#region File Description
//-----------------------------------------------------------------------------
// Animation.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion

#region File Information
//-----------------------------------------------------------------------------
// Animation.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion

#region Using Statements
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
#endregion

namespace CatapultGame
{
    class Animation
    {
        #region Fields
        // Animation variables
        Texture2D animatedCharacter;
        Point sheetSize;     
        Point currentFrame;
        public Point FrameSize { get; set; }

        public int FrameCount
        {
            get { return sheetSize.X * sheetSize.Y; }
        }

        public Vector2 Offset { get; set; }

        /// <summary>
        /// Returns or sets the current animation frame.
        /// </summary>
        public int FrameIndex
        {
            get
            {
                return sheetSize.X * currentFrame.Y + currentFrame.X;
            }
            set
            {
                if (value >= sheetSize.X * sheetSize.Y + 1)
                {
                    throw new InvalidOperationException(
                        "Specified frame index exeeds available frames");
                }

                currentFrame.Y = value / sheetSize.X;
                currentFrame.X = value % sheetSize.X;
            }
        }

        public bool IsActive { get; private set; }
        #endregion

        #region Initialization
        /// <summary>
        /// Constructor of an animation class
        /// </summary>
        /// <param name="frameSheet">Texture with animation frames sheet</param>
        /// <param name="size">Single frame size</param>
        /// <param name="frameSheetSize">The whole frame sheet size</param>
        /// <param name="interval">Interval between progressing to the next frame</param>
        public Animation(Texture2D frameSheet, Point size,
            Point frameSheetSize)
        {
            animatedCharacter = frameSheet;
            FrameSize = size;
            sheetSize = frameSheetSize;
            Offset = Vector2.Zero;
        }
        #endregion

        #region Update and Render
        /// <summary>
        /// Updates the animaton progress
        /// </summary>
        public void Update()
        {
            if (IsActive)
            {
                if (FrameIndex >= FrameCount - 1)
                {                  
                    IsActive = false;
                    FrameIndex = FrameCount - 1; // Stop at last frame 
                }
                else
                {
                    // Remember that updating "currentFrame" will also
                    // update the FrameIndex property.

                    currentFrame.X++;
                    if (currentFrame.X >= sheetSize.X)
                    {
                        currentFrame.X = 0;
                        currentFrame.Y++;
                    }
                    if (currentFrame.Y >= sheetSize.Y)
                        currentFrame.Y = 0;
                }             
            }           
        }

        /// <summary>
        /// Rendering of the animation
        /// </summary>
        /// <param name="spriteBatch">SpriteBatch in which current 
        /// frame will be rendered</param>
        /// <param name="position">The position of current frame</param>
        /// <param name="spriteEffect">SpriteEffect to apply on 
        /// current frame</param>
        public void Draw(SpriteBatch spriteBatch, Vector2 position, 
            SpriteEffects spriteEffect)
        {
            Draw(spriteBatch, position, 1.0f, spriteEffect);
        }

        /// <summary>
        /// Rendering of the animation
        /// </summary>
        /// <param name="spriteBatch">SpriteBatch in which current frame
        /// will be rendered</param>
        /// <param name="position">The position of the current frame</param>
        /// <param name="scale">Scale factor to apply on the current frame</param>
        /// <param name="spriteEffect">SpriteEffect to apply on the 
        /// current frame</param>
        public void Draw(SpriteBatch spriteBatch, Vector2 position, float scale, 
            SpriteEffects spriteEffect)
        {
            spriteBatch.Draw(animatedCharacter, position + Offset, new Rectangle(
                  FrameSize.X * currentFrame.X,
                  FrameSize.Y * currentFrame.Y,
                  FrameSize.X,
                  FrameSize.Y),
                  Color.White, 0f, Vector2.Zero, scale, spriteEffect, 0);
        }

        /// <summary>
        /// Causes the animation to start playing from a specified frame index
        /// </summary>
        /// <param name="frameIndex"></param>
        public void PlayFromFrameIndex(int frameIndex)
        {
            FrameIndex = frameIndex;
            IsActive = true;
        }
        #endregion
    }
}