//Except where stated all code and programs in this project are the copyright of Jim Blackler, 2008.
//jimblackler@gmail.com
//
//This is free software. Libraries and programs are distributed under the terms of the GNU Lesser
//General Public License. Please see the files COPYING and COPYING.LESSER.

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

namespace MiscControls
{
    /// <summary>
    /// A text box which is shown in compact form, but is able to expand when it has multiple
    /// lines of text to show, and is in focus.
    /// </summary>
    public class ExpandableTextBox : TextBox
    {
        int originalHeight;

        /// <summary>
        /// Constructor for the control
        /// </summary>
        public ExpandableTextBox()
        {
            InitializeComponent();

            originalHeight = Height;
        }

        private void InitializeComponent()
        {
            this.SuspendLayout();
            // 
            // ExpandableTextBox
            // 
            this.Multiline = true;
            this.Enter += new System.EventHandler(this.ExpandableTextBox_Enter);
            this.PreviewKeyDown += new System.Windows.Forms.PreviewKeyDownEventHandler(this.ExpandableTextBox_PreviewKeyDown);
            this.Leave += new System.EventHandler(this.ExpandableTextBox_Leave);
            this.TextChanged += new System.EventHandler(this.ExpandableTextBox_TextChanged);
            this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.ExpandableTextBox_KeyDown);
            this.ResumeLayout(false);

        }

        private void ExpandableTextBox_TextChanged(object sender, EventArgs e)
        {
            SetSize(false);

        }

        private void ExpandableTextBox_Leave(object sender, EventArgs e)
        {
            if (internalCall == 0)
            {
                Minimise();
            }
        }

        private void ExpandableTextBox_Enter(object sender, EventArgs e)
        {
            if (internalCall == 0)
            {
                SetSize(true);
            }
        }

        Control addTo;
        
        Control originalParent;
        
        int internalCall;
        
        int originalChildIndex;
        
        Control placeHolder;

        private void SetSize(bool justEntered)
        {
            if (Text.Contains(Environment.NewLine))
            {

                ScrollBars = ScrollBars.Vertical;

                if ((justEntered || Focused) && Height == originalHeight)
                {
                    originalParent = Parent;

                    // the placeholder preserves the layout of any layout managed parent panels
                    placeHolder = new TextBox();
                    placeHolder.Bounds = Bounds;

                    originalChildIndex = originalParent.Controls.GetChildIndex(this);

                    originalParent.SuspendLayout();

                    internalCall++;
                    originalParent.Controls.Remove(this);
                    internalCall--;

                    originalParent.Controls.Add(placeHolder);
                    originalParent.Controls.SetChildIndex(placeHolder, originalChildIndex);

                    // Get the control to add the expanded text box too ... probably the ultimate
                    // underlying form. The reason we don't just add to the Parent is that this might
                    // be a control with special layout control that will override our specified layout.
                    addTo = originalParent;
                    Size offset = new Size(0, 0);


                    while (addTo.Parent != null &&  addTo.LayoutEngine != LayoutEngine) // ours has default layout
                    {
                        offset += new Size(addTo.Location);
                        addTo = addTo.Parent;
                    }

                    Point newLocation = Location + offset;
                    Location = newLocation;
                    if (!Location.Equals(newLocation))
                    {
                        throw new Exception("Could not set location");
                    }

                    Size = new Size(Width, ExpandedHeight);

                    addTo.SuspendLayout();
                    
                    addTo.Controls.Add(this);

                    BringToFront();
                    Focus();

                    originalParent.ResumeLayout();
                    addTo.ResumeLayout();
                }



            }
            else
            {
                ScrollBars = ScrollBars.None;

                if (Minimise())
                {
                    Focus();
                }
            }

        }

        private bool Minimise()
        {
            if (Height != originalHeight)
            {
                if (addTo != null)
                {
                    addTo.SuspendLayout();
                    originalParent.SuspendLayout();

                    internalCall++;
                    addTo.Controls.Remove(this);
                    internalCall--;
                    originalParent.Controls.Remove(placeHolder);
                    originalParent.Controls.Add(this);
                    originalParent.Controls.SetChildIndex(this, originalChildIndex);

                    Size = new Size(Width, originalHeight);

                    originalParent.ResumeLayout();
                    addTo.ResumeLayout();

                    addTo = null;
                }

                return true;
            }
            else
            {
                return false;
            }

        }

        /// <summary>
        /// The height of the text box in pixels, when it is expanded for multi-line editing.
        /// </summary>
        public int ExpandedHeight
        {
            get { return expandedHeight; }
            set { expandedHeight = value; }
        }

        private int expandedHeight = 100;

        private void ExpandableTextBox_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
        {
            // using tab to change focus? Collapse control first or focus will get switched to a control on the parent page
            if (e.KeyCode == Keys.Tab)
            {
                if (Minimise())
                {
                    internalCall++;
                    Focus();
                    internalCall--;
                }
            }
            else if (e.KeyCode == Keys.Enter && e.Modifiers == Keys.None)
            {
                e.IsInputKey = true;
            }
 
        }

        private void ExpandableTextBox_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
 //               e.SuppressKeyPress = true;
            }
        }

    }
}