/* Copyright (c) 2005-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "ioloop.h"
#include "hash.h"
#include "mail-storage-private.h"
#include "mailbox-list-private.h"
#include "mailbox-guid-cache.h"

struct mailbox_guid_cache_rec {
	guid_128_t guid;
	const char *vname;
};

int mailbox_guid_cache_find(struct mailbox_list *list,
			    const guid_128_t guid, const char **vname_r)
{
	const struct mailbox_guid_cache_rec *rec;
	const uint8_t *guid_p = guid;

	if (!hash_table_is_created(list->guid_cache) ||
	    list->guid_cache_invalidated) {
		mailbox_guid_cache_refresh(list);
		rec = hash_table_lookup(list->guid_cache, guid_p);
	} else {
		rec = hash_table_lookup(list->guid_cache, guid_p);
		if (rec == NULL && list->guid_cache_updated) {
			mailbox_guid_cache_refresh(list);
			rec = hash_table_lookup(list->guid_cache, guid_p);
		}
	}
	if (rec == NULL) {
		*vname_r = NULL;
		return list->guid_cache_errors ? -1 : 0;
	}
	*vname_r = rec->vname;
	return 0;
}

static void mailbox_guid_cache_add_mailbox(struct mailbox_list *list,
					   const struct mailbox_info *info)
{
	struct mailbox *box;
	struct mailbox_metadata metadata;
	struct mailbox_guid_cache_rec *rec;
	uint8_t *guid_p;

	box = mailbox_alloc(list, info->vname, 0);
	if (mailbox_get_metadata(box, MAILBOX_METADATA_GUID,
				 &metadata) < 0) {
		e_error(box->event, "Couldn't get mailbox GUID: %s",
			mailbox_get_last_internal_error(box, NULL));
		list->guid_cache_errors = TRUE;
	} else if ((rec = hash_table_lookup(list->guid_cache,
			(const uint8_t *)metadata.guid)) != NULL) {
		e_warning(list->ns->user->event,
			  "Mailbox %s has duplicate GUID with %s: %s",
			  info->vname, rec->vname,
			  guid_128_to_string(metadata.guid));
	} else {
		rec = p_new(list->guid_cache_pool,
			    struct mailbox_guid_cache_rec, 1);
		memcpy(rec->guid, metadata.guid, sizeof(rec->guid));
		rec->vname = p_strdup(list->guid_cache_pool, info->vname);
		guid_p = rec->guid;
		hash_table_insert(list->guid_cache, guid_p, rec);
	}
	mailbox_free(&box);
}

void mailbox_guid_cache_refresh(struct mailbox_list *list)
{
	struct mailbox_list_iterate_context *ctx;
	const struct mailbox_info *info;

	if (!hash_table_is_created(list->guid_cache)) {
		list->guid_cache_pool =
			pool_alloconly_create("guid cache", 1024*16);
		hash_table_create(&list->guid_cache, list->guid_cache_pool, 0,
				  guid_128_hash, guid_128_cmp);
	} else {
		hash_table_clear(list->guid_cache, TRUE);
		p_clear(list->guid_cache_pool);
	}
	list->guid_cache_invalidated = FALSE;
	list->guid_cache_updated = FALSE;
	list->guid_cache_errors = FALSE;

	ctx = mailbox_list_iter_init(list, "*",
				     MAILBOX_LIST_ITER_SKIP_ALIASES |
				     MAILBOX_LIST_ITER_NO_AUTO_BOXES);
	while ((info = mailbox_list_iter_next(ctx)) != NULL) {
		if ((info->flags &
		     (MAILBOX_NOSELECT | MAILBOX_NONEXISTENT)) != 0)
			continue;
		T_BEGIN {
			mailbox_guid_cache_add_mailbox(list, info);
		} T_END;
	}
	if ((list->ns->prefix_len > 0) && !mail_namespace_prefix_is_inbox(list->ns)) {
		/* Also check if namespace prefix is a selectable mailbox
		   and add it to cache. Does not need to include INBOX since
		   it is added separately by mailbox_list_iter_init above. */
		const char *ns_vname = t_strndup(list->ns->prefix,
					         list->ns->prefix_len-1);
		const struct mailbox_info ns_info = {
			.vname = ns_vname,
			.ns = list->ns,
		};
		struct mailbox *box = mailbox_alloc(list, ns_vname, 0);
		enum mailbox_existence existence;
		if (mailbox_exists(box, FALSE, &existence) == 0 &&
		    existence == MAILBOX_EXISTENCE_SELECT)
			mailbox_guid_cache_add_mailbox(list, &ns_info);
		mailbox_free(&box);
	}

	if (mailbox_list_iter_deinit(&ctx) < 0)
		list->guid_cache_errors = TRUE;
}