#include <stddef.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/epoll.h>
#include <sys/timerfd.h>
#include <unistd.h>
#include <assert.h>
#include "wayland.h"

struct wl_event_loop {
	int epoll_fd;
	struct wl_list idle_list;
};

struct wl_event_source_interface {
	void (*dispatch)(struct wl_event_source *source,
			 struct epoll_event *ep);
	int (*remove)(struct wl_event_source *source);
};

struct wl_event_source {
	struct wl_event_source_interface *interface;
	struct wl_event_loop *loop;
};

struct wl_event_source_fd {
	struct wl_event_source base;
	int fd;
	wl_event_loop_fd_func_t func;
	void *data;
};

static void
wl_event_source_fd_dispatch(struct wl_event_source *source,
			    struct epoll_event *ep)
{
	struct wl_event_source_fd *fd_source = (struct wl_event_source_fd *) source;
	uint32_t mask;

	mask = 0;
	if (ep->events & EPOLLIN)
		mask |= WL_EVENT_READABLE;
	if (ep->events & EPOLLOUT)
		mask |= WL_EVENT_WRITEABLE;

	fd_source->func(fd_source->fd, mask, fd_source->data);
}

static int
wl_event_source_fd_remove(struct wl_event_source *source)
{
	struct wl_event_source_fd *fd_source =
		(struct wl_event_source_fd *) source;
	struct wl_event_loop *loop = source->loop;
	int fd;

	fd = fd_source->fd;
	free(source);

	return epoll_ctl(loop->epoll_fd, EPOLL_CTL_DEL, fd, NULL);
}

struct wl_event_source_interface fd_source_interface = {
	wl_event_source_fd_dispatch,
	wl_event_source_fd_remove
};

WL_EXPORT struct wl_event_source *
wl_event_loop_add_fd(struct wl_event_loop *loop,
		     int fd, uint32_t mask,
		     wl_event_loop_fd_func_t func,
		     void *data)
{
	struct wl_event_source_fd *source;
	struct epoll_event ep;

	source = malloc(sizeof *source);
	if (source == NULL)
		return NULL;

	source->base.interface = &fd_source_interface;
	source->base.loop = loop;
	source->fd = fd;
	source->func = func;
	source->data = data;

	ep.events = 0;
	if (mask & WL_EVENT_READABLE)
		ep.events |= EPOLLIN;
	if (mask & WL_EVENT_WRITEABLE)
		ep.events |= EPOLLOUT;
	ep.data.ptr = source;

	if (epoll_ctl(loop->epoll_fd, EPOLL_CTL_ADD, fd, &ep) < 0) {
		free(source);
		return NULL;
	}

	return &source->base;
}

WL_EXPORT int
wl_event_source_fd_update(struct wl_event_source *source, uint32_t mask)
{
	struct wl_event_source_fd *fd_source =
		(struct wl_event_source_fd *) source;
	struct wl_event_loop *loop = source->loop;
	struct epoll_event ep;

	ep.events = 0;
	if (mask & WL_EVENT_READABLE)
		ep.events |= EPOLLIN;
	if (mask & WL_EVENT_WRITEABLE)
		ep.events |= EPOLLOUT;
	ep.data.ptr = source;

	return epoll_ctl(loop->epoll_fd,
			 EPOLL_CTL_MOD, fd_source->fd, &ep);
}

struct wl_event_source_timer {
	struct wl_event_source base;
	int fd;
	wl_event_loop_timer_func_t func;
	void *data;
};

static void
wl_event_source_timer_dispatch(struct wl_event_source *source,
			       struct epoll_event *ep)
{
	struct wl_event_source_timer *timer_source =
		(struct wl_event_source_timer *) source;
	uint64_t expires;

	read(timer_source->fd, &expires, sizeof expires);

	timer_source->func(timer_source->data);
}

static int
wl_event_source_timer_remove(struct wl_event_source *source)
{
	struct wl_event_source_timer *timer_source =
		(struct wl_event_source_timer *) source;
	struct wl_event_loop *loop = source->loop;
	int fd;

	fd = timer_source->fd;
	free(source);

	return epoll_ctl(loop->epoll_fd, EPOLL_CTL_DEL, fd, NULL);
}

struct wl_event_source_interface timer_source_interface = {
	wl_event_source_timer_dispatch,
	wl_event_source_timer_remove
};

