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

namespace comal.timesheets
{
    public delegate void ItemSelectedEvent(CoreRow row);

    public interface ISelectionViewModel
    {
        Dictionary<String,CoreRow> Load();
    }

    public class SelectionViewModel<T> : ISelectionViewModel where T : Entity, IRemotable, IPersistent, new()
    {
        private Filter<T> _filter = null;

        private Expression<Func<T, object>>[] _visible = null;

        private Expression<Func<T, object>>[] _hidden = null;

        private SortOrder<T> _sort = 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;
            _visible = visible;
            _hidden = hidden == null ? new Expression<Func<T, object>>[] { } : hidden;
            _sort = sort;
            _format = format;
        }

        private Func<CoreRow, String> _format = null;

        public Dictionary<String, CoreRow> Load()
        {
            var columns = new Columns<T>(x=>x.ID);
            foreach (var column in _visible)
                columns.Add(column);
            foreach (var column in _hidden)
                columns.Add(column);

            var data = new Client<T>().Query(
                _filter,
                columns,
                _sort
            );

            Dictionary<String, CoreRow> result = new Dictionary<string, CoreRow>();
            foreach (var row in data.Rows)
            {

                if (_format != null)
                    result[_format(row)] = row;
                else
                {
                    List<object> display = new List<object>();
                    foreach (var visible in _visible)
                        display.Add(row.Get<T, object>(visible));
                    result[String.Join(" : ", display)] = row;
                }
                
            }
            return result;
        }


    }


    public partial class GenericSelectionPage  
    {

        public event ItemSelectedEvent OnItemSelected;

        private ISelectionViewModel _model = null;

        private Dictionary<String, CoreRow> _items = new Dictionary<String, CoreRow>();

        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();

                Items.ItemsSource = _items;

                await progress.DismissAsync();
            }
        }

        void Item_Selected(System.Object sender, Xamarin.Forms.SelectedItemChangedEventArgs e)
        {
            if (e.SelectedItem == null)
                return;
            KeyValuePair<string, CoreRow> selected = (KeyValuePair<string, CoreRow>)e.SelectedItem;
            OnItemSelected?.Invoke(selected.Value);
            if (AutoClose)
                Navigation.PopAsync();
        }

        void MaterialTextField_TextChanged(System.Object sender, Xamarin.Forms.TextChangedEventArgs e)
        {
            MaterialTextField field = sender as MaterialTextField;
            Items.ItemsSource = null;
            if (String.IsNullOrWhiteSpace(field.Text))
                Items.ItemsSource = _items;
            else
                Items.ItemsSource = new Dictionary<String,CoreRow>(_items.Where(x => x.Key.ToUpper().Contains(field.Text.ToUpper())));
        }
    }
}