def visitOr(blockcontext):
    operand1 = visitGeneric(blockcontext, "OPERAND1")
    if operand1 is None:
        operand1 = False
    operand2 = visitGeneric(blockcontext, "OPERAND2")
    if operand2 is None:
        operand2 = False
    return ["|", operand1, operand2]

def visitRepeat(blockcontext):
    block = blockcontext.block
    times = visitGeneric(blockcontext, "TIMES")
    if times == []:
        times = block.inputs["TIMES"][1][1]
    substack = visitSubstack(blockcontext, "SUBSTACK")
    return ["doRepeat", times, substack]

def visitSety(blockcontext):
    y = visitGeneric(blockcontext, "Y")
    return ["ypos:", y]

def visitSetx(blockcontext):
    x = visitGeneric(blockcontext, "X")
    return ["xpos:", x]

def visitChangexby(blockcontext):
    x = visitGeneric(blockcontext, "DX")
    return ["changeXposBy:", x]

def visitPointindirection(blockcontext):
    direction = visitGeneric(blockcontext, "DIRECTION")
    return ["heading:", direction]

def visitGlideto(blockcontext):
    secs = visitGeneric(blockcontext, "SECS")
    to = visitGeneric(blockcontext, "TO")
    log.warn("[Scratch3] block {} ({}) possibly not available in Scratch2".format(blockcontext.block.opcode, blockcontext.block.name))
    return ["glideTo:", secs, to] #TODO: not in scratch2?

def visitGoto(blockcontext):
    to = visitGeneric(blockcontext, "TO")
    return ["gotoSpriteOrMouse:", to]

def visitSeteffectto(blockcontext):
    block = blockcontext.block
    effect = block.fields["EFFECT"][0]
    value = visitGeneric(blockcontext, "VALUE")
    return ["setGraphicEffect:to:", effect, value]

def visitSayforsecs(blockcontext):
    message = visitGeneric(blockcontext, "MESSAGE")
    duration = visitGeneric(blockcontext, "SECS")
    return ["say:duration:elapsed:from:", message, duration]

def visitChangeeffectby(blockcontext):
    block = blockcontext.block
    effect = block.fields["EFFECT"][0]
    change = visitGeneric(blockcontext, "CHANGE")
    return ["changeGraphicEffect:by:", effect, change]

def visitSetsizeto(blockcontext):
    size = visitGeneric(blockcontext, "SIZE")
    return ["setSizeTo:", size]

def visitChangesizeby(blockcontext):
    size = visitGeneric(blockcontext, "CHANGE")
    return ["changeSizeBy:", size]

def visitSwitchbackdropto(blockcontext):
    backdrop = visitGeneric(blockcontext, "BACKDROP")
    return ["startScene", backdrop]

def visitSwitchcostumeto(blockcontext):
    costume = visitGeneric(blockcontext, "COSTUME")
    return ["lookLike:", costume]

def visitPlayuntildone(blockcontext):
    sound = visitGeneric(blockcontext, 'SOUND_MENU')
    return ['doPlaySoundAndWait', sound]

def visitTurnleft(blockcontext):
    degrees = visitGeneric(blockcontext, "DEGREES")
    return ["turnLeft:", degrees]

def visitGoforwardbackwardlayers(blockcontext):
    block = blockcontext.block
    direction = block.fields["FORWARD_BACKWARD"][0]
    change = visitGeneric(blockcontext, "NUM")
    return ["goBackByLayers:", change]

def visitGotoxy(blockcontext):
    x = visitGeneric(blockcontext, "X")
    y = visitGeneric(blockcontext, "Y")
    return ["gotoX:y:", x, y]

def visitWhengreaterthan(blockcontext):
    block = blockcontext.block
    sensor = block.fields["WHENGREATERTHANMENU"][0].lower()
    value = visitGeneric(blockcontext, "VALUE")
    return ["whenSensorGreaterThan", sensor, value]