using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Windows.Controls;
using TeamAAS_VP.Core;

namespace TeamAAS_VP.ValidationRules
{
    public class IPAddressValidationRule : 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, "IP address 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, "IP address 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 IP address 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, "IP address out of range.".Replace("\\n", Environment.NewLine).Replace("\\t", "\t"));

            var ipaddress = Common.ParseIpWithLeadingZeros(input);
            if (ipaddress == null)
            {
                return new ValidationResult(false, "Invalid IP address.".Replace("\\n", Environment.NewLine).Replace("\\t", "\t"));
            }
            input = ipaddress.ToString();

            // 检查是否为环回地址 (127.x.x.x)
            if (IsLoopbackAddress(input))
                return new ValidationResult(false, "Invalid IP address.".ToString().Replace("\\n", Environment.NewLine).Replace("\\t", "\t"));

            // 检查是否为全局 IP 地址
            if (IsGlobalIPAddress(input))
                return new ValidationResult(false, "Global IP addresses are not allowed.".Replace("\\n", Environment.NewLine).Replace("\\t", "\t"));

            return ValidationResult.ValidResult;
        }

        // 检查是否包含全角字符
        public 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
        public 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
        public 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;
        }

        //检查是否为环回地址(127.x.x.x)
        public bool IsLoopbackAddress(string input)
        {
            string[] parts = input.Split('.');
            if (parts.Length != 4)
                return false;

            return parts[0] == "127";
        }

        // 检查是否为全局 IP 地址
        public bool IsGlobalIPAddress(string input)
        {
            string[] parts = input.Split('.');
            int firstPart = int.Parse(parts[0]);

            // 私有 IP 地址范围：
            // 10.0.0.0 - 10.255.255.255
            // 172.16.0.0 - 172.31.255.255
            // 192.168.0.0 - 192.168.255.255
            if (firstPart == 10 ||
                (firstPart == 172 && int.Parse(parts[1]) >= 16 && int.Parse(parts[1]) <= 31) ||
                (firstPart == 192 && int.Parse(parts[1]) == 168))
            {
                return false; // 是私有 IP 地址
            }

            return true; // 是全局 IP 地址
        }
    }
}