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

namespace FastGithub
{
    /// <summary>
    /// FastGithub配置
    /// </summary>
    public class FastGithubConfig
    {
        private readonly ILogger<FastGithubConfig> logger;
        private ConcurrentDictionary<string, DomainConfig?> domainConfigCache;

        /// <summary>
        /// 未污染的dns
        /// </summary>  
        public IPEndPoint PureDns { get; private set; }

        /// <summary>
        /// 速度快的dns
        /// </summary>
        public IPEndPoint FastDns { get; private set; }

        /// <summary>
        /// 获取域名配置
        /// </summary>    
        public Dictionary<DomainMatch, DomainConfig> DomainConfigs { get; private set; }

        /// <summary>
        /// FastGithub配置
        /// </summary>
        /// <param name="options"></param>
        /// <param name="logger"></param>
        public FastGithubConfig(
            IOptionsMonitor<FastGithubOptions> options,
            ILogger<FastGithubConfig> logger)
        {
            this.logger = logger;

            var opt = options.CurrentValue;
            this.domainConfigCache = new ConcurrentDictionary<string, DomainConfig?>();
            this.PureDns = opt.PureDns.ToIPEndPoint();
            this.FastDns = opt.FastDns.ToIPEndPoint();
            this.DomainConfigs = opt.DomainConfigs.ToDictionary(kv => new DomainMatch(kv.Key), kv => kv.Value);

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

        /// <summary>
        /// 更新配置
        /// </summary>
        /// <param name="options"></param>
        private void Update(FastGithubOptions options)
        {
            try
            {
                this.domainConfigCache = new ConcurrentDictionary<string, DomainConfig?>();
                this.PureDns = options.PureDns.ToIPEndPoint();
                this.FastDns = options.FastDns.ToIPEndPoint();
                this.DomainConfigs = options.DomainConfigs.ToDictionary(kv => new DomainMatch(kv.Key), kv => kv.Value);
            }
            catch (Exception ex)
            {
                this.logger.LogError(ex.Message);
            }
        }

        /// <summary>
        /// 是否匹配指定的域名
        /// </summary>
        /// <param name="domain"></param>
        /// <returns></returns>
        public bool IsMatch(string domain)
        {
            return this.DomainConfigs.Keys.Any(item => item.IsMatch(domain));
        }

        /// <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, this.GetDomainConfig);
            return value != null;
        }

        /// <summary>
        /// 获取域名配置
        /// </summary>
        /// <param name="domain"></param>
        /// <returns></returns>
        private DomainConfig? GetDomainConfig(string domain)
        {
            var key = this.DomainConfigs.Keys.FirstOrDefault(item => item.IsMatch(domain));
            return key == null ? null : this.DomainConfigs[key];
        }
    }
}