#include <stdlib.h>
#include <math.h>
#include <stdio.h>
#include "vector_heap.h"

Vector* vec_new(double x, double y, double z) {
    Vector* result = (Vector*) malloc(sizeof(Vector));
    if (!result) {
        /* malloc failed */
        return NULL;
    }

    result->x = x;
    result->y = y;
    result->z = z;

    return result;
}

Vector* vec_new_null() {
    return vec_new(0.0,
                   0.0,
                   0.0);
}

Vector* vec_mul_scalar(Vector* v, double scalar) {
    return vec_new(v->x * scalar,
                   v->y * scalar,
                   v->z * scalar);
}

double vec_mul_dot(Vector* first, Vector *second) {
    return first->x * second->x +
           first->y * second->y +
           first->z * second->z;
}

Vector* vec_mul_cross(Vector* first, Vector *second) {
    return vec_new(first->y * second->z - first->z * second->y,
                   first->z * second->x - first->x * second->z,
                   first->x * second->y - first->y * second->x);
}

Vector* vec_add(Vector* first, Vector *second) {
    return vec_new(first->x + second->x,
                   first->y + second->y,
                   first->z + second->z);
}

Vector* vec_sub(Vector* first, Vector *second) {
    return vec_new(first->x - second->x,
                   first->y - second->y,
                   first->z - second->z);
}

int vec_equals(Vector* first, Vector *second) {
    return (first->x == second->x)
        && (first->y == second->y)
        && (first->z == second->z);
}

#define MAX_LENGTH 128

char* vec_to_str(Vector* v) {
    char* result = (char*) malloc(MAX_LENGTH + 1);
    snprintf(result, MAX_LENGTH, "[ %.2f  %.2f  %.2f ]", v->x, v->y, v->z);
    return result;
}

void vec_print(Vector* v) {
    char* str = vec_to_str(v);
    printf("%s", str);
    free(str);
}

double vec_length(Vector* v) {
    return sqrt(v->x * v->x
              + v->y * v->y
              + v->z * v->z);
}

Vector* vec_norm(Vector* v) {
    double length = vec_length(v);

    if (length == 0.0) {
        /* no norm for a null vector */
        return NULL;
    }

    return vec_new(v->x / length,
                   v->y / length,
                   v->z / length);
}

int vec_collinear(Vector* first, Vector* second) {
    Vector* cross = vec_mul_cross(first, second);
    Vector* null = vec_new_null();
    int result = vec_equals(null, cross);

    free(cross);
    free(null);

    return result;
}