#include <QtCore/QDateTime>
#include <QtCore/QSet>
#include <QtCore/QDebug>
#include <QtSql/QSqlDatabase>
#include <QtSql/QSqlQuery>

#include "global.h"
#include "board.h"
#include "xmlrpcinterface.h"
#include "xmlrpcreply.h"
#include "fetchtopicsaction.h"

FetchTopicsAction::FetchTopicsAction(int forumId, Board::TopicType type,
                                     int start, int end, Board *board) :
    Action(board), _forumId(forumId), _type(type), _start(start), _end(end)
{
}

bool FetchTopicsAction::isSupersetOf(Action *action) const
{
	FetchTopicsAction *other = qobject_cast<FetchTopicsAction*>(action);
	if (other) {
		if (other->_forumId == _forumId && other->_type == _type) {
			if (_end == FetchAllTopics) {
				// If this is fetching all topics, then this is a superset
				// of every other action... except those that also fetch all
				// topics.
				return other->_end != FetchAllTopics;
			} else if (other->_end == FetchAllTopics) {
				// If the other action fetches all topics, this cannot be a
				// superset
				return false;
			} else if (_start <= other->_start && _end >= other->_end) {
				// Otherwise, check if the range of posts fetched by this
				// action fully contains the other action.
				return true;
			}
		}
	}
	return false;
}

void FetchTopicsAction::execute()
{
	int end = _end;
	if (end == FetchAllTopics) {
		// Fetch topics in blocks of size 50.
		end = _start + MAX_FORUM_PAGE_SIZE - 1;
		// After finishing this action, a new one will be enqueued with the next 50.
	}

	switch (_type) {
	case Board::Normal:
		_call = _board->service()->asyncCall("get_topic",
		                                     QString::number(_forumId),
		                                     _start, end);
		break;
	case Board::Sticky:
		_call = _board->service()->asyncCall("get_topic",
		                                     QString::number(_forumId),
		                                     _start, end,
		                                     QString("TOP"));
		break;
	case Board::Announcement:
		_call = _board->service()->asyncCall("get_topic",
		                                     QString::number(_forumId),
		                                     _start, end,
		                                     QString("ANN"));
		break;
	}
	Q_ASSERT(_call);

	_call->setParent(this);
	connect(_call, SIGNAL(finished(XmlRpcPendingCall*)), SLOT(handleFinishedCall()));
}

void FetchTopicsAction::handleFinishedCall()
{
	XmlRpcReply<QVariantMap> result(_call);
	if (result.isValid()) {
		QVariantMap map = result;
		QVariantList topics = map["topics"].toList();
		QSqlDatabase db = _board->database();
		db.transaction();

		const int total_topic_num = map["total_topic_num"].toInt();
		int expected_end = _end == FetchAllTopics ? _start + MAX_FORUM_PAGE_SIZE - 1 : _end;
		QSet<int> current_topics = QSet<int>::fromList(getCurrentDbTopics(_start, expected_end));
		QSet<int> unchanged_topics = current_topics;

		if (_start >= total_topic_num) {
			// Workaround an issue where the service always returns one post.
			topics.clear();
		}

		Q_ASSERT(_start >= 0);
		int position = _start;

		QSqlQuery query(db);
		query.prepare("INSERT OR REPLACE INTO topics (forum_id, topic_id, topic_type, topic_title, topic_author_id, topic_author_name, is_subscribed, is_closed, icon_url, last_reply_time, reply_number, new_post, position, last_update_time) "
		              "VALUES (:forum_id, :topic_id, :topic_type, :topic_title, :topic_author_id, :topic_author_name, :is_subscribed, :is_closed, :icon_url, :last_reply_time, :reply_number, :new_post, :position, :last_update_time)");


		foreach (const QVariant& topic_v, topics) {
			QVariantMap topic = topic_v.toMap();
			bool ok = false;
			int forum_id = topic["forum_id"].toInt(&ok);
			if (!ok) {
				// Not fatal, just use the one we expected.
				forum_id = _forumId;
			}
			int topic_id = topic["topic_id"].toInt(&ok);
			if (!ok) {
				qWarning() << "No topic_id in" << topic;
				// This is now a fatal error.
				db.rollback();
				goto finish;
			}

