#ifndef _BASIC_GEOMETRY_VECTOR2_H_
#define _BASIC_GEOMETRY_VECTOR2_H_

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

#include <math.h>

typedef struct
{
    float x1, x2;
} vector2_fp32_t;

typedef struct
{
    double x1, x2;
} vector2_fp64_t;

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

inline void vector2_reset_fp32(vector2_fp32_t* vector)
{
    vector->x1 = 0.0f;
    vector->x2 = 0.0f;
}

inline void vector2_reset_fp64(vector2_fp64_t* vector)
{
    vector->x1 = 0.0;
    vector->x2 = 0.0;
}

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

inline void vector2_set_values_fp32(const float x1, const float x2, vector2_fp32_t* to)
{
    to->x1 = x1;
    to->x2 = x2;
}

inline void vector2_set_values_fp64(const double x1, const double x2, vector2_fp64_t* to)
{
    to->x1 = x1;
    to->x2 = x2;
}

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

inline void vector2_copy_fp32(const vector2_fp32_t* from, vector2_fp32_t* to)
{
    to->x1 = from->x1;
    to->x2 = from->x2;
}

inline void vector2_copy_fp64(const vector2_fp64_t* from, vector2_fp64_t* to)
{
    to->x1 = from->x1;
    to->x2 = from->x2;
}

// ==================== Swap ==================== //

inline void vector2_swap_fp32(vector2_fp32_t* vector1, vector2_fp32_t* vector2)
{
    const float x1 = vector2->x1;
    const float x2 = vector2->x2;

    vector2->x1 = vector1->x1;
    vector2->x2 = vector1->x2;

    vector1->x1 = x1;
    vector1->x2 = x2;
}

inline void vector2_swap_fp64(vector2_fp64_t* vector1, vector2_fp64_t* vector2)
{
    const double x1 = vector2->x1;
    const double x2 = vector2->x2;

    vector2->x1 = vector1->x1;
    vector2->x2 = vector1->x2;

    vector1->x1 = x1;
    vector1->x2 = x2;
}

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

inline void vector2_convert_fp64_to_fp32(const vector2_fp64_t* from, vector2_fp32_t* to)
{
    to->x1 = (float)from->x1;
    to->x2 = (float)from->x2;
}

inline void vector2_convert_fp32_to_fp64(const vector2_fp32_t* from, vector2_fp64_t* to)
{
    to->x1 = from->x1;
    to->x2 = from->x2;
}

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

inline void vector2_fp32_set_reverse(const vector2_fp32_t* from, vector2_fp32_t* to)
{
    to->x1 = -from->x1;
    to->x2 = -from->x2;
}

inline void vector2_fp64_set_reverse(const vector2_fp64_t* from, vector2_fp64_t* to)
{
    to->x1 = -from->x1;
    to->x2 = -from->x2;
}

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

inline void vector2_fp32_set_reverse_fp64(const vector2_fp64_t* from, vector2_fp32_t* to)
{
    to->x1 = (float) -from->x1;
    to->x2 = (float) -from->x2;
}

inline void vector2_fp64_set_reverse_fp32(const vector2_fp32_t* from, vector2_fp64_t* to)
{
    to->x1 = -from->x1;
    to->x2 = -from->x2;
}

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

inline float vector2_get_square_modulus_fp32(const vector2_fp32_t* vector)
{
    return vector->x1 * vector->x1 + vector->x2 * vector->x2;
}

inline double vector2_get_square_modulus_fp64(const vector2_fp64_t* vector)
{
    return vector->x1 * vector->x1 + vector->x2 * vector->x2;
}

inline float vector2_get_modulus_fp32(const vector2_fp32_t* vector)
{
    return sqrtf(vector2_get_square_modulus_fp32(vector));
}

inline double vector2_get_modulus_fp64(const vector2_fp64_t* vector)
{
    return sqrt(vector2_get_square_modulus_fp64(vector));
}

