inabox/InABox.Mobile/InABox.Mobile.Shared/Components/MobileGrid/MobileGridColumn.cs

using System;
using System.Globalization;
using System.Linq.Expressions;
using Syncfusion.SfDataGrid.XForms;
using Syncfusion.SfDataGrid.XForms.DataPager;
using Xamarin.Forms;
using XF.Material.Forms.Resources.Typography;
using XF.Material.Forms.UI;

namespace InABox.Mobile
{
    
    public abstract class MobileGridColumn<TEntity, TType> : IMobileGridColumn
    {
        
        public MobileGridColumn()
        {
            Alignment = TextAlignment.Center;
            Width = GridLength.Star;
        }
        

        public Expression<Func<TEntity,TType>> Column { get; set; }

        // This should come from CoreUtils
        public String ColumnName => Column?.ToString().Replace(" ","").Replace("x=>x.","") ?? "";
        
        public GridLength Width { get; set; }
        
        public String Caption { get; set; }
        
        public TextAlignment Alignment { get; set; }
        
        public Action<IMobileGridColumn, object> Tapped { get; set; }
        
        public abstract GridColumn CreateColumn();

        protected virtual View HeaderContent()
        {
            var label = new Label()
            {
                Text = String.IsNullOrWhiteSpace(Caption) 
                    ? ColumnName
                    : Caption,
                Margin = new Thickness(2,0),
                FontSize = Device.GetNamedSize(NamedSize.Micro, typeof(Label)),
                VerticalTextAlignment = TextAlignment.Center,
                HorizontalTextAlignment = Alignment,
            };
            return label;
        }

        private class MobileGridColumnConverter : IValueConverter
        {

            private Func<object,object> OnFormatValue;

            public MobileGridColumnConverter(Func<object,object> onformatvalue)
            {
                OnFormatValue = onformatvalue;
            }
            
            public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
            {
                return OnFormatValue?.Invoke(value);
            }

            public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
            {
                throw new NotImplementedException();
            }
        }
        
        public TColumn CreateColumn<TColumn>() where TColumn : GridColumn, new()
        {
            var result = new TColumn();
            
            result.MappingName = ColumnName;
            result.DisplayBinding =
                new Binding(ColumnName, BindingMode.OneWay, new MobileGridColumnConverter(FormatValue));
            
            if (Width.IsStar)
                result.ColumnSizer = ColumnSizer.Star;
            else if (Width.IsAuto)
                result.ColumnSizer = ColumnSizer.Auto;
            else
            {
                result.ColumnSizer = ColumnSizer.None;
                result.Width = Width.Value;
            }

            result.TextAlignment = Alignment;
            
            result.HeaderTextAlignment = Alignment;
            result.HeaderText = Caption;
            result.Padding = 0;
            result.CellTextSize = Device.GetNamedSize(NamedSize.Micro, typeof(Label));
            
            result.HeaderTemplate = new DataTemplate(() =>
            {
                var layout = new Grid()
                {
                    VerticalOptions = LayoutOptions.Fill,
                    RowSpacing = 0,
                    ColumnSpacing = 0
                };
                
                layout.RowDefinitions.Add(new RowDefinition() { Height = GridLength.Star });
                layout.RowDefinitions.Add(new RowDefinition() { Height = 1 });
                
                var content = HeaderContent();
                content.SetValue(Grid.RowProperty,0);
                layout.Children.Add(content);
                
                var box = new BoxView()
                {
                    HeightRequest = 1, 
                    BackgroundColor = Color.LightGray,
                    Margin = 0
                };
                box.SetValue(Grid.RowProperty,1);
                layout.Children.Add(box);
                
                return layout;
            });

            return result;

        }

        protected virtual object FormatValue(object value)
        {
            return value;
        }
    }
}