#include "loans.h"

contract *mort_init(int n, int d, float r, float P) {
	if ((n < 0)) return NULL;
	if ((d >= n)||(d < 0)) return NULL;
	contract *c = (contract *)calloc(1, sizeof(contract));
	c->n = (unsigned int)n;
	c->d = (unsigned int)d;
	c->r = r;
	c->P = P;

	return c;
}

float mort_update(contract *c) {
	if (c->k > c->n)
		return 0.0f;

	if (c->k == c->d) {
		c->A = - (c->P * c->r * powf(1.0f + c->r, (float)(c->n - c->k)));
		c->A = c->A / (1.0f - powf(1.0f + c->r, (float)(c->n - c->k)));
	}
	c->k++;
	c->I = c->r * c->P;

	if (c->k <= c->d)
		c->P += c->I;
	else {
		c->D = c->A - c->I;
		c->P = c->P - c->D;
		/* c->A is fixed ! */
	}

	return c->A;
}

void mort_free(contract *c) {
	free(c);
}