import os
import cv2
import numpy as np


def process_merged_image(file_path, output_folder):
    image = cv2.imread(file_path, cv2.IMREAD_UNCHANGED)
    if image is None:
        print(f"无法读取图像：{file_path}")
        return

    if image.shape[2] < 4:
        print(f"图像没有 alpha 通道：{file_path}")
        return

    alpha = image[:, :, 3]
    _, thresh = cv2.threshold(alpha, 0, 255, cv2.THRESH_BINARY)
    contours, _ = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

    if not contours:
        print("图像中没有非透明部分。")
        return

    for idx, cnt in enumerate(contours, start=1):
        rect = cv2.minAreaRect(cnt)
        box = cv2.boxPoints(rect)
        box = np.int32(box)

        width = int(rect[1][0])
        height = int(rect[1][1])

        if width == 0 or height == 0:
            print(f"第 {idx} 个最小矩形的宽度或高度为零，跳过。")
            continue

        src_pts = box.astype("float32")
        # 定义目标点为水平矩形
        dst_pts = np.array([
            [0, height - 1],
            [0, 0],
            [width - 1, 0],
            [width - 1, height - 1]
        ], dtype="float32")

        # 计算透视变换矩阵
        M = cv2.getPerspectiveTransform(src_pts, dst_pts)
        warped = cv2.warpPerspective(image, M, (width, height))

        base, ext = os.path.splitext(os.path.basename(file_path))
        extracted_filename = f"{base}_extracted_{idx}{ext}"
        extracted_path = os.path.join(output_folder, extracted_filename)

        # 保存带 alpha 通道的图像
        if warped.shape[2] == 4:
            cv2.imwrite(extracted_path, warped)
        else:
            # 如果没有 alpha 通道，转换为 RGB
            cv2.imwrite(extracted_path, cv2.cvtColor(warped, cv2.COLOR_BGR2RGB))

        print(f"提取并旋转后的图像已保存为：{extracted_path}")


def main():
    input_image = os.path.join('output3', 'merged_image.png')
    output_folder = 'output4'

    if not os.path.exists(output_folder):
        os.makedirs(output_folder)

    if not os.path.isfile(input_image):
        print(f"输入图像不存在：{input_image}")
        return

    print(f"正在处理图像：{input_image}")
    process_merged_image(input_image, output_folder)


if __name__ == "__main__":
    main()