Getting popular content from Profile Store using KQL

ContentTypeTrackingInterceptor.cs

[ServiceConfiguration(ServiceType = typeof(ITrackingDataInterceptor), Lifecycle = ServiceInstanceScope.Singleton)]
public class ContentTypeTrackingInterceptor : ITrackingDataInterceptor
{
    private IContentLoader _contentLoader;
    private IContentTypeRepository _contentTypeRepository;

    public int SortOrder => 100;

    public ContentTypeTrackingInterceptor(IContentLoader contentLoader, IContentTypeRepository contentTypeRepository)
    {
        _contentLoader = contentLoader;
        _contentTypeRepository = contentTypeRepository;
    }

    public void Intercept<TPayload>(TrackingData<TPayload> trackingData)
    {
        if (trackingData == null || trackingData.Payload == null)
        {
            return;
        }
        if (!(trackingData.Payload is EPiServer.Tracking.PageView.EpiPageViewWrapper payload))
        {
            return;
        }

        // Create replacement Epi payload object
        var pageView = new EpiPageViewWithType(payload.Epi);
        var page = _contentLoader.Get<IContent>(payload.Epi.ContentGuid);
        pageView.TypeId = page.ContentTypeID;
        payload.Epi = pageView;
    }
}

EpiPageViewWithType.cs

public class EpiPageViewWithType : EpiPageView
{
    public EpiPageViewWithType(EpiPageView pageView)
    {
        Ancestors = pageView.Ancestors;
        ContentGuid = pageView.ContentGuid;
        Language = pageView.Language;
        RecommendationClick = pageView.RecommendationClick;
        SiteId = pageView.SiteId;
    }
    public int TypeId { get; set; }
}

KqlTrendingArticlesBlock.cs

[ContentType(DisplayName = "KQL Trending Articles Block", GUID = "532baaef-214e-4bc3-ac82-bedde42d0e03", Description = "")]
public class KqlTrendingArticlesBlock : BlockData
{
    [CultureSpecific]
    [Display(
        Name = "Heading",
        Description = "Heading for this block",
        GroupName = SystemTabNames.Content,
        Order = 10)]
    public virtual string Heading { get; set; }

    [Display(
        Name = "No of items",
        Description = "The number of items to show",
        GroupName = SystemTabNames.Content,
        Order = 20)]
    [Required]
    public virtual int ItemCount { get; set; }

    [Display(
        Name = "Root page for items",
        Description = "The ancestor of the content items returned",
        GroupName = SystemTabNames.Content,
        Order = 30)]
    [Required]
    public virtual PageReference Root { get; set; }

    [Display(
        Name = "Agregation period (hours)",
        Description = "The number of hours to agregate data over",
        GroupName = SystemTabNames.Content,
        Order = 40)]
    [Required]
    public virtual int RecentHours { get; set; }

    public override void SetDefaultValues(ContentType contentType)
    {
        base.SetDefaultValues(contentType);
        RecentHours = 24;
        ItemCount = 5;
    }
}

KqlTrendingArticlesBlock\Index.cshtml

@model TrendingArticlesViewModel

<h2>@Model.Heading</h2>
<hr />
<ol>
    @foreach (var article in Model.TrendingArticles)
    {
        <li class="listResult">
            <h3>
                @Html.PageLink(article)
            </h3>
            <p class="date">@Html.DisplayFor(x => article.StartPublish)</p>
            <hr />
        </li>
    }
</ol>

KqlTrendingArticlesBlockController.cs

public class KqlTrendingArticlesBlockController : BlockController<KqlTrendingArticlesBlock>
{
    private IContentLoader _contentLoader;
    private IContentTypeRepository _contentTypeRepository;

    public KqlTrendingArticlesBlockController(IContentTypeRepository contentTypeRepository, IContentLoader contentLoader)
    {
        _contentTypeRepository = contentTypeRepository;
        _contentLoader = contentLoader;
    }

    public override ActionResult Index(KqlTrendingArticlesBlock currentBlock)
    {
        var lang = (currentBlock as ILocalizable).Language;
        var profileStoreHelper = new ProfileStoreHelper(_contentTypeRepository, _contentLoader);
        var trendingArticles = profileStoreHelper.GetPopularPages<ArticlePage>(ContentReference.StartPage, lang.Name, currentBlock.ItemCount, currentBlock.RecentHours);
        var viewModel = new TrendingArticlesViewModel
        {
            Heading = currentBlock.Heading,
            TrendingArticles = trendingArticles
        };
        return PartialView(viewModel);
    }

