/*

 * Copyright (c) 2014 Sunil Nimmagadda <sunil@nimmagadda.net>

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 */

#include <sys/param.h>

#include <sys/types.h>

#include <sys/tree.h>

#include <sys/stat.h>

#include <sys/socket.h>

#include <fcntl.h>

#include <dirent.h>

#include <stdio.h>

#include <string.h>

#include <syslog.h>

#include <unistd.h>

#include "pop3d.h"

static int init(struct mdrop *, size_t *, size_t *);

static int retr(struct mdrop *, unsigned int, size_t *, long *);

static int update(struct mdrop *);

static int new_to_cur(struct mdrop *);

static int msgcmp(struct msg *, struct msg *);

RB_PROTOTYPE(msgtree, msg, e.t_entry, msgcmp);

struct m_backend m_backend_maildir = {

	init,

	retr,

	update

};

/*

 * No resource management on error path as the process is

 * killed if an error occurs.

 */

static int

init(struct mdrop *m, size_t *nmsgs, size_t *sz)

{

	SHA1_CTX	ctx;

	struct stat	sb;

	u_char		buf[MAXBSIZE];

	DIR		*dirp;

	struct dirent	*dp;

	struct msg	*msg;

	u_char		*C;

	size_t		i;

	ssize_t		len;

	int		cur_fd, msg_fd;

	*nmsgs = 0;

	*sz = 0;

	if (new_to_cur(m) == -1) {

		logit(LOG_WARNING, "maildir: move msgs from new to cur failed");

		return (-1);

	}

	if ((cur_fd = openat(m->fd, "cur", O_RDONLY)) == -1) {

		logit(LOG_CRIT, "maildir: unable to open \"cur\" dir");

		return (-1);

	}

	if ((dirp = fdopendir(cur_fd)) == NULL)

		return (-1);

	while ((dp = readdir(dirp))) {

		if (dp->d_type != DT_REG)

			continue;

		if (strcmp(dp->d_name, ".") == 0 ||

		    strcmp(dp->d_name, "..") == 0)

			continue;

		msg = xcalloc(1, sizeof(*msg), "init");

		if ((msg->u.fname = strdup(dp->d_name)) == NULL)

			fatalx("init: strdup");

		if (fstatat(cur_fd, dp->d_name, &sb, 0) == -1) {

			logit(LOG_CRIT, "%s fstatat failed", dp->d_name);

			return (-1);

		}

		msg->sz = sb.st_size;

		if ((msg_fd = openat(cur_fd, dp->d_name, O_RDONLY)) == -1) {

			logit(LOG_CRIT, "%s openat failed", dp->d_name);

			return (-1);

		}

		SHA1Init(&ctx);

		while (( len = read(msg_fd, buf, sizeof(buf))) > 0) {

			SHA1Update(&ctx, (u_int8_t *)buf, len);

			for (C = buf; len--; ++C)

				if (*C == '\n')

					msg->nlines += 1;

		}

		SHA1End(&ctx, msg->hash);

		close(msg_fd);

		RB_INSERT(msgtree, &m->e.t_msgs, msg);

		m->nmsgs += 1;

	}

	/* allocate space for nmsgs of struct msg pointers */

	m->msgs_index = xcalloc(m->nmsgs, sizeof(msg), "init");

	*nmsgs = m->nmsgs;

	i = 0;

	*sz = 0;

	RB_FOREACH(msg, msgtree, &m->e.t_msgs) {

		m->msgs_index[i++] = msg;

		/* calculate maildir size by counting newline as 2 (CRLF) */

		*sz += msg->sz + msg->nlines;

	}

	closedir(dirp);

	close(cur_fd);

	return (0);

}

static int

new_to_cur(struct mdrop *m)

{

	DIR		*dirp;

	struct dirent	*dp;

	int		cur_fd, new_fd;

	if ((cur_fd = openat(m->fd, "cur", O_RDONLY)) == -1) {

		logit(LOG_CRIT, "maildir: unable to open \"cur\" dir");

		return (-1);

	}

	if ((new_fd = openat(m->fd, "new", O_RDONLY)) == -1) {

		logit(LOG_CRIT, "maildir: unable to open \"new\" dir");

		return (-1);

	}

	if ((dirp = fdopendir(new_fd)) == NULL)

		return (-1);

	while ((dp = readdir(dirp))) {

		if (dp->d_type != DT_REG)

			continue;

		if (strcmp(dp->d_name, ".") == 0 ||

		    strcmp(dp->d_name, "..") == 0)

			continue;

		if (renameat(new_fd, dp->d_name, cur_fd, dp->d_name) == -1) {

			logit(LOG_CRIT, "maildir: renameat failed");

			return (-1);

		}

	}

	closedir(dirp);

	close(cur_fd);

	close(new_fd);

	return (0);

}

static int

retr(struct mdrop *m, unsigned int idx, size_t *nlines, long *offset)

{

	char	buf[MAXPATHLEN];

	int	fd, r;

	*offset = 0;

	*nlines = m->msgs_index[idx]->nlines;

	r = snprintf(buf, sizeof(buf), "cur/%s", m->msgs_index[idx]->u.fname);

	if ((u_int)r >= sizeof(buf)) {

		logit(LOG_WARNING, "path too long");

		return (-1);

	}

	fd = openat(m->fd, buf, O_RDONLY);

	return (fd);

}

static int

update(struct mdrop *m)

{

	char	buf[MAXPATHLEN];

	size_t	i, j = 0;

	int	r;

	for (i = 0; i < m->nmsgs; i++)

		if (m->msgs_index[i]->flags & F_DELE)

			j += 1;

	if (j == 0) /* nothing to update */

		return (0);

	for (i = 0; i < m->nmsgs; i++) {

		if (!(m->msgs_index[i]->flags & F_DELE))

			continue;

		r = snprintf(buf, sizeof(buf), "cur/%s",

		    m->msgs_index[i]->u.fname);

		if ((u_int)r >= sizeof(buf)) {

			logit(LOG_WARNING, "path too long");

			return (1);

		}

		if (unlinkat(m->fd, buf, 0) == -1) {

			logit(LOG_CRIT, "%s unlink failed", buf);

			return (1);

		}

	}

	return (0);

}

static int

msgcmp(struct msg *m1, struct msg *m2)

{

	return strcmp(m1->u.fname, m2->u.fname);

}

RB_GENERATE(msgtree, msg, e.t_entry, msgcmp);