package vooga.examples.level;


import java.awt.Dimension;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Scanner;

import com.golden.gamedev.object.Sprite;

/**
 * @author Bhawana, Cameron, Derek
 * 
 *     This describes the type of level where the portion of the game space
 *     displayed on the screen moves with the position of the hero, similar
 *     to a side-scroller. Here, the hero is always in the center of the
 *     screen. <br>
 *         <br>
 *     Every time a new level is loaded, i.e., the LevelManager's nextLevel
 *     method is called, the Collection of Sprites returned should be stored
 *     in an instance variable, say allsprites. The getCurrentScreenSprites
 *     method needs to be invoked in the update method of the main game with
 *     allsprites as a parameter. All the Sprites returned by this method
 *     should then be updated to the screen.
 * 
 * <pre>
 * @code
 * LevelManager manager = new LevelManager();
 * Collection(Sprite) allSprites = manager.nextLevel();
 * 
 * public void update(long elapsedTime){
 * Collection<Sprite> currentSprites = ScrollerLevel.getCurrentScreenSprites(allSprites,heroX,heroY);
 * for(Sprite sprite : currentSprites){
 *      sprite.update(elapsedTime);
 * }
 * </pre>
 */
public class ScrollerLevel extends Level {
    private static Dimension myGameSpace;
    private static Dimension myScreenSize;

    /**
     * @param fileToBeRead
     *        - level file that contains Sprites' details
     * @param screenSize
     *        - Dimension of the Screen
     * @param gameSpace
     *        - Dimension of the gameSpace
     */
    public ScrollerLevel(Scanner fileToBeRead, Dimension screenSize,
            Dimension gameSpace) {
        super(fileToBeRead);
        myScreenSize = screenSize;
        myGameSpace = gameSpace;
    }

    /**
     * This method will be called in the update method of the main game class.
     * It returns all the sprites to be currently displayed on the screen,
     * ensuring that the hero is in the center of the screen.
     * 
     * @param allSprites - Collection of all the sprites for the current level
     * @param heroX - X coordinate of the hero, 
     * @param heroY - Y coordinate of the hero
     * 
     * @return Collection of Sprites to be updated to the screen
     */
    public static Collection<Sprite> getCurrentScreenSprites(
            Collection<Sprite> allSprites, double heroX, double heroY) {

        double screenWidth = myScreenSize.getWidth();
        double screenHeight = myScreenSize.getHeight();

        double xMin = getMin(heroX, screenWidth, myGameSpace.getWidth());
        double yMin = getMin(heroY, screenHeight, myGameSpace.getHeight());
        double xMax = xMin + screenWidth;
        double yMax = yMin + screenHeight;

        Collection<Sprite> currentSpritesList = new ArrayList<Sprite>();
        for (Sprite sprite : allSprites) {
            if (isInRange(sprite.getX(), xMin, xMax)
                    && isInRange(sprite.getY(), yMin, yMax)) {
                currentSpritesList.add(sprite);
            }
        }
        return currentSpritesList;
    }

    /**
     * This method returns the minimum value of the coordinate to be displayed
     * on the screen depending upon the current position of the hero.
     * 
     * @param heroCoordinate - hero's current position
     * @param screen - screen dimension
     * @param gameSpace - gameSpace dimension
     * @return minimum value of the coordinate to be displayed
     */
    private static double getMin(double heroCoordinate, double screen, double gameSpace) {
        if (heroCoordinate < screen / 2) {
            return 0;
        } 
        else if (heroCoordinate > (gameSpace - screen / 2)) {
            return gameSpace - screen;
        } 
        else{
            return heroCoordinate - screen / 2;
        }
    }
    
    /**
     * This method checks whether a Sprite's current position is in range or not,
     * i.e., if the sprite's current coordinates lie between the minimum and
     * maximum values of the displayed coordinates.
     *
     *@param value - Sprite's coordinate to be checked
     *@param min - minimum coordinate displayed on screen
     *@param max - maximum coordinate displayed on screen
     *@return a boolean which indicates whether the sprite's current coordinate is in range or not
     */
    private static boolean isInRange(double value, double min, double max) {
        return (min < value && value < max);
    }
}