using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using System.Web.UI;
using NewLife.Log;
using NewLife.Model;
using NewLife.Web;
using XCode.Membership;
#if !NET4
using TaskEx = System.Threading.Tasks.Task;
#endif

namespace XCode.Web
{
    /// <summary>用户行为模块，在线和操作记录</summary>
    public class UserBehaviorModule : IHttpModule
    {
        #region IHttpModule Members
        void IHttpModule.Dispose() { }

        /// <summary>初始化模块，准备拦截请求。</summary>
        /// <param name="context"></param>
        void IHttpModule.Init(HttpApplication context)
        {
            context.AcquireRequestState += OnSession;
            //context.PreRequestHandlerExecute += OnSession;
            context.PostRequestHandlerExecute += OnPost;
            context.Error += OnPost;
        }

        private void OnSession(Object sender, EventArgs e)
        {
            // 会话状态已创建一个会话 ID，但由于响应已被应用程序刷新而无法保存它
            // 避免后面使用SessionID时报错
            var sid = HttpContext.Current?.Session?.SessionID;
        }
        #endregion

        /// <summary>Web在线</summary>
        public static Boolean WebOnline { get; set; }

        /// <summary>访问记录</summary>
        public static Boolean WebBehavior { get; set; }

        /// <summary>访问统计</summary>
        public static Boolean WebStatistics { get; set; }

        void OnPost(Object sender, EventArgs e)
        {
            if (!WebOnline && !WebBehavior && !WebStatistics) return;

            var ctx = HttpContext.Current;
            if (ctx == null) return;

            var req = ctx.Request;
            if (req == null) return;

            var user = ctx.User?.Identity as IManageUser ?? ManageProvider.User as IManageUser;

            var sid = ctx.Session?.SessionID;
            var ip = WebHelper.UserHost;

            var page = GetPage(req);
            var title = GetTitle(ctx, req);
            var msg = GetMessage(ctx, req, title);

            TaskEx.Run(() =>
            {
                try
                {
                    // 统计网页状态
                    if (WebOnline && !sid.IsNullOrEmpty()) UserOnline.SetWebStatus(sid, page, msg, user, ip);

                    // 记录用户访问的Url
                    if (WebBehavior) SaveBehavior(user, ip, page, msg);

                    // 每个页面的访问统计
                    if (WebStatistics) SaveStatistics(ctx, user, ip, page, title);
                }
                catch (Exception ex)
                {
                    XTrace.WriteException(ex);
                }
            });
        }

        String GetMessage(HttpContext ctx, HttpRequest req, String title)
        {
            var sb = new StringBuilder(256);

            if (!title.IsNullOrEmpty()) sb.Append(title + " ");
            sb.AppendFormat("{0} {1}", req.HttpMethod, req.RawUrl);

            var err = GetError(ctx)?.Message;
            if (!err.IsNullOrEmpty()) sb.Append(" " + err);

            var ts = DateTime.Now - ctx.Timestamp;
            sb.AppendFormat(" {0:n0}ms", ts.TotalMilliseconds);

            return sb.ToString();
        }

        String GetTitle(HttpContext ctx, HttpRequest req)
        {
            var title = ctx.Items["Title"] + "";
            if (title.IsNullOrEmpty())
            {
                if (ctx.Handler is Page page) title = page.Title;
            }

            // 有些标题是 Description，需要截断处理
            if (title.Contains(",")) title = title.Substring(null, ",");
            if (title.Contains("，")) title = title.Substring(null, "，");
            if (title.Contains("。")) title = title.Substring(null, "。");

            return title;
        }

        String GetPage(HttpRequest req)
        {
            var p = req.Path;
            if (p.IsNullOrEmpty()) return null;

            var ss = p.Split('/');
            if (ss.Length == 0) return p;

            // 如果最后一段是数字，则可能是参数，需要去掉
            if (ss[ss.Length - 1].ToInt() > 0) p = "/" + ss.Take(ss.Length - 1).Join("/");

            return p;
        }

        /// <summary>忽略的后缀</summary>
        public static HashSet<String> ExcludeSuffixes { get; set; } = new HashSet<String>(StringComparer.OrdinalIgnoreCase) {
            ".js", ".css", ".png", ".jpg", ".gif", ".ico",  // 脚本样式图片
            ".woff", ".woff2", ".svg", ".ttf", ".otf", ".eot"   // 字体
        };

        void SaveBehavior(IManageUser user, String ip, String page, String msg)
        {
            if (page.IsNullOrEmpty()) return;

            // 过滤后缀
            var ext = Path.GetExtension(page);
            if (!ext.IsNullOrEmpty() && ExcludeSuffixes.Contains(ext)) return;

            LogProvider.Provider?.WriteLog("访问", "记录", msg, user?.ID ?? 0, user + "", ip);
        }

        void SaveStatistics(HttpContext ctx, IManageUser user, String ip, String page, String title)
        {
            var ts = DateTime.Now - ctx.Timestamp;

            // 访问统计
            //VisitStat.Add(page, title, (Int32)ts.TotalMilliseconds, user?.ID ?? 0, ip, GetError(ctx)?.Message);

            var model = new VisitStatModel
            {
                Time = DateTime.Now,
                Page = page,
                Title = title,
                Cost = (Int32)ts.TotalMilliseconds,
                User = user + "",
                IP = ip,
                Error = GetError(ctx)?.Message,
            };

            VisitStat.Process(model);
        }

        /// <summary>获取错误，排除HttpException</summary>
        /// <param name="ctx"></param>
        /// <returns></returns>
        Exception GetError(HttpContext ctx)
        {
            var ex = ctx?.Error;
            if (ex != null && ex is HttpException && ex.InnerException != null) ex = ex.InnerException;

            return ex;
        }
    }
}