#ifndef _GEOMETRY_VECTOR2_H_
#define _GEOMETRY_VECTOR2_H_

#include "basis.h"
#include "angle.h"

#include <math.h>

typedef struct
{
    float x1, x2;
} SPVector2;

typedef struct
{
    double x1, x2;
} DPVector2;

// =================== Reset ==================== //

static inline void sp_vector2_reset(SPVector2* vector)
{
    vector->x1 = 0.0f;
    vector->x2 = 0.0f;
}

static inline void dp_vector2_reset(DPVector2* vector)
{
    vector->x1 = 0.0;
    vector->x2 = 0.0;
}

// ==================== Set ===================== //

static inline void sp_vector2_set_values(const float x1, const float x2, SPVector2* to)
{
    to->x1 = x1;
    to->x2 = x2;
}

static inline void dp_vector2_set_values(const double x1, const double x2, DPVector2* to)
{
    to->x1 = x1;
    to->x2 = x2;
}

// ==================== Copy ==================== //

static inline void sp_vector2_copy(const SPVector2* from, SPVector2* to)
{
    to->x1 = from->x1;
    to->x2 = from->x2;
}

static inline void dp_vector2_copy(const DPVector2* from, DPVector2* to)
{
    to->x1 = from->x1;
    to->x2 = from->x2;
}

// ============= Copy to twin type ============== //

static inline void sp_vector2_copy_from_double(const DPVector2* from, SPVector2* to)
{
    to->x1 = (float)from->x1;
    to->x2 = (float)from->x2;
}

static inline void dp_vector2_copy_from_single(const SPVector2* from, DPVector2* to)
{
    to->x1 = from->x1;
    to->x2 = from->x2;
}

// =================== Reverse ================== //

static inline void sp_vector2_reverse(const SPVector2* from, SPVector2* to)
{
    to->x1 = -from->x1;
    to->x2 = -from->x2;
}

static inline void dp_vector2_reverse(const DPVector2* from, DPVector2* to)
{
    to->x1 = -from->x1;
    to->x2 = -from->x2;
}

// ============= Reverse twin type ============== //

static inline void sp_vector2_reverse_double(const DPVector2* from, SPVector2* to)
{
    to->x1 = -(float)from->x1;
    to->x2 = -(float)from->x2;
}

static inline void dp_vector2_reverse_single(const SPVector2* from, DPVector2* to)
{
    to->x1 = -from->x1;
    to->x2 = -from->x2;
}

// =================== Module =================== //

static inline float sp_vector2_get_square_module(const SPVector2* vector)
{
    return vector->x1 * vector->x1 + vector->x2 * vector->x2;
}

static inline double dp_vector2_get_square_module(const DPVector2* vector)
{
    return vector->x1 * vector->x1 + vector->x2 * vector->x2;
}

static inline float sp_vector2_get_module(const SPVector2* vector)
{
    return sqrtf(sp_vector2_get_square_module(vector));
}

static inline double dp_vector2_get_module(const DPVector2* vector)
{
    return sqrt(dp_vector2_get_square_module(vector));
}

// ================= Comparison ================= //

static inline int sp_vector2_is_zero(const SPVector2* vector)
{
    return sp_vector2_get_square_module(vector) <= SP_SQUARE_EPSYLON;
}

static inline int dp_vector2_is_zero(const DPVector2* vector)
{
    return dp_vector2_get_square_module(vector) <= DP_SQUARE_EPSYLON;
}

static inline int sp_vector2_is_unit(const SPVector2* vector)
{
    const float square_module = sp_vector2_get_square_module(vector);

    return 1.0f - SP_TWO_EPSYLON <= square_module && square_module <= 1.0f + SP_TWO_EPSYLON;
}

static inline int dp_vector2_is_unit(const DPVector2* vector)
{
    const double square_module = dp_vector2_get_square_module(vector);

    return 1.0f - DP_TWO_EPSYLON <= square_module && square_module <= 1.0f + DP_TWO_EPSYLON;
}

// ==================== Add ===================== //

static inline void sp_vector2_add(const SPVector2* vector1, const SPVector2* vector2, SPVector2* result)
{
    result->x1 = vector1->x1 + vector2->x1;
    result->x2 = vector1->x2 + vector2->x2;
}

static inline void dp_vector2_add(const DPVector2* vector1, const DPVector2* vector2, DPVector2* result)
{
    result->x1 = vector1->x1 + vector2->x1;
    result->x2 = vector1->x2 + vector2->x2;
}

