#region ================== Copyright (c) 2007 Pascal vd Heiden

/*
 * Copyright (c) 2007 Pascal vd Heiden, www.codeimp.com
 * This program is released under GNU General Public License
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 */

#endregion

#region ================== Namespaces

using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.Text;

#endregion

namespace CodeImp.DoomBuilder.Geometry
{
	public struct Vector2D
	{
		#region ================== Constants

		private const float TINY_VALUE = 0.0000000001f;

		#endregion

		#region ================== Variables

		// Coordinates
		public float x;
		public float y;
		
		#endregion
		
		#region ================== Constructors

		// Constructor
		public Vector2D(float x, float y)
		{
			this.x = x;
			this.y = y;
		}

		// Constructor
		public Vector2D(Vector3D v)
		{
			this.x = v.x;
			this.y = v.y;
		}
		
		#endregion

		#region ================== Statics

		// Conversion to Vector3D
		public static implicit operator Vector3D(Vector2D a)
		{
			return new Vector3D(a);
		}

		// This adds two vectors
		public static Vector2D operator +(Vector2D a, Vector2D b)
		{
			return new Vector2D(a.x + b.x, a.y + b.y);
		}

		// This adds to a vector
		public static Vector2D operator +(float a, Vector2D b)
		{
			return new Vector2D(a + b.x, a + b.y);
		}

		// This adds to a vector
		public static Vector2D operator +(Vector2D a, float b)
		{
			return new Vector2D(a.x + b, a.y + b);
		}

		// This subtracts two vectors
		public static Vector2D operator -(Vector2D a, Vector2D b)
		{
			return new Vector2D(a.x - b.x, a.y - b.y);
		}

		// This subtracts from a vector
		public static Vector2D operator -(Vector2D a, float b)
		{
			return new Vector2D(a.x - b, a.y - b);
		}

		// This subtracts from a vector
		public static Vector2D operator -(float a, Vector2D b)
		{
			return new Vector2D(a - b.x, a - b.y);
		}

		// This reverses a vector
		public static Vector2D operator -(Vector2D a)
		{
			return new Vector2D(-a.x, -a.y);
		}

		// This scales a vector
		public static Vector2D operator *(float s, Vector2D a)
		{
			return new Vector2D(a.x * s, a.y * s);
		}

		// This scales a vector
		public static Vector2D operator *(Vector2D a, float s)
		{
			return new Vector2D(a.x * s, a.y * s);
		}

		// This scales a vector
		public static Vector2D operator *(Vector2D a, Vector2D b)
		{
			return new Vector2D(a.x * b.x, a.y * b.y);
		}

		// This scales a vector
		public static Vector2D operator /(float s, Vector2D a)
		{
			return new Vector2D(a.x / s, a.y / s);
		}

		// This scales a vector
		public static Vector2D operator /(Vector2D a, float s)
		{
			return new Vector2D(a.x / s, a.y / s);
		}

		// This scales a vector
		public static Vector2D operator /(Vector2D a, Vector2D b)
		{
			return new Vector2D(a.x / b.x, a.y / b.y);
		}

		// This calculates the dot product
		public static float DotProduct(Vector2D a, Vector2D b)
		{
			// Calculate and return the dot product
			return a.x * b.x + a.y * b.y;
		}

		// This calculates the cross product
		public static Vector2D CrossProduct(Vector2D a, Vector2D b)
		{
			Vector2D result = new Vector2D();

			// Calculate and return the dot product
			result.x = a.y * b.x;
			result.y = a.x * b.y;
			return result;
		}
		
		// This compares a vector
		public static bool operator ==(Vector2D a, Vector2D b)
		{
			return (a.x == b.x) && (a.y == b.y);
		}

		// This compares a vector
		public static bool operator !=(Vector2D a, Vector2D b)
		{
			return (a.x != b.x) || (a.y != b.y);
		}
		
		// This reflects the vector v over mirror m
		// Note that mirror m must be normalized!
		// R = V - 2 * M * (M dot V)
		public static Vector2D Reflect(Vector2D v, Vector2D m)
		{
			// Get the dot product of v and m
			float dp = Vector2D.DotProduct(m, v);

			// Make the reflected vector
			Vector2D mv = new Vector2D();
			mv.x = v.x - (2f * m.x * dp);
			mv.y = v.y - (2f * m.y * dp);

			// Return the reflected vector
			return mv;
		}

		// This returns the reversed vector
		public static Vector2D Reversed(Vector2D v)
		{
			// Return reversed vector
			return new Vector2D(-v.x, -v.y);
		}

		// This returns a vector from an angle
		public static Vector2D FromAngle(float angle)
		{
			// Return vector from angle
			return new Vector2D((float)Math.Sin(angle), -(float)Math.Cos(angle));
		}

		// This returns a vector from an angle with a given legnth
		public static Vector2D FromAngle(float angle, float length)
		{
			// Return vector from angle
			return FromAngle(angle) * length;
		}
		
		#endregion

		#region ================== Methods

		// This calculates the angle
		public float GetAngle()
		{
			// Calculate and return the angle
			return -(float)Math.Atan2(-y, x) + (float)Math.PI * 0.5f;
		}

		// This calculates the length
		public float GetLength()
		{
			// Calculate and return the length
			return (float)Math.Sqrt(x * x + y * y);
		}

		// This calculates the square length
		public float GetLengthSq()
		{
			// Calculate and return the square length
			return x * x + y * y;
		}

		// This calculates the length
		public float GetManhattanLength()
		{
			// Calculate and return the length
			return Math.Abs(x) + Math.Abs(y);
		}

		// This returns a normalized vector
		public Vector2D GetNormal()
		{
			float lensq = this.GetLengthSq();
			if(lensq > TINY_VALUE)
			{
				// Divide each element by the length
				float mul = 1f / (float)Math.Sqrt(lensq);
				return new Vector2D(x * mul, y * mul);
			}
			else
			{
				// Cannot make normal
				return new Vector2D(0f, 0f);
			}
		}

		// This scales the vector
		public Vector2D GetScaled(float s)
		{
			// Scale the vector
			return new Vector2D(x * s, y * s);
		}

		// This changes the vector length
		public Vector2D GetFixedLength(float l)
		{
			// Normalize, then scale
			return this.GetNormal().GetScaled(l);
		}
		
		// Output
		public override string ToString()
		{
			return x + ", " + y;
		}

		// Transform
		public unsafe Vector2D GetTransformed(float offsetx, float offsety, float scalex, float scaley)
		{
			return new Vector2D((x + offsetx) * scalex, (y + offsety) * scaley);
		}

		// Inverse Transform
		public unsafe Vector2D GetInvTransformed(float invoffsetx, float invoffsety, float invscalex, float invscaley)
		{
			return new Vector2D((x * invscalex) + invoffsetx, (y * invscaley) + invoffsety);
		}
		
		#endregion
	}
}