/* notmuch - Not much of an email program, (just index and search)
 *
 * Copyright © 2012 Peter Wang
 *
 * 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: Peter Wang <novalazy@gmail.com>
 */

#include "notmuch-client.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

/* Like gethostname but guarantees that a null-terminated hostname is
 * returned, even if it has to make one up.
 * Returns true unless hostname contains a slash. */
static notmuch_bool_t
safe_gethostname (char *hostname, size_t len)
{
    if (gethostname (hostname, len) == -1) {
	strncpy (hostname, "unknown", len);
    }
    hostname[len - 1] = '\0';

    return (strchr (hostname, '/') == NULL);
}

/* Check the specified folder name does not contain a directory
 * component ".." to prevent writes outside of the Maildir hierarchy. */
static notmuch_bool_t
check_folder_name (const char *folder)
{
    const char *p = folder;

    for (;;) {
	if ((p[0] == '.') && (p[1] == '.') && (p[2] == '\0' || p[2] == '/'))
	    return FALSE;
	p = strchr (p, '/');
	if (!p)
	    return TRUE;
	p++;
    }
}

/* Make the given directory but succeed if it already exists. */
static int
mkdir_exists_ok (const char *path, int mode)
{
    int ret;

    ret = mkdir (path, mode);
    if (ret == 0 || errno == EEXIST)
	return 0;
    else
	return ret;
}

/* Make the given directory including its parent directory as necessary.
 * Return 0 on success, -1 on error. */
static int
mkdir_parents (char *path, int mode)
{
    struct stat st;
    char *start;
    char *end;
    int ret;

    /* First check the common case: directory already exists. */
    if (stat (path, &st) == 0)
	return (S_ISDIR (st.st_mode)) ? 0 : -1;

    for (start = path; *start != '\0'; start = end + 1) {
	/* start points to the first unprocessed character.
	 * Find the next slash from start onwards. */
	end = strchr (start, '/');

	/* If there are no more slashes then all the parent directories
	 * have been made.  Now attempt to make the whole path. */
	if (end == NULL)
	    return mkdir_exists_ok (path, mode);

	/* Make the path up to the next slash, unless the current
	 * directory component is actually empty. */
	if (end > start) {
	    *end = '\0';
	    ret = mkdir_exists_ok (path, mode);
	    *end = '/';
	    if (ret != 0)
		return ret;
	}
    }

    return 0;
}

/* Create the given maildir folder, i.e. dir and its subdirectories
 * 'cur', 'new', 'tmp'. */
static notmuch_bool_t
maildir_create_folder (void *ctx, const char *dir)
{
    const int mode = 0700;
    char *subdir;
    char *tail;

    /* Create 'cur' directory, including parent directories. */
    subdir = talloc_asprintf (ctx, "%s/cur", dir);
    if (! subdir) {
	fprintf (stderr, "Out of memory.\n");
	return FALSE;
    }
    if (mkdir_parents (subdir, mode) != 0)
	return FALSE;

    tail = subdir + strlen (subdir) - 3;

    /* Create 'new' directory. */
    strcpy (tail, "new");
    if (mkdir_exists_ok (subdir, mode) != 0)
	return FALSE;

    /* Create 'tmp' directory. */
    strcpy (tail, "tmp");
    if (mkdir_exists_ok (subdir, mode) != 0)
	return FALSE;

    talloc_free (subdir);
    return TRUE;
}

/* Open a unique file in the Maildir 'tmp' directory.
 * Returns the file descriptor on success, or -1 on failure.
 * On success, file paths into the 'tmp' and 'new' directories are returned
 * via tmppath and newpath. */
static int
maildir_open_tmp_file (void *ctx, const char *dir,
		       char **tmppath, char **newpath)
{
    pid_t pid;
    char hostname[256];
    struct timeval tv;
    char *filename;
    int fd = -1;

    /* We follow the Dovecot file name generation algorithm. */
    pid = getpid ();
    if (! safe_gethostname (hostname, sizeof (hostname))) {
	fprintf (stderr, "Error: invalid host name.\n");
	return -1;
    }
    do {
	gettimeofday (&tv, NULL);
	filename = talloc_asprintf (ctx, "%ld.M%ldP%d.%s",
				    tv.tv_sec, tv.tv_usec, pid, hostname);
	if (! filename) {
	    fprintf (stderr, "Out of memory\n");
	    return -1;
	}