// ================ Subtraction ================= //

static inline void sp_vector2_subtract(const SPVector2* minuend, const SPVector2* subtrahend, SPVector2* result)
{
    result->x1 = minuend->x1 - subtrahend->x1;
    result->x2 = minuend->x2 - subtrahend->x2;
}

static inline void dp_vector2_subtract(const DPVector2* minuend, const DPVector2* subtrahend, DPVector2* result)
{
    result->x1 = minuend->x1 - subtrahend->x1;
    result->x2 = minuend->x2 - subtrahend->x2;
}

// =============== Multiplication =============== //

static inline void sp_vector2_multiply(const SPVector2* multiplicand, const float multiplier, SPVector2* result)
{
    result->x1 = multiplicand->x1 * multiplier;
    result->x2 = multiplicand->x2 * multiplier;
}

static inline void dp_vector2_multiply(const DPVector2* multiplicand, const double multiplier, DPVector2* result)
{
    result->x1 = multiplicand->x1 * multiplier;
    result->x2 = multiplicand->x2 * multiplier;
}

// ================== Division ================== //

static inline void sp_vector2_divide(const SPVector2* dividend, const float divisor, SPVector2* result)
{
    result->x1 = dividend->x1 / divisor;
    result->x2 = dividend->x2 / divisor;
}

static inline void dp_vector2_divide(const DPVector2* dividend, const double divisor, DPVector2* result)
{
    result->x1 = dividend->x1 / divisor;
    result->x2 = dividend->x2 / divisor;
}

// ================ Append scaled =============== //

static inline void sp_vector2_append_scaled(SPVector2* basic_vector, const SPVector2* scalable_summand, const float scale)
{
    basic_vector->x1 += scalable_summand->x1 * scale;
    basic_vector->x2 += scalable_summand->x2 * scale;
}

static inline void dp_vector2_append_scaled(DPVector2* basic_vector, const DPVector2* scalable_summand, const double scale)
{
    basic_vector->x1 += scalable_summand->x1 * scale;
    basic_vector->x2 += scalable_summand->x2 * scale;
}

// ================== Average2 ================== //

static inline void sp_vector2_get_mean2(const SPVector2* vector1, const SPVector2* vector2, SPVector2* result)
{
    result->x1 = (vector1->x1 + vector2->x1) * 0.5f;
    result->x2 = (vector1->x2 + vector2->x2) * 0.5f;
}

static inline void dp_vector2_get_mean2(const DPVector2* vector1, const DPVector2* vector2, DPVector2* result)
{
    result->x1 = (vector1->x1 + vector2->x1) * 0.5;
    result->x2 = (vector1->x2 + vector2->x2) * 0.5;
}

// ================== Average3 ================== //

static inline void sp_vector2_get_mean3(const SPVector2* vector1, const SPVector2* vector2, const SPVector2* vector3, SPVector2* result)
{
    result->x1 = (vector1->x1 + vector2->x1 + vector3->x1) * SP_ONE_THIRD;
    result->x2 = (vector1->x2 + vector2->x2 + vector3->x2) * SP_ONE_THIRD;
}

static inline void dp_vector2_get_mean3(const DPVector2* vector1, const DPVector2* vector2, const DPVector2* vector3, DPVector2* result)
{
    result->x1 = (vector1->x1 + vector2->x1 + vector3->x1) * DP_ONE_THIRD;
    result->x2 = (vector1->x2 + vector2->x2 + vector3->x2) * DP_ONE_THIRD;
}

// =============== Scalar Product =============== //

static inline float sp_vector2_scalar(const SPVector2* vector1, const SPVector2* vector2)
{
    return vector1->x1 * vector2->x1 + vector1->x2 * vector2->x2;
}

static inline double dp_vector2_scalar(const DPVector2* vector1, const DPVector2* vector2)
{
    return vector1->x1 * vector2->x1 + vector1->x2 * vector2->x2;
}

// =============== Cross Product ================ //

static inline float sp_vector2_cross(const SPVector2* vector1, const SPVector2* vector2)
{
    return vector1->x1 * vector2->x2 - vector1->x2 * vector2->x1;
}

static inline double dp_vector2_cross(const DPVector2* vector1, const DPVector2* vector2, DPVector2* result)
{
    return vector1->x1 * vector2->x2 - vector1->x2 * vector2->x1;
}

