/* Copyright (C) 2002 Timo Sirainen */

/* ugly code here - text files are annoying to manage */

#include "lib.h"
#include "file-lock.h"
#include "mmap-util.h"
#include "write-full.h"
#include "imap-match.h"
#include "mail-storage.h"
#include "subscription-file.h"

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

#define SUBSCRIPTION_FILE_NAME ".subscriptions"

static int subsfile_set_syscall_error(struct mail_storage *storage,
				      const char *path, const char *function)
{
	i_assert(function != NULL);

	mail_storage_set_critical(storage,
				  "%s failed with subscription file %s: %m",
				  function, path);
	return FALSE;
}

static int subscription_open(struct mail_storage *storage, int update,
			     const char **path, void **mmap_base,
			     size_t *mmap_length)
{
	int fd;

	*path = t_strconcat(storage->dir, "/" SUBSCRIPTION_FILE_NAME, NULL);

	fd = update ? open(*path, O_RDWR | O_CREAT, 0660) :
		open(*path, O_RDONLY);
	if (fd == -1) {
		if (update || errno != ENOENT) {
                        subsfile_set_syscall_error(storage, "open()", *path);
			return -1;
		}

		return -2;
	}

	/* FIXME: we should work without locking, rename() would be easiest
	   but .lock would work too */
	if (file_wait_lock(fd, update ? F_WRLCK : F_RDLCK) <= 0) {
		subsfile_set_syscall_error(storage, "file_wait_lock()", *path);
		(void)close(fd);
		return -1;
	}

	*mmap_base = update ? mmap_rw_file(fd, mmap_length) :
		mmap_ro_file(fd, mmap_length);
	if (*mmap_base == MAP_FAILED) {
		*mmap_base = NULL;
		subsfile_set_syscall_error(storage, "mmap()", *path);
		(void)close(fd);
		return -1;
	}

	(void)madvise(*mmap_base, *mmap_length, MADV_SEQUENTIAL);
	return fd;
}

static int subscription_append(struct mail_storage *storage, int fd,
			       const char *name, size_t len, int prefix_lf,
			       const char *path)
{
	char *buf;

	if (lseek(fd, 0, SEEK_END) < 0)
		return subsfile_set_syscall_error(storage, "lseek()", path);

	/* @UNSAFE */
	buf = t_buffer_get(len+2);
	buf[0] = '\n';
	memcpy(buf+1, name, len);
	buf[len+1] = '\n';

	if (prefix_lf)
		len += 2;
	else {
		buf++;
		len++;
	}

	if (write_full(fd, buf, len) < 0) {
		subsfile_set_syscall_error(storage, "write_full()", path);
		return FALSE;
	}

	return TRUE;
}

int subsfile_set_subscribed(struct mail_storage *storage,
			    const char *name, int set)
{
	void *mmap_base;
	size_t mmap_length;
	const char *path;
	char *subscriptions, *end, *p;
	size_t namelen, afterlen, removelen;
	int fd,  failed, prefix_lf;

	if (strcasecmp(name, "INBOX") == 0)
		name = "INBOX";

	fd = subscription_open(storage, TRUE, &path, &mmap_base, &mmap_length);
	if (fd == -1)
		return FALSE;

	namelen = strlen(name);

	subscriptions = mmap_base;
	if (subscriptions == NULL)
		p = NULL;
	else {
		end = subscriptions + mmap_length;
		for (p = subscriptions; p != end; p++) {
			if (*p == *name && p+namelen <= end &&
			    strncmp(p, name, namelen) == 0) {
				/* make sure beginning and end matches too */
				if ((p == subscriptions || p[-1] == '\n') &&
				    (p+namelen == end || p[namelen] == '\n'))
					break;
			}
		}

		if (p == end)
			p = NULL;
	}

	failed = FALSE;
	if (p != NULL && !set) {
		/* remove it */
		afterlen = mmap_length - (size_t) (p - subscriptions);
		removelen = namelen < afterlen ? namelen+1 : namelen;

		if (removelen < afterlen)
			memmove(p, p+removelen, afterlen-removelen);

		if (ftruncate(fd, (off_t) (mmap_length - removelen)) == -1) {
			subsfile_set_syscall_error(storage, "ftruncate()",
						   path);
			failed = TRUE;
		}
	} else if (p == NULL && set) {
		/* append it */
		prefix_lf = mmap_length > 0 &&
			subscriptions[mmap_length-1] != '\n';
		if (!subscription_append(storage, fd, name, namelen,
					 prefix_lf, path))
			failed = TRUE;
	}

	if (mmap_base != NULL && munmap(mmap_base, mmap_length) < 0) {
		subsfile_set_syscall_error(storage, "munmap()", path);
		failed = TRUE;
	}

	if (close(fd) < 0) {
		subsfile_set_syscall_error(storage, "close()", path);
		failed = TRUE;
	}
	return !failed;
}

int subsfile_foreach(struct mail_storage *storage, const char *mask,
		     SubsFileForeachFunc func, void *context)
{
        struct imap_match_glob *glob;
	const char *path, *start, *end, *p, *line;
	void *mmap_base;
	size_t mmap_length;
	int fd, ret;

	fd = subscription_open(storage, FALSE, &path, &mmap_base, &mmap_length);
	if (fd < 0) {
		/* -2 = no subscription file, ignore */
		return fd == -1 ? -1 : 1;
	}

	glob = imap_match_init(mask, TRUE, storage->hierarchy_sep);

	start = mmap_base; end = start + mmap_length; ret = 1;
	while (ret) {
		t_push();

		for (p = start; p != end; p++) {
			if (*p == '\n')
				break;
		}

		line = t_strdup_until(start, p);
		if (line != NULL && *line != '\0' && imap_match(glob, line) > 0)
			ret = func(storage, line, context);
		t_pop();

		if (p == end)
			break;
		start = p+1;
	}

	if (mmap_base != NULL && munmap(mmap_base, mmap_length) < 0)
		subsfile_set_syscall_error(storage, "munmap()", path);
	if (close(fd) < 0)
		subsfile_set_syscall_error(storage, "close()", path);
	return ret;
}