using System;
using System.Drawing;
using System.Windows.Forms;

namespace Core.StlMes.Client.Mcp.Mch.Mcms
{
    public partial class SuggestText : ComboBox, IMessageFilter
    {
        private System.Windows.Forms.Control ComboParentForm; // Or use type "Form" 
        private int IgnoreTextChange;
        private ListBox listBoxChild;
        private bool MsgFilterActive;

        public SuggestText()
        {
            // Set up all the events we need to handle
            TextChanged += ComboListMatcher_TextChanged;
            SelectionChangeCommitted += ComboListMatcher_SelectionChangeCommitted;
            LostFocus += ComboListMatcher_LostFocus;
            MouseDown += ComboListMatcher_MouseDown;
            HandleDestroyed += ComboListMatcher_HandleDestroyed;
        }

        public bool PreFilterMessage(ref Message m)
        {
            if (m.Msg == 0x201) // Mouse click: WM_LBUTTONDOWN
            {
                var Pos = new Point(m.LParam.ToInt32() & 0xFFFF, m.LParam.ToInt32() >> 16);

                var Ctrl = FromHandle(m.HWnd);
                if (Ctrl != null)
                {
                    // Convert the point into our parent control's coordinates ...
                    Pos = ComboParentForm.PointToClient(Ctrl.PointToScreen(Pos));

                    // ... because we need to hide the list if user clicks on something other than the list-box
                    if (ComboParentForm != null)
                        if ((listBoxChild != null) &&
                            ((Pos.X < listBoxChild.Left) || (Pos.X > listBoxChild.Right) || (Pos.Y < listBoxChild.Top) ||
                             (Pos.Y > listBoxChild.Bottom)))
                            HideTheList();
                }
            }
            else if (m.Msg == 0x100) // WM_KEYDOWN
            {
                if ((listBoxChild != null) && listBoxChild.Visible)
                    switch (m.WParam.ToInt32())
                    {
                        case 0x1B: // Escape key
                            HideTheList();
                            return true;

                        case 0x26: // up key
                        case 0x28: // right key
                            // Change selection
                            var NewIx = listBoxChild.SelectedIndex + (m.WParam.ToInt32() == 0x26 ? -1 : 1);

                            // Keep the index valid!
                            if ((NewIx >= 0) && (NewIx < listBoxChild.Items.Count))
                                listBoxChild.SelectedIndex = NewIx;
                            return true;

                        case 0x0D: // return (use the currently selected item)
                            CopySelection();
                            return true;
                    }
            }

            return false;
        }

        private void ComboListMatcher_HandleDestroyed(object sender, EventArgs e)
        {
            if (MsgFilterActive)
                Application.RemoveMessageFilter(this);
        }

        ~SuggestText()
        {
        }

        private void ComboListMatcher_MouseDown(object sender, MouseEventArgs e)
        {
            HideTheList();
        }

        private void ComboListMatcher_LostFocus(object sender, EventArgs e)
        {
            if ((listBoxChild != null) && !listBoxChild.Focused)
                HideTheList();
        }

        private void ComboListMatcher_SelectionChangeCommitted(object sender, EventArgs e)
        {
            IgnoreTextChange++;
        }

        private void InitListControl()
        {
            if (listBoxChild == null)
            {
                // Find parent - or keep going up until you find the parent form
                ComboParentForm = Parent;

                if (ComboParentForm != null)
                {
                    // Setup a messaage filter so we can listen to the keyboard
                    if (!MsgFilterActive)
                    {
                        Application.AddMessageFilter(this);
                        MsgFilterActive = true;
                    }

                    listBoxChild = listBoxChild = new ListBox();
                    listBoxChild.Visible = false;
                    listBoxChild.Click += listBox1_Click;
                    ComboParentForm.Controls.Add(listBoxChild);
                    ComboParentForm.Controls.SetChildIndex(listBoxChild, 0); // Put it at the front
                }
            }
        }


        private void ComboListMatcher_TextChanged(object sender, EventArgs e)
        {
           

            if (IgnoreTextChange > 0)
            {
                IgnoreTextChange = 0;
                return;
            }

            InitListControl();

            if (listBoxChild == null)
                return;

            var SearchText = Text.Trim();

            listBoxChild.Items.Clear();

            // Don't show the list when nothing has been typed
            if (!string.IsNullOrWhiteSpace(SearchText))
                foreach (string Item in Items)
                    if ((Item != null) && Item.Contains(SearchText))
                        listBoxChild.Items.Add(Item);

            if (listBoxChild.Items.Count > 0)
            {
                var PutItHere = new Point(Left, Bottom);
                System.Windows.Forms.Control TheControlToMove = this;

                PutItHere = Parent.PointToScreen(PutItHere);

                TheControlToMove = listBoxChild;
                PutItHere = ComboParentForm.PointToClient(PutItHere);

                TheControlToMove.Show();
                TheControlToMove.Left = PutItHere.X;
                TheControlToMove.Top = PutItHere.Y;
                TheControlToMove.Width = Width;

                var TotalItemHeight = listBoxChild.ItemHeight*(listBoxChild.Items.Count + 1);
                TheControlToMove.Height = TotalItemHeight;

                TheControlToMove.BringToFront();
            }
            else
                HideTheList();
        }

        /// <summary>
        ///     Copy the selection from the list-box into the combo box
        /// </summary>
        private void CopySelection()
        {
            if (listBoxChild.SelectedItem != null)
            {
                SelectedItem = listBoxChild.SelectedItem;
                HideTheList();
                SelectAll();
            }
        }

        private void listBox1_Click(object sender, EventArgs e)
        {
            var ThisList = sender as ListBox;

            if (ThisList != null)
                CopySelection();
        }

        private void HideTheList()
        {
            if (listBoxChild != null)
                listBoxChild.Hide();
        }
    }
}