// Copyright (C) 2002-2007 Nikolaus Gebhardt
// This file is part of the "Irrlicht Engine".
// For conditions of distribution and use, see copyright notice in irrlicht.h

#ifndef __IRR_POINT_2D_H_INCLUDED__
#define __IRR_POINT_2D_H_INCLUDED__

#include "irrMath.h"

namespace irr
{
namespace core
{


//! 2d vector template class with lots of operators and methods.
template <class T>
class vector2d
{
public:

	vector2d() : X(0), Y(0) {}
	vector2d(T nx, T ny) : X(nx), Y(ny) {}
	vector2d(const vector2d<T>& other) : X(other.X), Y(other.Y) {}

	// operators

	vector2d<T> operator-() const { return vector2d<T>(-X, -Y); }

	vector2d<T>& operator=(const vector2d<T>& other) { X = other.X; Y = other.Y; return *this; }

	vector2d<T> operator+(const vector2d<T>& other) const { return vector2d<T>(X + other.X, Y + other.Y); }
	vector2d<T>& operator+=(const vector2d<T>& other) { X+=other.X; Y+=other.Y; return *this; }
	vector2d<T> operator+(const T v) const { return vector2d<T>(X + v, Y + v); }
	vector2d<T>& operator+=(const T v) { X+=v; Y+=v; return *this; }

	vector2d<T> operator-(const vector2d<T>& other) const { return vector2d<T>(X - other.X, Y - other.Y); }
	vector2d<T>& operator-=(const vector2d<T>& other) { X-=other.X; Y-=other.Y; return *this; }
	vector2d<T> operator-(const T v) const { return vector2d<T>(X - v, Y - v); }
	vector2d<T>& operator-=(const T v) { X-=v; Y-=v; return *this; }

	vector2d<T> operator*(const vector2d<T>& other) const { return vector2d<T>(X * other.X, Y * other.Y);	}
	vector2d<T>& operator*=(const vector2d<T>& other) { X*=other.X; Y*=other.Y; return *this; }
	vector2d<T> operator*(const T v) const { return vector2d<T>(X * v, Y * v);	}
	vector2d<T>& operator*=(const T v) { X*=v; Y*=v; return *this; }

	vector2d<T> operator/(const vector2d<T>& other) const { return vector2d<T>(X / other.X, Y / other.Y);	}
	vector2d<T>& operator/=(const vector2d<T>& other) { X/=other.X; Y/=other.Y; return *this; }
	vector2d<T> operator/(const T v) const { return vector2d<T>(X / v, Y / v);	}
	vector2d<T>& operator/=(const T v) { X/=v; Y/=v; return *this; }

	bool operator<=(const vector2d<T>&other) const { return X<=other.X && Y<=other.Y; }
	bool operator>=(const vector2d<T>&other) const { return X>=other.X && Y>=other.Y; }

	bool operator<(const vector2d<T>&other) const { return X<other.X && Y<other.Y; }
	bool operator>(const vector2d<T>&other) const { return X>other.X && Y>other.Y; }

	bool operator==(const vector2d<T>& other) const { return other.X==X && other.Y==Y; }
	bool operator!=(const vector2d<T>& other) const { return other.X!=X || other.Y!=Y; }

	// functions

	//! returns if this vector equals the other one, taking floating point rounding errors into account
	bool equals(const vector2d<T>& other) const
	{
		return core::equals(X, other.X) && core::equals(Y, other.Y);
	}

	void set(T nx, T ny) {X=nx; Y=ny; }
	void set(const vector2d<T>& p) { X=p.X; Y=p.Y;}

	//! Returns the length of the vector
	//! \return Returns the length of the vector.
	T getLength() const { return (T)sqrt((f64)(X*X + Y*Y)); }

	//! Returns the squared length of this vector
	/** This is useful because it is much faster than getLength(). */
	T getLengthSQ() const { return X*X + Y*Y; }

	//! Returns the dot product of this vector with another.
	T dotProduct(const vector2d<T>& other) const
	{
		return X*other.X + Y*other.Y;
	}

	//! Returns distance from another point. Here, the vector is interpreted
	//! as a point in 2 dimensional space.
	T getDistanceFrom(const vector2d<T>& other) const
	{
		return vector2d<T>(X - other.X, Y - other.Y).getLength();
	}

	//! Returns squared distance from another point. Here, the vector is
	//! interpreted as a point in 2 dimensional space.
	T getDistanceFromSQ(const vector2d<T>& other) const
	{
		return vector2d<T>(X - other.X, Y - other.Y).getLengthSQ();
	}

	//! rotates the point around a center by an amount of degrees.
	void rotateBy(f64 degrees, const vector2d<T>& center)
	{
		degrees *= DEGTORAD64;
		T cs = (T)cos(degrees);
		T sn = (T)sin(degrees);

		X -= center.X;
		Y -= center.Y;

		set(X*cs - Y*sn, X*sn + Y*cs);

