class Item : ActionRole {

    fun getNeighbourhood() = Play.instance.neighbourhood


    fun getBlock() = Play.instance.neighbourhood.blockAt( actor.x, actor.y )


    override fun begin() {
        val block = getBlock()
        if (! block.occupants.isEmpty() ) {
            if ( this !is Leg ) {
                println( "Warning there is already an occupant here" )
                actor.die()
            }
        } else {
            block.add(this)
        }
        super.begin()
    }

    override fun end() {
        getBlock().remove(this)
    }

    fun isSolid() = true


    fun isEmpty() = false

    fun occupant() : Occupant = null

    fun look( block : Block<Item> ) : Item {
        if ( block == null || block.occupants == null || block.occupants.isEmpty() ) {
            return NullItem.instance
        } else {
            return block.occupants.iterator().next()
        }
    }

    fun look( dx : int, dy : int ) = look(getBlock().neighbouringBlock(dx, dy))

    fun lookNorth() = look( 0, 1 )
    fun lookEast() = look( 1, 0 )
    fun lookSouth() = look( 0, -1 )
    fun lookWest() = look( -1, 0 )

    fun look( direction : int ) = look( getDeltaX(direction), getDeltaY(direction) )

    fun move( dx : int, dy : int ) {
        getBlock().remove(this)
        actor.x += getNeighbourhood().blockWidth * dx
        actor.y += getNeighbourhood().blockHeight * dy
        getBlock().add(this)
    }

    fun moveNorth() {
        move( 0, 1 )
    }
    fun moveEast() {
        move( 1, 0 )
    }
    fun moveSouth() {
        move( 0, -1 )
    }
    fun moveWest() {
        move( -1, 0 )
    }

    fun move( direction : int ) {
        move( getDeltaX(direction), getDeltaY(direction) )
    }

    fun getDeltaX( direction : int ) : int {
        direction = direction % 4
        if (direction < 0) direction += 4

        return if ( direction == 0 ) {
            1
        } else if ( direction == 2 ) {
            -1
        } else {
            0
        }
    }

    fun  getDeltaY( direction : int ) : int {
        direction = direction % 4
        if (direction < 0) direction += 4

        return if ( direction == 1 ) {
            1
        } else if ( direction == 3 ) {
            -1
        } else {
            0
        }
    }


    fun flash() : Action = (
        Delay( 0.1 ) then EventAction( actor, "other" ) then Delay( 0.1 ) then EventAction( actor, "default" )
    ).forever()


    fun kill() {
        actor.event( "die" )
        actor.die()
    }

}