# -*- coding: utf-8 -*-
"""
AI Vision 模块 - CLIP Vision Encoder ONNX 推理
"""

import os
import numpy as np
from PIL import Image
import onnxruntime as ort

# ============================================================================
# 全局模型单例（项目启动时加载一次）
# ============================================================================

MODEL_PATH = os.path.join(os.path.dirname(__file__), '..', '..', 'models', 'clip_vision.onnx')

# 加载选项：CPU 推理，禁用依赖库的启动开销
_session_options = ort.SessionOptions()
_session_options.graph_optimization_level = ort.GraphOptimizationLevel.ORT_ENABLE_ALL

ort_session: ort.InferenceSession = None


def load_clip_model():
    """启动时调用：全局加载 CLIP Vision 模型"""
    global ort_session
    if ort_session is not None:
        return ort_session

    if not os.path.exists(MODEL_PATH):
        raise FileNotFoundError(f"CLIP Vision 模型未找到: {MODEL_PATH}")

    ort_session = ort.InferenceSession(MODEL_PATH, sess_options=_session_options, providers=['CPUExecutionProvider'])
    print(f"✅ [AI Vision] CLIP 模型加载成功: {MODEL_PATH}")
    return ort_session


# ============================================================================
# CLIP 预处理常量
# ============================================================================

# ImageNet 标准归一化（CLIP 官方）
IMAGENET_MEAN = [0.485, 0.456, 0.406]
IMAGENET_STD = [0.229, 0.224, 0.225]

# 模型输入尺寸
INPUT_SIZE = 224


def _center_crop_and_resize(image: Image.Image) -> Image.Image:
    """
    CLIP 官方预处理：中心裁剪抗干扰
    - 将图片最短边缩放到 224
    - 从正中间切取 224x224 区域
    """
    w, h = image.size

    # 计算缩放后的目标尺寸
    if w < h:
        new_w = INPUT_SIZE
        new_h = int(h * INPUT_SIZE / w)
    else:
        new_h = INPUT_SIZE
        new_w = int(w * INPUT_SIZE / h)

    # 缩放
    image = image.resize((new_w, new_h), Image.BILINEAR)

    # 中心裁剪
    left = (new_w - INPUT_SIZE) // 2
    top = (new_h - INPUT_SIZE) // 2
    right = left + INPUT_SIZE
    bottom = top + INPUT_SIZE

    return image.crop((left, top, right, bottom))


def _normalize(image_np: np.ndarray) -> np.ndarray:
    """
    对 224x224x3 图像进行 CLIP 标准归一化
    image_np: shape (H, W, C), dtype uint8, 值域 [0, 255]
    返回: shape (C, H, W), dtype float32, 值域 [0, 1]
    """
    # HWC -> CHW
    image_np = image_np.transpose(2, 0, 1).astype(np.float32) / 255.0

    # 归一化
    for i, (mean, std) in enumerate(zip(IMAGENET_MEAN, IMAGENET_STD)):
        image_np[i] = (image_np[i] - mean) / std

    return image_np


# ============================================================================
# 主函数：提取图像 embedding
# ============================================================================

def get_image_embedding(image_path: str) -> list:
    """
    提取图像的 512 维 CLIP embedding 向量

    参数:
        image_path: 图像文件路径（支持本地路径或 URL）

    返回:
        list: 512 维浮点向量
    """
    if ort_session is None:
        load_clip_model()

    # 加载图像
    try:
        image = Image.open(image_path).convert('RGB')
    except Exception as e:
        raise ValueError(f"图像加载失败: {image_path}, 错误: {e}")

    # 中心裁剪
    image = _center_crop_and_resize(image)

    # 归一化
    input_data = _normalize(np.array(image))

    # 添加 batch 维度: (C, H, W) -> (1, C, H, W)
    input_data = np.expand_dims(input_data, axis=0)

    # 推理
    outputs = ort_session.run(None, {'images': input_data.astype(np.float32)})

    # 输出通常是 (1, 512) 的向量，取第一项并展平为 list
    embedding = outputs[0][0].tolist()

    return embedding