from __future__ import annotations

import cv2
import numpy as np

from app.exercises.dead_bug.types import Point


def angle(a: Point, b: Point, c: Point) -> float:
    ba = np.array([a.x - b.x, a.y - b.y], dtype=np.float32)
    bc = np.array([c.x - b.x, c.y - b.y], dtype=np.float32)
    denom = float(np.linalg.norm(ba) * np.linalg.norm(bc))
    if denom == 0:
        return 0.0
    cos_value = float(np.dot(ba, bc) / denom)
    return float(np.degrees(np.arccos(np.clip(cos_value, -1.0, 1.0))))


def distance(a: Point, b: Point) -> float:
    return float(np.hypot(a.x - b.x, a.y - b.y))


def calculate_metrics(
    lm: list[Point],
    *,
    left_shoulder: int,
    right_shoulder: int,
    left_elbow: int,
    right_elbow: int,
    left_wrist: int,
    right_wrist: int,
    left_hip: int,
    right_hip: int,
    left_knee: int,
    right_knee: int,
    left_ankle: int,
    right_ankle: int,
    visibility_threshold: float = 0.45,
) -> dict:
    left_elbow_angle = angle(lm[left_shoulder], lm[left_elbow], lm[left_wrist])
    right_elbow_angle = angle(lm[right_shoulder], lm[right_elbow], lm[right_wrist])
    left_knee_angle = angle(lm[left_hip], lm[left_knee], lm[left_ankle])
    right_knee_angle = angle(lm[right_hip], lm[right_knee], lm[right_ankle])

    shoulder_width = distance(lm[left_shoulder], lm[right_shoulder])
    hip_width = distance(lm[left_hip], lm[right_hip])
    scale = max(shoulder_width, hip_width, 0.08)

    left_arm_extended = (
        left_elbow_angle >= 145
        and distance(lm[left_shoulder], lm[left_wrist]) >= scale * 1.15
        and lm[left_wrist].y <= lm[left_shoulder].y + scale * 0.35
    )
    right_arm_extended = (
        right_elbow_angle >= 145
        and distance(lm[right_shoulder], lm[right_wrist]) >= scale * 1.15
        and lm[right_wrist].y <= lm[right_shoulder].y + scale * 0.35
    )

    left_leg_extended = (
        left_knee_angle >= 150
        and distance(lm[left_hip], lm[left_ankle]) >= scale * 1.55
        and lm[left_ankle].y >= lm[left_knee].y - scale * 0.2
    )
    right_leg_extended = (
        right_knee_angle >= 150
        and distance(lm[right_hip], lm[right_ankle]) >= scale * 1.55
        and lm[right_ankle].y >= lm[right_knee].y - scale * 0.2
    )

    feedback: list[str] = []
    if left_arm_extended and left_elbow_angle < 160:
        feedback.append("Straighten left arm")
    if right_arm_extended and right_elbow_angle < 160:
        feedback.append("Straighten right arm")
    if left_leg_extended and left_knee_angle < 165:
        feedback.append("Straighten left leg")
    if right_leg_extended and right_knee_angle < 165:
        feedback.append("Straighten right leg")

    return {
        "left_arm_extended": left_arm_extended,
        "right_arm_extended": right_arm_extended,
        "left_leg_extended": left_leg_extended,
        "right_leg_extended": right_leg_extended,
        "left_elbow_angle": left_elbow_angle,
        "right_elbow_angle": right_elbow_angle,
        "left_knee_angle": left_knee_angle,
        "right_knee_angle": right_knee_angle,
        "scale": scale,
        "feedback": feedback,
    }