/* query.cc - Support for searching a notmuch database
 *
 * Copyright © 2009 Carl Worth
 *
 * 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: Carl Worth <cworth@cworth.org>
 */

#include "notmuch-private.h"
#include "database-private.h"

#include <glib.h> /* GHashTable, GPtrArray */

#include <xapian.h>

struct _notmuch_query {
    notmuch_database_t *notmuch;
    const char *query_string;
    notmuch_sort_t sort;
};

struct _notmuch_messages {
    notmuch_database_t *notmuch;
    Xapian::MSetIterator iterator;
    Xapian::MSetIterator iterator_end;
};

struct _notmuch_threads {
    notmuch_database_t *notmuch;
    GPtrArray *threads;
    unsigned int index;
};

notmuch_query_t *
notmuch_query_create (notmuch_database_t *notmuch,
		      const char *query_string)
{
    notmuch_query_t *query;

#ifdef DEBUG_QUERY
    fprintf (stderr, "Query string is:\n%s\n", query_string);
#endif

    query = talloc (NULL, notmuch_query_t);
    if (unlikely (query == NULL))
	return NULL;

    query->notmuch = notmuch;

    query->query_string = talloc_strdup (query, query_string);

    query->sort = NOTMUCH_SORT_NEWEST_FIRST;

    return query;
}

void
notmuch_query_set_sort (notmuch_query_t *query, notmuch_sort_t sort)
{
    query->sort = sort;
}

notmuch_messages_t *
notmuch_query_search_messages (notmuch_query_t *query,
			       int first,
			       int max_messages)
{
    notmuch_database_t *notmuch = query->notmuch;
    const char *query_string = query->query_string;
    notmuch_message_list_t *message_list;
    Xapian::MSetIterator i;

    message_list = _notmuch_message_list_create (query);
    if (unlikely (message_list == NULL))
	return NULL;

    try {
	Xapian::Enquire enquire (*notmuch->xapian_db);
	Xapian::Query mail_query (talloc_asprintf (query, "%s%s",
						   _find_prefix ("type"),
						   "mail"));
	Xapian::Query string_query, final_query;
	Xapian::MSet mset;
	unsigned int flags = (Xapian::QueryParser::FLAG_BOOLEAN |
			      Xapian::QueryParser::FLAG_PHRASE |
			      Xapian::QueryParser::FLAG_LOVEHATE |
			      Xapian::QueryParser::FLAG_BOOLEAN_ANY_CASE |
			      Xapian::QueryParser::FLAG_WILDCARD |
			      Xapian::QueryParser::FLAG_PURE_NOT);

	if (strcmp (query_string, "") == 0) {
	    final_query = mail_query;
	} else {
	    string_query = notmuch->query_parser->
		parse_query (query_string, flags);
	    final_query = Xapian::Query (Xapian::Query::OP_AND,
					 mail_query, string_query);
	}

	switch (query->sort) {
	case NOTMUCH_SORT_OLDEST_FIRST:
	    enquire.set_sort_by_value (NOTMUCH_VALUE_TIMESTAMP, FALSE);
	    break;
	case NOTMUCH_SORT_NEWEST_FIRST:
	    enquire.set_sort_by_value (NOTMUCH_VALUE_TIMESTAMP, TRUE);
	    break;
	case NOTMUCH_SORT_MESSAGE_ID:
	    enquire.set_sort_by_value (NOTMUCH_VALUE_MESSAGE_ID, FALSE);
	    break;
	}

#if DEBUG_QUERY
	fprintf (stderr, "Final query is:\n%s\n", final_query.get_description().c_str());
#endif

	enquire.set_query (final_query);

	if (max_messages == -1)
	    max_messages = notmuch->xapian_db->get_doccount ();
	mset = enquire.get_mset (first, max_messages);

	for (i = mset.begin (); i != mset.end (); i++) {
	    notmuch_message_t *message;
	    notmuch_private_status_t status;

	    message = _notmuch_message_create (message_list, notmuch,
					       *i, &status);
	    if (message == NULL)
	    {
		if (status == NOTMUCH_PRIVATE_STATUS_NO_DOCUMENT_FOUND)
		    INTERNAL_ERROR ("A message iterator contains a "
				    "non-existent document ID.\n");
		break;
	    }

