/*
 * Copyright 2013 (c) Anna Schumaker.
 *
 * Queues are lists of tracks that the user has requested to play next.
 * Users of queues are expected to implement their own save and load functions,
 * and to provide a filled out queue_ops structure during initialization.
 */
#ifndef OCARINA_CORE_QUEUE_H
#define OCARINA_CORE_QUEUE_H

#include <core/file.h>
#include <core/tags/track.h>

struct queue;


struct queue_ops {
	/* Called to tell a higher layer that a queue has been initialized. */
	void *(*qop_init)(struct queue *, void *);

	/* Called to tell a higher layer that a queue is deinitializing. */
	void (*qop_deinit)(struct queue *);

	/* Called to tell a higher layer that a track has been added. */
	void (*qop_added)(struct queue *, unsigned int);

	/* Called to tell a higher layer that the queue has been cleared. */
	void (*qop_cleared)(struct queue *, unsigned int);
};


struct queue_iter {
	GList *it_iter; /* The current link in the GQueue.   */
	guint  it_pos;  /* The current index into the queue. */
};


struct queue {
	unsigned int   q_length;  /* The queue's total runtime (in seconds). */
	GQueue         q_tracks;  /* The queue's list of tracks.             */
	GSList        *q_sort;    /* The queue's sort order.                 */
	void          *q_private; /* The queue's private data.               */

	struct queue_iter       q_cur; /* The queue's last-played position.  */
	const struct queue_ops *q_ops; /* The queue's operations vector.     */
};



/* Called to initialize a queue iterator. */
static inline void queue_iter_init(struct queue *queue, struct queue_iter *it)
{
	it->it_iter = g_queue_peek_head_link(&queue->q_tracks);
	it->it_pos  = g_queue_link_index(&queue->q_tracks, it->it_iter);
}

/* Called to advance a queue iterator by one step. */
static inline void queue_iter_next(struct queue_iter *it)
{
	it->it_iter = g_list_next(it->it_iter);
	it->it_pos++;
}

/* Called to rewind a queue iterator by one step. */
static inline void queue_iter_prev(struct queue_iter *it)
{
	it->it_iter = g_list_previous(it->it_iter);
	it->it_pos--;
}

/* Called to set a queue iterator to a specific position. */
static inline void queue_iter_set(struct queue *queue, struct queue_iter *it,
				  unsigned int pos)
{
	it->it_iter = g_queue_peek_nth_link(&queue->q_tracks, pos);
	it->it_pos  = pos;
}

/* Called to access the value of a queue iterator. */
static inline struct track *queue_iter_val(struct queue_iter *it)
{
	return (it->it_iter) ? it->it_iter->data : NULL;
}

#define queue_for_each(queue, it) \
	for (queue_iter_init(queue, it); (it)->it_iter; queue_iter_next(it))



/* Called to initialize a queue. */
void queue_init(struct queue *, const struct queue_ops *, void *);

/* Called to deinitialize a queue. */
void queue_deinit(struct queue *);


/* Called to find the size of the queue. */
static inline unsigned int queue_size(struct queue *queue)
{
	return g_queue_get_length(&queue->q_tracks);
}

/* Called to access the queued track at a given index. */
static inline struct track *queue_at(struct queue *queue, unsigned int index)
{
	return (struct track *)g_queue_peek_nth(&queue->q_tracks, index);
}


/* Called to add a track to the queue. */
unsigned int queue_add(struct queue *, struct track *);

/* Called to add a track to the front of the queue. */
unsigned int queue_add_front(struct queue *, struct track *);

/* Called to remove all tracks from the queue. */
void queue_clear(struct queue *);

/* Called to check if a queue has a track. */
bool queue_has(struct queue *, struct track *);

#endif /* OCARINA_CORE_QUEUE_H */