Assassination class

public class AssassinateHandler implements Listener {

    public static HashMap<String, Integer> map = new HashMap<String, Integer>();

    public static String getCardinalDirection(Player player) {
        double rotation = (player.getLocation().getYaw() - 90) % 360;
        if (rotation < 0) {
            rotation += 360.0;
        }
         if (0 <= rotation && rotation < 22.5) {
            return "N";
        } else if (22.5 <= rotation && rotation < 67.5) {
            return "NE";
        } else if (67.5 <= rotation && rotation < 112.5) {
            return "E";
        } else if (112.5 <= rotation && rotation < 157.5) {
            return "SE";
        } else if (157.5 <= rotation && rotation < 202.5) {
            return "S";
        } else if (202.5 <= rotation && rotation < 247.5) {
            return "SW";
        } else if (247.5 <= rotation && rotation < 292.5) {
            return "W";
        } else if (292.5 <= rotation && rotation < 337.5) {
            return "NW";
        } else if (337.5 <= rotation && rotation < 360.0) {
            return "N";
        } else {
            return null;
        }
    }

    public boolean canAssassinate(Player target, Player damager) {
        String damagerDirection = getCardinalDirection(damager);
        switch (getCardinalDirection(target)) {
        case("N"):
            if (damagerDirection.equals("NE") || damagerDirection.equals("NW") || damagerDirection.equals("N"))
                return true; break;
        case("NE"):
            if (damagerDirection.equals("E") || damagerDirection.equals("N") || damagerDirection.equals("NE"))
                return true; break;
        case("E"):
            if (damagerDirection.equals("NE") || damagerDirection.equals("SE") || damagerDirection.equals("E"))
                return true; break;
        case("SE"):
            if (damagerDirection.equals("E") || damagerDirection.equals("S") || damagerDirection.equals("E"))
                return true; break;
        case("S"):
            if (damagerDirection.equals("SE") || damagerDirection.equals("SW") || damagerDirection.equals("S"))
                return true; break;
        case("SW"):
            if (damagerDirection.equals("W") || damagerDirection.equals("S") || damagerDirection.equals("SW"))
                return true; break;
        case("W"):
            if (damagerDirection.equals("NW") || damagerDirection.equals("SW") || damagerDirection.equals("W"))
                return true; break;
        case("NW"):
            if (damagerDirection.equals("N") || damagerDirection.equals("W") || damagerDirection.equals("NW"))
                return true; break;
        }
        return false;
    }

    public void recharge(final Player player) {
        Bukkit.getScheduler().scheduleSyncDelayedTask(Assassin.getPlugin(), new Runnable() {
            @Override
            public void run() {
                if (map.get(player.getName()) <= 0) {
                    CraftPlayer pl = (CraftPlayer) player;
                    PacketPlayOutRemoveEntityEffect packet = new PacketPlayOutRemoveEntityEffect(pl.getEntityId(), new MobEffect(20, 0, 200));
                    pl.getHandle().playerConnection.sendPacket(packet);
                    player.playSound(player.getLocation(), Sound.HORSE_ARMOR, 1, 1);
                    map.remove(player.getName());
                } else {
                    map.put(player.getName(), map.get(player.getName()) - 1);
                    recharge(player);
                }
            }
        }, 20);
    }

    @EventHandler
    public void backStab(EntityDamageByEntityEvent e) {
        if (e.getEntity() instanceof Player && e.getDamager() instanceof Player) {
            Player target = (Player) e.getEntity();
            Player damager = (Player) e.getDamager();

            CraftPlayer craftDamager = (CraftPlayer) damager;
            PacketPlayOutEntityEffect damagerPacket = new PacketPlayOutEntityEffect(damager.getEntityId(), new MobEffect(20, 0, 200));
            CraftPlayer craftTarget = (CraftPlayer) target;
            PacketPlayOutEntityEffect targetPacket = new PacketPlayOutEntityEffect(target.getEntityId(), new MobEffect(20, 0, 200));

            if (!map.containsKey(damager.getName())) {
                if (canAssassinate(target, damager)) {
                    e.setDamage(200D);

                    target.getWorld().playSound(target.getLocation(), Sound.WITHER_SHOOT, 1, 1);
                    damager.addPotionEffect(new PotionEffect(PotionEffectType.BLINDNESS, 21, 0));
                    target.addPotionEffect(new PotionEffect(PotionEffectType.BLINDNESS, 21, 0));
                    damager.addPotionEffect(new PotionEffect(PotionEffectType.SLOW, 25, 3));

                    craftDamager.getHandle().playerConnection.sendPacket(damagerPacket);

                    map.put(damager.getName(), 1);
                    recharge(damager);
                    return;
                }
            }

            boolean rechargeDamager = false;
            boolean rechargeTarget = false;

            if (!map.containsKey(damager.getName()))
            rechargeDamager = true;
            if (!map.containsKey(target.getName()))
            rechargeTarget = true;

            map.put(damager.getName(), 10);
            map.put(target.getName(), 10);

            if (rechargeDamager)
                recharge(damager);
            if (rechargeTarget)
                recharge(target);

            craftTarget.getHandle().playerConnection.sendPacket(targetPacket);
            craftDamager.getHandle().playerConnection.sendPacket(damagerPacket);
        }
    }
}