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

inline int vector2_fp32_is_zero(const vector2_fp32_t* vector)
{
    return vector2_get_square_modulus_fp32(vector) <= FP32_SQUARE_EPSYLON;
}

inline int vector2_fp64_is_zero(const vector2_fp64_t* vector)
{
    return vector2_get_square_modulus_fp64(vector) <= FP64_SQUARE_EPSYLON;
}

inline int vector2_fp32_is_unit(const vector2_fp32_t* vector)
{
    const float square_modulus = vector2_get_square_modulus_fp32(vector);

    return 1.0f - FP32_TWO_EPSYLON <= square_modulus && square_modulus <= 1.0f + FP32_TWO_EPSYLON;
}

inline int vector2_fp64_is_unit(const vector2_fp64_t* vector)
{
    const double square_modulus = vector2_get_square_modulus_fp64(vector);

    return 1.0f - FP64_TWO_EPSYLON <= square_modulus && square_modulus <= 1.0f + FP64_TWO_EPSYLON;
}

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

inline void vector2_add_fp32(const vector2_fp32_t* vector1, const vector2_fp32_t* vector2, vector2_fp32_t* sum)
{
    sum->x1 = vector1->x1 + vector2->x1;
    sum->x2 = vector1->x2 + vector2->x2;
}

inline void vector2_add_fp64(const vector2_fp64_t* vector1, const vector2_fp64_t* vector2, vector2_fp64_t* sum)
{
    sum->x1 = vector1->x1 + vector2->x1;
    sum->x2 = vector1->x2 + vector2->x2;
}

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

inline void vector2_subtract_fp32(const vector2_fp32_t* minuend, const vector2_fp32_t* subtrahend, vector2_fp32_t* difference)
{
    difference->x1 = minuend->x1 - subtrahend->x1;
    difference->x2 = minuend->x2 - subtrahend->x2;
}

inline void vector2_subtract_fp64(const vector2_fp64_t* minuend, const vector2_fp64_t* subtrahend, vector2_fp64_t* difference)
{
    difference->x1 = minuend->x1 - subtrahend->x1;
    difference->x2 = minuend->x2 - subtrahend->x2;
}

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

inline void vector2_multiply_fp32(const vector2_fp32_t* multiplicand, const float multiplier, vector2_fp32_t* product)
{
    product->x1 = multiplicand->x1 * multiplier;
    product->x2 = multiplicand->x2 * multiplier;
}

inline void vector2_multiply_fp64(const vector2_fp64_t* multiplicand, const double multiplier, vector2_fp64_t* product)
{
    product->x1 = multiplicand->x1 * multiplier;
    product->x2 = multiplicand->x2 * multiplier;
}

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

inline void vector2_divide_fp32(const vector2_fp32_t* dividend, const float divisor, vector2_fp32_t* quotient)
{
    vector2_multiply_fp32(dividend, 1.0f / divisor, quotient);
}

inline void vector2_fp64_divide(const vector2_fp64_t* dividend, const double divisor, vector2_fp64_t* quotient)
{
    vector2_multiply_fp64(dividend, 1.0 / divisor, quotient);
}

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

inline void vector2_add_scaled_fp32(vector2_fp32_t* basic_vector, const vector2_fp32_t* scalable_vector, const float scale)
{
    basic_vector->x1 += scalable_vector->x1 * scale;
    basic_vector->x2 += scalable_vector->x2 * scale;
}

inline void vector2_add_scaled_fp64(vector2_fp64_t* basic_vector, const vector2_fp64_t* scalable_vector, const double scale)
{
    basic_vector->x1 += scalable_vector->x1 * scale;
    basic_vector->x2 += scalable_vector->x2 * scale;
}

