package ch.epfl.maze.util;

import java.util.Collections;
import java.util.EnumSet;
import java.util.Set;

/**
 * Directions that an animal can take to move. They represent the four cardinal
 * points ({@code DOWN, UP, RIGHT, LEFT}) from the frame of reference of the
 * labyrinth, plus a default one : {@code NONE}.
 *
 * @author EPFL
 * @author Pacien TRAN-GIRARD
 */
public enum Direction {
    DOWN, UP, RIGHT, LEFT, NONE;

    /**
     * A set of all the possible directions that can be taken.
     */
    public static final Set<Direction> MOVING_DIRECTIONS = Collections.unmodifiableSet(EnumSet.of(
            Direction.DOWN,
            Direction.UP,
            Direction.RIGHT,
            Direction.LEFT
    ));

    /**
     * Returns the integer value of the direction
     *
     * @return Integer value of the direction
     */
    public int intValue() {
        switch (this) {
            case DOWN:
                return 0;

            case UP:
                return 1;

            case RIGHT:
                return 2;

            case LEFT:
                return 3;

            case NONE:
            default:
                return 4;
        }
    }

    /**
     * Converts the direction into an orthonormal vector, when possible.
     *
     * @return Orthonormal {@code Vector2D} that represents the direction.
     */
    public Vector2D toVector() {
        switch (this) {
            case DOWN:
                return new Vector2D(0, 1);

            case UP:
                return new Vector2D(0, -1);

            case RIGHT:
                return new Vector2D(1, 0);

            case LEFT:
                return new Vector2D(-1, 0);

            case NONE:
            default:
                return new Vector2D(0, 0);
        }
    }

    /**
     * Reverses the direction.
     *
     * @return The opposite direction.
     */
    public Direction reverse() {
        switch (this) {
            case DOWN:
                return UP;

            case UP:
                return DOWN;

            case RIGHT:
                return LEFT;

            case LEFT:
                return RIGHT;

            case NONE:
            default:
                return NONE;
        }
    }

    /**
     * Determines whether the argument is the opposite of another.
     *
     * @param d The direction to compare with
     * @return <b>true</b> if the direction is the opposite the argument,
     * <b>false</b> otherwise
     */
    public boolean isOpposite(Direction d) {
        return this == d.reverse();
    }

    /**
     * Converts the argument relative to the frame of reference given by the
     * direction that calls the method.
     *
     * @param dir The direction to convert
     * @return The direction converted to the frame of reference given by the
     * direction called.
     */
    public Direction relativeDirection(Direction dir) {
        switch (this) {
            case DOWN:
                return dir.reverse();

            case UP:
                return dir;

            case RIGHT:
                return dir.rotateLeft();

            case LEFT:
                return dir.rotateRight();

            case NONE:
            default:
                return NONE;
        }
    }

    /**
     * Converts the argument back to the frame of reference of the labyrinth
     *
     * @param dir The direction to convert back
     * @return The direction converted back to the frame of reference of the
     * labyrinth
     */
    public Direction unRelativeDirection(Direction dir) {
        switch (this) {
            case DOWN:
                return dir.reverse();

            case UP:
                return dir;

            case RIGHT:
                return dir.rotateRight();

            case LEFT:
                return dir.rotateLeft();

            case NONE:
            default:
                return NONE;
        }
    }

    /**
     * Rotates the direction to the right.
     *
     * @return The rotated direction to the right
     */
    public Direction rotateRight() {
        switch (this) {
            case DOWN:
                return LEFT;

            case UP:
                return RIGHT;

            case RIGHT:
                return DOWN;

            case LEFT:
                return UP;

            case NONE:
            default:
                return NONE;
        }
    }

    /**
     * Rotates the direction to the left.
     *
     * @return The rotated direction to the left
     */
    public Direction rotateLeft() {
        switch (this) {
            case DOWN:
                return RIGHT;

            case UP:
                return LEFT;

            case RIGHT:
                return UP;

            case LEFT:
                return DOWN;

            case NONE:
            default:
                return NONE;
        }
    }

    /**
     * Applies the change of coordinates relative to the frame of reference
     * of the direction that calls the method to all the directions in the
     * argument.
     *
     * @param dir The array of directions to convert
     * @return The directions converted to the frame of reference given by the
     * direction which calls the method
     */
    public Direction[] relativeDirections(Direction[] dir) {
        Direction[] relativeDirections = new Direction[dir.length];

        for (int i = 0; i < dir.length; i++) {
            relativeDirections[i] = this.relativeDirection(dir[i]);
        }

        return relativeDirections;
    }

}