/*

 * Geekttrss is a RSS feed reader application on the Android Platform.

 *

 *

 * This file is part of Geekttrss.

 *

 * Geekttrss 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.

 *

 * Geekttrss 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 Geekttrss.  If not, see <http://www.gnu.org/licenses/>.

 */

package com.geekorum.ttrss.session

/**

 * Simple interface for an Action that can be done and undone.

 */

interface Action {

    /**

     * Execute the action.

     */

    fun execute()

    /**

     * Undo the previously executed action.

     */

    fun undo()

}

/**

 * Allows to keep track of Actions that you may want to undo.

 */

class UndoManager<in T : Action> {

    private val actions = mutableListOf<T>()

    val nbActions get() = actions.size

    fun recordAction(action: T) {

        actions += action

    }

    fun undoAll() {

        for (action in actions.reversed()) {

            action.undo()

        }

        actions.clear()

    }

    fun clear() {

        actions.clear()

    }

}