/* Copyright (C) 2007 Timo Sirainen, LGPLv2.1 */

/*
   export DOVECOT=~/src/dovecot-1.0.0
   gcc -fPIC -g -shared -Wall -I$DOVECOT -I$DOVECOT/src/lib \
     -I$DOVECOT/src/lib-storage -I$DOVECOT/src/lib-mail \
     -I$DOVECOT/src/lib-imap -I$DOVECOT/src/imap \
     -DHAVE_CONFIG_H imap-alert-plugin.c -o imap_alert_plugin.so

   Usage:

   Write the text you want in the alert to /etc/dovecot.alert. Running imap
   processes check if the file has changed every 5 seconds. When it has, the
   file's contents are sent to IMAP client as:

   * OK [ALERT] <File contents>.

   The file should have only a single line, but newlines and some other
   illegal characters are automatically converted to spaces.

   You can change the ALERT_* macros below to change settings.
*/

#include "lib.h"
#include "ioloop.h"
#include "ostream.h"
#include "common.h"

#include <fcntl.h>
#include <unistd.h>

/* Check if file has changed every 5 seconds */
#define ALERT_CHECK_INTERVAL 5
/* Don't alert client more often than once every 60 seconds */
#define ALERT_SEND_INTERVAL 60
/* File to use for alert */
#define ALERT_FILE "/etc/dovecot.alert"

const char *imap_alert_plugin_version = PACKAGE_VERSION;

static void (*alert_next_hook_client_created)(struct client **client);

static struct timeout *to;
static time_t last_alert_check = 0, last_alert_sent = 0;

static void alert_send(struct client *client, const char *path)
{
	char buf[1024];
	int fd;
	ssize_t i, ret;

	last_alert_sent = 0;

	fd = open(path, O_RDONLY);
	if (fd == -1) {
		if (errno != ENOENT)
			i_error("open(%s) failed: %m", path);
		return;
	}

	ret = read(fd, buf, sizeof(buf)-1);
	if (ret < 0)
		i_error("read(%s) failed: %m", path);
	else {
		/* convert illegal characters to spaces */
		for (i = 0; i < ret; i++) {
			if (buf[i] == '\r' || buf[i] == '\n' ||
			    buf[i] == ']' || buf[i] == '\0')
				buf[i] = ' ';
		}
		while (ret > 0 && buf[ret-1] == ' ')
			ret--;
		buf[ret] = '\0';

		if (ret != 0) {
			const char *text =
				t_strconcat("* OK [ALERT] ", buf, "\r\n", NULL);

			o_stream_send_str(client->output, text);
			o_stream_flush(client->output);
			last_alert_sent = ioloop_time;
		}
	}
	if (close(fd) < 0)
		i_error("close(%s) failed: %m", path);
}

static void alert_timeout(void *context)
{
	struct client *client = context;

	if (client->output_lock != NULL)
		return;

	if (last_alert_check + ALERT_CHECK_INTERVAL < ioloop_time &&
	    last_alert_sent + ALERT_SEND_INTERVAL < ioloop_time) {
		last_alert_check = ioloop_time;
		alert_send(client, ALERT_FILE);
	}
}

static void alert_client_created(struct client **client)
{
	if (alert_next_hook_client_created != NULL)
		alert_next_hook_client_created(client);

	to = timeout_add(ALERT_CHECK_INTERVAL * 1000/2, alert_timeout, *client);
}

void imap_alert_plugin_init(void);
void imap_alert_plugin_deinit(void);

void imap_alert_plugin_init(void)
{
	alert_next_hook_client_created = hook_client_created;
	hook_client_created = alert_client_created;
}

void imap_alert_plugin_deinit(void)
{
	if (to != NULL)
		timeout_remove(&to);
	hook_client_created = alert_next_hook_client_created;
}