using InABox.Clients;
using InABox.Core;
using InABox.WPF;
using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Drawing;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;

namespace InABox.DynamicGrid;

public class DynamicGridClientDataComponent<T> : IDynamicGridDataComponent<T>
    where T : Entity, IRemotable, IPersistent, new()
{
    private readonly int ChunkSize = 500;

    public DynamicGrid<T> Grid { get; set; }

    public delegate void OnReloadEventHandler(object sender, Filters<T> criteria, Columns<T> columns, ref SortOrder<T>? sortby);
    
    public event OnReloadEventHandler? OnReload;

    public Column<T>[] FilterColumns;

    public DynamicGridClientDataComponent(DynamicGrid<T> grid)
    {
        Grid = grid;

        Grid.BeforeRefresh += Grid_BeforeRefresh;
        Grid.AfterRefresh += Grid_AfterRefresh;

        SetupFilterColumns();
    }

    [MemberNotNull(nameof(FilterColumns))]
    private void SetupFilterColumns()
    {
        if (typeof(T).GetCustomAttribute<AutoEntity>() is AutoEntity auto)
        {
            if (auto.Generator is not null)
            {
                var columns = auto.Generator.IDColumns;
                FilterColumns = columns.Select(x => new Column<T>(x.Property)).ToArray();
            }
            else
            {
                FilterColumns = Array.Empty<Column<T>>();
            }
        }
        else
        {
            FilterColumns = new[] { new Column<T>(x => x.ID) };
        }

        foreach (var column in FilterColumns)
        {
            Grid.AddHiddenColumn(column.Property);
        }
    }

    private CoreRow[]? SelectedBeforeRefresh;

    private void Grid_BeforeRefresh(object sender, BeforeRefreshEventArgs args)
    {
        SelectedBeforeRefresh = Grid.SelectedRows;
    }

    private void Grid_AfterRefresh(object sender, AfterRefreshEventArgs args)
    {
        if (SelectedBeforeRefresh is not null)
        {
            var selectedValues = SelectedBeforeRefresh
                .Select(x => FilterColumns.Select(c => x[c.Property]).ToList())
                .ToList();

            SelectedBeforeRefresh = null;

            var selectedRows = Grid.Data.Rows.Where(r =>
            {
                return selectedValues.Any(v =>
                {
                    for (int i = 0; i < v.Count; ++i)
                    {
                        if (v[i]?.Equals(r[FilterColumns[i].Property]) != true)
                            return false;
                    }
                    return true;
                });
            }).ToArray();

            Grid.SelectedRows = selectedRows;
            Grid.SelectItems(selectedRows);
        }
    }

    public Columns<T> LoadEditorColumns()
    {
        return DynamicGridUtils.LoadEditorColumns(Grid.DataColumns());
    }

    private Filter<T>? GetRowFilter(CoreRow row)
    {
        var newFilters = new Filters<T>();
        foreach (var column in FilterColumns)
        {
            newFilters.Add(new Filter<T>(column.Property).IsEqualTo(row[column.Property]));
        }
        return newFilters.Combine();
    }

    public void DeleteItems(CoreRow[] rows)
    {
        var deletes = new List<T>();
        foreach (var row in rows)
        {
            var delete = new T();
            foreach (var column in FilterColumns)
            {
                CoreUtils.SetPropertyValue(delete, column.Property, row[column.Property]);
            }

            //var delete = /* row.ToObject<TEntity>(); */ 
            deletes.Add(delete);
        }

        Client.Delete(deletes, "Deleted on User Request");
    }

    public T LoadItem(CoreRow row)
    {
        var id = row.Get<T, Guid>(x => x.ID);
        var filter = GetRowFilter(row);//new Filter<TEntity>(x => x.ID).IsEqualTo(id);
        return Client.Query(filter, LoadEditorColumns()).ToObjects<T>().FirstOrDefault()
            ?? throw new Exception($"No {typeof(T).Name} with ID {id}");
    }

    public T[] LoadItems(CoreRow[] rows)
    {
        Filter<T>? filter = null;
        var results = new List<T>();
        for (var i = 0; i < rows.Length; i += ChunkSize)
        {
            var chunk = rows.Skip(i).Take(ChunkSize);
            foreach (var row in chunk)
            {
                var newFilter = GetRowFilter(row);

                if (newFilter is not null)
                {
                    //var id = row.Get<TEntity, Guid>(x => x.ID);
                    if (filter is null)
                        filter = newFilter;//new Filter<TEntity>(x => x.ID).IsEqualTo(id);
                    else
                        filter = filter.Or(newFilter);//.Or(x => x.ID).IsEqualTo(id);
                }
            }

            var columns = LoadEditorColumns(); // new Columns<TEntity>().Default(ColumnType.IncludeOptional, ColumnType.IncludeForeignKeys, ColumnType.IncludeUserProperties);
            var data = Client.Query(filter, columns);
            results.AddRange(data.ToObjects<T>());
        }

        return results.ToArray();
    }

    public void SaveItem(T item)
    {
        Client.Save(item, "Edited by User");
    }

    public void SaveItems(T[] items)
    {
        Client.Save(items, "Edited by User");
    }

    public void Reload(
        Filters<T> criteria, Columns<T> columns, SortOrder<T>? sort,
        CancellationToken token, Action<QueryResult> action)
    {
        OnReload?.Invoke(this, criteria, columns, ref sort);
        if(Grid.Options.PageSize > 0)
        {
            var inSort = sort;
            Task.Run(() =>
            {
                
                var page = CoreRange.Database(Grid.Options.PageSize);
                var filter = criteria.Combine();
                
                while (!token.IsCancellationRequested)
                {
                    try
                    {
                        var data = Client.Query(filter, columns, inSort, page);
                        data.Offset = page.Offset;

                        if (token.IsCancellationRequested)
                        {
                            break;
                        }

                        var paged = data.Rows.Count == page.Limit;
                        action(new(data, paged));
                        if (!paged)
                            break;
                        
                        // Proposal - Let's slow it down a bit to enhance UI responsiveness?
                        Thread.Sleep(100);
                        
                        page.Next();
                    }
                    catch (Exception e)
                    {
                        action(new(e));
                        break;
                    }
                }
            }, token);
        }
        else
        {
            Client.Query(criteria.Combine(), columns, sort, (data, e) => action(data is not null ? new(data) : new(e!)));
        }
    }
}