How to set a portal exit location

I'm trying to create a plugin that lets players use a scroll to create a portal that takes them to a set location. I'm having some trouble figuring out how to create an exit portal at a specified location and connect it to the portal that they created using the scroll. Any help would be appreciated!

 

CraftBukkit/NMS does it automaticly
This is from the net.minecraft.server.BlockPortal class

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Code:java

 public void a(World world, int i, int j, int k, Entity entity) {
if ((entity.vehicle != null) || (entity.passenger != null))
return;
EntityPortalEnterEvent event = new EntityPortalEnterEvent(
entity.getBukkitEntity(), new Location(world.getWorld(), i, j,
k));
world.getServer().getPluginManager().callEvent(event);
 
entity.ah();
}

And from the net.minecraft.server.Entity class

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Code:java

public void ah() {
if (this.portalCooldown > 0) {
this.portalCooldown = ai();
} else {
double d0 = this.lastX - this.locX;
double d1 = this.lastZ - this.locZ;
 
if ((!(this.world.isStatic)) && (!(this.ao))) {
this.ar = Direction.a(d0, d1);
}
 
this.ao = true;
}
 
}

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Code:java

    public void C() {
        this.world.methodProfiler.a("entityBaseTick");
        if ((this.vehicle != null) && (this.vehicle.dead)) {
            this.vehicle = null;
        }
 
        this.P = this.Q;
        this.lastX = this.locX;
        this.lastY = this.locY;
        this.lastZ = this.locZ;
        this.lastPitch = this.pitch;
        this.lastYaw = this.yaw;
 
        if ((!(this.world.isStatic)) && (this.world instanceof WorldServer)) {
            this.world.methodProfiler.a("portal");
            MinecraftServer minecraftserver = ((WorldServer) this.world)
                    .getMinecraftServer();
 
            int i = D();
            if (this.ao) {
                if (this.vehicle == null)
                    if (this.ap++ >= i) {
                        this.ap = i;
                        this.portalCooldown = ai();
                        byte b0;
                        byte b0;
                        if (this.world.worldProvider.dimension == -1)
                            b0 = 0;
                        else {
                            b0 = -1;
                        }
 
                        b(b0);
                    }
 
                this.ao = false;
            } else {
                if (this.ap > 0) {
                    this.ap -= 4;
                }
 
                if (this.ap < 0) {
                    this.ap = 0;
                }
            }
 
            if (this.portalCooldown > 0) {
                this.portalCooldown -= 1;
            }
 
            this.world.methodProfiler.b();
        }
 
        if ((isSprinting()) && (!(M()))) {
            int j = MathHelper.floor(this.locX);
 
            int i = MathHelper.floor(this.locY - 0.2000000029802322D
                    - this.height);
            int k = MathHelper.floor(this.locZ);
            Block block = this.world.getType(j, i, k);
 
            if (block.getMaterial() != Material.AIR) {
                this.world.addParticle("blockcrack_" + Block.b(block) + "_"
                        + this.world.getData(j, i, k),
                        this.locX + (this.random.nextFloat() - 0.5D)
                                * this.width, this.boundingBox.b + 0.1D,
                        this.locZ + (this.random.nextFloat() - 0.5D)
                                * this.width, -this.motX * 4.0D, 1.5D,
                        -this.motZ * 4.0D);
            }
        }
 
        N();
        if (this.world.isStatic)
            this.fireTicks = 0;
        else if (this.fireTicks > 0) {
            if (this.fireProof) {
                this.fireTicks -= 4;
                if (this.fireTicks < 0)
                    this.fireTicks = 0;
            } else {
                if (this.fireTicks % 20 == 0) {
                    damageEntity(DamageSource.BURN, 1.0F);
                }
 
                this.fireTicks -= 1;
            }
        }
 
        if (P()) {
            E();
            this.fallDistance *= 0.5F;
        }
 
        if (this.locY < -64.0D) {
            G();
        }
 
        if (!(this.world.isStatic)) {
            a(0, this.fireTicks > 0);
        }
 
        this.justCreated = false;
        this.world.methodProfiler.b();
    }

You would want to use reflect/etc.. and force a event.

 

Is there a way to do it through the metadata of a block representing the portal created by the player? I don't completely understand metadata yet, and was just curious.