using System;
using System.Text.RegularExpressions;
using System.Collections.Generic;
using System.Text;
namespace ln.http
{
    public class SimpleHttpRouter : IHttpRouter
    {
        List<SimpleRoute> routes = new List<SimpleRoute>();

        public SimpleHttpRouter()
        {
        }

        public void AddSimpleRoute(string simpleRoute, IHttpRouter target) => AddSimpleRoute(simpleRoute, target, simpleRoute.Split('/').Length);
        public void AddSimpleRoute(string simpleRoute, IHttpRouter target, int priority)
        {
            string[] parts = simpleRoute.Split(new char[] { '/' },StringSplitOptions.RemoveEmptyEntries);
            StringBuilder stringBuilder = new StringBuilder("^");
            foreach (string part in parts)
            {
                if (part.StartsWith(":", StringComparison.InvariantCulture))
                    stringBuilder.AppendFormat("/(?<{0}>[^/]+)", part.Substring(1));
                else if (part.Equals("*"))
                    stringBuilder.AppendFormat("/(?<_>.*)");
                else
                    stringBuilder.AppendFormat("/{0}", part);
            }
            stringBuilder.Append("/?$");

            AddRoute(stringBuilder.ToString(), target, priority);
        }

        public void AddRoute(String route, IHttpRouter target) => AddRoute(route, target, 0);
        public void AddRoute(String route, IHttpRouter target,int priority)
        {
            lock (this)
            {
                routes.Add(new SimpleRoute(route, target, priority));
                routes.Sort((SimpleRoute a, SimpleRoute b) => b.Priority - a.Priority);
            }
        }

        public HttpResponse Route(string path, HttpRequest httpRequest)
        {
            foreach (SimpleRoute simpleRoute in routes.ToArray())
            {
                Match match = simpleRoute.Route.Match(path);
                if (match.Success)
                {
                    string residual = "";

                    foreach (Group group in match.Groups)
                    {
                        httpRequest?.SetParameter(group.Name, group.Value);
                        if (group.Name.Equals("_"))
                            residual = group.Value;
                    }
                    return simpleRoute.Target.Route(residual,httpRequest);
                }
            }
            throw new KeyNotFoundException();
        }
    

        public class SimpleRoute
        {
            public int Priority { get; }

            public Regex Route { get; }
            public IHttpRouter Target { get; }

            public SimpleRoute(string regex, IHttpRouter target) : this(regex, target, 0) { }
            public SimpleRoute(string regex, IHttpRouter target,int priority)
            {
                Route = new Regex(regex);
                Target = target;
                Priority = priority;
            }
        }
    }
}