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

inline void vector2_fp32_get_mean2(const vector2_fp32_t* vector1, const vector2_fp32_t* vector2, vector2_fp32_t* result)
{
    result->x1 = (vector1->x1 + vector2->x1) * 0.5f;
    result->x2 = (vector1->x2 + vector2->x2) * 0.5f;
}

inline void vector2_fp64_get_mean2(const vector2_fp64_t* vector1, const vector2_fp64_t* vector2, vector2_fp64_t* result)
{
    result->x1 = (vector1->x1 + vector2->x1) * 0.5;
    result->x2 = (vector1->x2 + vector2->x2) * 0.5;
}

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

inline void vector2_fp32_get_mean3(const vector2_fp32_t* vector1, const vector2_fp32_t* vector2, const vector2_fp32_t* vector3, vector2_fp32_t* result)
{
    result->x1 = (vector1->x1 + vector2->x1 + vector3->x1) * FP32_ONE_THIRD;
    result->x2 = (vector1->x2 + vector2->x2 + vector3->x2) * FP32_ONE_THIRD;
}

inline void vector2_fp64_get_mean3(const vector2_fp64_t* vector1, const vector2_fp64_t* vector2, const vector2_fp64_t* vector3, vector2_fp64_t* result)
{
    result->x1 = (vector1->x1 + vector2->x1 + vector3->x1) * FP64_ONE_THIRD;
    result->x2 = (vector1->x2 + vector2->x2 + vector3->x2) * FP64_ONE_THIRD;
}

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

inline float vector2_fp32_scalar_product(const vector2_fp32_t* vector1, const vector2_fp32_t* vector2)
{
    return vector1->x1 * vector2->x1 + vector1->x2 * vector2->x2;
}

inline double vector2_fp64_scalar_product(const vector2_fp64_t* vector1, const vector2_fp64_t* vector2)
{
    return vector1->x1 * vector2->x1 + vector1->x2 * vector2->x2;
}

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

inline float vector2_fp32_cross_product(const vector2_fp32_t* vector1, const vector2_fp32_t* vector2)
{
    return vector1->x1 * vector2->x2 - vector1->x2 * vector2->x1;
}

inline double vector2_fp64_cross_product(const vector2_fp64_t* vector1, const vector2_fp64_t* vector2)
{
    return vector1->x1 * vector2->x2 - vector1->x2 * vector2->x1;
}

// ============== Complex Product =============== //

inline void vector2_fp32_complex_product(const vector2_fp32_t* vector1, const vector2_fp32_t* vector2, vector2_fp32_t* result)
{
    const float x1 = vector1->x1 * vector2->x1 - vector1->x2 * vector2->x2;
    const float x2 = vector1->x1 * vector2->x2 + vector1->x2 * vector2->x1;

    result->x1 = x1;
    result->x2 = x2;
}

inline void vector2_fp64_complex_product(const vector2_fp64_t* vector1, const vector2_fp64_t* vector2, vector2_fp64_t* result)
{
    const double x1 = vector1->x1 * vector2->x1 - vector1->x2 * vector2->x2;
    const double x2 = vector1->x1 * vector2->x2 + vector1->x2 * vector2->x1;

    result->x1 = x1;
    result->x2 = x2;
}

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

inline int vector2_normalize_fp32(vector2_fp32_t* vector)
{
    const float square_modulus = vector2_get_square_modulus_fp32(vector);

    if (1.0f - FP32_TWO_EPSYLON <= square_modulus && square_modulus <= 1.0f + FP32_TWO_EPSYLON) {
        return 1;
    }

    if (square_modulus <= FP32_SQUARE_EPSYLON) {
        vector2_reset_fp32(vector);
        return 0;
    }

    vector2_multiply_fp32(vector, sqrtf(1.0f / square_modulus), vector);
    return 1;
}

inline int vector2_normalize_fp64(vector2_fp64_t* vector)
{
    const double square_modulus = vector2_get_square_modulus_fp64(vector);

    if (1.0 - FP64_TWO_EPSYLON <= square_modulus && square_modulus <= 1.0 + FP64_TWO_EPSYLON) {
        return 1;
    }

    if (square_modulus <= FP64_SQUARE_EPSYLON) {
        vector2_reset_fp64(vector);
        return 0;
    }

    vector2_multiply_fp64(vector, sqrt(1.0 / square_modulus), vector);
    return 1;
}

