/*
 * GUIScrollBar.cs
 * Authors: Mike DeMauro
 * Copyright (c) 2007-2008 Cornell University

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

using System;
using System.Collections.Generic;
using System.Text;
using tAC_Engine.GUI;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Util;

namespace tAC_Engine.GUI
{
	/// <summary>
	/// Defines the scroll bar GUI component
	/// </summary>
    public class GUIScrollBar : GUIContainer
    {
        #region Fields

		// The track height
		private float trackHeight;

		/// <summary>
		/// The pixel texture to use
		/// </summary>
        protected Texture2D mPixel;

        /// <summary>
		/// The color for the background
        /// </summary>
        protected Color mBackgroundColor = Color.White;

		/// <summary>
		/// The button component for the up button
		/// </summary>
        protected GUIButton mUpButton = new GUIButton();

		/// <summary>
		/// The button component for the down button
		/// </summary>
        protected GUIButton mDownButton = new GUIButton();

		/// <summary>
		/// The button component for the scroll button
		/// </summary>
        protected GUIButton mScrollButton = new GUIButton();

		/// <summary>
		/// Whether or not the scrollbar is currently being dragged
		/// </summary>
        protected bool mDragging = false;

		/// <summary>
		/// Current position of the scroll bar 
		/// </summary>
        protected int mScrollPosition = 0;

		/// <summary>
		/// Lowest position the scroll bar can go
		/// </summary>
        protected int mMinScrollPosition = 0;

		/// <summary>
		/// Highest postiion the scroll bar can go
		/// </summary>
        protected int mMaxScrollPosition = 0;

		/// <summary>
		/// The amount the  scroll bar moves every time it is moved without dragging
		/// </summary>
        protected int mLargeScrollAmount = 5;

        #endregion 

        #region Properties

		/// <summary>
		/// Gets/Sets the position of the scroll bar GUI
		/// </summary>
        public override Vector2 Position
        {
            get { return base.Position; }
            set
            {
                base.Position = value;
                updatePositions();
            }
        }

        /// <summary>
        /// Gets/Sets the screen offset for the scroll bar GUI
        /// </summary>
        public override Vector2 ScreenOffset
        {
            get { return base.ScreenOffset; }
            set
            {
                base.ScreenOffset = value;
                updatePositions();
            }
        }

		/// <summary>
		/// Gets/Sets the size of the scroll bar GUI
		/// </summary>
        public override Vector2 Size
        {
            get { return base.Size; }
            set 
			{
                base.Size = value;
                updateSizes();
            }
        }

        /// <summary>
        /// Gets/Sets the visibility of the scrollbar
        /// </summary>
        public override bool Visible
        {
            get { return base.Visible; }
            set
            {
                mUpButton.Visible = value;
                mDownButton.Visible = value;
                mScrollButton.Visible = value;
                base.Visible = value;
            }
        }

        /// <summary>
        /// Sets the texture to use when the up button is up
        /// </summary>
        public string UpButtonTextureUpName
        {
            set { mUpButton.ButtonUpName = value; }
        }

        /// <summary>
        /// Sets the texture to use when the up button is down
        /// </summary>
        public string UpButtonTextureDownName
        {
            set { mUpButton.ButtonDownName = value; }
        }

        /// <summary>
        /// Sets the texture to use when the up button is over
        /// </summary>
        public string UpButtonTextureOverName
        {
            set { mUpButton.ButtonOverName = value; }
        }
        
        /// <summary>
        /// Sets the texture to use when the down button is up
        /// </summary>
        public string DownButtonTextureUpName
        {
            set { mDownButton.ButtonUpName = value; }
        }

        /// <summary>
        /// Sets the texture to use when the down button is down
        /// </summary>
        public string DownButtonTextureDownName
        {
            set { mDownButton.ButtonDownName = value; }
        }

        /// <summary>
        /// Sets the texture to use when the down button is over
        /// </summary>
        public string DownButtonTextureOverName
        {
            set { mDownButton.ButtonOverName = value; }
        }

		/// <summary>
		/// Gets/Sets the position of the scroll bar component
		/// </summary>
        public int ScrollPosition
        {
            get { return mScrollPosition; }
            set { mScrollPosition = value; }
        }

