using System;
using System.Drawing;
using System.Windows.Forms;
using OpenTK;
using OpenTK.Input;

namespace ClassicalSharp {
	
	public abstract class Camera {
		public Game Window;
		
		public abstract Matrix4 GetProjection();
		
		public abstract Matrix4 GetView();
		
		public abstract bool IsThirdPerson { get; }
		
		public virtual void Tick( double elapsed ) {
		}
		
		public virtual void MouseZoom( MouseWheelEventArgs e ) {
		}
		
		public abstract void RegrabMouse();
		
		public virtual PickedPos GetPickedPos() {
			return null;
		}
	}
	
	public abstract class PerspectiveCamera : Camera {
		
		protected Player player;
		public PerspectiveCamera( Game window ) {
			Window = window;
			player = Window.LocalPlayer;
		}
		
		public override Matrix4 GetProjection() {
			float fovy = (float)Utils.DegreesToRadians( 70 );
			float aspectRatio = (float)Window.Width / Window.Height;
			return Matrix4.CreatePerspectiveFieldOfView( fovy, aspectRatio, 0.1f, Window.ViewDistance );
		}
		
		public override PickedPos GetPickedPos() {
			Vector3 dir = Utils.GetDirectionVector( player.YawRadians, player.PitchRadians + Math.PI );
			Vector3 eyePos = player.EyePosition;
			float reach = Window.LocalPlayer.ReachDistance;
			return Picking.GetPickedBlockPos( Window, eyePos, dir, reach );
		}
		
		Point previous, delta;
		Vector2 Orientation;
		void CentreMousePosition() {
			if( !Window.Focused ) return;
			Point current = Cursor.Position;
			delta = new Point( current.X - previous.X, current.Y - previous.Y );
			Rectangle bounds = Window.Bounds;
			int cenX = bounds.Left + bounds.Width / 2;
			int cenY = bounds.Top + bounds.Height / 2;
			Cursor.Position = new Point( cenX, cenY );
			previous = new Point( cenX, cenY );
		}
		
		public override void RegrabMouse() {
			Rectangle bounds = Window.Bounds;
			int cenX = bounds.Left + bounds.Width / 2;
			int cenY = bounds.Top + bounds.Height / 2;
			Cursor.Position = new Point( cenX, cenY );
			previous = new Point( cenX, cenY );
			delta = Point.Empty;
		}
		
		const float sensitivity = 0.01f; // max 0.025?
		private void UpdateMouseRotation() {
			Orientation.X += delta.X * sensitivity;
			Orientation.Y += delta.Y * sensitivity;

			Clamp( ref Orientation.Y, halfPi + 0.01f, threeHalfPi - 0.01f );
			LocationUpdate update = LocationUpdate.MakeOri(
				(float)Utils.RadiansToDegrees( Orientation.X ),
				(float)Utils.RadiansToDegrees( Orientation.Y - Math.PI )
			);
			Window.LocalPlayer.SetLocation( update, true );
		}
		const float halfPi = (float)( Math.PI / 2 );
		const float threeHalfPi = (float)( 3 * Math.PI / 2 );

		public override void Tick( double elapsed ) {
			if( Window.ScreenLockedInput ) return;
			CentreMousePosition();
			UpdateMouseRotation();
		}
		
		static void Clamp( ref float value, float min, float max ) {
			if( value < min ) value = min;
			if( value > max ) value = max;
		}
	}
	
	public class ThirdPersonCamera : PerspectiveCamera {
		
		public ThirdPersonCamera( Game window ) : base( window ) {
		}
		
		float distance = 3;		
		public override void MouseZoom( MouseWheelEventArgs e ) {
			distance -= e.DeltaPrecise;
			if( distance < 2 ) distance = 2;
		}
		
		public override Matrix4 GetView() {
			Vector3 eyePos = player.EyePosition;
			Vector3 cameraPos = eyePos - Utils.GetDirectionVector( player.YawRadians, player.PitchRadians + Math.PI ) * distance;
			return Matrix4.LookAt( cameraPos, eyePos, Vector3.UnitY );
		}
		
		public override bool IsThirdPerson {
			get { return true; }
		}
	}
	
	public class FirstPersonCamera : PerspectiveCamera {
		
		public FirstPersonCamera( Game window ) : base( window ) {
		}
		
		public override Matrix4 GetView() {
			Vector3 eyePos = player.EyePosition;
			Vector3 cameraDir = Utils.GetDirectionVector( player.YawRadians, player.PitchRadians + Math.PI );
			return Matrix4.LookAt( eyePos, eyePos + cameraDir, Vector3.UnitY );
		}
		
		public override bool IsThirdPerson {
			get { return false; }
		}
	}
}