#include <errno.h>
#include <sys/epoll.h>

#include "event.h"
#include "trace.h"

static int epoll_fd = -1;

static int init_event_handler(void)
{
	epoll_fd = epoll_create(1);
	if (epoll_fd < 0) {
		pr_err("Failed to create epoll socket: %m\n");
		return -1;
	}

	return 0;
}

int register_event_handler(struct eventhandler_entry *handler)
{
	struct epoll_event ev;
	int ret = 0;

	if (epoll_fd < 0)
		ret = init_event_handler();

	if (ret < 0)
		return ret;

	if (handler->fd < 0) {
		pr_err("Invalid file descriptor of %d for handler %s\n",
			handler->fd, handler->name);
		return -1;
	}

	if (!handler->handle_event) {
		pr_err("Handler %s missing callback function\n", handler->name);
		return -1;
	}

	pr_debug("Registering handler for \"%s\", fd=%d\n",
		handler->name, handler->fd);

	ev.data.fd = handler->fd;
	ev.data.ptr = handler;
	ev.events = handler->events;
	ret = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, handler->fd, &ev);
	if (ret) {
		pr_err("Failed to add epoll_fd: %m\n");
		return -1;
	}

	return 0;
}

int poll_events(int timeout_ms)
{
	struct epoll_event event;
	struct eventhandler_entry *handler;
	int ret;

	ret = epoll_wait(epoll_fd, &event, 1, timeout_ms);

	if (ret == -1) {
		if (errno != EINTR) {
			pr_err("epoll_wait: %m\n");
			return -1;
		}

		/*
		 * If epoll_wait() was interrupted, better start
		 * everything again from the beginning
		 */
		return 0;
	}

	if (ret == 0) {
		pr_info("Timed out\n");
		goto out;
	}

	handler = event.data.ptr;

	if (!handler || !handler->handle_event) {
		pr_err("Corrupted event handler for fd %d\n",
			event.data.fd);
		goto out;
	}

	pr_debug("Running handler %s to handle events from fd %d\n",
		handler->name, handler->fd);
	handler->handle_event(handler);

out:
	return ret;
}