MetadataController.cs

using Coscine.ApiCommons;
using Coscine.ApiCommons.Exceptions;
using Coscine.Database.Models;
using Coscine.Database.Util;
using Coscine.Metadata;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Newtonsoft.Json.Linq;
using System;
using System.Linq;
using System.Web;
using VDS.RDF;
using VDS.RDF.Parsing;
using VDS.RDF.Writing;

namespace Coscine.Api.Metadata.Controllers
{
    /// <summary>
    /// This controller represents the actions which can be performed with a Metadata storage.
    /// </summary>
    [Authorize]
    public class MetadataController : Controller
    {
        private readonly Authenticator _authenticator;
        private readonly ResourceModel _resourceModel;
        private readonly RdfStoreConnector _rdfStoreConnector;
        private readonly string ApplicationProfileUrl = "https://purl.org/coscine/ap/";

        /// <summary>
        /// MetadataController constructor specifying an authenticator and a ResourceModel.
        /// </summary>
        public MetadataController()
        {
            _authenticator = new Authenticator(this, Program.Configuration);
            _resourceModel = new ResourceModel();
            _rdfStoreConnector = new RdfStoreConnector(Program.Configuration.GetStringAndWait("coscine/local/virtuoso/additional/url"));
        }

        /// <summary>
        /// This method returns all application profiles.
        /// </summary>
        /// <returns>profiles</returns>
        [HttpGet("[controller]/profiles/")]
        public IActionResult GetProfiles()
        {
            var applicationProfiles = _rdfStoreConnector.GetApplicationProfiles();
            return Json(new JArray(applicationProfiles));
        }

        /// <summary>
        /// This method returns the application profile for the given profileUrl.
        /// </summary>
        /// <param name="profile">Url of the application profile</param>
        /// <returns>Json with the application profile</returns>
        [HttpGet("[controller]/profiles/{profile}")]
        public IActionResult GetProfile(string profile)
        {
            string profileUrl = profile.StartsWith("http") ? HttpUtility.UrlDecode(profile) : $"{ApplicationProfileUrl}{profile}/";

            var graph = _rdfStoreConnector.GetGraph(profileUrl);

            var tripleStore = new TripleStore();
            tripleStore.Add(graph);

            var outStoreJson = VDS.RDF.Writing.StringWriter.Write(tripleStore, new JsonLdWriter());

            var json = JToken.Parse(outStoreJson);

            return Ok(json);
        }

        /// <summary>
        /// Returns the application profile with the fixed values for the given resource.
        /// </summary>
        /// <param name="profile">Url of the application profile</param>
        /// <param name="resourceId">Id of the resource</param>
        /// <returns>JSON with the application profile or StatusCode 403</returns>
        [HttpGet("[controller]/profiles/{profile}/{resourceId}")]
        public IActionResult GetApplicationProfileComplete(string profile, string resourceId)
        {
            var user = _authenticator.GetUser();

            var resource = _resourceModel.GetById(Guid.Parse(resourceId));

            if (user == null || !_resourceModel.HasAccess(user, resource, UserRoles.Owner, UserRoles.Member))
            {
                return Forbid("User is no project member!");
            }

            string profileUrl = profile.StartsWith("http") ? HttpUtility.UrlDecode(profile) : $"{ApplicationProfileUrl}{profile}/";

            var graph = _rdfStoreConnector.GetGraph(profileUrl);
            var fixedValuesGraph = new Graph();

            fixedValuesGraph.LoadFromString(resource.FixedValues, new RdfJsonParser());

            graph.Merge(fixedValuesGraph);

            var tripleStore = new TripleStore();
            tripleStore.Add(graph);

            var outStoreJson = VDS.RDF.Writing.StringWriter.Write(tripleStore, new JsonLdWriter());

            var json = JToken.Parse(outStoreJson);

            return Ok(json);

        }

        /// <summary>
        /// This method returns a list of all vocabularies.
        /// </summary>
        /// <throws>Exception for the code that has not been implemented</throws>
        [HttpGet("[controller]/vocabularies/")]
        public IActionResult GetVocabularies()
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// This method returns a specific vocabulary.
        /// </summary>
        /// <param name="path">Url of the vocabulary</param>
        /// <returns>JSON with the requested vocabulary</returns>
        [HttpGet("[controller]/vocabularies/{path}")]
        public IActionResult GetVocabulary(string path)
        {
            var graph = _rdfStoreConnector.GetGraph(HttpUtility.UrlDecode(path));

            var de = new JArray();
            foreach (var kv in _rdfStoreConnector.GetVocabularyLabels(graph, "de"))
            {
                JObject obj = new JObject
                {
                    ["value"] = kv.Key,
                    ["name"] = kv.Value
                };
                de.Add(obj);
            }

            var en = new JArray();
            foreach (var kv in _rdfStoreConnector.GetVocabularyLabels(graph, "en"))
            {
                JObject obj = new JObject
                {
                    ["value"] = kv.Key,
                    ["name"] = kv.Value
                };
                en.Add(obj);
            }

            JObject json = new JObject
            {
                ["de"] = de,
                ["en"] = en
            };

            return Json(json);
        }

        /// <summary>
        /// This method returns instances.
        /// </summary>
        /// <param name="projectId">Id of the project</param>
        /// <param name="className">class name</param>
        /// <returns>instances as Json, or throw an Exception if the user has not beed authorized</returns>
        [HttpGet("[controller]/instances/{projectId}/{className}")]
        public IActionResult GetClassInstances(Guid projectId, string className)
        {
            var user = _authenticator.GetUser();
            ProjectModel projectModel = new ProjectModel();
            if (projectModel.HasAccess(user, projectModel.GetById(projectId), UserRoles.Owner, UserRoles.Member))
            {
                if (!Uri.TryCreate(HttpUtility.UrlDecode(className), UriKind.Absolute, out Uri uri))
                {
                    throw new ArgumentException("ClassName is not a valid Uri.");
                }
                var graph = _rdfStoreConnector.GetClassGraph(uri);

                var de = new JArray();
                foreach (var kv in _rdfStoreConnector.GetVocabularyLabels(graph, "de"))
                {
                    JObject obj = new JObject
                    {
                        ["value"] = kv.Key,
                        ["name"] = kv.Value
                    };
                    de.Add(obj);
                }

                var en = new JArray();
                foreach (var kv in _rdfStoreConnector.GetVocabularyLabels(graph, "en"))
                {
                    JObject obj = new JObject
                    {
                        ["value"] = kv.Key,
                        ["name"] = kv.Value
                    };
                    en.Add(obj);
                }

                JObject json = new JObject
                {
                    ["de"] = de,
                    ["en"] = en
                };

                return Json(json);
            }
            else
            {
                throw new NotAuthorizedException("User is no project member!");
            }
        }
    }
}