"""
密码安全服务

提供密码强度检测和弱口令验证功能
"""
import re
from typing import List, Dict, Tuple
from enum import Enum


class PasswordStrength(Enum):
    """密码强度枚举"""
    WEAK = "weak"
    MEDIUM = "medium"
    STRONG = "strong"
    VERY_STRONG = "very_strong"


class PasswordSecurityService:
    """密码安全服务类"""

    WEAK_PASSWORDS = [
        "123456", "12345678", "123456789", "1234567890",
        "password", "password123", "admin", "root", "user",
        "qwerty", "abc123", "letmein", "welcome", "monkey",
        "dragon", "baseball", "football", "soccer", "trustno1",
        "master", "hello", "login", "admin123", "password1",
        "123123", "111111", "888888", "000000", "qwerty123",
        "admin123", "user123", "pass123", "login123", "welcome1",
        "admin@123", "root@123", "user@123", "pass@123", "login@123",
        "123qwe", "qwe123", "abc123", "111222", "333444",
        "666777", "999888", "123321", "654321", "987654",
        "123abc", "abc123", "12345a", "a12345", "678901"
    ]

    # 常见密码模式
    COMMON_PATTERNS = [
        r'^\d{6,}$',  # 纯数字，6位以上
        r'^[a-z]{6,}$',  # 纯小写字母，6位以上
        r'^[A-Z]{6,}$',  # 纯大写字母，6位以上
        r'^[a-zA-Z]{6,}$',  # 纯字母，6位以上
        r'^[a-zA-Z0-9]{6,}$',  # 字母+数字，6位以上
        r'^.{8,}$',  # 任意字符，8位以上
    ]

    @staticmethod
    def check_password_strength(password: str) -> Tuple[PasswordStrength, List[str]]:
        """
        检测密码强度

        Args:
            password: 要检测的密码

        Returns:
            Tuple[密码强度, 建议列表]
        """
        suggestions = []

        # 1. 检查密码长度
        if len(password) < 8:
            suggestions.append("密码长度至少8位")
            return PasswordStrength.WEAK, suggestions
        elif len(password) < 12:
            suggestions.append("建议密码长度至少12位")
        elif len(password) >= 16:
            suggestions.append("密码长度很好")

        # 2. 检查是否是弱口令
        if password.lower() in PasswordSecurityService.WEAK_PASSWORDS:
            suggestions.append("密码过于常见，容易被猜测")
            return PasswordStrength.WEAK, suggestions

        # 3. 检查常见模式
        has_common_pattern = False
        for pattern in PasswordSecurityService.COMMON_PATTERNS:
            if re.match(pattern, password):
                has_common_pattern = True
                break

        if has_common_pattern:
            suggestions.append("密码过于简单，建议使用更复杂的组合")

        # 4. 检查字符类型
        has_upper = any(c.isupper() for c in password)
        has_lower = any(c.islower() for c in password)
        has_digit = any(c.isdigit() for c in password)
        has_special = any(not c.isalnum() for c in password)

        type_count = sum([has_upper, has_lower, has_digit, has_special])

        if type_count < 3:
            suggestions.append("建议包含大小写字母、数字和特殊符号的组合")

        # 5. 检查连续字符
        if PasswordSecurityService._has_sequential_chars(password):
            suggestions.append("避免使用连续的字符序列")

        # 6. 检查重复字符
        if PasswordSecurityService._has_repeated_chars(password):
            suggestions.append("避免使用大量重复的字符")

        # 7. 综合评分
        score = 0
        # 长度评分
        if len(password) >= 16:
            score += 3
        elif len(password) >= 12:
            score += 2
        else:
            score += 1

        # 字符类型评分
        score += type_count

        # 特殊字符评分
        if has_special:
            score += 2

        # 综合判断强度
        if score >= 8:
            return PasswordStrength.VERY_STRONG, suggestions
        elif score >= 6:
            return PasswordStrength.STRONG, suggestions
        elif score >= 4:
            return PasswordStrength.MEDIUM, suggestions
        else:
            return PasswordStrength.WEAK, suggestions

    @staticmethod
    def is_password_weak(password: str) -> bool:
        """
        检查密码是否为弱口令

        Args:
            password: 要检查的密码

        Returns:
            True 如果是弱口令，False 否则
        """
        strength, _ = PasswordSecurityService.check_password_strength(password)
        return strength == PasswordStrength.WEAK

    @staticmethod
    def validate_password_requirements(password: str) -> Tuple[bool, List[str]]:
        """
        验证密码是否符合基本要求 (长度>=8，且包含大小写、数字、特殊符号中的至少两种)
        """
        errors = []

        # 1. 长度检查（保持至少 8 位的基础底线）
        if len(password) < 8:
            errors.append("密码长度至少8位")

        # 2. 统计密码包含的字符种类
        has_upper = any(c.isupper() for c in password)
        has_lower = any(c.islower() for c in password)
        has_digit = any(c.isdigit() for c in password)
        has_special = any(not c.isalnum() for c in password)

        # 算出包含了多少种类型 (True会当作1，False当作0)
        type_count = sum([has_upper, has_lower, has_digit, has_special])

        # 3. 核心修改：四大类中，只要满足 >= 2 种即可
        if type_count < 2:
            errors.append("密码必须包含大写字母、小写字母、数字、特殊符号中的至少两种组合")

        return len(errors) == 0, errors

    @staticmethod
    def _has_sequential_chars(password: str, min_length: int = 3) -> bool:
        """
        检查是否包含连续字符

        Args:
            password: 密码
            min_length: 最小连续长度

        Returns:
            True 如果包含连续字符
        """
        for i in range(len(password) - min_length + 1):
            substring = password[i:i+min_length]
            # 检查数字连续
            if substring.isdigit():
                if all(ord(substring[j+1]) - ord(substring[j]) == 1 for j in range(len(substring)-1)):
                    return True
            # 检查字母连续
            elif substring.isalpha():
                if all(ord(substring[j+1]) - ord(substring[j]) == 1 for j in range(len(substring)-1)):
                    return True
        return False

    @staticmethod
    def _has_repeated_chars(password: str, max_repeats: int = 3) -> bool:
        """
        检查是否包含重复字符

        Args:
            password: 密码
            max_repeats: 最大重复次数

        Returns:
            True 如果包含重复字符
        """
        for i in range(len(password)):
            if i + max_repeats <= len(password):
                char = password[i]
                if all(password[j] == char for j in range(i, i + max_repeats)):
                    return True
        return False