using System;
using System.Text.RegularExpressions;

namespace Kill.Utils
{
    /// <summary>
    /// 验证工具类
    /// 提供常用的数据验证方法
    /// </summary>
    public static class ValidationUtils
    {
        #region 邮箱验证

        /// <summary>
        /// 验证邮箱格式是否有效（正则验证，更严格）
        /// </summary>
        public static bool IsValidEmailStrict(string email)
        {
            if (string.IsNullOrEmpty(email))
                return false;

            // RFC 5322 标准邮箱正则
            string pattern = @"^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$";
            return Regex.IsMatch(email, pattern);
        }

        #endregion

        #region 密码验证

        /// <summary>
        /// 验证简单密码格式（6位数字）
        /// </summary>
        public static bool IsValidSimplePassword(string password)
        {
            if (string.IsNullOrEmpty(password))
                return false;

            // 6位数字
            string pattern = @"^\d{6}$";
            return Regex.IsMatch(password, pattern);
        }

        /// <summary>
        /// 验证复杂密码格式（6-16位，同时包含数字、字母和特殊字符）
        /// </summary>
        public static bool IsValidComplexPassword(string password)
        {
            if (string.IsNullOrEmpty(password))
                return false;

            // 长度6-16位
            if (password.Length < 6 || password.Length > 16)
                return false;

            // 必须包含数字
            bool hasDigit = Regex.IsMatch(password, @"\d");
            // 必须包含字母
            bool hasLetter = Regex.IsMatch(password, @"[a-zA-Z]");
            // 必须包含特殊字符（支持半角和全角符号）
            bool hasSpecial = Regex.IsMatch(password, @"[!@#$%^&*()_+\-=\[\]{};':""\\|,.<>\/?]|\p{P}");

            return hasDigit && hasLetter && hasSpecial;
        }

        /// <summary>
        /// 检查是否包含连续或重复的三个及以上数字或字母（大小写不敏感）
        /// </summary>
        public static bool IsValidNoRepeatOrConsecutive(string password)
        {
            for (int i = 0; i <= password.Length - 3; i++)
            {
                char c0 = password[i];
                char c1 = password[i + 1];
                char c2 = password[i + 2];

                if (!char.IsLetterOrDigit(c0) || !char.IsLetterOrDigit(c1) || !char.IsLetterOrDigit(c2))
                    continue;

                bool isRepeated;
                if (char.IsLetter(c0))
                    isRepeated = char.ToLower(c0) == char.ToLower(c1) && char.ToLower(c1) == char.ToLower(c2);
                else
                    isRepeated = c0 == c1 && c1 == c2;

                if (isRepeated) return false;

                if (char.IsDigit(c0) && char.IsDigit(c1) && char.IsDigit(c2))
                {
                    if ((c1 - c0 == 1 && c2 - c1 == 1) || (c0 - c1 == 1 && c1 - c2 == 1))
                        return false;
                }
                else if (char.IsLetter(c0))
                {
                    char l0 = char.ToLower(c0), l1 = char.ToLower(c1), l2 = char.ToLower(c2);
                    if ((l1 - l0 == 1 && l2 - l1 == 1) || (l0 - l1 == 1 && l1 - l2 == 1))
                        return false;
                }
            }
            return true;
        }

        /// <summary>
        /// 检查密码是否包含邮箱中任意连续两个字符
        /// </summary>
        public static bool IsValidNotEmailPart(string password, string email)
        {
            if (string.IsNullOrEmpty(email)) return true;

            string emailName = email.Contains('@') ? email.Split('@')[0] : email;
            string pwdLower = password.ToLower();

            for (int i = 0; i <= emailName.Length - 2; i++)
            {
                string pair = emailName.Substring(i, 2).ToLower();
                if (pwdLower.Contains(pair))
                    return false;
            }
            return true;
        }

        #endregion
    }
}