#ifndef MM_CHANNEL_H_
#define MM_CHANNEL_H_

/*
 * machinarium.
 *
 * cooperative multitasking engine.
*/

typedef struct mm_channel_t mm_channel_t;

struct mm_channel_t {
	mm_list_t incoming;
	int       incoming_count;
	mm_list_t readers;
	int       readers_count;
};

static inline void
mm_channel_init(mm_channel_t *channel)
{
	mm_list_init(&channel->incoming);
	channel->incoming_count = 0;
	mm_list_init(&channel->readers);
	channel->readers_count = 0;
}

static inline void
mm_channel_write(mm_channel_t *channel, mm_msg_t *msg)
{
	mm_list_append(&channel->incoming, &msg->link);
	channel->incoming_count++;

	if (! channel->readers_count)
		return;

	mm_list_t *first;
	first = mm_list_pop(&channel->readers);
	mm_fiber_t *fiber;
	fiber = mm_container_of(first, mm_fiber_t, link_channel);
	channel->readers_count--;

	mm_scheduler_wakeup(&mm_self->scheduler, fiber);
}

static inline mm_msg_t*
mm_channel_read(mm_channel_t *channel, int time_ms)
{
	if (channel->incoming_count > 0)
		goto fetch;

	mm_fiber_t *fiber;
	fiber = mm_scheduler_current(&mm_self->scheduler);
	mm_list_append(&channel->readers, &fiber->link_channel);
	channel->readers_count++;

	mm_call_t call;
	mm_call(&call, time_ms);
	if (call.status != 0) {
		/* timedout or cancel */
		assert(channel->readers_count > 0);
		channel->readers_count--;
		mm_list_unlink(&fiber->link_channel);
		return NULL;
	}

fetch:
	if (channel->incoming_count > 0) {
		mm_list_t *first;
		first = mm_list_pop(&channel->readers);
		channel->incoming_count--;
		mm_msg_t *msg;
		msg = mm_container_of(first, mm_msg_t, link);
		return msg;
	}
	return NULL;
}

#endif