		/// <summary>
		/// Gets/Sets the minimum scroll position of the scroll bar component
		/// </summary>
        public int MinScrollPosition
        {
            get { return mMinScrollPosition; }
            set { mMinScrollPosition = value; }
        }

		/// <summary>
		/// Gets/Sets the maximum position of the scroll bar component
		/// </summary>
        public int MaxScrollPosition
        {
            get { return mMaxScrollPosition; }
            set { mMaxScrollPosition = value; }
        }

        /// <summary>
        /// Gets/Sets the amount scrolled when track is clicked
        /// </summary>
        public int LargeScrollAmount
        {
            get { return mMaxScrollPosition; }
            set { mMaxScrollPosition = value; }
        }

        #endregion

		#region Creation

		/// <summary>
		/// Constructor
		/// </summary>
        public GUIScrollBar()
        {
            Add(mUpButton);
            Add(mDownButton);
            Add(mScrollButton);
		}

		#endregion

		#region Initialization

		/// <summary>
        /// Initializes the component. Override this method to load any non-graphics
        /// resources and query for any required services.
        /// </summary>
        public override void Initialize()
        {
            updatePositions();
            updateSizes();

            mUpButton.ButtonPressed += new EventHandler(mUpButton_ButtonPressed);
            mDownButton.ButtonPressed += new EventHandler(mDownButton_ButtonPressed);
            mScrollButton.ButtonPressed += new EventHandler(mScrollButton_ButtonPressed);

            base.Initialize();
		}

		#endregion

		#region Management

		/// <summary>
		/// Loads all the necessary information for content dependent objects
		/// </summary>
        public override void LoadContent()
        {
            if (mParentScreen != null)
            {
                // create pixel
                mPixel = new Texture2D(mParentScreen.GraphicsDevice, 1, 1, 1, TextureUsage.None, SurfaceFormat.Color);
                Color[] pixels = new Color[1];
                pixels[0] = Color.White;
                mPixel.SetData(pixels);
            }

            base.LoadContent();
		}

		#endregion

		#region Update

		/// <summary>
		/// Updates the state of the scroll bar GUI
		/// </summary>
		/// <param name="gameTime">The time that has passed in game</param>
        public override void Update(GameTime gameTime)
        {
            if (mParentScreen != null)
            {
                if (mDragging)
                {
                    float newY = mParentScreen.InputHandler.MouseLocation.Y;

                    if (newY > mDownButton.Bounds.Top - mScrollButton.Size.Y)
                    {
                        newY = mDownButton.Bounds.Top - mScrollButton.Size.Y;
                    }
                    else if(newY < mUpButton.Bounds.Bottom)
                    {
                        newY = mUpButton.Bounds.Bottom;
                    }

                    mScrollButton.Position = new Vector2(mScrollButton.Position.X, newY);

                    int newScrollPos = (int)((mScrollButton.Position.Y - mUpButton.Size.Y) / (trackHeight / mMaxScrollPosition));
                    if (newScrollPos != mScrollPosition)
                    {
                        mScrollPosition = newScrollPos;

                        if (ScrollChanged != null)
                            ScrollChanged.Invoke(this, EventArgs.Empty);
                    }
                }
            }

            //mUpButton.LayerDepth = mLayerDepth + 0.001f;
            //mDownButton.LayerDepth = mLayerDepth + 0.001f;
            //mScrollButton.LayerDepth = mLayerDepth + 0.001f;

            base.Update(gameTime);
        }

		/// <summary>
		/// Updates the position of the scroll bar components (as well as the screen tranform)
		/// </summary>
		protected void updatePositions()
		{
			mUpButton.Position = mPosition;
			mDownButton.Position = new Vector2(mPosition.X, mPosition.Y + mSize.Y - mDownButton.Size.Y);
			mScrollButton.Position = new Vector2(mPosition.X, mUpButton.Bounds.Bottom + (mScrollPosition * trackHeight / mMaxScrollPosition));

            mUpButton.ScreenOffset = mScreenOffset;
            mDownButton.ScreenOffset = mScreenOffset;
            mScrollButton.ScreenOffset = mScreenOffset;
		}

