/* notmuch - Not much of an email program, (just index and search)
 *
 * Copyright © 2010 David Bremner
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see http://www.gnu.org/licenses/ .
 *
 * Author: David Bremner <david@tethera.net>
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <talloc.h>
#include <stdarg.h>

#include "log-private.h"
#include "notmuch.h"

/*
 * Return a file descriptor to the open log file, or -1 if an error
 * occurs.
 *
 */

notmuch_log_t *
notmuch_log_open (void *ctx,const char *path, notmuch_log_buffering_t buffering)
{
    int fd;
    notmuch_log_t *log;

    log=talloc (ctx, notmuch_log_t);
    if (log==NULL)
	return NULL;

    fd = open (path, O_CREAT|O_WRONLY|O_APPEND, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
    if (fd < 0) {
	fprintf (stderr, "Failed to open %s: %s\n",
		 path, strerror (errno));
	return NULL;
    }

    log->file_desc = fd;
    log->buffer = NULL;
    log->txn_id = NULL;
    log->txn_depth = 0;
    log->buffering = buffering;
    return log;
}

static notmuch_status_t
_log_write (int file_desc, const char *buffer, size_t len){

    struct flock lock;

    lock.l_type = F_WRLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = 0;
    lock.l_len = 0;

    if (fcntl (file_desc, F_SETLKW, &lock) != 0) {
	fprintf (stderr, "Failed to lock  %s\n",
		 strerror (errno));

	return NOTMUCH_STATUS_FILE_ERROR;
    }

    while (len > 0)
    {
	int written;

	written = write(file_desc, buffer, len);
	if (written < 0 || (written == 0 && errno !=0))
	{
	    fprintf (stderr, "Failed to write %zd characters: %s\n",
		     len, strerror (errno));

	    return NOTMUCH_STATUS_FILE_ERROR;
	}

	len -= written;
	buffer += written;

    }

    if (fdatasync (file_desc) != 0) {
	fprintf (stderr, "Failed to sync:  %s\n",
		 strerror (errno));

	return NOTMUCH_STATUS_FILE_ERROR;
    }

    lock.l_type=F_UNLCK;

    if (fcntl (file_desc, F_SETLK, &lock) != 0) {
	fprintf (stderr, "Failed to unlock:  %s\n",
		 strerror (errno));

	return NOTMUCH_STATUS_FILE_ERROR;
    }

    return NOTMUCH_STATUS_SUCCESS;
}

void
notmuch_log_sync (notmuch_log_t *log)
{
    if (log->buffer) {
	_log_write(log->file_desc, log->buffer, strlen (log->buffer));
	talloc_free(log->buffer);
	log->buffer=NULL;
    }

};


/* This function was derived from the print_string_ptr function of
 * cJSON (http://cjson.sourceforge.net/) and is used by permission of
 * the following license:
 *
 * Copyright (c) 2009 Dave Gamble
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

static char *
_log_escape_chararray(const void *ctx, const char *str, const size_t len)
{
    const char *ptr;
    char *ptr2;
    char *out;
    size_t loop;
    size_t required;

    for (loop = 0, required = 0, ptr = str;
	 loop < len;
	 loop++, required++, ptr++) {
	if ((unsigned char)(*ptr) <= ' ')
	    required++;
    }

    /*
     * + 1 for trailing NULL.
     */
    out = talloc_array (ctx, char, required + 1);

    ptr = str;
    ptr2 = out;

    for (loop = 0; loop < len; loop++) {
	if ((unsigned char)(*ptr) > 32 && *ptr != '\"' && *ptr != '\\') {
		*ptr2++ = *ptr++;
	    } else {
		*ptr2++ = '\\';
		switch (*ptr++) {
		    case ' ':   *ptr2++ = ' ';	break;
		    case '\\':	*ptr2++ = '\\';	break;
		    case '\b':	*ptr2++ = 'b';	break;
		    case '\f':	*ptr2++ = 'f';	break;
		    case '\n':	*ptr2++ = 'n';	break;
		    case '\r':	*ptr2++ = 'r';	break;
		    case '\t':	*ptr2++ = 't';	break;
		    default:	 ptr2--;	break;
		}
	    }
    }
    *ptr2++ = '\0';

    return out;
}

static char*
_log_escape_string (void *ctx, const char *str)
{
    return _log_escape_chararray (ctx, str, strlen(str));
}

/*
 * Log a series of strings as a space delimited line.  Spaces and
 * backslashes will be escaped by adding a backslash in front.
 */

static notmuch_status_t
_log_append_string (notmuch_log_t *log, const char *str)
{
    if (log->buffer == NULL) {
	log->buffer = talloc_strdup (log, str);
    } else {
	log->buffer = talloc_strdup_append (log->buffer, str);
    }

    if (log->buffer == NULL){
	return NOTMUCH_STATUS_OUT_OF_MEMORY;
    }

    if (log->buffering == NOTMUCH_LOG_BUFFER_NONE)
	notmuch_log_sync(log);

    return NOTMUCH_STATUS_SUCCESS;
}


/*
 *  Log a null terminated list of strings as a single space delimited log line.
 *  spaces and newlines are escaped.
 */

void
notmuch_log_words (notmuch_log_t *log, const char *word, ...)
{
    va_list args;
    const char *str;
    char *timestamp;

    timestamp = talloc_asprintf (log, "%ld", (long)time(NULL));
    _log_append_string(log,timestamp);
    talloc_free(timestamp);

    va_start (args, word);

    for (str = word; str != NULL; str = va_arg (args, const char *)) {
	_log_append_string (log, " ");
	_log_append_string(log, _log_escape_string (log, str));
    }

    va_end(args);

    _log_append_string(log, "\n");
    if (log->buffering <= NOTMUCH_LOG_BUFFER_LINE)
	notmuch_log_sync(log);

};

void
notmuch_log_start_transaction (notmuch_log_t *log)
{
    /* XXX This should probably be something like a uuid */
    if (log->txn_depth == 0) {
	log->txn_id = talloc_asprintf (log, "%ld", random());
    }
    log->txn_depth++;

    notmuch_log_words(log,"TX_START",
		      talloc_asprintf (log, "%s.%d", log->txn_id, log->txn_depth));
};

void
notmuch_log_finish_transaction (notmuch_log_t *log)
{
    notmuch_log_words(log,"TX_END",
		      talloc_asprintf (log, "%s.%d", log->txn_id, log->txn_depth));

    log->txn_depth--;

    if (log->txn_depth == 0){
	talloc_free (log->txn_id);
	log->txn_id = NULL;
    }
};