import cv2
import numpy as np
import torch


def preprocess_face(face_bgr: np.ndarray) -> torch.Tensor:
    """
    بياخد صورة وجه (BGR من OpenCV) ويرجعها Tensor جاهز للموديل
    """
    face = cv2.resize(face_bgr, (112, 112))
    face = cv2.cvtColor(face, cv2.COLOR_BGR2RGB)
    face = np.transpose(face, (2, 0, 1))
    face_tensor = torch.from_numpy(face).unsqueeze(0).float()
    face_tensor.div_(255).sub_(0.5).div_(0.5)
    return face_tensor


def cosine_similarity(a: np.ndarray, b: np.ndarray) -> float:
    """Cosine similarity بين embedding واحد وembedding تاني"""
    a = a.flatten()
    b = b.flatten()
    denom = (np.linalg.norm(a) * np.linalg.norm(b)) + 1e-8
    return float(np.dot(a, b) / denom)