using System;
using System.Globalization;
using System.Net;
using System.Text.RegularExpressions;
using System.Windows.Controls;

namespace TeamAAS_VP.ValidationRules
{
    public class SubnetMaskValidationRule : ValidationRule
    {
        public override ValidationResult Validate(object value, CultureInfo cultureInfo)
        {
            string input = value as string;

            // 检查输入是否为空
            if (string.IsNullOrWhiteSpace(input))
                return new ValidationResult(false, "Subnet mask cannot be empty.".Replace("\\n", Environment.NewLine).Replace("\\t", "\t"));

            // 检查是否包含全角字符
            if (ContainsFullWidthCharacters(input))
                return new ValidationResult(false, "Subnet mask contains full-width characters.".Replace("\\n", Environment.NewLine).Replace("\\t", "\t"));

            // 检查是否为有效的 IPv4 格式
            if (!IsValidIPv4Format(input))
                return new ValidationResult(false, "Invalid subnet mask format.".Replace("\\n", Environment.NewLine).Replace("\\t", "\t"));

            // 检查每个部分的数值是否在 0 到 255 之间
            if (!IsValidIPv4Range(input))
                return new ValidationResult(false, "Subnet mask out of range.".Replace("\\n", Environment.NewLine).Replace("\\t", "\t"));

            // 检查是否为有效的子网掩码
            if (!IsValidSubnetMask(input))
                return new ValidationResult(false, "Invalid subnet mask.".Replace("\\n", Environment.NewLine).Replace("\\t", "\t"));

            return ValidationResult.ValidResult;
        }

        // 检查是否包含全角字符
        private bool ContainsFullWidthCharacters(string input)
        {
            foreach (char c in input)
            {
                if (c >= 0xFF01 && c <= 0xFF5E) // 全角字符范围
                    return true;
            }
            return false;
        }

        // 检查是否为有效的 IPv4 格式
        private bool IsValidIPv4Format(string input)
        {
            string pattern = @"^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$";
            return Regex.IsMatch(input, pattern);
        }

        // 检查每个部分的数值是否在 0 到 255 之间
        private bool IsValidIPv4Range(string input)
        {
            string[] parts = input.Split('.');
            foreach (string part in parts)
            {
                if (!int.TryParse(part, out int number) || number < 0 || number > 255)
                    return false;
            }
            return true;
        }

        // 检查是否为有效的子网掩码
        private bool IsValidSubnetMask(string input)
        {
            string[] parts = input.Split('.');
            int[] maskParts = new int[4];
            for (int i = 0; i < 4; i++)
            {
                maskParts[i] = int.Parse(parts[i]);
            }

            // 将子网掩码转换为二进制形式
            uint mask = (uint)(maskParts[0] << 24 | maskParts[1] << 16 | maskParts[2] << 8 | maskParts[3]);

            // 检查是否为连续的 1 和 0
            bool foundZero = false;
            for (int i = 31; i >= 0; i--)
            {
                uint bit = (mask >> i) & 1;
                if (bit == 0)
                {
                    foundZero = true;
                }
                else if (foundZero)
                {
                    // 如果发现 1 在 0 之后，说明不是有效的子网掩码
                    return false;
                }
            }

            return true;
        }
    }
}