using System;
using System.Text.RegularExpressions;

namespace FastGithub.Configuration
{
 /// <summary>
 /// 表示域名表达式
 /// *表示除.之外任意0到多个字符
 /// </summary>
 public class DomainPattern : IComparable<DomainPattern>
 {
 private readonly Regex regex;
 private readonly string domainPattern;

 /// <summary>
 /// 域名表达式
 /// *表示除.之外任意0到多个字符
 /// </summary>
 /// <param name="domainPattern">域名表达式</param>
 public DomainPattern(string domainPattern)
 {
 this.domainPattern = domainPattern;
 var regexPattern = Regex.Escape(domainPattern).Replace(@"\*", @"[^\.]*");
 this.regex = new Regex($"^{regexPattern}$", RegexOptions.IgnoreCase);
 }

 /// <summary>
 /// 与目标比较
 /// </summary>
 /// <param name="other"></param>
 /// <returns></returns>
 public int CompareTo(DomainPattern? other)
 {
 if (other is null)
 {
 return 1;
 }

 var segmentsX = this.domainPattern.Split('.');
 var segmentsY = other.domainPattern.Split('.');
 var value = segmentsX.Length - segmentsY.Length;
 if (value != 0)
 {
 return value;
 }

 for (var i = segmentsX.Length - 1; i >= 0; i--)
 {
 var x = segmentsX[i];
 var y = segmentsY[i];

 value = Compare(x, y);
 if (value == 0)
 {
 continue;
 }
 return value;
 }

 return 0;
 }


 /// <summary>
 /// 比较两个分段
 /// </summary>
 /// <param name="x">abc</param>
 /// <param name="y">abc*</param>
 /// <returns></returns>
 private static int Compare(string x, string y)
 {
 var valueX = x.Replace('*', char.MaxValue);
 var valueY = y.Replace('*', char.MaxValue);
 return valueX.CompareTo(valueY);
 }

 /// <summary>
 /// 是否与指定域名匹配
 /// </summary>
 /// <param name="domain"></param>
 /// <returns></returns>
 public bool IsMatch(string domain)
 {
 return this.regex.IsMatch(domain);
 }

 /// <summary>
 /// 转换为文本
 /// </summary>
 /// <returns></returns>
 public override string ToString()
 {
 return this.domainPattern;
 }
 }
}