using System;

using System.IO;

using Delta.Engine;

using Delta.InputSystem;

using Delta.Utilities;

using Delta.Utilities.Datatypes;

using Delta.Utilities.Helpers;

using NUnit.Framework;



namespace Delta.Rendering.Cameras

{

	/// <summary>

	/// 3D isometric perspective camera which works as LookAtCamera and has its 

	/// target but the different is that it has isometric projection.

	/// </summary>

	public class IsometricCamera : BaseCamera

	{

		#region Constants

		/// <summary>

		/// The current version of the implementation of this Camera class.

		/// </summary>

		private const int ImplementationVersion = 1;



		/// <summary>

		/// The Move speed Per Second.

		/// </summary>

		private const float MPS = 100.0f;

		#endregion



		#region Position (Public)

		/// <summary>

		/// The camera position

		/// </summary>

		public override Vector Position

		{

			get

			{

				return position;

			}

			set

			{

				position = value;

				Target = position + (lookDirection * distance);

			}

		}

		#endregion



		#region Target (Public)

		/// <summary>

		/// The camera target position.

		/// </summary>

		public override Vector Target

		{

			get

			{

				return target;

			}

			set

			{

				target = value;

				position = target - (lookDirection * distance);

			}

		}

		#endregion



		#region Distance (Public)

		/// <summary>

		/// The distance between target position and camera position.

		/// </summary>

		public override float Distance

		{

			get

			{

				return distance;

			}

			set

			{

				// The effect of the distance is invariant for the IsometricCamera

				// because it uses orthographics projection so we actually "fake"

				// the behavior of zooming/unzooming by scaling the whole world



				// only positive values are accepted for distance!

				if (value > 0.0f)

				{

					distance = value;



					// update the camera position

					position = target - (lookDirection * distance);



					// the larger the distance, the lower the scaling

					// + some additional adjustment

					scale = Matrix.CreateScale(distance);

				}

			}

		}

		#endregion



		#region LookDirection (Public)

		/// <summary>

		/// override the look direction to prevent the set accessor is making

		/// bad stuff. An isometric camera always have the same lookdirection,

		/// which is set in the constructor.

		/// </summary>

		public override Vector LookDirection

		{

			get

			{

				return lookDirection;

			}

			set

			{

			}

		}

		#endregion



		#region Private



		#region scale (Private)

		/// <summary>

		/// Scaling that emulates the Distance property for the isometric camera

		/// </summary>

		private Matrix scale;

		#endregion



		#endregion



		#region Constructors

		/// <summary>

		/// Create isometric camera

		/// </summary>

		/// <param name="setPosition">Camera initial position.</param>

		public IsometricCamera(Vector setPosition)

			: base(setPosition)

		{

			lookDirection = new Vector(1, 1, -1);

			// Set some default values

			Distance = 1f;

		}

		#endregion



		#region Zoom (Public)

		/// <summary>

		/// Zoom in or out. if respectFPS is set to true, Time.Delta will be taken

		/// into account. E.g.: set this to true for hold-able buttons.

		/// </summary>

		/// <param name="zoomIn">if set to <c>true</c> [zoom in].</param>

		public void Zoom(bool zoomIn)

		{

			if (IsLocked)

			{

				return;

			}

			float zoomSpeed = MathHelper.Max(Distance, 0.1f) * 0.1f *

			                  MPS * (Time.Delta * 10f);

			// Limit zoomSpeed, else we get into millions too quickly

			zoomSpeed = MathHelper.Min(zoomSpeed, 10 * Time.Delta);

			Distance += zoomIn

			            	? -zoomSpeed

			            	: zoomSpeed;

		}

		#endregion



		#region UpdateProjectionMatrix (Public)

		/// <summary>

		/// Update projection matrix

		/// </summary>

		public override void UpdateProjectionMatrix()

		{

			// isometric uses an orthographic projection.

			float halfWidth = Application.Window.ViewportPixelWidth;

			float halfHeight = Application.Window.ViewportPixelHeight;

			projectionMatrix = Matrix.CreateOrthographic(-halfWidth, halfWidth,

				halfHeight, -halfHeight, NearPlane, FarPlane);

		}

		#endregion



		#region Save (Public)

		/// <summary>

		/// Override saving data from BinaryStream.

