// Copyright (c) 2023, Marvin Borner <dev@marvinborner.de>
// SPDX-License-Identifier: MIT

#include <math.h>
#include <time.h>
#include <stdlib.h>

#include <schedule.h>
#include <lib/pqueue.h>
#include <parse.h>
#include <map.h>

static struct pqueue *queue;

static pqueue_pri_t get_pri(void *a)
{
	struct term *term = a;
	return (parse_get_max_depth() - term->depth + 1) * term->refs;
}

static int cmp_pri(pqueue_pri_t next, pqueue_pri_t curr)
{
	return next < curr;
}

static void set_pos(void *a, size_t position)
{
	(void)a;
	(void)position;
}

// skewed random number generator
// prefers smaller numbers
static size_t choose_position(void)
{
	size_t size = pqueue_size(queue);
	return size - (size_t)sqrt(((size_t)rand() % (size_t)pow(size, 2)));
}

void schedule(void)
{
	while (pqueue_size(queue) > 0) {
		size_t position = choose_position();
		struct term *term = pqueue_pop_at(queue, position);
		// TODO: reduce term
	}
}

void schedule_init(void)
{
	srand(time(0));
	queue = map_to_pqueue(cmp_pri, get_pri, set_pos);
}

void schedule_destroy(void)
{
	pqueue_free(queue);
}