	*tmppath = talloc_asprintf (ctx, "%s/tmp/%s", dir, filename);
	if (! *tmppath) {
	    fprintf (stderr, "Out of memory\n");
	    return -1;
	}

	fd = open (*tmppath, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 0600);
    } while (fd == -1 && errno == EEXIST);

    if (fd == -1) {
	fprintf (stderr, "Error: opening %s: %s\n", *tmppath, strerror (errno));
	return -1;
    }

    *newpath = talloc_asprintf (ctx, "%s/new/%s", dir, filename);
    if (! *newpath) {
	fprintf (stderr, "Out of memory\n");
	close (fd);
	unlink (*tmppath);
	return -1;
    }

    talloc_free (filename);

    return fd;
}

/* Atomically move the new message file from the Maildir 'tmp' directory
 * to the 'new' directory.
 *
 * We follow the Dovecot recommendation to simply use rename()
 * instead of link() and unlink().  See also:
 * http://wiki.dovecot.org/MailboxFormat/Maildir#Mail_delivery
 */
static notmuch_bool_t
maildir_move_tmp_to_new (const char *tmppath, const char *newpath)
{
    if (rename (tmppath, newpath) != 0) {
	fprintf (stderr, "Error: rename() failed: %s\n", strerror (errno));
	return FALSE;
    }

    return TRUE;
}

/* Copy the contents of fdin into fdout. */
static notmuch_bool_t
copy_fd_data (int fdin, int fdout)
{
    char buf[4096];
    char *p;
    ssize_t remain;
    ssize_t written;

    for (;;) {
	remain = read (fdin, buf, sizeof(buf));
	if (remain == 0)
	    break;
	if (remain < 0) {
	    if (errno == EINTR)
		continue;
	    fprintf (stderr, "Error: reading from standard input: %s\n",
		     strerror (errno));
	    return FALSE;
	}

	p = buf;
	do {
	    written = write (fdout, p, remain);
	    if (written == 0)
		return FALSE;
	    if (written < 0) {
		if (errno == EINTR)
		    continue;
		fprintf (stderr, "Error: writing to temporary file: %s",
			 strerror (errno));
		return FALSE;
	    }
	    p += written;
	    remain -= written;
	} while (remain > 0);
    }

    return TRUE;
}

/* Add the specified message file to the notmuch database, applying tags.
 * The file is renamed to encode notmuch tags as maildir flags. */
static notmuch_bool_t
add_file_to_database (notmuch_database_t *notmuch, const char *path,
		      const char **new_tags,
		      const notmuch_tag_operation_t *tag_ops)
{
    notmuch_message_t *message;
    notmuch_status_t status;
    int i;

    status = notmuch_database_add_message (notmuch, path, &message);
    switch (status) {
    case NOTMUCH_STATUS_SUCCESS:
	break;
    case NOTMUCH_STATUS_DUPLICATE_MESSAGE_ID:
	fprintf (stderr, "Warning: duplicate message.\n");
	break;
    default:
    case NOTMUCH_STATUS_FILE_NOT_EMAIL:
    case NOTMUCH_STATUS_READ_ONLY_DATABASE:
    case NOTMUCH_STATUS_XAPIAN_EXCEPTION:
    case NOTMUCH_STATUS_OUT_OF_MEMORY:
    case NOTMUCH_STATUS_FILE_ERROR:
    case NOTMUCH_STATUS_NULL_POINTER:
    case NOTMUCH_STATUS_TAG_TOO_LONG:
    case NOTMUCH_STATUS_UNBALANCED_FREEZE_THAW:
    case NOTMUCH_STATUS_UNBALANCED_ATOMIC:
    case NOTMUCH_STATUS_LAST_STATUS:
	fprintf (stderr, "Error: failed to add `%s' to notmuch database: %s\n",
		 path, notmuch_status_to_string (status));
	return FALSE;
    }

    notmuch_message_freeze (message);

    /* Apply the new.tags, as would happen were the message added by
     * 'notmuch new'. */
    for (i = 0; new_tags[i]; i++) {
	notmuch_message_add_tag (message, new_tags[i]);
    }

