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

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

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

        public class State
        {
            public int StartIdx;
            public string Search;
        }

        /// <summary>
        /// Could be use with dict/startIdKey for use on different pages
        /// </summary>
        private static State CurrentState = new State();



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

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

        [Inject]
        private HttpClient Http { get; set; }

        [Inject]
        private IJSRuntime JSRuntime { get; set; }

        private string errorMsg { get; set; }
        private string dispMode { get; set; }

        private string PageInfo
        {
            get
            {
                var res = $"{StartIdx + 1}-{StartIdx + 0 + pageSize} ";
                if (totalPostsFound != null)
                {
                    if (totalPostsFound == 1)
                    {
                        res += $"(of 1)";
                    }
                    else if (totalPostsFound > 1)
                    {
                        res += $"(of {totalPostsFound})";
                    }
                }
                return res;
            }
        }

        private ElementReference ScrollAnchorElement;

        private string SearchText { get; set; }

        private int StartIdx
        {
            get
            {
                return startIdx;
            }
            set
            {
                startIdx = value;
                OnStartIdxChanged();
            }
        }
        private int startIdx = 0;

        private int pageSize = 6;

        private int pageMaxSize = 6;

        private int? totalPostsFound = null;

        private List<BlogPostHeader> selectedPosts = new List<BlogPostHeader>();


        public void Dispose()
        {
            BlogDb.BlogPostsChanged -= BlogDb_BlogPostsChanged;

        }


        public async void StartSearch(string searchString)
        {
            System.Diagnostics.Debug.WriteLine($"Got searchstring {searchString}");
            SearchText = searchString;
            //            await SelectPosts();
            //            StateHasChanged();
            UpdateSearch();
        }

        protected override async Task OnInitializedAsync()
        {

            StartIdx = CurrentState.StartIdx;
            SearchText = CurrentState.Search;

            BlogDb.BlogPostsChanged += BlogDb_BlogPostsChanged;

            await SelectPosts();
        }

        private async void BlogDb_BlogPostsChanged(object sender, EventArgs e)
        {
            await SelectPosts();
            this.StateHasChanged();
        }

        private void GotoFirst()
        {
            System.Diagnostics.Debug.WriteLine("Goto first");
            StartIdx = 0;
        }

        private void GotoNext()
        {
            StartIdx += pageMaxSize;
        }

        private void GotoPrev()
        {
            StartIdx -= pageMaxSize;
        }


        private async void ClearSearch()
        {
            errorMsg = null;
            SearchText = "";
            startIdx = 0;
            totalPostsFound = null;
            await SelectPosts();
            StateHasChanged();
            CurrentState.StartIdx = StartIdx;
            CurrentState.Search = "";
        }

        private async void UpdateSearch()
        {
            errorMsg = null;
            startIdx = 0;
            totalPostsFound = null;
            await SelectPosts();
            StateHasChanged();
            CurrentState.StartIdx = StartIdx;
            CurrentState.Search = SearchText;
            _ =  JSRuntime.InvokeVoidAsync("scrollElmIntoView", ScrollAnchorElement);
        }


        private async void OnStartIdxChanged()
        {
            if (startIdx < 0) startIdx = 0;
            await SelectPosts();
            if (selectedPosts.Count == 0 && startIdx > 0)
            {
                // Too far, go back one page
                StartIdx -= pageMaxSize;
                await SelectPosts();

                // Bad input? instruct DB to find last page
                if (selectedPosts.Count == 0 && startIdx > 0)
                {
                    await SelectPosts(true);
                }
            }
            StateHasChanged();
            CurrentState.StartIdx = StartIdx;
        }




        private async Task SelectPosts(bool findLastPage = false)
        {

            bool fulltextIsLocallyAvail = await BlogDb.IsEagerLoading();
            bool isOnline = NetworkStatus.IsOnline;

            var bps = new BlogPostSearch(() => BlogDb.GetCachedPostsAsync(), () => BlogDb.GetHeadersAsync(), SearchText);

            if (!bps.IsNonEmptyTerm)
            {
                dispMode = "Last posts";
            }
            else
            {
                // Brutal fulltext search.. Should be good for the first 100 articles or so...
                dispMode = "Search";
            }

            if (!bps.IsNonEmptyTerm)
            {
                var res = await bps.ExecAsync(startIdx, pageMaxSize, findLastPage);
                pageSize = res.Count;
                totalPostsFound = await BlogDb.GetHeadersAsync()
                    .Where(a => "PUBLIC".Equals(a.Access))
                    .Where(p => (p.StickyMenuPos ?? -1) < 0)
                    .CountAsync();

                selectedPosts = res;
            }
            else
            {
                bool needsFullText = bps.RequiresFullText;
             
                if (!fulltextIsLocallyAvail && needsFullText)
                {
                    if (!isOnline)
                    {
                        errorMsg = "Offline, search not possible";
                        return;
                    }
                    else
                    {
                        try
                        {
                            var url = $"/BlogPosts/search?searchTerm={System.Net.WebUtility.UrlEncode(SearchText)}&startIdx={startIdx}&pageMaxSize={pageMaxSize}&findLastPage={findLastPage}";
                            var ids = await Http.GetJsonAsync<List<String>>(url);
                            var res = new List<BlogPostHeader>();
                            foreach (var id in ids)
                            {
                                var bp = await BlogDb.GetHeaderAsync(id);
                                if (bp != null)
                                {
                                    res.Add(bp);
                                }
                                await Task.Yield();
                            }
                            pageSize = res.Count;
                            selectedPosts = res;
                        }
                        catch (Exception ex)
                        {
                            System.Diagnostics.Debug.WriteLine($"Exception during search: {ex}");
                            errorMsg = $"Error during search: {ex.Message}";
                        }
                    }
                }
                else
                {
                    var efetch = BlogDb.GetCachedPostsAsync();
                    var res = await bps.ExecAsync(startIdx, pageMaxSize, findLastPage);
                    pageSize = res.Count;
                    selectedPosts = res;
                }
            }
        }
    }
}