WL_EXPORT struct wl_event_source *
wl_event_loop_add_timer(struct wl_event_loop *loop,
			wl_event_loop_timer_func_t func,
			void *data)
{
	struct wl_event_source_timer *source;
	struct epoll_event ep;

	source = malloc(sizeof *source);
	if (source == NULL)
		return NULL;

	source->base.interface = &timer_source_interface;
	source->base.loop = loop;

	source->fd = timerfd_create(CLOCK_MONOTONIC, 0);
	if (source->fd < 0) {
		fprintf(stderr, "could not create timerfd\n: %m");
		free(source);
		return NULL;
	}

	source->func = func;
	source->data = data;

	ep.events = EPOLLIN;
	ep.data.ptr = source;

	if (epoll_ctl(loop->epoll_fd, EPOLL_CTL_ADD, source->fd, &ep) < 0) {
		free(source);
		return NULL;
	}

	return &source->base;
}

WL_EXPORT int
wl_event_source_timer_update(struct wl_event_source *source, int ms_delay)
{
	struct wl_event_source_timer *timer_source =
		(struct wl_event_source_timer *) source;
	struct itimerspec its;

	its.it_interval.tv_sec = 0;
	its.it_interval.tv_nsec = 0;
	its.it_value.tv_sec = 0;
	its.it_value.tv_nsec = ms_delay * 1000 * 1000;
	if (timerfd_settime(timer_source->fd, 0, &its, NULL) < 0) {
		fprintf(stderr, "could not set timerfd\n: %m");
		return -1;
	}

	return 0;
}

struct wl_event_source_idle {
	struct wl_event_source base;
	struct wl_list link;
	wl_event_loop_idle_func_t func;
	void *data;
};

static void
wl_event_source_idle_dispatch(struct wl_event_source *source,
			      struct epoll_event *ep)
{
	assert(0);
}

static int
wl_event_source_idle_remove(struct wl_event_source *source)
{
	struct wl_event_source_idle *idle_source =
		(struct wl_event_source_idle *) source;

	wl_list_remove(&idle_source->link);

	return 0;
}

struct wl_event_source_interface idle_source_interface = {
	wl_event_source_idle_dispatch,
	wl_event_source_idle_remove
};

WL_EXPORT struct wl_event_source *
wl_event_loop_add_idle(struct wl_event_loop *loop,
		       wl_event_loop_idle_func_t func,
		       void *data)
{
	struct wl_event_source_idle *source;

	source = malloc(sizeof *source);
	if (source == NULL)
		return NULL;

	source->base.interface = &idle_source_interface;
	source->base.loop = loop;

	source->func = func;
	source->data = data;
	wl_list_insert(loop->idle_list.prev, &source->link);

	return &source->base;
}

WL_EXPORT int
wl_event_source_remove(struct wl_event_source *source)
{
	source->interface->remove(source);

	return 0;
}

WL_EXPORT struct wl_event_loop *
wl_event_loop_create(void)
{
	struct wl_event_loop *loop;

	loop = malloc(sizeof *loop);
	if (loop == NULL)
		return NULL;

	loop->epoll_fd = epoll_create(16);
	if (loop->epoll_fd < 0) {
		free(loop);
		return NULL;
	}
	wl_list_init(&loop->idle_list);

	return loop;
}

WL_EXPORT void
wl_event_loop_destroy(struct wl_event_loop *loop)
{
	close(loop->epoll_fd);
	free(loop);
}

#define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])

static void
dispatch_idles(struct wl_event_loop *loop)
{
	struct wl_event_source_idle *source, *next;

	source = container_of(loop->idle_list.next,
			      struct wl_event_source_idle, link);

	while (&source->link != &loop->idle_list) {
		source->func(source->data);
		next = container_of(source->link.next,
				    struct wl_event_source_idle, link);
		free(source);
		source = next;
	}

	wl_list_init(&loop->idle_list);
}

WL_EXPORT int
wl_event_loop_wait(struct wl_event_loop *loop)
{
	struct epoll_event ep[32];
	struct wl_event_source *source;
	int i, count, timeout;

	if (wl_list_empty(&loop->idle_list))
		timeout = -1;
	else
		timeout = 0;

	count = epoll_wait(loop->epoll_fd, ep, ARRAY_LENGTH(ep), timeout);
	if (count < 0)
		return -1;

	for (i = 0; i < count; i++) {
		source = ep[i].data.ptr;
		source->interface->dispatch(source, &ep[i]);
	}

	if (count == 0)
		dispatch_idles(loop);

	
	return 0;
}