}

ProfileStoreHelper.cs

public class ProfileStoreHelper
{
    //Settings
    private string _apiRootUrl = ConfigurationManager.AppSettings["episerver:profiles.ProfileApiBaseUrl"];
    private string _appKey = ConfigurationManager.AppSettings["episerver:profiles.ProfileApiSubscriptionKey"];
    private string _eventUrl = "/api/v2.0/TrackEvents/preview";
    private string _scope = ConfigurationManager.AppSettings["episerver:profiles.Scope"] ?? SiteDefinition.Current.Id.ToString();

    private IContentLoader _contentLoader;
    private IContentTypeRepository _contentTypeRepository;

    public ProfileStoreHelper(IContentTypeRepository contentTypeRepository = null, IContentLoader contentLoader = null)
    {
        _contentTypeRepository = contentTypeRepository ?? ServiceLocator.Current.GetInstance<IContentTypeRepository>();
        _contentLoader = contentLoader ?? ServiceLocator.Current.GetInstance<IContentLoader>();
    }

    /// <summary>
    /// Get pages of a given type
    /// </summary>
    public IEnumerable<T> GetPopularPages<T>(ContentReference ancestor, string lang, int resultCount = 5, int recentHours = 24) where T : PageData
    {
        var contentTypeId = _contentTypeRepository.Load<T>().ID;
        var ancestorGuid = _contentLoader.Get<IContent>(ancestor).ContentGuid;
        var hits = GetRecentContentResponse(ancestorGuid, lang, resultCount, recentHours, contentTypeId);
        return hits?.Items?.Select(x => _contentLoader.Get<T>(x.Value)) ?? Enumerable.Empty<T>();
    }

    /// <summary>
    /// Get all popular content regardless of type
    /// </summary>
    public IEnumerable<IContent> GetPopularPages(ContentReference ancestor, string lang, int resultCount = 5, int recentHours = 24)
    {
        var ancestorGuid = _contentLoader.Get<IContent>(ancestor).ContentGuid;
        var hits = GetRecentContentResponse(ancestorGuid, lang, resultCount, recentHours);
        return hits?.Items?.Select(x => _contentLoader.Get<IContent>(x.Value)) ?? Enumerable.Empty<IContent>();
    }

    /// <summary>
    /// Make request to profile store API
    /// </summary>
    private RecentContentResponse GetRecentContentResponse(Guid ancestorGuid, string lang, int resultCount = 5, int recentHours = 24, int typeId = 0)
    {
        var requestBody = $"{{\"Query\": \"{GenerateKQLQuery(ancestorGuid, lang, resultCount, recentHours, typeId)}\", \"Scope\": \"{_scope}\" }}";
        var req = new RestRequest(_eventUrl, Method.POST);
        req.AddHeader("Authorization", $"epi-single {_appKey}");
        req.AddParameter("application/json-patch+json", requestBody, ParameterType.RequestBody);
        req.RequestFormat = DataFormat.Json;
        req.AddBody(requestBody);
        var client = new RestClient(_apiRootUrl);
        var getEventResponse = client.Execute(req);
        return JsonConvert.DeserializeObject<RecentContentResponse>(getEventResponse.Content);
    }

    /// <summary>
    /// Construct KQL query
    /// </summary>
    private string GenerateKQLQuery(Guid ancestorGuid, string lang, int resultCount = 5, int recentHours = 24, int typeId = 0)
    {
        var kqlQueryObj = @"Events 
            | where EventTime between(ago({0}h) .. now()) 
                and EventType == 'epiPageView' 
                and Payload.epi.language == '{1}' 
                and Payload.epi.ancestors contains('{2}') 
                {3}
            | summarize Count = count() by Value = tostring(Payload.epi.contentGuid)
            | top {4} by Count desc";
        //Only add type restriction if a type has been specified
        var typeQuery = typeId > 0 ? $"and Payload.epi.typeId == {typeId}" : string.Empty;
        return string.Format(kqlQueryObj, recentHours, lang, ancestorGuid.ToString(), typeQuery, resultCount);
    }
}

public class RecentContentResponse
{
    public int Count { get; set; }
    public RecentContentResponseItem[] Items { get; set; }
}

public class RecentContentResponseItem
{
    public Guid Value { get; set; }
}