using Microsoft.Extensions.Options;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Net;

namespace FastGithub.Configuration
{
 /// <summary>
 /// FastGithub配置
 /// </summary>
 public class FastGithubConfig
 {
 private SortedDictionary<DomainPattern, DomainConfig> domainConfigs;
 private ConcurrentDictionary<string, DomainConfig?> domainConfigCache;

 /// <summary>
 /// http代理端口
 /// </summary>
 public int HttpProxyPort { get; set; }

 /// <summary>
 /// 回退的dns
 /// </summary>
 public IPEndPoint[] FallbackDns { get; set; }

 /// <summary>
 /// FastGithub配置
 /// </summary>
 /// <param name="options"></param>
 /// <param name="logger"></param>
 public FastGithubConfig(IOptionsMonitor<FastGithubOptions> options)
 {
 var opt = options.CurrentValue;

 this.HttpProxyPort = opt.HttpProxyPort;
 this.FallbackDns = opt.FallbackDns;
 this.domainConfigs = ConvertDomainConfigs(opt.DomainConfigs);
 this.domainConfigCache = new ConcurrentDictionary<string, DomainConfig?>();

 options.OnChange(opt => this.Update(opt));
 }

 /// <summary>
 /// 更新配置
 /// </summary>
 /// <param name="options"></param>
 private void Update(FastGithubOptions options)
 {
 this.HttpProxyPort = options.HttpProxyPort;
 this.FallbackDns = options.FallbackDns;
 this.domainConfigs = ConvertDomainConfigs(options.DomainConfigs);
 this.domainConfigCache = new ConcurrentDictionary<string, DomainConfig?>();
 }

 /// <summary>
 /// 配置转换
 /// </summary>
 /// <param name="domainConfigs"></param>
 /// <returns></returns>
 private static SortedDictionary<DomainPattern, DomainConfig> ConvertDomainConfigs(Dictionary<string, DomainConfig> domainConfigs)
 {
 var result = new SortedDictionary<DomainPattern, DomainConfig>();
 foreach (var kv in domainConfigs)
 {
 result.Add(new DomainPattern(kv.Key), kv.Value);
 }
 return result;
 }

 /// <summary>
 /// 是否匹配指定的域名
 /// </summary>
 /// <param name="domain"></param>
 /// <returns></returns>
 public bool IsMatch(string domain)
 {
 return this.TryGetDomainConfig(domain, out _);
 }

 /// <summary>
 /// 尝试获取域名配置
 /// </summary>
 /// <param name="domain"></param>
 /// <param name="value"></param>
 /// <returns></returns>
 public bool TryGetDomainConfig(string domain, [MaybeNullWhen(false)] out DomainConfig value)
 {
 value = this.domainConfigCache.GetOrAdd(domain, GetDomainConfig);
 return value != null;

 DomainConfig? GetDomainConfig(string domain)
 {
 var key = this.domainConfigs.Keys.FirstOrDefault(item => item.IsMatch(domain));
 return key == null ? null : this.domainConfigs[key];
 }
 }

 /// <summary>
 /// 获取所有域名表达式
 /// </summary>
 /// <returns></returns>
 public DomainPattern[] GetDomainPatterns()
 {
 return this.domainConfigs.Keys.ToArray();
 }
 }
}