    /* Apply the tags specified on the command-line. */
    for (i = 0; tag_ops[i].tag; i++) {
	if (tag_ops[i].remove)
	    notmuch_message_remove_tag (message, tag_ops[i].tag);
	else
	    notmuch_message_add_tag (message, tag_ops[i].tag);
    }

    notmuch_message_thaw (message);

    notmuch_message_tags_to_maildir_flags (message);

    notmuch_message_destroy (message);

    return TRUE;
}

static notmuch_bool_t
insert_message (void *ctx, notmuch_database_t *notmuch, int fdin,
		const char *dir, const char **new_tags,
		const notmuch_tag_operation_t *tag_ops)
{
    char *tmppath;
    char *newpath;
    int fdout;
    notmuch_bool_t ret;

    fdout = maildir_open_tmp_file (ctx, dir, &tmppath, &newpath);
    if (fdout < 0) {
	return FALSE;
    }
    ret = copy_fd_data (fdin, fdout);
    if (ret && fsync (fdout) != 0) {
	fprintf (stderr, "Error: fsync failed: %s\n", strerror (errno));
	ret = FALSE;
    }
    close (fdout);
    if (ret) {
	ret = maildir_move_tmp_to_new (tmppath, newpath);
    }
    if (!ret) {
	unlink (tmppath);
	return FALSE;
    }

    ret = add_file_to_database (notmuch, newpath, new_tags, tag_ops);
    if (!ret) {
	/* XXX maybe there should be an option to keep the file in maildir? */
	unlink (newpath);
	return FALSE;
    }

    return TRUE;
}

int
notmuch_insert_command (void *ctx, int argc, char *argv[])
{
    notmuch_config_t *config;
    notmuch_database_t *notmuch;
    const char *db_path;
    const char **new_tags;
    size_t new_tags_length;
    const char *folder = NULL;
    notmuch_bool_t create_folder = FALSE;
    notmuch_tag_operation_t *tag_ops;
    int tag_ops_count;
    char *maildir;
    int opt_index;
    notmuch_bool_t ret;

    notmuch_opt_desc_t options[] = {
	{ NOTMUCH_OPT_STRING, &folder, "folder", 0, 0 },
	{ NOTMUCH_OPT_BOOLEAN, &create_folder, "create-folder", 0, 0 },
	{ NOTMUCH_OPT_END, 0, 0, 0, 0 }
    };

    opt_index = parse_arguments (argc, argv, options, 1);

    if (opt_index < 0) {
	fprintf (stderr, "Error: bad argument to notmuch insert: %s\n",
		 argv[-opt_index]);
	return 1;
    }

    /* Array of tagging operations (add or remove), terminated with an
     * empty element. */
    tag_ops = talloc_array (ctx, notmuch_tag_operation_t, argc - opt_index + 1);
    if (tag_ops == NULL) {
	fprintf (stderr, "Out of memory.\n");
	return 1;
    }

    opt_index = parse_tag_operations (opt_index, argc, argv,
				      tag_ops, &tag_ops_count);
    if (opt_index < 0)
	return 1;

    tag_ops[tag_ops_count].tag = NULL;

    if (opt_index != argc) {
	fprintf (stderr, "Error: bad argument to notmuch insert: %s\n",
		 argv[opt_index]);
	return 1;
    }

    config = notmuch_config_open (ctx, NULL, NULL);
    if (config == NULL)
	return 1;

    db_path = notmuch_config_get_database_path (config);
    new_tags = notmuch_config_get_new_tags (config, &new_tags_length);

    if (folder != NULL) {
	if (! check_folder_name (folder)) {
	    fprintf (stderr, "Error: bad folder name: %s\n", folder);
	    return 1;
	}
	maildir = talloc_asprintf (ctx, "%s/%s", db_path, folder);
    } else {
	maildir = talloc_asprintf (ctx, "%s", db_path);
    }
    if (! maildir) {
	fprintf (stderr, "Out of memory\n");
	return 1;
    }
    if (create_folder && ! maildir_create_folder (ctx, maildir)) {
	fprintf (stderr, "Error: creating maildir %s: %s\n",
		 maildir, strerror (errno));
	return 1;
    }

    if (notmuch_database_open (notmuch_config_get_database_path (config),
			       NOTMUCH_DATABASE_MODE_READ_WRITE, &notmuch))
	return 1;

    ret = insert_message (ctx, notmuch, STDIN_FILENO, maildir, new_tags,
			  tag_ops);

    notmuch_database_destroy (notmuch);

    return (ret) ? 0 : 1;
}