		/// </summary>

		/// <param name="dataWriter">Binary writer used for writing data.</param>

		public override void Save(BinaryWriter dataWriter)

		{

			base.Save(dataWriter);



			// Save the implementation version first

			dataWriter.Write(ImplementationVersion);



			// just need to save the scale matrix here

			scale.Save(dataWriter);

		}

		#endregion



		#region Load (Public)

		/// <summary>

		/// Override loading data from BinaryStream.

		/// </summary>

		/// <param name="reader">Binary reader used for reading data.</param>

		public override void Load(BinaryReader reader)

		{

			base.Load(reader);



			// First read the implementation version

			int version = reader.ReadInt32();

			switch (version)

			{

					// Version 1

				case 1:

					// Need just to read the scale matrix here

					scale.Load(reader);

					break;



				default:

					Log.InvalidVersionWarning(GetType().Name + ": " + Name,

						version, ImplementationVersion);

					break;

			}

		}

		#endregion



		#region Methods (Private)



		#region SetupInputCommands

		/// <summary>

		/// Setup the connection between input commands and camera movement.

		/// </summary>

		protected override void SetupInputCommands()

		{

			#region Zoom

			Input.Commands[Command.CameraZoomIn].Add(delegate

			{

				Zoom(true);

			});

			Input.Commands[Command.CameraZoomOut].Add(delegate

			{

				Zoom(false);

			});

			#endregion

		}

		#endregion



		#region UpdateViewMatrix

		protected override void UpdateViewMatrix()

		{

			base.UpdateViewMatrix();

		}

		#endregion



		#endregion



		/// <summary>

		/// Tests

		/// </summary>

		internal class IsometricCameraTests

		{

			#region TestSaveAndLoad (LongRunning)

			/// <summary>

			/// Test save and load functionality of the Graph class

			/// </summary>

			[Test, Category("LongRunning")]

			public void TestSaveAndLoad()

			{

				// Creation of the graph

				IsometricCamera isoCamera = new IsometricCamera(new Vector(3, -6, 8))

				{

					// BaseCamera

					LookDirection = new Vector(-1, 2, -1),

					Target = new Vector(3, 4, 1),

					Rotation = new Vector(3, 1, 0),

					FieldOfView = 65,

					FarPlane = 205,

					NearPlane = 0.15f,

					AlwaysNeedsUpdate = true,

					IsLocked = true,

					// IsometricCamera

					scale = Matrix.CreateScale(0.3f, 1.4f, 0.58f),

				};



				// Saving

				MemoryStream savedStream = new MemoryStream();

				BinaryWriter writer = new BinaryWriter(savedStream);

				isoCamera.Save(writer);

				writer.Flush();

				writer = null;



				// Loading

				savedStream.Position = 0;

				BinaryReader reader = new BinaryReader(savedStream);

				IsometricCamera loadedCamera = new IsometricCamera(Vector.Zero);

				loadedCamera.Load(reader);



				// Checking

				// BaseCamera values

				Assert.Equal(loadedCamera.LookDirection, isoCamera.LookDirection);

				Assert.Equal(loadedCamera.Target, isoCamera.Target);

				Assert.Equal(loadedCamera.Rotation, isoCamera.Rotation);

				Assert.Equal(loadedCamera.FieldOfView, isoCamera.FieldOfView);

				Assert.Equal(loadedCamera.FarPlane, isoCamera.FarPlane);

				Assert.Equal(loadedCamera.NearPlane, isoCamera.NearPlane);

				Assert.Equal(loadedCamera.AlwaysNeedsUpdate,

					isoCamera.AlwaysNeedsUpdate);

				Assert.Equal(loadedCamera.IsLocked, isoCamera.IsLocked);

				// IsometricCamera values

				Assert.Equal(loadedCamera.scale, isoCamera.scale);

			}

			#endregion

		}

	}

}