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

inline int vector2_fp32_set_normalized(const vector2_fp32_t* vector, vector2_fp32_t* result)
{
    vector2_copy_fp32(vector, result);
    return vector2_normalize_fp32(result);
}

inline int vector2_fp64_set_normalized(const vector2_fp64_t* vector, vector2_fp64_t* result)
{
    vector2_copy_fp64(vector, result);
    return vector2_normalize_fp64(result);
}

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

float vector2_get_angle_fp32(const vector2_fp32_t* vector1, const vector2_fp32_t* vector2, const angle_unit_t unit);

double vector2_get_angle_fp64(const vector2_fp64_t* vector1, const vector2_fp64_t* vector2, const angle_unit_t unit);

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

inline float vector2_get_square_distance_fp32(const vector2_fp32_t* vector1, const vector2_fp32_t* vector2)
{
    const float dx1 = (vector1->x1 - vector2->x1);
    const float dx2 = (vector1->x2 - vector2->x2);

    return dx1 * dx1 + dx2 * dx2;
}

inline double vector2_get_square_distance_fp64(const vector2_fp64_t* vector1, const vector2_fp64_t* vector2)
{
    const double dx1 = (vector1->x1 - vector2->x1);
    const double dx2 = (vector1->x2 - vector2->x2);

    return dx1 * dx1 + dx2 * dx2;
}

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

inline float vector2_get_distance_fp32(const vector2_fp32_t* vector1, const vector2_fp32_t* vector2)
{
    return sqrtf(vector2_get_square_distance_fp32(vector1, vector2));
}

inline double vector2_get_distance_fp64(const vector2_fp64_t* vector1, const vector2_fp64_t* vector2)
{
    return sqrt(vector2_get_square_distance_fp64(vector1, vector2));
}

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

inline int vector2_are_equal_fp32(const vector2_fp32_t* vector1, const vector2_fp32_t* vector2)
{
    const float square_modulus1 = vector2_get_square_modulus_fp32(vector1);
    const float square_modulus2 = vector2_get_square_modulus_fp32(vector2);
    const float square_modulus3 = vector2_get_square_distance_fp32(vector1, vector2);

    // 2.0f means dimension amount
    if (square_modulus1 < FP32_EPSYLON_EFFECTIVENESS_LIMIT || square_modulus2 < FP32_EPSYLON_EFFECTIVENESS_LIMIT) {
        return square_modulus3 < (2.0f * FP32_SQUARE_EPSYLON);
    }

    if (square_modulus1 <= square_modulus2) {
        return square_modulus3 <= (2.0f * FP32_SQUARE_EPSYLON) * square_modulus2;
    }

    return square_modulus3 <= (2.0f * FP32_SQUARE_EPSYLON) * square_modulus1;
}

inline int vector2_are_equal_fp64(const vector2_fp64_t* vector1, const vector2_fp64_t* vector2)
{
    const double square_modulus1 = vector2_get_square_modulus_fp64(vector1);
    const double square_modulus2 = vector2_get_square_modulus_fp64(vector2);
    const double square_modulus3 = vector2_get_square_distance_fp64(vector1, vector2);

    // 2.0 means dimension amount
    if (square_modulus1 < FP64_EPSYLON_EFFECTIVENESS_LIMIT || square_modulus2 < FP64_EPSYLON_EFFECTIVENESS_LIMIT) {
        return square_modulus3 < (2.0 * FP64_SQUARE_EPSYLON);
    }

    if (square_modulus1 <= square_modulus2) {
        return square_modulus3 <= (2.0 * FP64_SQUARE_EPSYLON) * square_modulus2;
    }

    return square_modulus3 <= (2.0 * FP64_SQUARE_EPSYLON) * square_modulus1;
}

#endif