	    _notmuch_message_list_add_message (message_list, message);
	}

    } catch (const Xapian::Error &error) {
	fprintf (stderr, "A Xapian exception occurred performing query: %s\n",
		 error.get_msg().c_str());
	fprintf (stderr, "Query string was: %s\n", query->query_string);
	notmuch->exception_reported = TRUE;
    }

    return _notmuch_messages_create (message_list);
}

/* Glib objects force use to use a talloc destructor as well, (but not
 * nearly as ugly as the for messages due to C++ objects). At
 * this point, I'd really like to have some talloc-friendly
 * equivalents for the few pieces of glib that I'm using. */
static int
_notmuch_threads_destructor (notmuch_threads_t *threads)
{
    g_ptr_array_free (threads->threads, TRUE);

    return 0;
}

notmuch_threads_t *
notmuch_query_search_threads (notmuch_query_t *query,
			      int first,
			      int max_threads)
{
    notmuch_threads_t *threads;
    notmuch_thread_t *thread;
    const char *thread_id;
    notmuch_messages_t *messages;
    notmuch_message_t *message;
    GHashTable *seen;
    int messages_seen = 0, threads_seen = 0;

    threads = talloc (query, notmuch_threads_t);
    if (threads == NULL)
	return NULL;

    threads->notmuch = query->notmuch;
    threads->threads = g_ptr_array_new ();
    threads->index = 0;

    talloc_set_destructor (threads, _notmuch_threads_destructor);

    seen = g_hash_table_new_full (g_str_hash, g_str_equal,
				  free, NULL);

    while (max_threads < 0 || threads_seen < first + max_threads)
    {
	int messages_seen_previously = messages_seen;

	for (messages = notmuch_query_search_messages (query,
						       messages_seen,
						       max_threads);
	     notmuch_messages_has_more (messages);
	     notmuch_messages_advance (messages))
	{
	    message = notmuch_messages_get (messages);

	    thread_id = notmuch_message_get_thread_id (message);

	    if (! g_hash_table_lookup_extended (seen,
						thread_id, NULL,
						(void **) &thread))
	    {
		if (threads_seen >= first) {
		    thread = _notmuch_thread_create (query, query->notmuch,
						     thread_id,
						     query->query_string);
		    g_ptr_array_add (threads->threads, thread);
		} else {
		    thread = NULL;
		}

		g_hash_table_insert (seen, xstrdup (thread_id), thread);

		threads_seen++;
	    }

	    notmuch_message_destroy (message);

	    messages_seen++;

	    if (max_threads >= 0 && threads_seen >= first + max_threads)
		break;
	}

	/* Stop if we're not seeing any more messages. */
	if (messages_seen == messages_seen_previously)
	    break;
    }

    g_hash_table_unref (seen);

    return threads;
}

void
notmuch_query_destroy (notmuch_query_t *query)
{
    talloc_free (query);
}

notmuch_bool_t
notmuch_threads_has_more (notmuch_threads_t *threads)
{
    return (threads->index < threads->threads->len);
}

notmuch_thread_t *
notmuch_threads_get (notmuch_threads_t *threads)
{
    if (! notmuch_threads_has_more (threads))
	return NULL;

    return (notmuch_thread_t *) g_ptr_array_index (threads->threads,
						   threads->index);
}

void
notmuch_threads_advance (notmuch_threads_t *threads)
{
    threads->index++;
}

void
notmuch_threads_destroy (notmuch_threads_t *threads)
{
    talloc_free (threads);
}