url-shortener/UrlShortenerApp.cs

using HashidsNet;
using LiteDB;
using Tesses.WebServer;

namespace UrlShortener
{
    internal class UrlShortenerApp : Server
    {
        private Config config;
        private IHashids ids;

        private ILiteCollection<UrlShortenEntry> Collection()
        {
            var database=new LiteDatabase(Path.Combine("data","database.db"));
            return database.GetCollection<UrlShortenEntry>("Urls");
        }

        public UrlShortenerApp(Config config, IHashids ids)
        {
            this.config = config;
            this.ids = ids;
        }

        public override async Task GetAsync(ServerContext ctx)
        {
            string id=ctx.UrlPath.Substring(1);

            if(GetUrl(id,out var destUrl))
            {
                await ctx.SendRedirectAsync(destUrl);
            }
            else
            {
                await ctx.SendRedirectAsync(RelToRoot($"/404.html?id={id}"));
            }
        }

        private bool GetUrl(string id, out string destUrl)
        {
            destUrl = "";
            if(ids.TryDecodeSingleLong(id,out var idOut))
            {
               var col= Collection();
               var item = col.FindById(idOut);
               if(item != null)
               {
                    destUrl = item.Url;
                    return true;
               }
            }
            return false;
        }

        public string RelToRoot(string path)
        {
            return $"{config.UrlRoot.TrimEnd('/')}/{path.TrimStart('/')}";
        }

        internal void Run()
        {
            MountableServer server=new MountableServer(new StaticServer(Path.Combine("data","www")));
            RouteServer api=new RouteServer();
            server.Mount("/s/",this);
            server.Mount("/api/v1/",api);
            api.Add("/AddEntry",AddEntryAsync,"POST");
            api.Add("/GetEntry",GetEntryAsync);
            server.StartServer(config.Port);
        }

        private async Task GetEntryAsync(ServerContext ctx)
        {
            if(ctx.QueryParams.TryGetFirst("id",out var id))
            {
                if(ids.TryDecodeSingleLong(id,out var idOut))
                {
                    var col= Collection();
                    var item = col.FindById(idOut);
                    if(item != null)
                    {
                        await ctx.SendJsonAsync(new{Url = item.Url, Success=true,Created=item.Created});
                        return;
                    }
                }
            }
            
                await ctx.SendJsonAsync(new{Success = false});
            
        }

        private async Task AddEntryAsync(ServerContext ctx)
        {
            ctx.ParseBody();
            if(ctx.QueryParams.TryGetFirst("url",out var url))
            {
                var itemLS=Collection();
                var date = DateTime.Now;
                var id=itemLS.Insert(new UrlShortenEntry(){Url = url,Created = date});
                string id2=ids.EncodeLong(id.AsInt64);
                await ctx.SendJsonAsync(new{
                    Success=true,
                    Url = RelToRoot($"/s/{id2}"),
                    Created = date,
                    Id = id2
                });
            }
            else
            {
                await ctx.SendJsonAsync(new{Success = false});
            }
        }
    }
}