/*=============================================================================

  Library: CTK

  Copyright (c) 2010 German Cancer Research Center,
    Division of Medical and Biological Informatics

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

=============================================================================*/

#ifndef CTKPLUGINDATABASE_P_H
#define CTKPLUGINDATABASE_P_H

#include <QtSql>
#include <QList>


namespace ctk {

// CTK class forward declarations
class PluginStorage;
class PluginArchive;

class PluginDatabase {

  public:
    PluginDatabase(PluginStorage* storage);

    virtual ~PluginDatabase();

    /**
     * Opens the plugin database. If the database does not
     * yet exist, it is created using the path from getDatabasePath().
     *
     * @see setDatabasePath(const QString&)
     * @see getDatabasePath()
     * @see PluginDatabaseException
     *
     * @throws PluginDatabaseException
     */
    void open();

    /**
     * Closes the plugin database. Throws a PluginDatabaseException
     * of type DB_CONNECTION_INVALID if the database is invalid.
     *
     * @throws PluginDatabaseException
     */
    void close();

    /**
     * Checks if the database is open
     */
    bool isOpen() const;

    /**
     * Sets the path of the service database to \a databasePath
     */
    void setDatabasePath(const QString &databasePath);

    /**
     * Returns the path of the plugin database
     */
    QString getDatabasePath() const;

    /**
     * Get a Qt resource cached in the database. The resource path \a res
     * must be relative to the plugin specific resource prefix, but may
     * start with a '/'.
     *
     * @param pluginId The id of the plugin from which to get the resource
     * @param res The path to the resource in the plugin
     * @return The byte array of the cached resource
     *
     * @throws PluginDatabaseException
     */
    QByteArray getPluginResource(long pluginId, const QString& res) const;

    /**
     * Get a list of resource entries under the given path.
     *
     * @param pluginId The id of the plugin from which to get the entries
     * @param path A resource path relative to the plugin specific resource prefix.
     * @return A QStringList containing the cached resource entries.
     *
     * @throws PluginDatabaseException
     */
    QStringList findResourcesPath(long pluginId, const QString& path) const;

    /**
     * Inserts a new plugin into the database. This method assumes that
     * the an entry with the same \a location and \a localPath does not
     * yet exist in the database.
     *
     * @param location The URL to the plugin.
     * @param localPath The path to the plugin library on the local file system.
     * @param createArchive If \c true (default) a new PluginArchive instance is returned.
     *
     * @throws PluginDatabaseException
     */
    PluginArchive* insertPlugin(const QUrl& location, const QString& localPath, bool createArchive = true);

    /**
     * Removes all persisted data related to the given PluginArchive.
     *
     * @throws PluginDatabaseException
     */
    void removeArchive(const PluginArchive* pa);

    /**
     * Reads the persisted plugin data and returns a PluginArchive object
     * for each plugin which is not in state UNINSTALLED.
     *
     * @throws PluginDatabaseException
     */
    QList<PluginArchive*> getPluginArchives() const;


  private:

    enum TransactionType{Read, Write};

    /**
     *  Helper method that creates the database tables:
     *
     * @throws PluginDatabaseException
     */
    void createTables();
    bool dropTables();

    /**
     * Helper method that checks if all the expected tables exist in the database.
     *
     * Returns true if they all exist and false if any of them don't
     */
    bool checkTables() const;

    /**
     * Checks the database connection.
     *
     * @throws PluginDatabaseException
     */
    void checkConnection() const;

    /**
     * Compares the persisted plugin modification time with the
     * file system modification time and updates the database
     * if the persisted data is outdated.
     *
     * This should only be called once when the database is initially opened.
     */
    void updateDB();

    /**
     * Helper function that executes the sql query specified in \a statement.
     * It is assumed that the \a statement uses positional placeholders and
     * corresponding parameters are placed in the list of \a bindValues.
     *
     * Aside: This function may be safely called standalone or within an explicit
     * transaction.  If called standalone, it's single query is implicitly
     * wrapped in it's own transaction.
     *
     * @throws PluginDatabaseException
     */
    void executeQuery(QSqlQuery* query, const QString &statement, const QList<QVariant> &bindValues = QList<QVariant>()) const;

    /**
     * Begins a transcaction based on the \a type which can be Read or Write.
     *
     * @throws PluginDatabaseException
     */
    void beginTransaction(QSqlQuery* query, TransactionType);

    /**
     * Commits a transaction
     *
     * @throws PluginDatabaseException
     */
    void commitTransaction(QSqlQuery* query);

    /**
     * Rolls back a transaction
     *
     * @throws PluginDatabaseException
     */
    void rollbackTransaction(QSqlQuery* query);


    QString m_databasePath;
    QString m_connectionName;
    bool m_isDatabaseOpen;
    bool m_inTransaction;
    PluginStorage* m_PluginStorage;
};

}

#endif // CTKPLUGINDATABASE_P_H