/*
 * GUIButton.cs
 * Authors: Bradley Blankenship, 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 Microsoft.Xna.Framework.Graphics;
using Util;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using System;

namespace tAC_Engine.GUI
{
    /// <summary>
    /// Represents a button for use by the GUI.
    /// </summary>
    public class GUIButton : GUIComponent
    {
        #region Button State

        /// <summary>
		/// The enumeration of the button's state
        /// </summary>
        public enum ButtonState
        {
			/// <summary>
			/// State for when a button is up
			/// </summary>
            UP,
			/// <summary>
			/// State for when a button is down
			/// </summary>
            DOWN,
            /// <summary>
			/// State for when a button has the mouse over it
			/// </summary>
            OVER
        }

        #endregion

        #region Fields

        /// <summary>
		/// The state of the button
        /// </summary>
        protected ButtonState mState;

        /// <summary>
        /// The name of the texture for button up state
        /// </summary>
        protected string mButtonUpName = @"Textures\BasicButtonUp";

        /// <summary>
        /// The name of the texture for button down state
        /// </summary>
        protected string mButtonDownName = @"Textures\BasicButtonDown";

        /// <summary>
        /// The name of the texture for mouseover state
        /// </summary>
        protected string mButtonOverName = @"Textures\BasicButtonDown";

        /// <summary>
		/// The textures representing being up and down
        /// </summary>
        protected Texture2D mButtonUp;

		/// <summary>
        /// The textures representing being up and down
		/// </summary>
        protected Texture2D mButtonDown;

        /// <summary>
        /// The texture representing being over
        /// </summary>
        protected Texture2D mButtonOver;

        /// <summary>
		/// The current texture of the button
        /// </summary>
        protected Texture2D mCurrentTexture;

        /// <summary>
        /// The font for the button
        /// </summary>
        protected SpriteFont mSpriteFont;

        /// <summary>
        /// The text for the button
        /// </summary>
        protected string mText;

        /// <summary>
        /// The position for the text (calculated to be cenetered based on the text of the button)
        /// </summary>
        protected Vector2 mTextPosition = Vector2.Zero;

        /// <summary>
        /// A custom offset for the text (exposed externally)
        /// </summary>
        protected Vector2 mTextCustomOffset = Vector2.Zero;

        /// <summary>
        /// Whether the button has changed state or not
        /// </summary>
        protected bool mStateChanged = false;

        /// <summary>
        /// The text color
        /// </summary>
        protected Color mTextColor = Color.Black;

        /// <summary>
        /// Size of the source border in texels
        /// </summary>
        protected int mBorderSizeSource = 0;

        /// <summary>
        /// Size of the destination border in pixels
        /// </summary>
        protected int mBorderSizeDest = 0;

        /// <summary>
		/// Icon texture
        /// </summary>
        protected Texture2D mIcon;

        /// <summary>
		/// The position for the icon
        /// </summary>
        protected Rectangle mIconDestination = Rectangle.Empty;

        #endregion

        #region Texture Rectangles

		/// <summary>
		/// Destination rectangle for the center of the button
		/// </summary>
        protected Rectangle centerDest = Rectangle.Empty;
		/// <summary>
		/// Source rectangle for the center of the button
		/// </summary>
        protected Rectangle centerSource = Rectangle.Empty;

		/// <summary>
		/// Destination rectangle for the top left of the button
		/// </summary>
        protected Rectangle topLeftDest = Rectangle.Empty;
		/// <summary>
		/// Source rectangle for the top left of the button
		/// </summary>
        protected Rectangle topLeftSource = Rectangle.Empty;

		/// <summary>
		/// Destination rectangle for the top of the button
		/// </summary>
        protected Rectangle topDest = Rectangle.Empty;
		/// <summary>
		/// Source rectangle for the top of the button
		/// </summary>
        protected Rectangle topSource = Rectangle.Empty;

		/// <summary>
		/// Destination rectangle for the top right of the button
		/// </summary>
        protected Rectangle topRightDest = Rectangle.Empty;
		/// <summary>
		/// Source rectangle for the top right of the button
		/// </summary>
        protected Rectangle topRightSource = Rectangle.Empty;

		/// <summary>
		/// Destination rectangle for the right of the button
		/// </summary>
        protected Rectangle rightDest = Rectangle.Empty;
		/// <summary>
		/// Source rectangle for the right of the button
		/// </summary>
        protected Rectangle rightSource = Rectangle.Empty;

