using MultiTerm.Core.ViewModel;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Linq;
using System.Collections.Specialized;
using System.Collections.ObjectModel;
using System.Diagnostics;

namespace MultiTerm.Wpf.CustomControl;

public class MultiFormatDataView : Control
{
    private static readonly Dictionary<StackPanel, MultiFormatDataView> itemParentPairs = new();
    private const string itemsControlTemplateName = "PART_ItemsControl";
    private const string itemsTextBoxTemplateName = "PART_ItemsTextBox";
    private const string buttonClearTemplateName = "PART_ButtonClear";
    private const string realizedItemsCountTemplateName = "PART_RealizedItemsCountDisplay";
    private const string selectedAbsoluteTimeTextBlockTemplateName = "PART_SelectedAbsoluteTimeTextBlock";
    private const string selectedTimediffTextBlockTemplateName = "PART_SelectedTimediffTextBlock";
    private ListBox? itemsControl;
    private ICollectionView? collectionView;
    private TextBox? itemsTextBox;
    private TextBlock? selectedAbsoluteTimeTextBlock;
    private TextBlock? selectedTimediffTextBlock;

    #region Dependency Properties
    public static readonly DependencyProperty DataSourceProperty =
        DependencyProperty.Register("DataSource",
        typeof(MultiFormatDataViewModel), typeof(MultiFormatDataView),
        new PropertyMetadata(null, OnDataSourcePropertyChanged));

    public static readonly DependencyProperty IsTimeDisplayedProperty =
        DependencyProperty.Register("IsTimeDisplayed",
        typeof(bool), typeof(MultiFormatDataView),
        new PropertyMetadata(false));

    public static readonly DependencyProperty RealizedItemsCountProperty =
        DependencyProperty.Register("RealizedItemsCount",
        typeof(uint), typeof(MultiFormatDataView),
        new PropertyMetadata((uint)0, OnRealizedItemsCountChanged));

    public static readonly DependencyProperty ItemLoadedProperty =
        DependencyProperty.RegisterAttached("ItemLoaded",
        typeof(bool),
        typeof(MultiFormatDataView),
        new UIPropertyMetadata(false, OnItemLoaded));

    public static readonly DependencyProperty ItemUnloadedProperty =
        DependencyProperty.RegisterAttached("ItemUnloaded",
        typeof(bool),
        typeof(MultiFormatDataView),
        new UIPropertyMetadata(false, OnItemUnloaded));

    public static readonly RoutedEvent ClearRequestedEvent;


    /// <summary>
    /// .NET Property for <see cref="DataSourceProperty"/>.
    /// </summary>
    [Bindable(true)]
    public MultiFormatDataViewModel DataSource
    {
        get { return (MultiFormatDataViewModel)GetValue(DataSourceProperty); }
        set { SetValue(DataSourceProperty, value); }
    }

    /// <summary>
    /// .NET Property for <see cref="IsTimeDisplayedProperty"/>.
    /// </summary>
    [Bindable(true)]
    public bool IsTimeDisplayed
    {
        get { return (bool)GetValue(IsTimeDisplayedProperty); }
        set { SetValue(IsTimeDisplayedProperty, value); }
    }

    /// <summary>
    /// .NET Property for <see cref="RealizedItemsCountProperty"/>.
    /// </summary>
    [Bindable(true)]
    public uint RealizedItemsCount
    {
        get { return (uint)GetValue(RealizedItemsCountProperty); }
        set { SetValue(RealizedItemsCountProperty, value); }
    }

    /// <summary>
    /// .NET Property for <see cref="ItemLoadedProperty"/>.
    /// </summary>
    public bool ItemLoaded
    {
        get { return (bool)GetValue(ItemLoadedProperty); }
        set { SetValue(ItemLoadedProperty, value); }
    }

    /// <summary>
    /// .NET Property for <see cref="RealizedItemsCountProperty"/>.
    /// </summary>
    public bool ItemUnloaded
    {
        get { return (bool)GetValue(ItemUnloadedProperty); }
        set { SetValue(ItemUnloadedProperty, value); }
    }

    /// <summary>
    /// .NET Property for <see cref="ClearRequestedEvent"/>
    /// </summary>
    public event RoutedEventHandler ClearRequested
    {
        add { this.AddHandler(ClearRequestedEvent, value); }
        remove { this.RemoveHandler(ClearRequestedEvent, value); }
    }
    #endregion

    static MultiFormatDataView()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(MultiFormatDataView), new FrameworkPropertyMetadata(typeof(MultiFormatDataView)));

