import java.util.Scanner;

/**
 * FrontendInterface - CS400 Project 1: iSongly
 */
public interface FrontendInterface {

    //public Frontend(Scanner in, BackendInterface backend)
    // Your constructor must have the signature above. All methods below must
    // rely only on the provided Scanner to read input from the user, and only
    // on the provided BackendInterface to compute the results of different
    // user queries by calling the methods of BackendInterface.

    /**
     * Repeatedly gives the user an opportunity to issue new commands until
     * they select Q to quit. Uses the scanner passed to the constructor to
     * read user input.
     */
    public void runCommandLoop();
    
    /**
     * Displays the menu of command options to the user.  Giving the user the
     * instructions of entering L, G, F, D, or Q (case insensitive) to load a
     * file, get songs, set filter, display the top five, or quit.
     */
    public void displayMainMenu();

    // Each of the following commands are designed to handle the user
    // interaction associated with a different Main Menu command.
    
    /**
     * Provides text-based user interface for prompting the user to select
     * the csv file that they would like to load, provides feedback about
     * whether this is successful vs any errors are encountered.
     * [L]oad Song File
     *
     * When the user enters a valid filename, the file with that name
     * should be loaded.
     * Uses the scanner passed to the constructor to read user input and
     * the backend passed to the constructor to load the file provided
     * by the user. If the backend indicates a problem with finding or
     * reading the file by throwing an IOException, a message is displayed
     * to the user, and they will be asked to enter a new filename.
     */
    public void loadFile();
    
    /**
     * Provides text-based user interface and error handling for retrieving a
     * list of song titles that are sorted by Year.  The user should be
     * given the opportunity to optionally specify a minimum and/or maximum
     * Year to limit the number of songs displayed to that range.
     * [G]et Songs by Year
     *
     * When the user enters only two numbers (pressing enter after each), the
     * first of those numbers should be interpreted as the minimum, and the
     * second as the maximum Year.
     * Uses the scanner passed to the constructor to read user input and
     * the backend passed to the constructor to retrieve the list of sorted
     * songs.
     */
    public void getSongs();

    /**
     * Provides text-based user interface and error handling for setting a
     * filter threshold.  This and future requests to retrieve songs will
     * will only return the titles of songs that are smaller than the
     * user specified Loudness.  The user should also be able to clear
     * any previously specified filters.
     * [F]ilter Songs by Loudness
     *
     * When the user enters only a single number, that number should be used
     * as the new filter threshold.
     * Uses the scanner passed to the constructor to read user input and
     * the backend passed to the constructor to set the filters provided by
     * the user and retrieve songs that maths the filter criteria.
     */
    public void setFilter();

    /**
     * Displays the titles of up to five of the most Danceable songs within the
     * previously set Year range and smaller than the specified
     * Loudness.  If there are no such songs, then this method should
     * indicate that and recommend that the user change their current range or
     * filter settings.
     * [D]isplay five most Danceable
     *
     * The user should not need to enter any input when running this command.
     * Uses the backend passed to the constructor to retrieve the list of up
     * to five songs.
     */
    public void displayTopFive();

}