		X += center.X;
		Y += center.Y;
	}

	//! normalizes the vector.
	vector2d<T>& normalize()
	{
		T l = X*X + Y*Y;
		if (l == 0)
			return *this;
		l = core::reciprocal_squareroot ( (f32)l );
		X *= l;
		Y *= l;
		return *this;
	}

	//! Calculates the angle of this vector in grad in the trigonometric sense.
	//! This method has been suggested by Pr3t3nd3r.
	//! \return Returns a value between 0 and 360.
	f64 getAngleTrig() const
	{
		if (X == 0)
			return Y < 0 ? 270 : 90;
		else
		if (Y == 0)
			return X < 0 ? 180 : 0;

		if ( Y > 0)
			if (X > 0)
				return atan(Y/X) * RADTODEG64;
			else
				return 180.0-atan(Y/-X) * RADTODEG64;
		else
			if (X > 0)
				return 360.0-atan(-Y/X) * RADTODEG64;
			else
				return 180.0+atan(-Y/-X) * RADTODEG64;
	} 

	//! Calculates the angle of this vector in grad in the counter trigonometric sense.
	//! \return Returns a value between 0 and 360.
	inline f64 getAngle() const
	{
		if (Y == 0)  // corrected thanks to a suggestion by Jox
			return X < 0 ? 180 : 0; 
		else if (X == 0) 
			return Y < 0 ? 90 : 270;

		f64 tmp = Y / getLength();
		tmp = atan(sqrt(1 - tmp*tmp) / tmp) * RADTODEG64;

		if (X>0 && Y>0)
			return tmp + 270;
		else
		if (X>0 && Y<0)
			return tmp + 90;
		else
		if (X<0 && Y<0)
			return 90 - tmp;
		else
		if (X<0 && Y>0)
			return 270 - tmp;

		return tmp;
	}

	//! Calculates the angle between this vector and another one in grad.
	//! \return Returns a value between 0 and 90.
	inline f64 getAngleWith(const vector2d<T>& b) const
	{
		f64 tmp = X*b.X + Y*b.Y;

		if (tmp == 0.0)
			return 90.0;

		tmp = tmp / sqrt((f64)((X*X + Y*Y) * (b.X*b.X + b.Y*b.Y)));
		if (tmp < 0.0)
			tmp = -tmp;

		return atan(sqrt(1 - tmp*tmp) / tmp) * RADTODEG64;
	}

	//! Returns if this vector interpreted as a point is on a line between two other points.
	/** It is assumed that the point is on the line. */
	//! \param begin: Beginning vector to compare between.
	//! \param end: Ending vector to compare between.
	//! \return True if this vector is between begin and end.  False if not.
	bool isBetweenPoints(const vector2d<T>& begin, const vector2d<T>& end) const
	{
		T f = (end - begin).getLengthSQ();
		return getDistanceFromSQ(begin) < f && 
			getDistanceFromSQ(end) < f;
	}

	//! returns interpolated vector
	//! \param other: other vector to interpolate between
	//! \param d: value between 0.0f and 1.0f.
	vector2d<T> getInterpolated(const vector2d<T>& other, f32 d) const
	{
		T inv = (T) 1.0 - d;
		return vector2d<T>(other.X*inv + X*d, other.Y*inv + Y*d);
	}

	//! Returns (quadratically) interpolated vector between this and the two given ones.
	/** \param v2: second vector to interpolate with
	\param v3: third vector to interpolate with
	\param d: value between 0.0f and 1.0f. */
	vector2d<T> getInterpolated_quadratic(const vector2d<T>& v2, const vector2d<T>& v3, const T d) const
	{
		// this*(1-d)*(1-d) + 2 * v2 * (1-d) + v3 * d * d;
		const T inv = (T) 1.0 - d;
		const T mul0 = inv * inv;
		const T mul1 = (T) 2.0 * d * inv;
		const T mul2 = d * d;

		return vector2d<T> ( X * mul0 + v2.X * mul1 + v3.X * mul2,
					Y * mul0 + v2.Y * mul1 + v3.Y * mul2);
	}

	//! sets this vector to the linearly interpolated vector between a and b.
	/** \param a: first vector to interpolate with
	\param b: second vector to interpolate with
	\param t: value between 0.0f and 1.0f. */
	void interpolate(const vector2d<T>& a, const vector2d<T>& b, const f32 t)
	{
		X = b.X + ( ( a.X - b.X ) * t );
		Y = b.Y + ( ( a.Y - b.Y ) * t );
	}

	// member variables
	T X, Y;
};

	//! Typedef for f32 2d vector.
	typedef vector2d<f32> vector2df;
	//! Typedef for integer 2d vector.
	typedef vector2d<s32> vector2di;

	template<class S, class T>
	vector2d<T> operator*(const S scalar, const vector2d<T>& vector) { return vector*scalar; }

} // end namespace core
} // end namespace irr

#endif