		/// <summary>
		/// Destination rectangle for the bottom right of the button
		/// </summary>
        protected Rectangle bottomRightDest = Rectangle.Empty;
		/// <summary>
		/// Source rectangle for the bottom right of the button
		/// </summary>
        protected Rectangle bottomRightSource = Rectangle.Empty;
		
		/// <summary>
		/// Destination rectangle for the bottom of the button
		/// </summary>
        protected Rectangle bottomDest = Rectangle.Empty;
        /// <summary>
		/// Source rectangle for the bottom of the button
        /// </summary>
		protected Rectangle bottomSource = Rectangle.Empty;

		/// <summary>
		/// Destination rectangle for the bottom left of the button
		/// </summary>
        protected Rectangle bottomLeftDest = Rectangle.Empty;
		/// <summary>
		/// Source rectangle for the bottom left of the button
		/// </summary>
        protected Rectangle bottomLeftSource = Rectangle.Empty;

		/// <summary>
		/// Destination rectangle for the left of the button
		/// </summary>
        protected Rectangle leftDest = Rectangle.Empty;
		/// <summary>
		/// Source rectangle for the left of the button
		/// </summary>
        protected Rectangle leftSource = Rectangle.Empty;

        #endregion

        #region Properties

        /// <summary>
        /// Allows access to the size of the component.
        /// </summary>
        public override Vector2 Size
        {
            get { return base.Size; }
            set
            {
                base.Size = value;
                updatePositions();
            }
        }

        /// <summary>
        /// Allows access to the position of the component.
        /// </summary>
        public override Vector2 Position
        {
            get { return base.Position; }
            set
            {
                base.Position = value;
                updatePositions();
            }
        }

        /// <summary>
        /// Specifies an offset for the text label
        /// </summary>
        public virtual Vector2 TextOffset
        {
            get { return mTextCustomOffset; }
            set { mTextCustomOffset = value; }
        }

        /// <summary>
        /// Allows access to the button state internally.
        /// </summary>
        public ButtonState State
        {
            get { return mState; }
            set
            {
                // Only if the state is new
                if (value != mState)
                {
                    HasChanged = true;
                    mState = value;
					if (mState == ButtonState.UP)
					{
						mCurrentTexture = mButtonUp;
					}
					else if(mState == ButtonState.DOWN)
					{
						mCurrentTexture = mButtonDown;
					}
                    else if (mState == ButtonState.OVER)
                    {
                        mCurrentTexture = mButtonOver;
                    }
                }
            }
        }

        /// <summary>
        /// The name of the texture to load for the button up state
        /// </summary>
        public string ButtonUpName
        {
            get { return mButtonUpName; }
            set { mButtonUpName = value; }
        }

        /// <summary>
        /// The name of the texture to load for the button down state
        /// </summary>
        public string ButtonDownName
        {
            get { return mButtonDownName; }
            set { mButtonDownName = value; }
        }

        /// <summary>
        /// The name of the texture to load for the button over state
        /// </summary>
        public string ButtonOverName
        {
            get { return mButtonOverName; }
            set { mButtonOverName = value; }
        }

        /// <summary>
        /// Allows access to the button's up texture internally.
        /// </summary>
        public Texture2D ButtonUp
        {
            get { return mButtonUp; }
            set
            {
                mButtonUp = value;
                if (State == ButtonState.UP)
                {
                    // Set the current texture
                    mCurrentTexture = mButtonUp;
                }
            }
        }

        /// <summary>
        /// Allows access to the button's down texture internally.
        /// </summary>
        public Texture2D ButtonDown
        {
            get { return mButtonDown; }
            set
            {
                mButtonDown = value;
                if (State == ButtonState.DOWN)
                {
                    // Set the current texture
                    mCurrentTexture = mButtonDown;
                }
            }
        }

        /// <summary>
        /// Allows access to the button's over texture internally.
        /// </summary>
        public Texture2D ButtonOver
        {
            get { return mButtonOver; }
            set
            {
                mButtonOver = value;
                if (State == ButtonState.OVER)
                {
                    // Set the current texture
                    mCurrentTexture = mButtonOver;
                }
            }
        }

        /// <summary>
        /// Allow saccess to the button's current display texture.
        /// </summary>
        protected Texture2D CurrentTexture
        {
            get { return mCurrentTexture; }
            set { mCurrentTexture = value; updatePositions(); }
        }