        ClearRequestedEvent = EventManager.RegisterRoutedEvent("ClearRequested",
            RoutingStrategy.Bubble, typeof(RoutedEventArgs),
            typeof(MultiFormatDataView));
    }

    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();

        // get itemsControl from template
        if (GetTemplateChild(itemsControlTemplateName) is ListBox listBox)
        {
            this.itemsControl = listBox;
            this.itemsControl.SelectionChanged += ItemsControl_SelectionChanged;
        }
        else
        {
            throw new Exception($"Implementation fault, {itemsControlTemplateName} not found in template.");
        }

        // get itemsTextBox from template
        if (GetTemplateChild(itemsTextBoxTemplateName) is TextBox tb)
        {
            this.itemsTextBox = tb;
            this.itemsTextBox.SelectionChanged += TextBoxCharOnlyView_SelectionChanged;
            this.itemsTextBox.TextChanged += TextBoxCharOnlyView_TextChanged;
        }
        else
        {
            throw new Exception($"Implementation fault, {itemsTextBoxTemplateName} not found in template.");
        }

        // register to button event
        if (GetTemplateChild(buttonClearTemplateName) is Button button)
        {
            button.Click += OnClearButtonClicked; ;
        }

        // hide realized items count when not debugging
        if (Debugger.IsAttached == false)
        {
            if (GetTemplateChild(realizedItemsCountTemplateName) is UIElement realizedItemsUiElement)
            {
                realizedItemsUiElement.Visibility = Visibility.Hidden;
            }
        }

        // get time textblocks
        if (GetTemplateChild(selectedAbsoluteTimeTextBlockTemplateName) is TextBlock satTb)
        {
            this.selectedAbsoluteTimeTextBlock = satTb;
        }
        if (GetTemplateChild(selectedTimediffTextBlockTemplateName) is TextBlock stdTb)
        {
            this.selectedTimediffTextBlock = stdTb;
        }
    }

    private static void OnDataSourcePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // extract instance and guard null
        if (d is not MultiFormatDataView mfdv) { return; }
        // guard DataSource is null
        if (mfdv.DataSource == null) { return; }

        // manually create collection view
        ICollectionView cv = CollectionViewSource.GetDefaultView(mfdv.DataSource.Data);
        // add grouping 
        PropertyGroupDescription groupDescription = new(nameof(ByteDataViewModel.LineIdentifier));
        cv.GroupDescriptions.Add(groupDescription);
        // add live grouping
        if (cv is ICollectionViewLiveShaping cvLiveShaping && cvLiveShaping.CanChangeLiveGrouping)
        {
            cvLiveShaping.LiveGroupingProperties.Add(nameof(ByteDataViewModel.LineIdentifier));
            cvLiveShaping.IsLiveGrouping = true;
        }
        // save collection view
        mfdv.collectionView = cv;
        // apply collection view as itemssource
        mfdv.itemsControl!.ItemsSource = cv;

        // register to collection changed event
        if (mfdv.DataSource.Data is INotifyCollectionChanged incc)
        {
            incc.CollectionChanged += mfdv.Data_CollectionChanged;
        }

        // create bindings
        CreateTemplateBinding($"{nameof(mfdv.DataSource)}.{nameof(mfdv.DataSource.DataAsString)}", mfdv.itemsTextBox, TextBox.TextProperty);
        CreateTemplateBinding($"{nameof(mfdv.DataSource)}.{nameof(mfdv.DataSource.SelectedDataFirstAbsoluteTime)}", mfdv.selectedAbsoluteTimeTextBlock, TextBlock.TextProperty);
        CreateTemplateBinding($"{nameof(mfdv.DataSource)}.{nameof(mfdv.DataSource.SelectedDataTimediff)}", mfdv.selectedTimediffTextBlock, TextBlock.TextProperty);
    }

    private void Data_CollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
    {
        // TEMP scroll to added item if not null
        //if (e.Action == NotifyCollectionChangedAction.Add && e.NewItems != null && e.NewItems[0] != null)
        //{
        //    this.itemsControl!.ScrollIntoView(e.NewItems[0]);
        //}
    }

    private void OnClearButtonClicked(object sender, RoutedEventArgs e)
    {
        // raise clear requested event
        RoutedEventArgs args = new(ClearRequestedEvent);
        RaiseEvent(args);
    }

    #region Selected Items handling
    private void ItemsControl_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        // get sender as listbox
        if(e.OriginalSource is not ListBox senderListBox) { throw new ArgumentException($"{nameof(ItemsControl_SelectionChanged)} got non expected type as sender {sender}"); }

