"""Gesture recognizer interfaces.

The production recognizer is intentionally thin in this skeleton. It validates
that optional CV dependencies are available and keeps the protocol independent
from any specific model implementation.
"""

from __future__ import annotations

from dataclasses import dataclass
from typing import Any, Protocol

from .cameras import MotionAgentDependencyError
from .events import GestureName, SkeletonEvent, SkeletonJoint, now_ms


@dataclass(frozen=True)
class GestureObservation:
    gesture: GestureName
    confidence: float
    intensity: float = 1.0
    timestamp_ms: int | None = None


class GestureRecognizer(Protocol):
    name: str

    def recognize(self, frame: Any) -> GestureObservation | None:
        """Return a gesture observation for the current frame."""

    def debug_skeleton(
        self,
        frame: Any,
        *,
        camera_id: str,
        mode: str,
        matched_gesture: GestureName | None = None,
        confidence: float = 0.0,
    ) -> SkeletonEvent | None:
        """Return normalized skeleton debug data when available."""


class MediaPipeGestureRecognizer:
    name = "mediapipe-opencv"

    def __init__(self) -> None:
        try:
            import cv2  # noqa: F401
            import mediapipe  # noqa: F401
        except ImportError as exc:
            raise MotionAgentDependencyError(
                "MediaPipe and OpenCV are required for live gesture recognition. "
                "Add mediapipe and opencv-python with uv, or use --dry-run for protocol testing."
            ) from exc

    def recognize(self, frame: Any) -> GestureObservation | None:
        _ = frame
        return None

    def debug_skeleton(
        self,
        frame: Any,
        *,
        camera_id: str,
        mode: str,
        matched_gesture: GestureName | None = None,
        confidence: float = 0.0,
    ) -> SkeletonEvent | None:
        _ = frame, camera_id, mode, matched_gesture, confidence
        return None


class NullGestureRecognizer:
    name = "dry-run"

    def recognize(self, frame: Any) -> GestureObservation | None:
        _ = frame
        return None

    def debug_skeleton(
        self,
        frame: Any,
        *,
        camera_id: str,
        mode: str,
        matched_gesture: GestureName | None = None,
        confidence: float = 0.0,
    ) -> SkeletonEvent | None:
        _ = frame
        now = now_ms()
        sway = ((now // 250) % 6 - 2.5) * 0.015
        joints = [
            SkeletonJoint("head", 0.5, 0.18, 1.0),
            SkeletonJoint("neck", 0.5, 0.3, 1.0),
            SkeletonJoint("left_shoulder", 0.38, 0.34, 1.0),
            SkeletonJoint("right_shoulder", 0.62, 0.34, 1.0),
            SkeletonJoint("left_elbow", 0.31 + sway, 0.48, 0.95),
            SkeletonJoint("right_elbow", 0.69 - sway, 0.48, 0.95),
            SkeletonJoint("left_wrist", 0.24 + sway, 0.62, 0.9),
            SkeletonJoint("right_wrist", 0.76 - sway, 0.62, 0.9),
        ]
        bones = [
            ("head", "neck"),
            ("neck", "left_shoulder"),
            ("neck", "right_shoulder"),
            ("left_shoulder", "left_elbow"),
            ("left_elbow", "left_wrist"),
            ("right_shoulder", "right_elbow"),
            ("right_elbow", "right_wrist"),
        ]
        return SkeletonEvent(
            joints=joints,
            bones=bones,
            matched_gesture=matched_gesture,
            confidence=confidence,
            camera_id=camera_id,
            mode=mode,
        )