        /// <summary>
        /// Allows access to the font of the button internally.
        /// </summary>
        public SpriteFont Font
        {
            get { return mSpriteFont; }
            set
            {
                mSpriteFont = value;
                UpdateTextPosition();
            }
        }

        /// <summary>
        /// Allows internal access for manipulating the button text.
        /// </summary>
        public string Text
        {
            get { return mText; }
            set
            {
                mText = value;
                UpdateTextPosition();
            }
        }

        /// <summary>
        /// Allows access to the value to determine if that state's changed locally.
        /// </summary>
        protected bool HasChanged
        {
            get { return mStateChanged; }
            set { mStateChanged = value; }
        }

        /// <summary>
        /// Allows access to the text color.
        /// </summary>
        public Color TextColor
        {
            get { return mTextColor; }
            set { mTextColor = value; }
        }

        /// <summary>
        /// Size of the source border in texels
        /// </summary>
        public int BorderSizeSource
        {
            get { return mBorderSizeSource; }
            set { mBorderSizeSource = value; }
        }

        /// <summary>
        /// Size of the destination border in pixels
        /// </summary>
        public int BorderSizeDest
        {
            get { return mBorderSizeDest; }
            set { mBorderSizeDest = value; }
        }

        /// <summary>
        /// Name of the Icon texture to be loaded
        /// </summary>
        public Texture2D Icon
        {
            get { return mIcon; }
            set { mIcon = value; }
        }

        #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()
        {
            // Set the button's state up
            State = ButtonState.UP;

            // Now re-initialize to store the base data
            Resize();
		}

		#endregion

		#region Management

		/// <summary>
		/// Loads all the necessary informatiion for content dependent objects
		/// </summary>
        public override void LoadContent()
        {
            // If the parent screen is not null
            if (mParentScreen != null)
            {
                // If we do not have a texture for our up state
                if (mButtonUp == null)
                {
                    // Load the basic texture for an up button
                     mButtonUp = mParentScreen.Content.Load<Texture2D>(mButtonUpName);
                }
                mCurrentTexture = mButtonUp;

                // If we do not have a texture for our down state
                if (mButtonDown == null)
                {
                    // Load the basic texture for a down button
                    mButtonDown = mParentScreen.Content.Load<Texture2D>(mButtonDownName);
                }

                // If we do not have a texture for over state
                if (mButtonOver == null)
                {
                    mButtonOver = mParentScreen.Content.Load<Texture2D>(mButtonOverName);
                }

                updatePositions();
            }
            base.LoadContent();
        }

        #endregion

        #region Rescale

        /// <summary>
        /// Adjusts the Size of this component based on the size of the texture
        /// </summary>
        /// <param name="uniformScale"></param>
        public void Rescale(float uniformScale)
        {
            Rescale(uniformScale, uniformScale);
        }

        /// <summary>
        /// Adjusts the Size of this component based on the size of the texture
        /// </summary>
        /// <param name="xScale"></param>
        /// <param name="yScale"></param>
        public void Rescale(float xScale, float yScale)
        {
            System.Diagnostics.Debug.Assert(mButtonUp != null, "Must have a texture before calling Rescale");

            Size = new Vector2(mButtonUp.Width * xScale, mButtonUp.Height * yScale);
        }

        #endregion

        #region Event Handling

		/// <summary>
		/// Event for when a button is pressed
		/// </summary>
        public event EventHandler ButtonPressed;
        
		/// <summary>
		/// Event for when a button is released
		/// </summary>
		public event EventHandler ButtonReleased;

        /// <summary>
        /// Removes all handlers from the ButtonReleased event.
        /// </summary>
        public void RemoveButtonReleasedHandlers()
        {
            ButtonReleased = null;
        }

        /// <summary>
        /// Handle the given event.
        /// </summary>
        /// <param name="e">The event to handle.</param>
        public override bool HandleMouseEvent(MouseInputEvent e)
        {
            // The return value
            bool retVal = false;

			// If we're visible
			if (Visible && Enabled)
			{
				// Check to see if it's within our bounds
				if (IsInside(e.Location))
				{
					// Switch on the given codes
					switch (e.EventCode)
					{
						// Evaluate for a left mouse button press
						case (int)GUIEventCodes.LEFT_MOUSE_CLICKED:
							State = ButtonState.DOWN;

							// Invoke Event if we're enabled
							if (ButtonPressed != null)
								ButtonPressed.Invoke(this, EventArgs.Empty);

							break;

