#include "matrix4x4.h"
#include "../util/util.h"
#include <SDL2/SDL.h>

void mat4_identity(mat4_t *a)
{
    int i;
    for(i = 0; i < 4*4; i++)
    {
        a->data[i] = 0.0f;
    }
    a->data[0 + 0 * 4] = 1.0f;
    a->data[1 + 1 * 4] = 1.0f;
    a->data[2 + 2 * 4] = 1.0f;
    a->data[3 + 3 * 4] = 1.0f;
}

mat4_t mat4_mul(const mat4_t* a, const mat4_t* b)
{
    int i, j, k;
    GLfloat sum = 0.0f;
    mat4_t c;
    mat4_identity(&c);
    for(i = 0; i < 4; i++)
        for(j = 0; j < 4; j++){
            for(k = 0; k < 4; k++){
                sum += a->data[i + k * 4] * b->data[k + j * 4];
            }
            c.data[i + j * 4] = sum;
            sum = 0.0f;
        }

    return c;
}

mat4_t mat4_translate(const vec3_t *a)
{
    mat4_t b;
    mat4_identity(&b);
    b.data[0 + 3 * 4] = a->x;
    b.data[1 + 3 * 4] = a->y;
    b.data[2 + 3 * 4] = a->z;
    return b;
}

mat4_t mat4_scale(GLfloat x, GLfloat y, GLfloat z)
{
    mat4_t b;
    mat4_identity(&b);
    b.data[0 + 0 * 4] = x;
    b.data[1 + 1 * 4] = y;
    b.data[2 + 2 * 4] = z;
    return b;
}

mat4_t mat4_rotate(GLfloat degrees, const vec3_t* a)
{
    mat4_t b;
    mat4_identity(&b);
    GLfloat c = SDL_cosf(toRadians(degrees)), s = SDL_sinf(toRadians(degrees)), o = 1-c;
    b.data[0 + 0 * 4] = a->x * a->x * o + c;
    b.data[0 + 1 * 4] = a->x * a->y * o - a->z * s;
    b.data[0 + 2 * 4] = a->x * a->z * o + a->y * s;

    b.data[1 + 0 * 4] = a->x * a->y * o + a->z * s;
    b.data[1 + 1 * 4] = a->y * a->y * o + c;
    b.data[1 + 2 * 4] = a->y * a->z * o - a->x * s;

    b.data[2 + 0 * 4] = a->x * a->z * o - a->y * s;
    b.data[2 + 1 * 4] = a->y * a->z * o + a->x * s;
    b.data[2 + 2 * 4] = a->z * a->z * o + c;
    return b;
}

mat4_t mat4_rotate_x(GLfloat degrees)
{
    mat4_t a;
    mat4_identity(&a);
    GLfloat c = SDL_cosf(toRadians(degrees)), s = SDL_sinf(toRadians(degrees));
    a.data[1 + 1 * 4] = c;
    a.data[2 + 1 * 4] = s;
    a.data[1 + 2 * 4] = -s;
    a.data[2 + 2 * 4] = c;
    return a;
}

mat4_t mat4_rotate_y(GLfloat degrees)
{
    mat4_t a;
    mat4_identity(&a);
    GLfloat c = SDL_cosf(toRadians(degrees)), s = SDL_sinf(toRadians(degrees));
    a.data[0 + 0 * 4] = c;
    a.data[2 + 0 * 4] = -s;
    a.data[0 + 2 * 4] = s;
    a.data[2 + 2 * 4] = c;
    return a;
}

mat4_t mat4_rotate_z(GLfloat degrees)
{
    mat4_t a;
    mat4_identity(&a);
    GLfloat c = SDL_cosf(toRadians(degrees)), s = SDL_sinf(toRadians(degrees));
    a.data[0 + 0 * 4] = c;
    a.data[1 + 0 * 4] = s;
    a.data[0 + 1 * 4] = -s;
    a.data[1 + 1 * 4] = c;
    return a;
}

mat4_t mat4_perspective(GLfloat fov, GLfloat aspect, GLfloat zNear, GLfloat zFar)
{
    mat4_t a;
    GLubyte i, j;
    for(i = 0; i < 4; i++)
        for(j = 0; j < 4; j++)
            a.data[i + j * 4] = 0.0f;
    fov = toRadians(fov); //To radians

    a.data[0 + 0 * 4] = ( (1.0f / SDL_tanf( fov/2.0f )) / aspect);
    a.data[1 + 1 * 4] = (1.0f / SDL_tanf( fov/2.0f ));
    a.data[2 + 2 * 4] = -( (zFar + zNear) / (zFar - zNear) );
    a.data[2 + 3 * 4] = -( ( 2.0f * zFar * zNear) / (zFar - zNear) );
    a.data[3 + 2 * 4] = -1.0f;

    return a;
}

mat4_t
mat4_orthographic(GLfloat left, GLfloat right, GLfloat bottom, GLfloat top)
{
    mat4_t a;
    mat4_identity(&a);
    a.data[0 + 0 * 4] = 2.0f / (right - left);
    a.data[1 + 1 * 4] = 2.0f / (top - bottom);
    a.data[2 + 2 * 4] = -1.0f;

    a.data[0 + 3 * 4] = (left + right) / (left - right);
    a.data[1 + 3 * 4] = (bottom + top) / (bottom - top);

    return a;
}

mat4_t mat4_lookAt(vec3_t* eye, vec3_t* center, vec3_t* up)
{
    vec3_t temp = vec3_sub(center, eye);

    vec3_t f = vec3_normalize(&temp);
    vec3_t u = vec3_normalize(up);
    temp = vec3_cross_mul(&f, &u);
    vec3_t s = vec3_normalize(&temp);
    u = vec3_cross_mul(&s, &f);

    mat4_t a;
    mat4_identity(&a);

    a.data[0 + 0 * 4] = s.x;
    a.data[0 + 1 * 4] = s.y;
    a.data[0 + 2 * 4] = s.z;
    a.data[1 + 0 * 4] = u.x;
    a.data[1 + 1 * 4] = u.y;
    a.data[1 + 2 * 4] = u.z;
    a.data[2 + 0 * 4] =-f.x;
    a.data[2 + 1 * 4] =-f.y;
    a.data[2 + 2 * 4] =-f.z;
    a.data[0 + 3 * 4] =-vec3_dot_mul(&s, eye);
    a.data[1 + 3 * 4] =-vec3_dot_mul(&u, eye);
    a.data[2 + 3 * 4] = vec3_dot_mul(&f, eye);

    return a;
}

vec3_t mat4_mul_vec3(const mat4_t* a, const vec3_t* b)
{
    vec3_t c;
    c.x = a->data[0 + 0 * 4] * b->x + a->data[0 + 1 * 4] * b->y + a->data[0 + 2 * 4] * b->z + a->data[0 + 3 * 4];
    c.y = a->data[1 + 0 * 4] * b->x + a->data[1 + 1 * 4] * b->y + a->data[1 + 2 * 4] * b->z + a->data[1 + 3 * 4];
    c.z = a->data[2 + 0 * 4] * b->x + a->data[2 + 1 * 4] * b->y + a->data[2 + 2 * 4] * b->z + a->data[2 + 3 * 4];
    return c;
}