			query.bindValue(":forum_id", forum_id);
			query.bindValue(":topic_id", topic_id);
			query.bindValue(":topic_type", _type);
			query.bindValue(":topic_title", decodeTopicText(topic["topic_title"]));
			query.bindValue(":topic_author_id", topic["topic_author_id"].toInt());
			query.bindValue(":topic_author_name", decodeTopicText(topic["topic_author_name"]));
			query.bindValue(":is_subscribed", topic["is_subscribed"].toBool() ? 1 : 0);
			query.bindValue(":is_closed", topic["is_closed"].toBool() ? 1 : 0);
			query.bindValue(":icon_url", topic["icon_url"].toString());
			query.bindValue(":last_reply_time", topic["last_reply_time"].toDateTime().toUTC());
			query.bindValue(":reply_number", topic["reply_number"].toInt());
			query.bindValue(":new_post", topic["new_post"].toBool() ? 1 : 0);
			query.bindValue(":position", position);
			query.bindValue(":last_update_time", QDateTime::currentDateTimeUtc());

			position++;

			if (!query.exec()) {
				qWarning() << "Failed to store topic info for:" << topic_id;
				handleDatabaseError("storing topic info", query);
				db.rollback();
				goto finish;
			}

			unchanged_topics.remove(topic_id);
		}

		int fetched_end = position - 1;
		bool eof = fetched_end < expected_end;
		if (eof) {
			// Service did not return as many topics as we expected, thus we
			// can safely delete any topics after the current position.
			query.prepare("DELETE FROM topics "
			              "WHERE forum_id = :forum_id AND topic_type = :topic_type "
			              " AND position >= :position");
			query.bindValue(":forum_id", _forumId);
			query.bindValue(":topic_type", _type);
			query.bindValue(":position", position);
			if (query.exec()) {
				position += query.numRowsAffected(); // Advance the position counter
			} else {
				handleDatabaseError("deleting topics", query);
				db.rollback();
				goto finish;
			}

			if (!unchanged_topics.empty()) {
				// The topics that were in the begin..end range but were not updated
				// need to be removed.
				query.prepare("DELETE FROM topics WHERE topic_id = :topic_id");
				foreach (int topic_id, unchanged_topics) {
					query.bindValue(":topic_id", topic_id);
					if (!query.exec()) {
						handleDatabaseError("deleting topics", query);
						db.rollback();
						goto finish;
					}
					position++;
				}
			}
		} else if (!unchanged_topics.empty()) {
			// The topics that were in the begin..end range but were not updated
			// need to be renumbered.
			query.prepare("UPDATE topics SET position = :position WHERE topic_id = :topic_id");
			foreach (int topic_id, unchanged_topics) {
				query.bindValue(":position", position);
				query.bindValue(":topic_id", topic_id);
				if (!query.exec()) {
					handleDatabaseError("updating topic position", query);
					db.rollback();
					goto finish;
				}
				position++;
			}

			Q_ASSERT(position >= expected_end + 1);
		}

		db.commit();
		if (position > _start) {
			_board->notifyForumTopicsChanged(_forumId, _type,
			                                 _start, position - 1);
		}
		if (_end == FetchAllTopics && !eof) {
			// Ok, let's prepare to fetch the next block of topics because
			// there are probably more of them
			int next_start = fetched_end + 1;
			_board->enqueueAction(new FetchTopicsAction(_forumId,
			                                            _type,
			                                            next_start,
			                                            FetchAllTopics,
			                                            _board));
		}
	} else {
		qWarning() << "Could not fetch topics";
		// TODO emit error ...
	}
finish:
	emit finished(this);
	_call->deleteLater();
}

QString FetchTopicsAction::decodeTopicText(const QVariant &v)
{
	QByteArray ba = v.toByteArray();
	return QString::fromUtf8(ba.constData(), ba.length());
}

QList<int> FetchTopicsAction::getCurrentDbTopics(int start, int end)
{
	QSqlQuery query(_board->database());
	query.prepare("SELECT topic_id FROM topics "
	              "WHERE forum_id = :forum_id AND topic_type = :topic_type AND "
	              " position BETWEEN :start AND :end "
	              "ORDER by position ASC");
	query.bindValue(":forum_id", _forumId);
	query.bindValue(":topic_type", _type);
	query.bindValue(":start", start);
	query.bindValue(":end", end);
	if (query.exec()) {
		QList<int> list;
		while (query.next()) {
			list << query.value(0).toInt();
		}
		return list;
	} else {
		qWarning() << "Could not get current topics list:" << query.lastError().text();
		return QList<int>();
	}
}