						// Evaluate for a left mouse button release
						case (int)GUIEventCodes.LEFT_MOUSE_RELEASED:
							State = ButtonState.UP;

							// Invoke Event if we're enabled
							if (ButtonReleased != null)
								ButtonReleased.Invoke(this, EventArgs.Empty);

							break;

                        case (int)GUIEventCodes.MOUSE_OVER:
                            State = ButtonState.OVER;
                            break;

                        case (int)GUIEventCodes.MOUSE_OUT:
                            State = ButtonState.UP;
                            break;
					}

					// Set the ret val to true
					retVal = true;

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

            // Return
            return retVal;
        }

        /// <summary>
        /// Handle the given key input event.
        /// </summary>
        /// <param name="e">The key input event to handle.</param>
        public override bool HandleKeyEvent(KeyInputEvent e)
        {
            return false;
        }

        #endregion

		#region Update

		/// <summary>
		/// Update the button.
		/// </summary>
		/// <param name="gameTime">The current game time.</param>
		public override void Update(GameTime gameTime)
		{}

		/// <summary>
		/// Update the position of the text for the button.
		/// </summary>
		private void UpdateTextPosition()
		{
			// Check to make sure they're not null
			if (Font != null && Text != null)
			{
				// The position for the text
				Vector2 size = Font.MeasureString(Text);
                Vector2 centerOffset = new Vector2((Size.X - size.X) / 2, (Size.Y - size.Y) / 2);
                Vector2 sumOffset = centerOffset + mTextCustomOffset;
                float offsetLength = sumOffset.Length();
                double offsetRotation = Math.Atan2(sumOffset.Y, sumOffset.X);
                Vector2 rotatedOffset = new Vector2((float)(Math.Cos(offsetRotation + mRotation) * offsetLength), (float)(Math.Sin(offsetRotation + mRotation) * offsetLength));
                mTextPosition = Position + rotatedOffset;
			}
		}

		/// <summary>
		/// Updates teh button GUI
		/// </summary>
		protected void updatePositions()
		{
			// Update background rectangles
			if (mCurrentTexture != null)
			{
				centerDest = new Rectangle(mBounds.X + mBorderSizeDest, mBounds.Y + mBorderSizeDest, Bounds.Width - mBorderSizeDest * 2, Bounds.Height - mBorderSizeDest * 2);
				centerSource = new Rectangle(mBorderSizeSource, mBorderSizeSource, CurrentTexture.Width - mBorderSizeSource * 2, CurrentTexture.Height - mBorderSizeSource * 2);

				topLeftDest = new Rectangle(mBounds.X, mBounds.Y, mBorderSizeDest, mBorderSizeDest);
				topLeftSource = new Rectangle(0, 0, mBorderSizeSource, mBorderSizeSource);

				topDest = new Rectangle(mBounds.X + mBorderSizeDest, mBounds.Y, mBounds.Width - mBorderSizeDest * 2, mBorderSizeDest);
				topSource = new Rectangle(mBorderSizeSource, 0, CurrentTexture.Width - mBorderSizeSource * 2, mBorderSizeSource);

				topRightDest = new Rectangle(mBounds.X + mBounds.Width - mBorderSizeDest, mBounds.Y, mBorderSizeDest, mBorderSizeDest);
				topRightSource = new Rectangle(CurrentTexture.Width - mBorderSizeSource, 0, mBorderSizeSource, mBorderSizeSource);

				rightDest = new Rectangle(mBounds.X + mBounds.Width - mBorderSizeDest, mBounds.Y + mBorderSizeDest, mBorderSizeDest, mBounds.Height - mBorderSizeDest * 2);
				rightSource = new Rectangle(CurrentTexture.Width - mBorderSizeSource, mBorderSizeSource, mBorderSizeSource, CurrentTexture.Height - mBorderSizeSource * 2);

				bottomRightDest = new Rectangle(mBounds.X + mBounds.Width - mBorderSizeDest, mBounds.Y + mBounds.Height - mBorderSizeDest, mBorderSizeDest, mBorderSizeDest);
				bottomRightSource = new Rectangle(CurrentTexture.Width - mBorderSizeSource, CurrentTexture.Height - mBorderSizeSource, mBorderSizeSource, mBorderSizeSource);

