using FastGithub.Configuration;
using FastGithub.DomainResolve;
using System;
using System.Collections.Concurrent;

namespace FastGithub.Http
{
 /// <summary>
 /// HttpClient工厂
 /// </summary>
 sealed class HttpClientFactory : IHttpClientFactory
 {
 private readonly IDomainResolver domainResolver;

 /// <summary>
 /// 首次生命周期
 /// </summary>
 private readonly TimeSpan firstLiftTime = TimeSpan.FromSeconds(10d);

 /// <summary>
 /// 非首次生命周期
 /// </summary>
 private readonly TimeSpan nextLifeTime = TimeSpan.FromSeconds(100d);

 /// <summary>
 /// LifetimeHttpHandler清理器
 /// </summary>
 private readonly LifetimeHttpHandlerCleaner httpHandlerCleaner = new();

 /// <summary>
 /// LazyOf(LifetimeHttpHandler)缓存
 /// </summary>
 private readonly ConcurrentDictionary<LifeTimeKey, Lazy<LifetimeHttpHandler>> httpHandlerLazyCache = new();


 /// <summary>
 /// HttpClient工厂
 /// </summary>
 /// <param name="domainResolver"></param>
 public HttpClientFactory(IDomainResolver domainResolver)
 {
 this.domainResolver = domainResolver;
 }

 /// <summary>
 /// 创建httpClient
 /// </summary>
 /// <param name="domain"></param>
 /// <param name="domainConfig"></param>
 /// <returns></returns>
 public HttpClient CreateHttpClient(string domain, DomainConfig domainConfig)
 {
 var lifeTimeKey = new LifeTimeKey(domain, domainConfig);
 var lifetimeHttpHandler = this.httpHandlerLazyCache.GetOrAdd(lifeTimeKey, CreateLifetimeHttpHandlerLazy).Value;
 return new HttpClient(lifetimeHttpHandler, disposeHandler: false);

 Lazy<LifetimeHttpHandler> CreateLifetimeHttpHandlerLazy(LifeTimeKey lifeTimeKey)
 {
 return new Lazy<LifetimeHttpHandler>(() => this.CreateLifetimeHttpHandler(lifeTimeKey, this.firstLiftTime), true);
 }
 }

 /// <summary>
 /// 创建LifetimeHttpHandler
 /// </summary>
 /// <param name="lifeTimeKey"></param>
 /// <param name="lifeTime"></param>
 /// <returns></returns>
 private LifetimeHttpHandler CreateLifetimeHttpHandler(LifeTimeKey lifeTimeKey, TimeSpan lifeTime)
 {
 return new LifetimeHttpHandler(this.domainResolver, lifeTimeKey, lifeTime, this.OnLifetimeHttpHandlerDeactivate);
 }

 /// <summary>
 /// 当有httpHandler失效时
 /// </summary>
 /// <param name="lifetimeHttpHandler">httpHandler</param>
 private void OnLifetimeHttpHandlerDeactivate(LifetimeHttpHandler lifetimeHttpHandler)
 {
 var lifeTimeKey = lifetimeHttpHandler.LifeTimeKey;
 this.httpHandlerLazyCache[lifeTimeKey] = CreateLifetimeHttpHandlerLazy(lifeTimeKey);
 this.httpHandlerCleaner.Add(lifetimeHttpHandler);

 Lazy<LifetimeHttpHandler> CreateLifetimeHttpHandlerLazy(LifeTimeKey lifeTimeKey)
 {
 return new Lazy<LifetimeHttpHandler>(() => this.CreateLifetimeHttpHandler(lifeTimeKey, this.nextLifeTime), true);
 }
 }
 }
}