		/// <summary>
		/// Updates all the sizes of the scroll bar components
		/// </summary>
		protected void updateSizes()
		{
			mUpButton.Size = new Vector2(mSize.X, mSize.X);
			mDownButton.Size = new Vector2(mSize.X, mSize.X);
			trackHeight = mSize.Y - mUpButton.Size.Y - mDownButton.Size.Y;
			mScrollButton.Size = new Vector2(mSize.X, trackHeight / mMaxScrollPosition);
			updatePositions();
		}

		#endregion

		#region Event Handling

		/// <summary>
		/// Event for when the scroll bar has been modified
		/// </summary>
		public event EventHandler ScrollChanged;

		/// <summary>
		/// Event that processes when the up button is pressed
		/// </summary>
		/// <param name="sender">The sender of the event</param>
		/// <param name="e">The associated arguments with the event</param>
        internal void mUpButton_ButtonPressed(object sender, EventArgs e)
        {
            if (mScrollPosition > mMinScrollPosition)
            {
                --mScrollPosition;
                updatePositions();

                if (ScrollChanged != null)
                    ScrollChanged.Invoke(this, EventArgs.Empty);
            }
        }

		/// <summary>
		/// Event that processed when the down button is pressed
		/// </summary>
		/// <param name="sender">The sender of the event</param>
		/// <param name="e">The associated arguments with the event</param>
        internal void mDownButton_ButtonPressed(object sender, EventArgs e)
        {
            if (mScrollPosition < mMaxScrollPosition)
            {
                ++mScrollPosition;
                updatePositions();

                if (ScrollChanged != null)
                    ScrollChanged.Invoke(this, EventArgs.Empty);
            }
        }

		/// <summary>
		/// Event that processes when the scroll button is pressed
		/// </summary>
		/// <param name="sender">The sender of the event</param>
		/// <param name="e">The associated arguments with the event</param>
        void mScrollButton_ButtonPressed(object sender, EventArgs e)
        {
            mDragging = true;
        }

        /// <summary>
        /// Handle the given event.
        /// </summary>
        /// <param name="e">The event to handle.</param>
        public override bool HandleMouseEvent(MouseInputEvent e)
        {
            if (e.EventCode == (int)GUIEventCodes.LEFT_MOUSE_RELEASED && mDragging)
            {
                mDragging = false;
                
            } else 
            
            // Check to see if it's within our bounds
            if (Bounds.Contains(e.X, e.Y))
            {
                // Let a component handle it first if able
                if (base.HandleMouseEvent(e))
                    return true;

                // Evaluate for a left mouse button press
                if (e.EventCode == (int)GUIEventCodes.LEFT_MOUSE_CLICKED)
                {
                    // TODO: change scroll position based on track position
                    if (e.Y > mScrollButton.Bounds.Bottom)
                    {
                        mScrollPosition += mLargeScrollAmount;
                        if (mScrollPosition > mMaxScrollPosition)
                            mScrollPosition = mMaxScrollPosition;
                        updatePositions();
                    }
                    else if (e.Y < mScrollButton.Bounds.Top)
                    {
                        mScrollPosition -= mLargeScrollAmount;
                        if (mScrollPosition < mMinScrollPosition)
                            mScrollPosition = mMinScrollPosition;
                        updatePositions();
                    }

                    if (ScrollChanged != null)
                        ScrollChanged.Invoke(this, EventArgs.Empty);

					// Set the event args if they're null
					if (e.EventArgs == null)
					{
						// Set the event args to us
						e.EventArgs = this;
					}

                    return true;
                }
            }

            return false;
        }

        #endregion

        #region Draw

		/// <summary>
		/// Renders the scroll bar Gui
		/// </summary>
		/// <param name="gameTime">Time that has passed in game</param>
        public override void Draw(GameTime gameTime)
        {
            if (mIsVisible)
            {
                // Draw Background
                Batch.Draw(mPixel, Bounds, mBackgroundColor);

                base.Draw(gameTime);
            }
        }

        #endregion
    }
}