				bottomDest = new Rectangle(mBounds.X + mBorderSizeDest, mBounds.Y + mBounds.Height - mBorderSizeDest, mBounds.Width - mBorderSizeDest * 2, mBorderSizeDest);
				bottomSource = new Rectangle(mBorderSizeSource, CurrentTexture.Height - mBorderSizeSource, CurrentTexture.Width - mBorderSizeSource * 2, mBorderSizeSource);

				bottomLeftDest = new Rectangle(mBounds.X, mBounds.Y + mBounds.Height - mBorderSizeDest, mBorderSizeDest, mBorderSizeDest);
				bottomLeftSource = new Rectangle(0, CurrentTexture.Height - mBorderSizeSource, mBorderSizeSource, mBorderSizeSource);

				leftDest = new Rectangle(mBounds.X, mBounds.Y + mBorderSizeDest, mBorderSizeDest, mBounds.Height - mBorderSizeDest * 2);
				leftSource = new Rectangle(0, mBorderSizeSource, mBorderSizeSource, CurrentTexture.Height - mBorderSizeSource * 2);
			}

			// Update icon and text
			if (mIcon == null)
			{
				// Update the text position
				UpdateTextPosition();
				mTextPosition.X += mBorderSizeDest;
				mTextPosition.Y += mBorderSizeDest;
			}
			else
			{
				mIconDestination.X = mBorderSizeDest + (int)(mPosition.X - mScreenOffset.X);
				mIconDestination.Y = mBorderSizeDest + (int)(mPosition.Y - mScreenOffset.Y);
				mIconDestination.Height = (int)mSize.Y - mBorderSizeDest * 2;
				mIconDestination.Width = (int)(mIcon.Width * ((float)mIconDestination.Height / mIcon.Height));
				mTextPosition.X = mIconDestination.X + mIcon.Width + mPosition.X;
				mTextPosition.Y = mBorderSizeDest + mPosition.Y;
			}
		}

		/// <summary>
		/// Reinitialize the button to being up.
		/// </summary>
		public override void Resize()
		{
			// Set the button's state up
			State = ButtonState.UP;

			// If the parent screen is not null
			if (ParentScreen != null)
			{
				// Set the current texture to the up one
				CurrentTexture = ButtonUp;
			}
		}

		#endregion

		#region Draw

		/// <summary>
        /// Draw the button.
        /// </summary>
        /// <param name="gameTime">The current game time.</param>
        public override void Draw(Microsoft.Xna.Framework.GameTime gameTime)
        {
            // Do this if we're visible
            if (Visible)
            {
                // If we have a current texture, draw it
                if (CurrentTexture != null)
                {
                    if (mBorderSizeSource <= 0 && mBorderSizeDest <= 0)
                    {
                        // Draw the background texture
						Batch.Draw(CurrentTexture, Bounds, null, mAddColor, mRotation, Vector2.Zero, mSpriteEffects, mLayerDepth);
                    }
                    else
                    {
                        // TODO: Support rotation in bordered buttons
                        // Draw with scaled borders
						Batch.Draw(CurrentTexture, topRightDest, topRightSource, mAddColor);
						Batch.Draw(CurrentTexture, centerDest, centerSource, mAddColor);
						Batch.Draw(CurrentTexture, topLeftDest, topLeftSource, mAddColor);
						Batch.Draw(CurrentTexture, topDest, topSource, mAddColor);
						Batch.Draw(CurrentTexture, topRightDest, topRightSource, mAddColor);
						Batch.Draw(CurrentTexture, rightDest, rightSource, mAddColor);
						Batch.Draw(CurrentTexture, bottomRightDest, bottomRightSource, mAddColor);
						Batch.Draw(CurrentTexture, bottomDest, bottomSource, mAddColor);
						Batch.Draw(CurrentTexture, bottomLeftDest, bottomLeftSource, mAddColor);
						Batch.Draw(CurrentTexture, leftDest, leftSource, mAddColor);
                    }
                }

                // If we have text and a font
                if (Font != null && Text != null)
                {
                    // Draw the text to the screen
                    Batch.DrawString(Font, mText, mTextPosition - mScreenOffset, mTextColor, mRotation, Vector2.Zero, 1f, SpriteEffects.None, mLayerDepth);
                }

                if (mIcon != null)
                {
                    Batch.Draw(mIcon, mIconDestination, null, mAddColor, mRotation, Vector2.Zero, mSpriteEffects, 0);
                }
            }
        }

        #endregion
    }
}