import random
import string
import io
from PIL import Image, ImageDraw, ImageFont, ImageFilter

class CaptchaService:
    @staticmethod
    def generate_captcha():
        # 生成随机 4 位字符
        chars = string.ascii_uppercase + string.digits
        captcha_text = ''.join(random.choices(chars, k=4))
        
        # 图像参数
        width, height = 120, 50
        background = (255, 255, 255)
        image = Image.new('RGB', (width, height), background)
        draw = ImageDraw.Draw(image)
        
        # 尝试加载字体，如果失败则使用默认
        try:
            # 在 Windows 上寻找常用路径
            font_path = "C:\\Windows\\Fonts\\arial.ttf"
            font = ImageFont.truetype(font_path, 32)
        except:
            font = ImageFont.load_default()
            
        # 绘制文本
        for i, char in enumerate(captcha_text):
            # 随机颜色和轻微旋转/偏移
            color = (random.randint(0, 150), random.randint(0, 150), random.randint(0, 150))
            draw.text((15 + i * 25, 5), char, font=font, fill=color)
            
        # 增加噪点线
        for _ in range(5):
            x1 = random.randint(0, width)
            y1 = random.randint(0, height)
            x2 = random.randint(0, width)
            y2 = random.randint(0, height)
            draw.line((x1, y1, x2, y2), fill=(random.randint(0, 255), random.randint(0, 255), random.randint(0, 255)), width=1)
            
        # 增加噪点点
        for _ in range(30):
            draw.point((random.randint(0, width), random.randint(0, height)), fill=(0, 0, 0))
            
        # 轻微模糊
        image = image.filter(ImageFilter.SMOOTH)
        
        # 保存到内存
        buf = io.BytesIO()
        image.save(buf, format='PNG')
        return captcha_text, buf.getvalue()