ln.http.resources/collections/JSONCollectionResource<T>.cs

// /**
//  * 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 ln.json.mapping;
using ln.json;

namespace ln.http.resources.collections
{
    public class JSONCollectionResource<TENTITY, TIDENT> : Resource where TENTITY : class
    {
        public JSONMapper JSONMapper { get; set; }
        public EntityMapper<TENTITY> EntityMapper { get;}

        IEntityCollectionInterface<TENTITY, TIDENT> entityCollectionInterface;

        public JSONCollectionResource(Resource container, IEntityCollectionInterface<TENTITY,TIDENT> entityCollectionInterface)
            : base(container, typeof(TENTITY).Name)
        {
            this.entityCollectionInterface = entityCollectionInterface;
            this.JSONMapper = JSONMapper.DefaultMapper;
            EntityMapper = new EntityMapper<TENTITY>(JSONMapper);
        }

        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) => GetResponse(httpRequest, new Queue<string>());
        public override HttpResponse GetResponse(HttpRequest httpRequest, Queue<string> pathStack)
        {
            CollectionResult collectionResult = null;

            if (pathStack.Count == 0)
            {
                switch (httpRequest.Method)
                {
                    case "GET":
                        collectionResult = Query(httpRequest);
                        break;
                    case "POST":
/*
                        T ni = PostItem(httpRequest);
                        object documentID = collection.Mapper.GetDocumentID(ni);
                        httpResponse.SetHeader("Location", String.Format("/{0}/{1}", String.Join("/", this.Path), documentID.ToString()));
                        httpResponse.StatusCode = 201;
                        responseValue = ni;
*/
                        break;
                    case "DESC":
                        collectionResult = Describe(httpRequest);
                        break;
                    default:
                        throw new NotSupportedException();
                }
            }
            else
            {
                String documentID = pathStack.Dequeue();
                TIDENT ident = this.JSONMapper.FromJson<TIDENT>(this.JSONMapper.ToJson(documentID));
                TENTITY entity = entityCollectionInterface.GetEntity(ident);

                switch (httpRequest.Method)
                {
                    case "GET":
                        collectionResult = new CollectionResult();
                        collectionResult.Values.Add(entity);
                        break;
                    case "PUT":
                        break;
                    default:
                        throw new NotSupportedException();
                }
            }

            HttpResponse httpResponse = ConstructResponse(httpRequest, collectionResult);
            return httpResponse;
        }

        private CollectionResult Describe(HttpRequest request)
        {
            CollectionResult collectionResult = new CollectionResult();
            collectionResult.Descriptor = new JSONObject();

            JSONArray jProperties = new JSONArray();

            /* ToDo: Implement or remove */
            //foreach (FieldInfo fieldInfo in EntityMapper.publicFields.Values)
            //{
            //    String skyType = JSONMapper.GetSkyType(fieldInfo.FieldType);
            //    if (skyType != null)
            //    {
            //        JObject field = new JObject();
            //        field.Add("name", JToken.FromObject(fieldInfo.Name));
            //        field.Add("type", JToken.FromObject(skyType));
            //        jProperties.Add(field);
            //    }
            //}
            //foreach (PropertyInfo propertyInfo in EntityMapper.publicProperties.Values)
            //{
            //    String skyType = JSONConvert.GetSkyType(propertyInfo.PropertyType);
            //    if (skyType != null)
            //    {
            //        JObject field = new JObject();
            //        field.Add("name", JToken.FromObject(propertyInfo.Name));
            //        field.Add("type", JToken.FromObject(skyType));
            //        jProperties.Add(field);
            //    }
            //}

            collectionResult.Descriptor.Add("properties", jProperties);
            return collectionResult;
        }

        private CollectionResult Query(HttpRequest request)
        {
            CollectionResult collectionResult = new CollectionResult();

            foreach (TENTITY entity in entityCollectionInterface.List())
                collectionResult.Values.Add(entity);

            return collectionResult;
        }

        private string ConstructEntityURL(HttpRequest request,TIDENT identity)
        {
            return string.Format("{0}/{1}", String.Join("/", Path), identity.ToString());
        }

        private HttpResponse ConstructResponse(HttpRequest request,CollectionResult collectionResult)
        {
            HttpResponse response = new HttpResponse(request);

            JSONObject surround = new JSONObject();
            JSONObject jvalues = new JSONObject();

            foreach (TENTITY entity in collectionResult.Values)
            {
                TIDENT identity = entityCollectionInterface.GetIdentity(entity);
                jvalues.Add(ConstructEntityURL(request, identity), EntityMapper.MapEntity(entity));
            }
            surround.Add("values", jvalues);

            JSONObject jfailed = new JSONObject();
            foreach (TIDENT id in collectionResult.Failed.Keys)
            {
                    jfailed.Add(id.ToString(), new JSONString(collectionResult.Failed[id]));
            }
            surround.Add("failed", jfailed);

            if (collectionResult.Descriptor != null)
            {
                surround.Add("desc", collectionResult.Descriptor);
            }

            response.SetHeader("content-type", "application/json");
            response.ContentWriter.Write(surround.ToString());

            return response;
        }

        class CollectionResult
        {
            public List<TENTITY> Values { get; } = new List<TENTITY>();
            public Dictionary<TIDENT, String> Failed { get; } = new Dictionary<TIDENT, string>();

            public JSONObject Descriptor { get; set; }
        }

    }
}