using Rac.Common;
using Rac.Tools;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Mime;
using System.Text;

namespace Rac
{
    public class OfflineWebServer : BaseService
    {
        private readonly string _dbFilePath;
        private DataAccess _db;
        private HttpListener _server;

        private Uri _homeUrl;
        private HashSet<string> _hostInclude;
        private string[] _excludeUrlPrefixes;

        private Encoding _defaultEncoding;

        public OfflineWebServer(string dbFilePath)
        {
            _dbFilePath = dbFilePath;
        }

        public override void Start()
        {
            if (false == File.Exists(_dbFilePath))
            {
                LogFatal($"Can not find database file:{_dbFilePath}");
                return;
            }
            _db = new DataAccess(_dbFilePath);
            var conf = new ConfigAdapter(_db.GetConfigs());

            _defaultEncoding = null != conf.DefaultCharset ? Encoding.GetEncoding(conf.DefaultCharset) : Encoding.UTF8;

            _hostInclude = new HashSet<string>(conf.HostsInclude);
            _excludeUrlPrefixes = conf.UrlPrefixExclude;

            _homeUrl = new Uri(conf.HomeUrl);

            _server = new HttpListener();
            _server.Prefixes.Add("http://*:" + conf.OwsPort + "/");
            _server.Start();
            _server.BeginGetContext(ProcessRequest, null);
            LogInfo($"OWS runing on " + (string.Join("|", _server.Prefixes)));
        }

        private string UrlTranscode(Uri uri, string link = null, bool includedOnly = false)
        {
            if (true == link?.ToLower().StartsWith("mailto:")) return link;

            //       http://host:port/path?query#hash
            // -->> /http/host/port/path?query#hash
            if (false == string.IsNullOrEmpty(link)) uri = new Uri(uri, link);

            if (includedOnly)
            {
                var url = uri.ToString();
                if (_excludeUrlPrefixes.Any(p => url.StartsWith(p))) return link;

                var hos = uri.Host;
                if (hos != _homeUrl.Host && false == _hostInclude.Contains(hos)) return link;
            }

            return $"/{uri.Scheme}/{uri.Host}/{uri.Port}{uri.PathAndQuery}{uri.Fragment}";
        }

        private void ProcessRequest(IAsyncResult ar)
        {
            var ctx = _server.EndGetContext(ar);

            LogTrace($"{ctx.Request.HttpMethod} {ctx.Request.RawUrl} From {ctx.Request.RemoteEndPoint}");

            //turn scheme/host/port to virtual path

            if (ctx.Request.Url.LocalPath == "/")
            {
                ctx.Response.Redirect(UrlTranscode(_homeUrl));
            }
            else
            {
                var path = ctx.Request.Url.GetComponents(UriComponents.PathAndQuery | UriComponents.Fragment, UriFormat.SafeUnescaped);
                var parts = path.Split('/');

                //check request path format /scheme/host/port/...
                if (parts.Length < 4)
                {
                    ctx.Response.StatusCode = 400;
                    ctx.Response.StatusDescription = "Bad Archive Request";
                    ctx.Response.ContentType = "text/html; charset=utf-8";
                    var buffer = Encoding.UTF8.GetBytes("<h1>400 Bad Archive Request</h1>");
                    ctx.Response.OutputStream.Write(buffer, 0, buffer.Length);
                }
                else
                {
                    //decode to raw url pass to db
                    try
                    {
                        var decodedUrl = $"{parts[1]}://{parts[2]}:{parts[3]}/{string.Join("/", parts.Skip(4))}";
                        var decodedUri = new Uri(decodedUrl);
                        var archiveUrl = decodedUri.ToString();

                        var entry = _db.GetEntry(archiveUrl);
                        if (entry == null || entry.StatusCode == 0)
                        {
                            ctx.Response.StatusCode = 404;
                            ctx.Response.StatusDescription = "ArchiveEntryNotFound";
                            ctx.Response.ContentType = "text/html; charset=utf-8";
                            var buffer = Encoding.UTF8.GetBytes($"<h1>404 Not Found In Archive by {archiveUrl}</h1>");
                            ctx.Response.OutputStream.Write(buffer, 0, buffer.Length);
                        }
                        else
                        {
                            var headers = HttpHeaderUtility.ParseStringLines(entry.Headers);

                            ctx.Response.StatusCode = entry.StatusCode;
                            ctx.Response.StatusDescription = entry.StatusDescription;

                            string contentType = null;
                            var contentEncoding = _defaultEncoding;

                            // replace all urls to /scheme/host/port/path?query#hash
                            //  in header location
                            //  in HTML(href/src/embedded css)
                            //  in CSS (url)

                            foreach (var header in headers)
                            {
                                if (header.Name == "location") header.Value = UrlTranscode(decodedUri, header.Value);
                                if (header.Name == "content-type")
                                {
                                    var ct = new ContentType(header.Value);
                                    contentType = ct.MediaType;
                                    if (null != ct.CharSet) contentEncoding = Encoding.GetEncoding(ct.CharSet);
                                }
                                ctx.Response.Headers.Set(header.Name, header.Value);
                            }

                            var output = entry.Content;

                            if (contentType == "text/html")
                            {
                                var replaced = LinkProcessor.ReplaceHtmlLinks(entry.Content, p => UrlTranscode(decodedUri, p, true), ref contentEncoding);
                                output = contentEncoding.GetBytes(replaced);
                            }
                            else if (contentType == "text/css")
                            {
                                var css = contentEncoding.GetString(entry.Content);
                                var replaced = LinkProcessor.ReplaceCssLinks(css, p => UrlTranscode(decodedUri, p, true));
                                output = contentEncoding.GetBytes(replaced);
                            }

                            try
                            {
                                ctx.Response.OutputStream.Write(output, 0, output.Length);
                            }
                            catch (Exception e)
                            {
                                LogError($"Error when writing output: {e.Message}");
                            }
                        }
                    }
                    catch (Exception e)
                    {
                        ctx.Response.StatusCode = 500;
                        ctx.Response.StatusDescription = "ArchiveEntryNotFound";
                        ctx.Response.ContentType = "text/html; charset=utf-8";
                        var buffer = Encoding.UTF8.GetBytes($"<h1>Error</h1><pre>{e}</pre>");
                        ctx.Response.OutputStream.Write(buffer, 0, buffer.Length);
                    }
                }
            }

            try
            {
                LogTrace($"{ctx.Request.HttpMethod} {ctx.Request.RawUrl} -- {ctx.Response.StatusCode}");
                ctx.Response.Close();
            }
            catch
            {
                //Do nothing!
            }

            _server.BeginGetContext(ProcessRequest, null);
        }

        public override void Stop()
        {
            _server.Stop();
        }
    }
}