"""
密码强度检测服务

提供密码强度评估功能
"""
import re
from app.schemas.password_strength_schema import (
    PasswordStrengthLevel,
    PasswordStrengthResponse
)


class PasswordStrengthService:
    """密码强度检测服务"""
    
    @staticmethod
    def check_password_strength(password: str) -> PasswordStrengthResponse:
        """
        检测密码强度
        
        强度等级定义：
        - 弱(weak): 只有小写字母和数字，或单一类型
        - 中(medium): 包含小写字母、数字和特殊符号（至少2种）
        - 强(strong): 包含大小写字母、数字和特殊符号（至少3种，且包含大小写）
        
        Args:
            password: 待检测的密码
            
        Returns:
            PasswordStrengthResponse: 密码强度检测结果
        """
        if not password:
            return PasswordStrengthResponse(
                strength=PasswordStrengthLevel.WEAK,
                score=0,
                suggestions=["密码不能为空"],
                meets_requirements=False
            )
        
        # 检测各种字符类型
        has_lowercase = bool(re.search(r'[a-z]', password))
        has_uppercase = bool(re.search(r'[A-Z]', password))
        has_digit = bool(re.search(r'\d', password))
        has_special = bool(re.search(r'[!@#$%^&*(),.?":{}|<>_\-+=\[\]\\\/;\'`~]', password))
        
        # 计算包含的字符类型数量
        type_count = sum([has_lowercase, has_uppercase, has_digit, has_special])
        
        # 密码长度
        length = len(password)
        
        # 初始化分数和建议
        score = 0
        suggestions = []
        
        # 长度评分 (最多40分)
        if length >= 12:
            score += 40
        elif length >= 8:
            score += 30
        elif length >= 6:
            score += 20
        else:
            score += 10
            suggestions.append("密码长度至少需要8个字符")
        
        # 字符类型评分 (最多60分)
        score += type_count * 15
        
        # 判断强度等级
        strength = PasswordStrengthLevel.WEAK
        meets_requirements = length >= 6 and type_count >= 2
        
        if has_uppercase and has_lowercase and has_digit and has_special and length >= 8:
            # 强：包含大小写字母、数字、特殊符号
            strength = PasswordStrengthLevel.STRONG
            if length < 12:
                suggestions.append("建议密码长度达到12位以上")
        elif type_count >= 2 and length >= 8:
            # 中：至少包含2种字符类型
            strength = PasswordStrengthLevel.MEDIUM
            if not has_uppercase:
                suggestions.append("添加大写字母可以提高密码强度")
            if not has_special:
                suggestions.append("添加特殊符号可以提高密码强度")
            if not (has_uppercase and has_lowercase):
                suggestions.append("同时包含大小写字母可以提高密码强度")
        else:
            # 弱：其他情况
            strength = PasswordStrengthLevel.WEAK
            if not has_lowercase:
                suggestions.append("请添加小写字母")
            if not has_digit:
                suggestions.append("请添加数字")
            if not has_special:
                suggestions.append("请添加特殊符号（如 !@#$%^&*）")
            if not has_uppercase:
                suggestions.append("请添加大写字母")
        
        # 检查常见弱密码模式
        common_patterns = [
            r'12345', r'password', r'qwerty', r'abc', r'111', r'000',
            r'admin', r'user', r'test', r'123456'
        ]
        for pattern in common_patterns:
            if re.search(pattern, password.lower()):
                score = max(0, score - 20)
                suggestions.append("避免使用常见的密码模式")
                strength = PasswordStrengthLevel.WEAK
                break
        
        # 确保分数在0-100之间
        score = max(0, min(100, score))
        
        return PasswordStrengthResponse(
            strength=strength,
            score=score,
            suggestions=suggestions,
            meets_requirements=meets_requirements
        )