/*
 * Copyright (c) 2002-2004 Niels Provos <provos@citi.umich.edu>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/types.h>

#ifdef HAVE_CONFIG_H
#include "event-config.h"
#endif

#ifdef _EVENT_HAVE_SYS_TIME_H
#include <sys/time.h>
#endif

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#ifdef _EVENT_HAVE_STDARG_H
#include <stdarg.h>
#endif
#ifdef _EVENT_HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef WIN32
#include <winsock2.h>
#endif

#include "event2/util.h"
#include "event2/bufferevent.h"
#include "event2/buffer.h"
#include "event2/buffer_compat.h"
#include "event2/bufferevent_struct.h"
#include "event2/bufferevent_compat.h"
#include "event2/event.h"
#include "log-internal.h"
#include "mm-internal.h"
#include "bufferevent-internal.h"
#include "util-internal.h"

/* prototypes */
static int be_socket_enable(struct bufferevent *, short);
static int be_socket_disable(struct bufferevent *, short);
static void be_socket_destruct(struct bufferevent *);
static void be_socket_adj_timeouts(struct bufferevent *);
static int be_socket_flush(struct bufferevent *, short, enum bufferevent_flush_mode);

const struct bufferevent_ops bufferevent_ops_socket = {
	"socket",
	0,
	be_socket_enable,
	be_socket_disable,
	be_socket_destruct,
	be_socket_adj_timeouts,
        be_socket_flush,
};

static int
be_socket_add(struct event *ev, const struct timeval *tv)
{
	if (tv->tv_sec == 0 && tv->tv_usec == 0)
		return event_add(ev, NULL);
	else
		return event_add(ev, tv);
}

static void
bufferevent_socket_outbuf_cb(struct evbuffer *buf,
    const struct evbuffer_cb_info *cbinfo,
    void *arg)
{
	struct bufferevent *bufev = arg;

	if (cbinfo->n_added &&
	    (bufev->enabled & EV_WRITE) &&
	    !event_pending(&bufev->ev_write, EV_WRITE, NULL)) {
		/* Somebody added data to the buffer, and we would like to
		 * write, and we were not writing.  So, start writing. */
		be_socket_add(&bufev->ev_write, &bufev->timeout_write);
	}
}

static void
bufferevent_readcb(evutil_socket_t fd, short event, void *arg)
{
	struct bufferevent *bufev = arg;
	struct evbuffer *input;
	int res = 0;
	short what = EVBUFFER_READ;
	int howmuch = -1;

	if (event == EV_TIMEOUT) {
		what |= EVBUFFER_TIMEOUT;
		goto error;
	}

	input = bufev->input;

	/*
	 * If we have a high watermark configured then we don't want to
	 * read more data than would make us reach the watermark.
	 */
	if (bufev->wm_read.high != 0) {
		howmuch = bufev->wm_read.high - EVBUFFER_LENGTH(input);
		/* we somehow lowered the watermark, stop reading */
		if (howmuch <= 0) {
			bufferevent_wm_suspend_read(bufev);
			return;
		}
	}

	evbuffer_unfreeze(input, 0);
	res = evbuffer_read(input, fd, howmuch);
	evbuffer_freeze(input, 0);

	if (res == -1) {
		int err = evutil_socket_geterror(fd);
		if (EVUTIL_ERR_RW_RETRIABLE(err))
			goto reschedule;
		/* error case */
		what |= EVBUFFER_ERROR;
	} else if (res == 0) {
		/* eof case */
		what |= EVBUFFER_EOF;
	}

	if (res <= 0)
		goto error;


	/* Invoke the user callback - must always be called last */
	if (EVBUFFER_LENGTH(input) >= bufev->wm_read.low &&
            bufev->readcb != NULL)
		(*bufev->readcb)(bufev, bufev->cbarg);

	return;

 reschedule:
	return;

 error:
	event_del(&bufev->ev_read);
	(*bufev->errorcb)(bufev, what, bufev->cbarg);

}

static void
bufferevent_writecb(evutil_socket_t fd, short event, void *arg)
{
	struct bufferevent *bufev = arg;
	int res = 0;
	short what = EVBUFFER_WRITE;

	if (event == EV_TIMEOUT) {
		what |= EVBUFFER_TIMEOUT;
		goto error;
	}

	if (EVBUFFER_LENGTH(bufev->output)) {
	    evbuffer_unfreeze(bufev->output, 1);
	    res = evbuffer_write(bufev->output, fd);
	    evbuffer_freeze(bufev->output, 1);
	    if (res == -1) {
			int err = evutil_socket_geterror(fd);
			if (EVUTIL_ERR_RW_RETRIABLE(err))
				goto reschedule;
		    what |= EVBUFFER_ERROR;
	    } else if (res == 0) {
		    /* eof case */
		    what |= EVBUFFER_EOF;
	    }
	    if (res <= 0)
		    goto error;
	}

	if (EVBUFFER_LENGTH(bufev->output) == 0)
		event_del(&bufev->ev_write);

