#region Copyright & License Information
/*
 * Copyright 2007-2011 The OpenRA Developers (see AUTHORS)
 * This file is part of OpenRA, which is free software. It is made
 * available to you under the terms of the GNU General Public License
 * as published by the Free Software Foundation. For more information,
 * see COPYING.
 */
#endregion

using System;
using System.Collections.Generic;

namespace OpenRA.Graphics
{
	public class Animation
	{
		string name;
		public Sequence CurrentSequence { get; private set; }
		int frame = 0;
		bool backwards = false;
		bool tickAlways;

		Func<int> facingFunc;

		public string Name { get { return name; } }

		public Animation(string name)
			: this(name, () => 0)	{}

		public Animation(string name, Func<int> facingFunc)
		{
			this.name = name.ToLowerInvariant();
			this.tickFunc = () => {};
			this.facingFunc = facingFunc;
		}

		public Sprite Image
		{
			get
			{
				return backwards
					? CurrentSequence.GetSprite(CurrentSequence.Start + CurrentSequence.Length - frame - 1, facingFunc())
					: CurrentSequence.GetSprite(frame, facingFunc());
			}
		}

		public IEnumerable<IRenderable> Render(WPos pos, int zOffset, PaletteReference palette, float scale)
		{
			yield return new SpriteRenderable(Image, pos, CurrentSequence.ZOffset + zOffset, palette, scale);
		}

		public IEnumerable<IRenderable> Render(WPos pos, PaletteReference palette)
		{
			return Render(pos, 0, palette, 1f);
		}

		public void Play(string sequenceName)
		{
			PlayThen(sequenceName, null);
		}

		public void PlayRepeating(string sequenceName)
		{
			backwards = false;
			tickAlways = false;
			CurrentSequence = SequenceProvider.GetSequence(name, sequenceName);
			frame = 0;
			tickFunc = () =>
			{
				++frame;
				if (frame >= CurrentSequence.Length)
					frame = 0;
			};
		}

		public bool ReplaceAnim(string sequenceName)
		{
			if (!HasSequence(sequenceName))
				return false;

			CurrentSequence = SequenceProvider.GetSequence(name, sequenceName);
			frame %= CurrentSequence.Length;
			return true;
		}

		public void PlayThen(string sequenceName, Action after)
		{
			backwards = false;
			tickAlways = false;
			CurrentSequence = SequenceProvider.GetSequence(name, sequenceName);
			frame = 0;
			tickFunc = () =>
			{
				++frame;
				if (frame >= CurrentSequence.Length)
				{
					frame = CurrentSequence.Length - 1;
					tickFunc = () => { };
					if (after != null) after();
				}
			};
		}

		public void PlayBackwardsThen(string sequenceName, Action after)
		{
			PlayThen(sequenceName, after);
			backwards = true;
		}

		public void PlayFetchIndex(string sequenceName, Func<int> func)
		{
			backwards = false;
			tickAlways = true;
			CurrentSequence = SequenceProvider.GetSequence(name, sequenceName);
			frame = func();
			tickFunc = () => frame = func();
		}

		int timeUntilNextFrame;
		Action tickFunc;

		public void Tick()
		{
			Tick(40); // tick one frame
		}

		public bool HasSequence(string seq) { return SequenceProvider.HasSequence(name, seq); }

		public void Tick(int t)
		{
			if (tickAlways)
				tickFunc();
			else
			{
				timeUntilNextFrame -= t;
				while (timeUntilNextFrame <= 0)
				{
					tickFunc();
					timeUntilNextFrame += CurrentSequence != null ? CurrentSequence.Tick : 40; // 25 fps == 40 ms
				}
			}
		}

		public void ChangeImage(string newImage, string newAnimIfMissing)
		{
			newImage = newImage.ToLowerInvariant();

			if (name != newImage)
			{
				name = newImage.ToLowerInvariant();
				if (!ReplaceAnim(CurrentSequence.Name))
					ReplaceAnim(newAnimIfMissing);
			}
		}

		public Sequence GetSequence(string sequenceName)
		{
			return SequenceProvider.GetSequence(name, sequenceName);
		}
	}
}