font_path=display.get("message_font_path", "").strip(),
            port=server.get("port", 8080),
            default_duration=float(server.get("default_duration_seconds", 20)),
            api_token=token,
            rate_limit=rate.get("requests_per_minute", 20),
            password_hash=dashboard.get("password_hash", "").strip(),
            session_timeout_hours=dashboard.get("session_timeout_hours", 8),
            config_path=p,
        )

    def save_password_hash(self, hashed: str) -> None:
        _update_config_field(self.config_path, "password_hash", hashed)
        self.password_hash = hashed


def _update_config_field(config_path: Path, key: str, value: str) -> None:
    """Update a quoted string field in config.toml using regex replacement."""
    content = config_path.read_text()
    pattern = rf'^({re.escape(key)}\s*=\s*)"[^"]*"'

    def replacer(m: re.Match) -> str:
        return f'{m.group(1)}"{value}"'

    new_content = re.sub(pattern, replacer, content, flags=re.MULTILINE)
    if new_content == content:
        print(f"Warning: Could not update '{key}' in {config_path}. Field not found.")
        return
    config_path.write_text(new_content)