	/*
	 * Invoke the user callback if our buffer is drained or below the
	 * low watermark.
	 */
	if (bufev->writecb != NULL &&
	    EVBUFFER_LENGTH(bufev->output) <= bufev->wm_write.low)
		(*bufev->writecb)(bufev, bufev->cbarg);

	return;

 reschedule:
	if (EVBUFFER_LENGTH(bufev->output) == 0)
		event_del(&bufev->ev_write);
	return;

 error:
	event_del(&bufev->ev_write);
	(*bufev->errorcb)(bufev, what, bufev->cbarg);
}

struct bufferevent *
bufferevent_socket_new(struct event_base *base, evutil_socket_t fd,
    enum bufferevent_options options)
{
	struct bufferevent *bufev;

	if ((bufev = mm_calloc(1, sizeof(struct bufferevent))) == NULL)
		return NULL;

	if (bufferevent_init_common(bufev, base, &bufferevent_ops_socket,
				    options) < 0) {
		mm_free(bufev);
		return NULL;
	}

	event_assign(&bufev->ev_read, bufev->ev_base, fd,
	    EV_READ|EV_PERSIST, bufferevent_readcb, bufev);
	event_assign(&bufev->ev_write, bufev->ev_base, fd,
	    EV_WRITE|EV_PERSIST, bufferevent_writecb, bufev);

	evbuffer_add_cb(bufev->output, bufferevent_socket_outbuf_cb, bufev);

	evbuffer_freeze(bufev->input, 0);
	evbuffer_freeze(bufev->output, 1);

	return bufev;
}

/*
 * Create a new buffered event object.
 *
 * The read callback is invoked whenever we read new data.
 * The write callback is invoked whenever the output buffer is drained.
 * The error callback is invoked on a write/read error or on EOF.
 *
 * Both read and write callbacks maybe NULL.  The error callback is not
 * allowed to be NULL and have to be provided always.
 */

struct bufferevent *
bufferevent_new(evutil_socket_t fd, evbuffercb readcb, evbuffercb writecb,
    everrorcb errorcb, void *cbarg)
{
	struct bufferevent *bufev;

	if (!(bufev = bufferevent_socket_new(NULL, fd, 0)))
		return NULL;

	bufferevent_setcb(bufev, readcb, writecb, errorcb, cbarg);

	return bufev;
}


static int
be_socket_enable(struct bufferevent *bufev, short event)
{
	if (event & EV_READ) {
		if (be_socket_add(&bufev->ev_read,&bufev->timeout_read) == -1)
			return -1;
	}
	if (event & EV_WRITE) {
		if (be_socket_add(&bufev->ev_write,&bufev->timeout_write) == -1)
			return -1;
	}
	return 0;
}

static int
be_socket_disable(struct bufferevent *bufev, short event)
{
	if (event & EV_READ) {
		if (event_del(&bufev->ev_read) == -1)
			return -1;
	}
	if (event & EV_WRITE) {
		if (event_del(&bufev->ev_write) == -1)
			return -1;
	}
	return 0;
}

static void
be_socket_destruct(struct bufferevent *bufev)
{
	evutil_socket_t fd;
	assert(bufev->be_ops == &bufferevent_ops_socket);

	fd = event_get_fd(&bufev->ev_read);

	event_del(&bufev->ev_read);
	event_del(&bufev->ev_write);

	if (bufev->options & BEV_OPT_CLOSE_ON_FREE)
		EVUTIL_CLOSESOCKET(fd);
}

static void
be_socket_adj_timeouts(struct bufferevent *bufev)
{
	if (event_pending(&bufev->ev_read, EV_READ, NULL))
		be_socket_add(&bufev->ev_read, &bufev->timeout_read);
	if (event_pending(&bufev->ev_write, EV_WRITE, NULL))
		be_socket_add(&bufev->ev_write, &bufev->timeout_write);
}

static int
be_socket_flush(struct bufferevent *bev, short iotype,
    enum bufferevent_flush_mode mode)
{
        return 0;
}


void
bufferevent_setfd(struct bufferevent *bufev, evutil_socket_t fd)
{
	assert(bufev->be_ops == &bufferevent_ops_socket);

	event_del(&bufev->ev_read);
	event_del(&bufev->ev_write);

	event_assign(&bufev->ev_read, bufev->ev_base, fd,
	    EV_READ|EV_PERSIST, bufferevent_readcb, bufev);
	event_assign(&bufev->ev_write, bufev->ev_base, fd,
	    EV_WRITE|EV_PERSIST, bufferevent_writecb, bufev);
}

/* XXXX Should non-socket buffferevents support this? */
int
bufferevent_priority_set(struct bufferevent *bufev, int priority)
{
	if (bufev->be_ops != &bufferevent_ops_socket)
		return -1;

	if (event_priority_set(&bufev->ev_read, priority) == -1)
		return (-1);
	if (event_priority_set(&bufev->ev_write, priority) == -1)
		return (-1);

	return (0);
}

/* XXXX Should non-socket buffferevents support this? */
int
bufferevent_base_set(struct event_base *base, struct bufferevent *bufev)
{
	int res;
	if (bufev->be_ops != &bufferevent_ops_socket)
		return -1;

	bufev->ev_base = base;

	res = event_base_set(base, &bufev->ev_read);
	if (res == -1)
		return (res);

	res = event_base_set(base, &bufev->ev_write);
	return (res);
}