"""
MerlinConfig — load and save user gesture-to-action mappings.

Config file: ~/.merlin/config.yaml
If the file does not exist, defaults are used and written on first save.
"""

from __future__ import annotations

from dataclasses import dataclass, field, asdict
from pathlib import Path
from typing import Optional

import yaml

CONFIG_PATH = Path.home() / ".merlin" / "config.yaml"

DEFAULT_MAPPINGS: dict[str, str] = {
    "left_blink": "left_click",
    "right_blink": "right_click",
    "both_blink": "double_click",
    "head_nod": "key_enter",
    "head_shake": "key_escape",
    "head_tilt_left": "scroll_up",
    "head_tilt_right": "scroll_down",
    "open_palm": "key_space",
    "pinch": "drag_start",
    "fist": "key_ctrl_z",
    "gaze_left": "scroll_left",
    "gaze_right": "scroll_right",
    "gaze_up": "scroll_up",
    "gaze_down": "scroll_down",
}


@dataclass
class MerlinConfig:
    mappings: dict[str, str] = field(default_factory=lambda: dict(DEFAULT_MAPPINGS))
    confidence_threshold: float = 0.80
    camera_device: int = 0
    dwell_ms: int = 800
    blink_threshold: float = 0.20

    @classmethod
    def load(cls, path: Path = CONFIG_PATH) -> MerlinConfig:
        if not path.exists():
            return cls()
        with path.open() as f:
            data = yaml.safe_load(f) or {}
        return cls(
            mappings=data.get("mappings", DEFAULT_MAPPINGS),
            confidence_threshold=float(data.get("confidence_threshold", 0.80)),
            camera_device=int(data.get("camera_device", 0)),
            dwell_ms=int(data.get("dwell_ms", 800)),
            blink_threshold=float(data.get("blink_threshold", 0.20)),
        )

    def save(self, path: Path = CONFIG_PATH) -> None:
        path.parent.mkdir(parents=True, exist_ok=True)
        with path.open("w") as f:
            yaml.safe_dump(asdict(self), f, default_flow_style=False)