prs/prs.mobile.new/PRS.Mobile/CustomControls/Selection Screens/GenericSelectionPage.xaml.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Linq.Expressions;
using InABox.Clients;
using InABox.Core;
using InABox.Mobile;
using Xamarin.Forms;
using XF.Material.Forms.UI;
using XF.Material.Forms.UI.Dialogs;

namespace PRS.Mobile
{

    public class SelectionViewModelImageHeightConverter : AbstractConverter<ImageSource, int>
    {
        public int Value { get; set; }
        
        protected override int Convert(ImageSource value, object? parameter = null)
        {
            return value != null ? Value : 0;
        }
    }
    
    public class ItemSelectedEventArgs : EventArgs
    {
        public CoreRow Row { get; private set; }
        public String Formatted { get; private set; }

        public ItemSelectedEventArgs(CoreRow row, String formatted)
        {
            Row = row;
            Formatted = formatted;
        }
    }
    
    public delegate void ItemSelectedEvent(object sender, ItemSelectedEventArgs args);

    public interface ISelectionViewModel
    {
        SelectionViewModelItem[] Load();
        IFilter? Filter { get; set; }
        IColumns VisibleColumns { get; set; }
        Type Type { get; }
    }

    public class SelectionViewModelItem
    {
        public String Display { get; set; }
        public CoreRow Row { get; set; }
        public ImageSource Image { get; set; }
    }

    public class SelectionViewModel<T> : ISelectionViewModel where T : Entity, IRemotable, IPersistent, new()
    {
        
        public Type Type => typeof(T);
        
        public IFilter? Filter { get; set; }
        
        public IColumns VisibleColumns { get; set; }
        
        public IColumns HiddenColumns { get; set; }
        
        public ISortOrder? Sort { get; set; }

        public Func<CoreRow, string>? Format { get; set; }

        private Column<T>? ImageColumn()
        {
            var columns = new Columns<T>(ColumnTypeFlags.None).Add(x => x.ID);
            foreach (var column in VisibleColumns)
                columns.Add(column);
            foreach (var column in HiddenColumns)
                columns.Add(column);
            foreach (var column in columns)
            {
                var prop = CoreUtils.GetProperty<T>(column.Property);
                var editor = EditorUtils.GetEditor(prop.PropertyType);
                if (editor is ImageDocumentEditor)
                    return column;
            }
            return null;
        }
        
        public SelectionViewModel(Filter<T>? filter, Expression<Func<T, object>>[] visible, Expression<Func<T, object>>[]? hidden = null, SortOrder<T>? sort = null, Func<CoreRow, string>? format = null)
        {
            Filter = filter;
            
            VisibleColumns = new Columns<T>(ColumnTypeFlags.None);
            foreach (var visiblecolumn in visible)
                VisibleColumns.Add(visiblecolumn);
            
            HiddenColumns = new Columns<T>(ColumnTypeFlags.None);
            if (hidden != null)
            {
                foreach (var hiddencolumn in hidden)
                    HiddenColumns.Add(hiddencolumn);
            }

            Sort = sort;
            
            Format = format;
        }

        public SelectionViewModel()
        {
            Filter = LookupFactory.DefineFilter<T>();
            VisibleColumns = new Columns<T>(ColumnTypeFlags.None);
            HiddenColumns = new Columns<T>(ColumnTypeFlags.None);

            var columns = LookupFactory.DefineColumns<T>();
            foreach (var column in columns)
            {
                var editor = EditorUtils.GetEditor(CoreUtils.GetProperty(typeof(T), column.Property).PropertyType);
                if (editor?.Visible != Visible.Default)
                    VisibleColumns.Add(column);
                else
                    HiddenColumns.Add(column);
            }
            
            Sort = LookupFactory.DefineSort<T>();

            Format = row => LookupFactory.FormatLookup<T>(row.ToDictionary(), new[] { "ID" });
            
        }
        
        public SelectionViewModelItem[] Load()
        {
            var filter = Filter as Filter<T>;
            var sort = Sort as SortOrder<T>;
            
            var columns = new Columns<T>(ColumnTypeFlags.None).Add(x=>x.ID);
            foreach (var column in VisibleColumns)
                columns.Add(column);
            foreach (var column in HiddenColumns)
                columns.Add(column);
            
            MultiQuery query = new MultiQuery();
            
            query.Add<T>(filter,columns,sort);

            var imgcol = ImageColumn();
            if (imgcol != null)
                query.Add(new Filter<Document>(x => x.ID).InQuery<T>(new SubQuery<T>(filter, imgcol)));

            query.Query();
            
            var data = query.Get<T>();
            
            var docs = query.Contains<Document>()
                ? query.Get<Document>().ToDictionary<Document, Guid, byte[]>(x => x.ID, x => x.Data)
                : new Dictionary<Guid, byte[]>() { };

            List<SelectionViewModelItem> items = new List<SelectionViewModelItem>();
            
            foreach (var row in data.Rows)
            {
                String display = Format != null
                     ? Format(row)
                     : String.Join(" : ", VisibleColumns.ColumnNames().Select(x => row[x]).ToArray());
                ImageSource img = (imgcol != null) && (docs.TryGetValue(row.Get<Guid>(imgcol.Property), out byte[] imgdata))
                    ? ImageSource.FromStream(() => new MemoryStream(imgdata))
                    : null;
                items.Add(new SelectionViewModelItem()
                {
                    Display = display, Row = row, Image = img
                });
            }
            return items.ToArray();
        }
        
    }


    public partial class GenericSelectionPage  
    {

        public event ItemSelectedEvent OnItemSelected;

        private ISelectionViewModel _model;

        private SelectionViewModelItem[] _items = { };

        public bool AutoClose { get; set; } = true;

        public GenericSelectionPage(String title, ISelectionViewModel model)
        {
            _model = model;
            InitializeComponent();
            Title = title;
        }

        bool bFirst = true;

        protected override async void OnAppearing()
        {
            base.OnAppearing();

            if (bFirst)
            {
                bFirst = false;
                var progress = await MaterialDialog.Instance.LoadingDialogAsync(message: "Loading Data");

                _items = _model.Load();
                
                _list.ItemsSource = _items;

                await progress.DismissAsync();
            }
        }

        void Item_Selected(Object sender, SelectedItemChangedEventArgs e)
        {
            if (e.SelectedItem == null)
                return;
            SelectionViewModelItem selected = e.SelectedItem as SelectionViewModelItem;
            OnItemSelected?.Invoke(this, new ItemSelectedEventArgs(selected.Row, selected.Display));
            if (AutoClose)
                Navigation.PopAsync();
        }
        
        private void MobileSearchBar_OnTextChanged(object sender, MobileSearchBarTextChangedArgs args)
        {
            _list.ItemsSource = null;
            _list.ItemsSource = String.IsNullOrWhiteSpace(args.Text) 
                ? _items 
                : _items.Where(x => x.Display.ToUpper().Contains(args.Text.ToUpper()));
        }
    }
}