// /**
//  * File: CollectionResource<T>.cs
//  * Author: haraldwolff
//  *
//  * This file and it's content is copyrighted by the Author and / or copyright holder.
//  * Any use wihtout proper permission is illegal and may lead to legal actions.
//  *
//  *
//  **/
using System;
using System.Collections.Generic;
using System.Linq;
using ln.http.exceptions;
using ln.json;
using ln.json.mapping;
namespace ln.http.resources
{
    public delegate IEnumerable<T> EnumerationDelegate<T>();

    public delegate T LookupDelegate<T>(string ID);
    public delegate String GetResourceNameDelegate<T>(T o);

    public delegate T CreateDelegate<T>();
    public delegate bool DeleteDelegate<T>(T o);
    public delegate bool StoreDelegate<T>(T o);

    public class ObjectContainerResource<T> : Resource where T:class
    {
        public EnumerationDelegate<T> Enumeration { get; set; }
        public LookupDelegate<T> Lookup { get; set; }
        public GetResourceNameDelegate<T> GetResourceName { get; set; }
        public CreateDelegate<T> Create { get; set; }
        public DeleteDelegate<T> Delete { get; set; }
        public StoreDelegate<T> Store { get; set; }

        public ObjectContainerResource(Resource container)
            : this(container, typeof(T).Name)
        {}

        public ObjectContainerResource(Resource container, String name)
            : base(container, name)
        {
        }
        public ObjectContainerResource(Resource container, String name,
            EnumerationDelegate<T> Enumeration,
            LookupDelegate<T> Lookup,
            GetResourceNameDelegate<T> GetResourceName,
            CreateDelegate<T> Create,
            DeleteDelegate<T> Delete,
            StoreDelegate<T> Store
            )
            : base(container, name)
        {
            this.Enumeration = Enumeration;
            this.Lookup = Lookup;
            this.GetResourceName = GetResourceName;
            this.Create = Create;
            this.Delete = Delete;
            this.Store = Store;
        }

        public override bool HandlesDispatching => true;
        public override void AddResource(Resource resource) => throw new NotSupportedException();
        public override void RemoveResource(Resource resource) => throw new NotSupportedException();
        public override IEnumerable<Resource> GetResources() => throw new NotImplementedException();
        public override bool Contains(string name) => throw new NotImplementedException();

        public override HttpResponse GetResponse(HttpRequest httpRequest,Queue<string> pathStack)
        {
            object responseValue = null;
            HttpResponse httpResponse = new HttpResponse(httpRequest);
            httpResponse.SetHeader("content-type", "application/json");

            if (pathStack.Count == 0)
            {
                switch (httpRequest.Method)
                {
                    case "GET":
                        T[] resources = Query(httpRequest);
                        JSONObject result = new JSONObject();
                        foreach (T resource in resources)
                            result.Add(String.Format("{0}/{1}",String.Join("/",Path),GetResourceName(resource)), JSONMapper.DefaultMapper.ToJson(resource));

                        responseValue = result;
                        break;
                    case "POST":
                        T ni = PostItem(httpRequest);
                        string resourceName = GetResourceName(ni);
                        httpResponse.SetHeader("Location", String.Format("/{0}/{1}", String.Join("/", this.Path),resourceName.ToString()));
                        httpResponse.StatusCode = 201;
                        responseValue = ni;
                        break;
                    default:
                        throw new NotSupportedException();
                }
            }
            else
            {
                String resourceName = String.Join("/", pathStack);
                T resource = Lookup(resourceName);

                switch (httpRequest.Method)
                {
                    case "PUT":
                        JSONMapper.DefaultMapper.Apply(httpRequest.ContentReader.ReadToEnd(), resource);
                        bool updated = Store(resource);

                        if (updated)
                        {
                            responseValue = resource;
                            httpResponse.StatusCode = 200;
                        } else 
                        {
                            httpResponse.StatusCode = 500;
                        }

                        break;
                    default:
                        throw new NotSupportedException();
                }
            }

            httpResponse.ContentWriter.Write(
                    responseValue is JSONValue ? (responseValue as JSONValue).ToString() : JSONMapper.DefaultMapper.ToJson(responseValue).ToString()
                );
            return httpResponse;
        }

        public override HttpResponse GetResponse(HttpRequest httpRequest)
        {
            return GetResponse(httpRequest, new Queue<string>());
        }

        private T[] Query(HttpRequest httpRequest)
        { 
            return Enumeration().ToArray();
        }

        private T PostItem(HttpRequest httpRequest)
        {
            T newResource = Create();
            JSONMapper.DefaultMapper.Apply(httpRequest.ContentReader.ReadToEnd(), newResource);

            if (!Store(newResource))
                throw new HttpException(500, "Object not created, may already exist");

            return newResource;
        }

    }
}