using System.Globalization;
using System.Text.RegularExpressions;

namespace IRaCIS.Core.Application.Helper;

public static class IRCEmailPasswordHelper
{
    private static readonly Random Random = new Random();

    //显示位数：3分之2的位数，向上取整
    //取哪几个个值：最后一位和前面几位
    //其他：3个***。
    //比如：hlj23@126.com
    //为：hlj***3@126.com

    //he@126.com
    //为：h*** e@126.com

    public static string MaskEmail(string email)
    {

        // 找到 "@" 符号的位置
        int atIndex = email.IndexOf('@');

        string visiblePartBefore = email.Substring(0, atIndex);

        string afterAt = email.Substring(atIndex + 1);

        int visibleLength = (int)Math.Ceiling((double)visiblePartBefore.Length * 2 / 3);

        // 替换中间两位字符为星号
        string hiddenPartBeforeAt = visiblePartBefore.Substring(0, visibleLength - 1) + "***" + visiblePartBefore.Last();


        // 组合隐藏和可见部分
        string hiddenEmail = hiddenPartBeforeAt + "@" + afterAt;

        return hiddenEmail;
    }

    /// <summary>
    /// 密码必须包含：1）8 – 32 个字符；2）至少1个数字；3) 至少1个大写字母；4）至少1个小写字母；5）至少1个特殊字符 (~!-@#$%^&*_+?)
    /// </summary>
    /// <returns></returns>
    public static string GenerateRandomPassword(int length)
    {
        // 必须包含的字符组
        const string numbers = "0123456789";
        const string upperCaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        const string lowerCaseLetters = "abcdefghijklmnopqrstuvwxyz";
        const string specialCharacters = "~!-@#$%^&*_+?";

        // 随机选择至少一个字符
        char[] requiredCharacters =
        {
        numbers[Random.Next(numbers.Length)],
        upperCaseLetters[Random.Next(upperCaseLetters.Length)],
        lowerCaseLetters[Random.Next(lowerCaseLetters.Length)],
        specialCharacters[Random.Next(specialCharacters.Length)]
        };

        // 构建剩余的字符集，用于填充密码的其余部分
        string allCharacters = numbers + upperCaseLetters + lowerCaseLetters + specialCharacters;

        // 确保密码长度满足用户要求
        char[] password = new char[length];

        // 将必须包含的字符放入密码中
        requiredCharacters.CopyTo(password, 0);

        // 填充剩余的字符
        for (int i = requiredCharacters.Length; i < length; i++)
        {
            password[i] = allCharacters[Random.Next(allCharacters.Length)];
        }

        // 随机打乱密码字符顺序
        return new string(password.OrderBy(_ => Random.Next()).ToArray());
    }



    // https://learn.microsoft.com/zh-cn/dotnet/standard/base-types/how-to-verify-that-strings-are-in-valid-email-format
    /// <summary>
    /// 微软官方邮件验证  很宽松
    /// </summary>
    /// <param name="email"></param>
    /// <returns></returns>
    public static bool IsValidEmail(string email)
    {
        if (string.IsNullOrWhiteSpace(email))
            return false;

        try
        {
            // Normalize the domain
            email = Regex.Replace(email, @"(@)(.+)$", DomainMapper,
                                  RegexOptions.None, TimeSpan.FromMilliseconds(200));

            // Examines the domain part of the email and normalizes it.
            string DomainMapper(Match match)
            {
                // Use IdnMapping class to convert Unicode domain names.
                var idn = new IdnMapping();

                // Pull out and process domain name (throws ArgumentException on invalid)
                string domainName = idn.GetAscii(match.Groups[2].Value);

                return match.Groups[1].Value + domainName;
            }
        }
        catch (RegexMatchTimeoutException e)
        {
            return false;
        }
        catch (ArgumentException e)
        {
            return false;
        }

        try
        {
            return Regex.IsMatch(email,
                @"^[^@\s]+@[^@\s]+\.[^@\s]+$",
                RegexOptions.IgnoreCase, TimeSpan.FromMilliseconds(250));
        }
        catch (RegexMatchTimeoutException)
        {
            return false;
        }
    }
}