using MultiTerm.Core.ViewModel;
using System;
using System.Collections;
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 MultiTerm.Protocols.Model;
using System.Collections.ObjectModel;

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 buttonClearTemplateName = "btnClear";
    private const string selectorTemplateName = "comboBoxSelector";
    private const string textBoxCharOnlyViewTemplateName = "PART_CharOnlyTextBox";
    private ListBox? itemsControl;
    private TextBox? tbCharOnlyView;
    private ICollectionView? collectionView;

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

    public static readonly DependencyProperty SelectorItemsSourceProperty =
        DependencyProperty.Register("SelectorItemsSource",
        typeof(IEnumerable), typeof(MultiFormatDataView),
        new PropertyMetadata(null, OnSelectorItemsSourceChanged));

    public static readonly DependencyProperty SelectorSelectedItemProperty =
        DependencyProperty.Register("SelectorSelectedItem",
        typeof(object), typeof(MultiFormatDataView),
        new PropertyMetadata(null, OnSelectorSelectedItemChanged));

    public static readonly DependencyProperty SelectorDescriptionProperty =
        DependencyProperty.Register("SelectorDescription",
        typeof(string), typeof(MultiFormatDataView),
        new PropertyMetadata(string.Empty, OnSelectorDescriptionChanged));

    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 DataSourceProperty.
    /// </summary>
    [Bindable(true)]
    public ICommunicationDataViewModel<ByteDataViewModel, ExtendedByte> DataSource
    {
        get { return (ICommunicationDataViewModel<ByteDataViewModel, ExtendedByte>)GetValue(DataSourceProperty); }
        set { SetValue(DataSourceProperty, value); }
    }

    /// <summary>
    /// .NET Property for SelectorItemsSource.
    /// </summary>
    [Bindable(true)]
    public IEnumerable SelectorItemsSource
    {
        get { return (IEnumerable)GetValue(SelectorItemsSourceProperty); }
        set { SetValue(SelectorItemsSourceProperty, value); }
    }

    /// <summary>
    /// .NET Property for SelectorSelectedItem.
    /// </summary>
    [Bindable(true)]
    public string SelectorSelectedItem
    {
        get { return (string)GetValue(SelectorSelectedItemProperty); }
        set { SetValue(SelectorSelectedItemProperty, value); }
    }

    /// <summary>
    /// .NET Property for SelectorDescription.
    /// </summary>
    [Bindable(true)]
    public string SelectorDescription
    {
        get { return (string)GetValue(SelectorDescriptionProperty); }
        set { SetValue(SelectorDescriptionProperty, value); }
    }

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

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

    /// <summary>
    /// .NET Property for ItemUnloaded.
    /// </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();
        this.Unloaded += MultiFormatDataView_Unloaded;

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

        // get button from template, ignore if it does not exist
        if (GetTemplateChild(buttonClearTemplateName) is Button button)
        {
            button.Click += OnClearButtonClicked; ;
        }
    }

    private static void OnDataSourcePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // extract instance and guard null
        if (d is not MultiFormatDataView mfdv) { 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 binding for textbox (DataAsString)
        var binding = new Binding()
        {
            RelativeSource = new RelativeSource(RelativeSourceMode.TemplatedParent),
            Path = new PropertyPath($"{nameof(mfdv.DataSource)}.{nameof(mfdv.DataSource.DataAsString)}")
        };
        BindingOperations.SetBinding(mfdv.tbCharOnlyView, TextBox.TextProperty, binding);
    }


    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]);
        //}
    }

    /// <summary>
    /// On Unload remove event handler.
    /// </summary>
    private void MultiFormatDataView_Unloaded(object sender, RoutedEventArgs e)
    {
        if (DataSource is INotifyCollectionChanged incc)
        {
            incc.CollectionChanged -= Data_CollectionChanged;
        }
    }

    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)
    {
        // if there are no changes => return
        if (e.AddedItems.Count <= 0 && e.RemovedItems.Count <= 0) { return; }

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

        // otherwise update internal list
        foreach (ByteDataViewModel item in e.RemovedItems)
        {
            this.DataSource.Selected.Remove(item);
        }
        foreach (ByteDataViewModel item in e.AddedItems)
        {
            this.DataSource.Selected.Add(item);
        }
    }

    private void TextBoxCharOnlyView_SelectionChanged(object sender, RoutedEventArgs e)
    {
        var newSelection = new ObservableCollection<ByteDataViewModel>();
        int selectionStartIndex = this.tbCharOnlyView!.SelectionStart;
        // TEMP OLD
        // extract text from the beginning to the start of the selected text
        var textFromBeginningToStartOfSelection = this.tbCharOnlyView!.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(CommunicationDataViewModel.NewlineSequence).Length;
        // any newline sequences introduced (more than one lines found)
        if (foundAmountOfLines > 1)
        {
            // calculated amount of characters that were introduced
            foundManuallyIntroducedNewlineSequenceCharacters = (foundAmountOfLines - 1) * CommunicationDataViewModel.NewlineSequence.Length;
        }

        // iterate through length of selection
        for (int i = 0; i < this.tbCharOnlyView!.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.tbCharOnlyView?.ScrollToEnd();
    }
    #endregion

    #region Selector (ComboBox) handling
    private static void OnSelectorItemsSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // extract instance and guard null
        //if (d is not MultiFormatDataView mfdv) { return; }
        // extract instance of new Value and guard null
        //if (e.NewValue is not IEnumerable enumerable) { return; }

        // nothing to do
    }

    private static void OnSelectorDescriptionChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // nothing to do
    }

    private static void OnSelectorSelectedItemChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        // nothing to do
    }

    #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
}