using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows.Forms;

namespace JD.UserControls.QuickOpenDialogs
{
    /// <summary>
    /// The control used to prompt user.
    /// </summary>
    /// <remarks>Internal to clarify the usage of the form, we only expose what we want from Control.</remarks>
    internal partial class QuickOpenControl : UserControl
    {
        #region Variables

        private readonly HashSet<Keys> m_downKeys = new HashSet<Keys>();

        #endregion

        #region Constructor

        public QuickOpenControl()
        {
            InitializeComponent();

            SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
            SetStyle(ControlStyles.Selectable, false);
            SetStyle(ControlStyles.SupportsTransparentBackColor, true);
            UpdateStyles();

            textBox.KeyDown += textBox_KeyDown;
            textBox.KeyUp += textBox_KeyUp;
            textBox.MouseWheel += textBox_MouseWheel;

            listBox.SelectedIndexChanged += listBox_SelectionChanged;
        }

        #endregion

        #region Properties

        public ListBox ListBox
        {
            get { return listBox; }
        }

        public int VisibleItemCount
        {
            get { return listBox.ClientSize.Height / listBox.ItemHeight; }
        }

        #endregion

        #region Methods

        protected override bool ProcessCmdKey(ref System.Windows.Forms.Message msg, Keys keyData)
        {
            keyData &= ~Keys.Modifiers;

            if (keyData == Keys.Enter)
            {
                CancelEventArgs e = new CancelEventArgs();
                OnActivated(e);
                
                // Returning false will let the textbox handle Enter, which will make a 'ding' sound
                // which provides a nice feedback that there is no valid item to activate
                return !e.Cancel;
            }

            return base.ProcessCmdKey(ref msg, keyData);
        }

        private bool HandleNavigationKeyPress(Keys key, bool repeating)
        {
            key &= ~Keys.Modifiers;

            switch (key)
            {
                case Keys.Up:
                    MoveSelection(-1, repeating);
                    break;

                case Keys.Down:
                    MoveSelection(1, repeating);
                    break;

                case Keys.PageUp:
                    MoveSelection(-VisibleItemCount, repeating);
                    break;

                case Keys.PageDown:
                    MoveSelection(VisibleItemCount, repeating);
                    break;

                default:
                    return false;
            }

            return true;
        }

        private void MoveSelection(int count, bool repeating)
        {
            int listCount = listBox.Items.Count;

            if (listCount > 0)
            {
                int max = listCount - 1;
                int current = listBox.SelectedIndex;
                int nextIndex = current + count;

                bool wrapSelection = !repeating && (current == 0 || current == max);

                if (nextIndex < 0) nextIndex = wrapSelection ? max : 0;
                else if (nextIndex > max) nextIndex = wrapSelection ? 0 : max;

                // Clear before so it works in a multi select scenario
				// see ItemPickerExtension
                listBox.SelectedItems.Clear();
                listBox.SelectedIndex = nextIndex;
            }
        }

        private bool IsKeyDown(Keys key)
        {
            return m_downKeys.Contains(key & ~Keys.Modifiers);
        }

        private void SetKeyDown(Keys key)
        {
            m_downKeys.Add(key & ~Keys.Modifiers);
        }

        private void SetKeyUp(Keys key)
        {
            m_downKeys.Remove(key & ~Keys.Modifiers);
        }

        #endregion

        #region Events

        public event EventHandler<CancelEventArgs> Activated;

        private void OnActivated(CancelEventArgs e)
        {
            Activated?.Invoke(this, e);
        }

        public Converter<Keys, bool> ProcessDialogKeyEvent;

        protected override bool ProcessDialogKey(Keys keyData)
        {
            var dialogKey = ProcessDialogKeyEvent;
            if (dialogKey != null && dialogKey(keyData))
            {
                return true;
            }

            return base.ProcessDialogKey(keyData);
        }

        #endregion

        #region Event Handlers

        private void listBox_SelectionChanged(object sender, EventArgs e)
        {
            if (!textBox.Focused)
            {
                textBox.Select();
            }
        }

        private void listBox_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            OnActivated(new CancelEventArgs());
        }

        private void textBox_KeyDown(object sender, KeyEventArgs e)
        {
            var repeating = IsKeyDown(e.KeyData);

            e.Handled = HandleNavigationKeyPress(e.KeyData, repeating);

            SetKeyDown(e.KeyData);
        }

        private void textBox_KeyUp(object sender, KeyEventArgs e)
        {
            SetKeyUp(e.KeyData);
        }

        void textBox_MouseWheel(object sender, MouseEventArgs e)
        {
            var scrollCount  = (int)((float)-e.Delta / SystemInformation.MouseWheelScrollDelta) * SystemInformation.MouseWheelScrollLines;

            listBox.TopIndex += scrollCount;
        }

        #endregion
    }
}