// =============== Normalization ================ //

static inline int sp_vector2_normalize(SPVector2* vector)
{
    const float square_module = sp_vector2_get_square_module(vector);

    if (1.0f - SP_TWO_EPSYLON <= square_module && square_module <= 1.0f + SP_TWO_EPSYLON) {
        return 1;
    }

    if (square_module <= SP_SQUARE_EPSYLON) {
        sp_vector2_reset(vector);
        return 0;
    }

    sp_vector2_divide(vector, sqrtf(square_module), vector);
    return 1;
}

static inline int dp_vector2_normalize(DPVector2* vector)
{
    const double square_module = dp_vector2_get_square_module(vector);

    if (1.0 - DP_TWO_EPSYLON <= square_module && square_module <= 1.0 + DP_TWO_EPSYLON) {
        return 1;
    }

    if (square_module <= DP_SQUARE_EPSYLON) {
        dp_vector2_reset(vector);
        return 0;
    }

    dp_vector2_divide(vector, sqrt(square_module), vector);
    return 1;
}

// =============== Get Normalized =============== //

static inline int sp_vector2_get_normalized(const SPVector2* vector, SPVector2* result)
{
    sp_vector2_copy(vector, result);
    return sp_vector2_normalize(result);
}

static inline int dp_vector2_get_normalized(const DPVector2* vector, DPVector2* result)
{
    dp_vector2_copy(vector, result);
    return dp_vector2_normalize(result);
}

// =================== Angle ==================== //

float sp_vector2_angle(const SPVector2* vector1, const SPVector2* vector2, const angle_unit_t unit);

double dp_vector2_angle(const DPVector2* vector1, const DPVector2* vector2, const angle_unit_t unit);

// =============== Square Distance ============== //

static inline float sp_vector2_get_square_distance(const SPVector2* vector1, const SPVector2* vector2)
{
    const float dx1 = (vector1->x1 - vector2->x1);
    const float dx2 = (vector1->x2 - vector2->x2);

    return dx1 * dx1 + dx2 * dx2;
}

static inline double dp_vector2_get_square_distance(const DPVector2* vector1, const DPVector2* vector2)
{
    const double dx1 = (vector1->x1 - vector2->x1);
    const double dx2 = (vector1->x2 - vector2->x2);

    return dx1 * dx1 + dx2 * dx2;
}

// ================== Distance ================== //

static inline float sp_vector2_get_distance(const SPVector2* vector1, const SPVector2* vector2)
{
    return sqrtf(sp_vector2_get_square_distance(vector1, vector2));
}

static inline double dp_vector2_get_distance(const DPVector2* vector1, const DPVector2* vector2)
{
    return sqrt(dp_vector2_get_square_distance(vector1, vector2));
}

// ================== Are Equal ================= //

static inline int sp_vector2_are_equal(const SPVector2* vector1, const SPVector2* vector2)
{
    const float square_module1 = sp_vector2_get_square_module(vector1);
    const float square_module2 = sp_vector2_get_square_module(vector2);
    const float square_module3 = sp_vector2_get_square_distance(vector1, vector2);

    // 2.0f means dimension amount
    if (square_module1 < SP_EPSYLON_EFFECTIVENESS_LIMIT || square_module2 < SP_EPSYLON_EFFECTIVENESS_LIMIT) {
        return square_module3 < (2.0f * SP_SQUARE_EPSYLON);
    }

    if (square_module1 <= square_module2) {
        return square_module3 <= (2.0f * SP_SQUARE_EPSYLON) * square_module2;
    }

    return square_module3 <= (2.0f * SP_SQUARE_EPSYLON) * square_module1;
}

static inline int dp_vector2_are_equal(const DPVector2* vector1, const DPVector2* vector2)
{
    const double square_module1 = dp_vector2_get_square_module(vector1);
    const double square_module2 = dp_vector2_get_square_module(vector2);
    const double square_module3 = dp_vector2_get_square_distance(vector1, vector2);

    // 2.0 means dimension amount
    if (square_module1 < DP_EPSYLON_EFFECTIVENESS_LIMIT || square_module2 < DP_EPSYLON_EFFECTIVENESS_LIMIT) {
        return square_module3 < (2.0 * DP_SQUARE_EPSYLON);
    }

    if (square_module1 <= square_module2) {
        return square_module3 <= (2.0 * DP_SQUARE_EPSYLON) * square_module2;
    }

    return square_module3 <= (2.0 * DP_SQUARE_EPSYLON) * square_module1;
}

#endif