blog3000/Blog3000/Client/Shared/TopTopics.razor.cs

using Microsoft.AspNetCore.Components;
using Blog3000.Shared;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Blog3000.Client.Shared
{
    public partial class TopTopics: IDisposable
    {

        [Parameter]
        public EventCallback<string> OnTopicClick { get; set; }


        [Inject]
        private BlogDb BlogDb { get; set; }

        [Inject]
        private Config Config { get; set; }

        public class Topic {
            public string DispId;
            public List<BlogPostHeader> Posts = new List<BlogPostHeader>();
        }

      
        private List<Topic> topics = new List<Topic>();

        public void Dispose()
        {
            BlogDb.BlogPostsChanged -= BlogDb_BlogPostsChanged;
            Config.ConfigChanged -= Config_ConfigChanged;
        }

        protected override async Task OnInitializedAsync()
        {
            topics = await UpdateTopicsAsync();
            BlogDb.BlogPostsChanged += BlogDb_BlogPostsChanged;
            Config.ConfigChanged += Config_ConfigChanged; ;
        }

        
        private async void BlogDb_BlogPostsChanged(object sender, EventArgs e)
        {
            await RefreshAsync();
        }


        private async void Config_ConfigChanged(object sender, EventArgs e)
        {
            await RefreshAsync();
        }


        private async Task RefreshAsync()
        {
            topics = new List<Topic>(); // Clear to force rebuild
            StateHasChanged();
            topics = await UpdateTopicsAsync();
            StateHasChanged();
        }


        private async Task<List<Topic>> UpdateTopicsAsync()
        {
            var dict = new Dictionary<string, Topic>();

            foreach (var bp in await BlogDb.GetHeadersAsync().ToListAsync()) /*FromCachedPosts*/
            {
                if (bp != null && bp.Topics != null)
                {
                    foreach (var t in bp.Topics)
                    {                        
                        foreach (var tt in Config?.Main?.TopTopics ?? new string[] { })
                        {                     
                            if (String.Equals(tt, t))
                            {
                                Topic tp;
                                if (!dict.TryGetValue(t, out tp))
                                {
                                    tp = new Topic();
                                    tp.DispId = t;
                                    dict.Add(tp.DispId, tp);
                                }
                                tp.Posts.Add(bp);
                            }
                        }
                    }
                }
            }

            return new List<Topic>(dict.Values);
        }

    }
}