#ifndef PRIORITY_QUEUE_H_
#define PRIORITY_QUEUE_H_

#include "structs.h"

/* This is basically a sorted linked list
 * Pro tip: if you always use the same priority, this becomes a regular queue */
struct PositionPQNode_s {
    Position pos;
    size_t priority; /* Lower is "better" */
    struct PositionPQNode_s *next;
};

typedef struct PositionPQNode_s PositionPQ;

/* Create a new PositionPQ with pos and priority */
PositionPQ *ppq_new(Position pos, size_t priority);

/* Insert a pos with priority into a given PositionPQ */
#define PPQ_INSERT_SUCCESS 0
#define PPQ_INSERT_NEW 1 /* ppq was NULL, created a new one */
#define PPQ_INSERT_ALREADY 2 /* pos is already in ppq */
int ppq_insert(PositionPQ **ppq, Position pos, size_t priority);

/* Remove and return the position with the lowest priority */
Position ppq_pop(PositionPQ **ppq);

/* Remove a given pos fron ppq */
void ppq_remove(PositionPQ **ppq, Position pos);

/* Change the priority of a given pos, moving it to a different place in the
 * linked list ("POTENTIALLY NOT NEEDED" since we don't use different weights */
void ppq_reprioritize(PositionPQ *ppq, Position pos, size_t priority);

void ppq_print(PositionPQ *ppq);

void ppq_free(PositionPQ *ppq);

#endif /* PRIORITY_QUEUE_H_ */