#include <allegro.h>
#include "shadow.h"

static layer_t* create_layer(int z);
static void destroy_layer(layer_t* l);

/* Initialize a fresh scene with no layers */
lscene_t* create_lscene(void)
{
	lscene_t* s = malloc(sizeof(lscene_t));
	s->c = 0;
	s->l = NULL;
	return s;
}

/* Fully deallocate a scene */
void destroy_lscene(lscene_t* s)
{
	int i;
	for (i = 0; i < s->c; i++)
		destroy_layer(s->l[i]);
	free(s->l);
	free(s);
}

/* Insert a layer with given z value */
/* TODO: reconsider what happens with equal z values */
BITMAP* add_layer(lscene_t* s, int z)
{
	int i;
	/* Locate correct position to insert */
	for (i = 0; i < s->c && s->l[i]->z > z; i++);
	/* Grow layer pointer array */
	s->l = realloc(s->l, sizeof(layer_t*) * (s->c + 1));
	/* Make room in the middle of the array for the new layer */
	memmove(&s->l[i + 1], &s->l[i], (s->c - i) * sizeof(layer_t*));
	/* Insert! */
	s->c++;
	s->l[i] = create_layer(z);
	return s->l[i]->img;
}

/* Allocate a new layer */
static layer_t* create_layer(int z)
{
	layer_t* l = malloc(sizeof(layer_t));
	l->img = create_bitmap_ex(INTERNAL_DEPTH, SCREEN_WIDTH, SCREEN_HEIGHT);
	l->z = z;
	return l;
}

/* Deallocate a layer */
static void destroy_layer(layer_t* l)
{
	destroy_bitmap(l->img);
	free(l);
}