// ClassicalSharp copyright 2014-2016 UnknownShadow200 | Licensed under MIT
using System;
using ClassicalSharp.Entities;
using ClassicalSharp.Events;
using ClassicalSharp.GraphicsAPI;
using ClassicalSharp.Model;
using OpenTK;

namespace ClassicalSharp.Renderers {
	
	public class HeldBlockRenderer : IGameComponent {
		
		internal byte type;
		internal BlockModel block;
		internal HeldBlockAnimation anim;
		
		Game game;		
		FakePlayer held;
		Matrix4 heldBlockProj;		
		
		public void Init( Game game ) {
			this.game = game;
			block = new BlockModel( game );
			block.NoShade = true;
			held = new FakePlayer( game );
			game.Events.ProjectionChanged += ProjectionChanged;
			
			anim = new HeldBlockAnimation();
			anim.Init( game, this );
		}

		public void Ready( Game game ) { }
		public void Reset( Game game ) { }
		public void OnNewMap( Game game ) { }
		public void OnNewMapLoaded( Game game ) { }
		
		public void Render( double delta ) {
			if( game.Camera.IsThirdPerson || !game.ShowBlockInHand ) return;

			Vector3 last = anim.pos;
			anim.pos = Vector3.Zero;
			type = game.Inventory.HeldBlock;
			block.CosX = 1; block.SinX = 0;
			block.SwitchOrder = false;			
			if( anim.doAnim ) anim.Update( delta, last );
			
			SetMatrix();
			game.Graphics.SetMatrixMode( MatrixType.Projection );
			game.Graphics.LoadMatrix( ref heldBlockProj );
			bool translucent = game.BlockInfo.IsTranslucent[type];
			
			game.Graphics.Texturing = true;
			if( translucent ) game.Graphics.AlphaBlending = true;
			else game.Graphics.AlphaTest = true;
			game.Graphics.DepthTest = false;
			
			SetPos();
			block.Render( held );
			
			game.Graphics.LoadMatrix( ref game.Projection );
			game.Graphics.SetMatrixMode( MatrixType.Modelview );
			game.Graphics.LoadMatrix( ref game.View );
			
			game.Graphics.Texturing = false;
			if( translucent ) game.Graphics.AlphaBlending = false;
			else game.Graphics.AlphaTest = false;
			game.Graphics.DepthTest = true;
		}
		
		static Vector3 nOffset = new Vector3( 0.56f, -0.72f, -0.72f );
		static Vector3 sOffset = new Vector3( 0.46f, -0.52f, -0.72f );		
		void SetMatrix() {
			Player p = game.LocalPlayer;
			Vector3 eyePos = p.EyePosition;
			Matrix4 m = Matrix4.LookAt( eyePos, eyePos - Vector3.UnitZ, Vector3.UnitY ) * game.Camera.tiltM;
			game.Graphics.LoadMatrix( ref m );
		}
	   
		void SetPos() {
			// Based off details from http://pastebin.com/KFV0HkmD (Thanks goodlyay!)
			BlockInfo info = game.BlockInfo;
			Vector3 offset = info.IsSprite[type] ? sOffset : nOffset;
			Player p = game.LocalPlayer;
			held.ModelScale = 0.4f;
		   
			held.Position = p.EyePosition + anim.pos;
			held.Position += offset;
			if( !info.IsSprite[type] ) {
				float height = info.MaxBB[type].Y - info.MinBB[type].Y;
				held.Position.Y += 0.2f * (1 - height);
			}
		   
			held.Position.X -= game.Camera.bobbingHor;
			held.Position.Y -= game.Camera.bobbingVer;
			held.Position.Z -= game.Camera.bobbingHor;
			   
			held.HeadYawDegrees = -45 + anim.angleY;
			held.YawDegrees = -45 + anim.angleY;
			held.PitchDegrees = 0;
			held.Block = type;
		}
		
		void ProjectionChanged( object sender, EventArgs e ) {
			float aspectRatio = (float)game.Width / game.Height;
			float zNear = game.Graphics.MinZNear;
			heldBlockProj = Matrix4.CreatePerspectiveFieldOfView( 70 * Utils.Deg2Rad,
																 aspectRatio, zNear, game.ViewDistance );
		}
		
		public void Dispose() {
			game.Events.ProjectionChanged -= ProjectionChanged;
			anim.Dispose();
		}
	}
	
	/// <summary> Skeleton implementation of a player entity so we can reuse
	/// block model rendering code. </summary>
	internal class FakePlayer : Player {
		
		public FakePlayer( Game game ) : base( game ) {
		}
		public byte Block;
		
		public override void SetLocation( LocationUpdate update, bool interpolate ) { }
		
		public override void Tick( double delta ) { }

		public override void RenderModel( double deltaTime, float t ) { }
		
		public override void RenderName() { }
	}
}