#include "mons_math/mat2.h"

const mons_mat2 MONS_MAT2_ZERO = {
    {0, 0},
    {0, 0},
};

const mons_mat2 MONS_MAT2_IDENTITY = {
    {1, 0},
    {0, 1},
};

mons_mat2 mons_mat2_add(mons_mat2 a, mons_mat2 b) {
    mons_mat2 result = {
        mons_vec2_add(a.m1, b.m1),
        mons_vec2_add(a.m2, b.m2),
    };
    return result;
}

void mons_mat2_add_inplace(mons_mat2 *a, mons_mat2 b) {
    mons_vec2_add_inplace(&a->m1, b.m1);
    mons_vec2_add_inplace(&a->m2, b.m2);
}

mons_mat2 mons_mat2_mul_f(mons_mat2 a, float b) {
    mons_mat2 result = {
        mons_vec2_mul_f(a.m1, b),
        mons_vec2_mul_f(a.m2, b),
    };
    return result;
}

mons_mat2 mons_mat2_mul_i(mons_mat2 a, int b) {
    mons_mat2 result = {
        mons_vec2_mul_i(a.m1, b),
        mons_vec2_mul_i(a.m2, b),
    };
    return result;
}

mons_mat2 mons_mat2_mul(mons_mat2 a, mons_mat2 b) {
    mons_vec2 b_n1 = mons_mat2_n1(b);
    mons_vec2 b_n2 = mons_mat2_n2(b);

    mons_mat2 result = {
        {
            mons_vec2_dot(a.m1, b_n1),
            mons_vec2_dot(a.m1, b_n2),
        },
        {
            mons_vec2_dot(a.m2, b_n1),
            mons_vec2_dot(a.m2, b_n2),
        },
    };
    return result;
}

void mons_mat2_mul_f_inplace(mons_mat2 *a, float b) {
    mons_vec2_mul_f_inplace(&a->m1, b);
    mons_vec2_mul_f_inplace(&a->m2, b);
}

void mons_mat2_mul_i_inplace(mons_mat2 *a, int b) {
    mons_vec2_mul_i_inplace(&a->m1, b);
    mons_vec2_mul_i_inplace(&a->m2, b);
}

mons_mat2 mons_mat2_transpose(mons_mat2 a) {
    mons_mat2 result = {
        mons_mat2_n1(a),
        mons_mat2_n2(a),
    };
    return result;
}

void mons_mat2_transpose_inplace(mons_mat2 *a) { *a = mons_mat2_transpose(*a); }

mons_vec2 mons_mat2_n1(mons_mat2 a) {
    mons_vec2 result = {
        a.m1.x,
        a.m2.x,
    };
    return result;
}

mons_vec2 mons_mat2_n2(mons_mat2 a) {
    mons_vec2 result = {
        a.m1.y,
        a.m2.y,
    };
    return result;
}

float mons_mat2_determinant(mons_mat2 a) {
    // ad - bc
    return (a.m1.x * a.m2.y) - (a.m1.y * a.m2.x);
}

mons_mat2 mons_mat2_adjoint(mons_mat2 a) {
    /*
     * d -b
     * -c a
     */
    mons_mat2 result = {{
                            a.m2.y,
                            -a.m1.y,
                        },
                        {
                            -a.m2.x,
                            a.m1.x,
                        }};
    return result;
}

mons_mat2 mons_mat2_inverse(mons_mat2 a) {
    return mons_mat2_mul_f(mons_mat2_adjoint(a),
                           1.0 / mons_mat2_determinant(a));
}

int mons_mat2_equal(mons_mat2 a, mons_mat2 b) {
    return mons_vec2_equal(a.m1, b.m1) && mons_vec2_equal(a.m2, b.m2);
}