        // if there is something selected in the textbox => clear selection first
        if (this.itemsTextBox != null && this.itemsTextBox.SelectionLength > 0) { this.itemsTextBox.Select(0, 0); }

        // get selected items from list box
        var selectedItems = senderListBox.SelectedItems.OfType<ByteDataViewModel>().ToList();

        // sort items according to time (uses IComparable of ByteDataViewModel)
        // wpf does some odd sorting. described here: https://stackoverflow.com/questions/50155415/wpf-listview-selecteditems-returns-wrong-item-order-if-you-shift-select-from-b
        // sorting the items by ticks provides a solution in this case
        selectedItems.Sort();

        // genereate new observable collection
        this.DataSource.Selected = new ObservableCollection<ByteDataViewModel>(selectedItems);
    }

    private void TextBoxCharOnlyView_SelectionChanged(object sender, RoutedEventArgs e)
    {
        var newSelection = new ObservableCollection<ByteDataViewModel>();
        int selectionStartIndex = this.itemsTextBox!.SelectionStart;
        // extract text from the beginning to the start of the selected text
        var textFromBeginningToStartOfSelection = this.itemsTextBox!.Text.Substring(0, selectionStartIndex);
        // count amount of manually introduced newline sequences in this text section (these to not exist in the data source!)
        var foundManuallyIntroducedNewlineSequenceCharacters = 0;
        var foundAmountOfLines = textFromBeginningToStartOfSelection.Split(MultiFormatDataViewModel.NewlineSequence).Length;
        // any newline sequences introduced (more than one lines found)
        if (foundAmountOfLines > 1)
        {
            // calculated amount of characters that were introduced
            foundManuallyIntroducedNewlineSequenceCharacters = (foundAmountOfLines - 1) * MultiFormatDataViewModel.NewlineSequence.Length;
        }

        // iterate through length of selection
        for (int i = 0; i < this.itemsTextBox!.SelectionLength; i++)
        {
            // subtracting the counted newline sequences and adding i (length)
            int elementPositionInCollection = selectionStartIndex - foundManuallyIntroducedNewlineSequenceCharacters + i;
            // add element to new selection list
            newSelection.Add(this.DataSource.Data.ElementAt(elementPositionInCollection));
            // next item does not exist => break loop
            if(this.DataSource.Data.ElementAtOrDefault(elementPositionInCollection + 1) == null)
            {
                break;
            }
        }

        // update property
        this.DataSource.Selected = newSelection;
    }

    private void TextBoxCharOnlyView_TextChanged(object sender, TextChangedEventArgs e)
    {
        this.itemsTextBox?.ScrollToEnd();
    }
    #endregion

    #region Realized Item Count
    private static void OnRealizedItemsCountChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // NOP
    }

    private static void OnItemLoaded(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // extract instance and guard null
        if (d is not StackPanel stackPanel) { return; }

        // check if value was set to true
        if (e.NewValue is bool boolean && boolean == true)
        {
            // find visual parent of correct type, throw exception if not found
            var parentMFDV = UIHelper.FindVisualParent<MultiFormatDataView>(stackPanel) ?? 
                throw new NullReferenceException($"Could not find parent of type " +
                    $"{nameof(MultiFormatDataView)} in {nameof(stackPanel)}");

            // add to static dictionary
            itemParentPairs.Add(stackPanel, parentMFDV);
            // increment counter
            parentMFDV.RealizedItemsCount++;
        }
    }

    private static void OnItemUnloaded(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // extract instance and guard null
        if (d is not StackPanel stackPanel) { return; }

        // check if value was set to true
        if (e.NewValue is bool boolean && boolean == true)
        {
            // get parent from static dictionary
            var parentMFDV = itemParentPairs[stackPanel];
            // remove the element from the dictionary
            itemParentPairs.Remove(stackPanel);
            // decrement counter
            parentMFDV.RealizedItemsCount--;
        }
    }
    #endregion

    #region Helpers
    private static void CreateTemplateBinding(string propertyPath, DependencyObject? dependencyObject, DependencyProperty dependencyProperty)
    {
        // ignore when dependency object is null
        if(dependencyObject == null) { return; }

        // create
        var binding = new Binding()
        {
            RelativeSource = new RelativeSource(RelativeSourceMode.TemplatedParent),
            Path = new PropertyPath(propertyPath)
        };

        // bind
        BindingOperations.SetBinding(dependencyObject, dependencyProperty, binding);
    }

    #endregion
}