/* metadata.cc - API for database metadata
 *
 * Copyright © 2015 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 "notmuch.h"
#include "notmuch-private.h"
#include "database-private.h"

struct _notmuch_metadata {
    notmuch_database_t *notmuch;
    Xapian::TermIterator *iterator;
    notmuch_metadata_class_t mclass;
    char *current_key;
};

static int
_notmuch_metadata_destroy (notmuch_metadata_t *list) {
    delete list->iterator;
    return 0;
}
static
const char *
_find_metadata_prefix (notmuch_metadata_class_t mclass)
{
    switch (mclass) {
    case NOTMUCH_METADATA_CONFIG:
	return "C";
    default:
	return NULL;
    }
}

notmuch_status_t _make_key(void *ctx, notmuch_metadata_class_t mclass,
			    const char *in, const char **out)
{
    const char *term;
    const char *prefix = NULL;

    if (!out)
	return NOTMUCH_STATUS_NULL_POINTER;

    prefix = _find_metadata_prefix(mclass);
    if (!prefix)
	return NOTMUCH_STATUS_UNSUPPORTED_OPERATION;

    term = talloc_asprintf (ctx, "%s%s",
			    prefix, in);
    if (!term)
	return NOTMUCH_STATUS_OUT_OF_MEMORY;

    *out = term;
    return NOTMUCH_STATUS_SUCCESS;
}

notmuch_status_t
notmuch_database_set_metadata (notmuch_database_t *notmuch,
			       notmuch_metadata_class_t mclass,
			       const char *key,
			       const char *value)
{
    notmuch_status_t status;
    Xapian::WritableDatabase *db;
    const char *key_term = NULL;
    void *local;

    local = talloc_new (NULL);

    status = _notmuch_database_ensure_writable (notmuch);
    if (status)
	goto DONE;

    status = _make_key (local, mclass, key, &key_term);
    if (status)
	goto DONE;

    try {
	db = static_cast <Xapian::WritableDatabase *> (notmuch->xapian_db);
	db->set_metadata (key_term, value);
    } catch (const Xapian::Error &error) {
	status = NOTMUCH_STATUS_XAPIAN_EXCEPTION;
	notmuch->exception_reported = TRUE;
	if (! notmuch->exception_reported) {
	    _notmuch_database_log (notmuch, "Error: A Xapian exception occurred setting metadata: %s\n",
				   error.get_msg().c_str());
	}
    }
 DONE:
    talloc_free (local);

    return status;
}

static notmuch_status_t
_metadata_value (notmuch_database_t *notmuch,
		 notmuch_metadata_class_t mclass,
		 const char *key,
		 std::string &value)
{
    notmuch_status_t status;

    const char *key_term = NULL;
    void *local;

    local = talloc_new (NULL);

    status = _make_key (local, mclass, key, &key_term);
    if (status)
	goto DONE;

    try {

	value = notmuch->xapian_db->get_metadata (key_term);

    } catch (const Xapian::Error &error) {
	status = NOTMUCH_STATUS_XAPIAN_EXCEPTION;
	notmuch->exception_reported = TRUE;
	if (! notmuch->exception_reported) {
	    _notmuch_database_log (notmuch, "Error: A Xapian exception occurred getting metadata: %s\n",
				   error.get_msg().c_str());
	}
    }

 DONE:
    talloc_free (local);
    return status;
}

notmuch_status_t
notmuch_database_get_metadata (notmuch_database_t *notmuch,
			       notmuch_metadata_class_t mclass,
			       const char *key,
			       char **value) {
    std::string strval;
    notmuch_status_t status;

    if (!value)
	return NOTMUCH_STATUS_NULL_POINTER;

    status = _metadata_value (notmuch, mclass, key, strval);
    if (status)
	return status;

    *value = strdup (strval.c_str ());

    return NOTMUCH_STATUS_SUCCESS;
}

notmuch_status_t
notmuch_database_get_all_metadata (notmuch_database_t *notmuch,
				   notmuch_metadata_class_t mclass,
				   notmuch_metadata_t **out)
{
    notmuch_metadata_t *list = NULL;
    notmuch_status_t status = NOTMUCH_STATUS_SUCCESS;

    const char *prefix = _find_metadata_prefix (mclass);

    list = talloc (notmuch, notmuch_metadata_t);
    if (!list) {
	status = NOTMUCH_STATUS_OUT_OF_MEMORY;
	goto DONE;
    }

    talloc_set_destructor(list, _notmuch_metadata_destroy);
    list->iterator = new Xapian::TermIterator;
    list->notmuch = notmuch;
    list->mclass = mclass;
    list->current_key = NULL;

    try {

	*list->iterator = notmuch->xapian_db->metadata_keys_begin();
	list->iterator->skip_to (prefix);

    } catch (const Xapian::Error &error) {
	_notmuch_database_log (notmuch, "A Xapian exception occurred getting metadata iterator: %s.\n",
			       error.get_msg().c_str());
	notmuch->exception_reported = TRUE;
	status = NOTMUCH_STATUS_XAPIAN_EXCEPTION;
    }

    *out = list;

 DONE:
    if (status && list)
	talloc_free (list);

    return status;
}

notmuch_bool_t
notmuch_metadata_valid (notmuch_metadata_t *metadata)
{
    const char *prefix = _find_metadata_prefix (metadata->mclass);
    if (*(metadata->iterator) == metadata->notmuch->xapian_db->metadata_keys_end())
	return FALSE;

    return (strncmp((**(metadata->iterator)).c_str (), prefix, strlen (prefix)) == 0);
}

const char *
notmuch_metadata_key (notmuch_metadata_t *metadata)
{
    const char *prefix = _find_metadata_prefix (metadata->mclass);

    if (metadata->current_key)
	talloc_free (metadata->current_key);
    metadata->current_key = talloc_strdup (metadata, (**(metadata->iterator)).c_str () + strlen (prefix));

    return  metadata->current_key;
}

const char *
notmuch_metadata_value (notmuch_metadata_t *metadata)
{
    const char *key = notmuch_metadata_key (metadata);
    char *val;
    notmuch_status_t status;

    status=notmuch_database_get_metadata (metadata->notmuch, metadata->mclass, key, &val);
    if (status)
	return NULL;

    return val;
}