-- Lesson 3: Making Decisions

BOX_SIZE  = 20
BOX_SPEED = 2

width  = overlayGetWidth()
height = overlayGetHeight()
maxX   = width - BOX_SIZE - 1
maxY   = height - BOX_SIZE - 1

boxX = width // 2
boxY = height // 2

movingLeft  = false
movingRight = false
movingUp    = false
movingDown  = false


function onInputPressed(what)
    if what == SWITCH_LEFT then
        movingLeft = true
    elseif what == SWITCH_RIGHT then
        movingRight = true
    elseif what == SWITCH_UP then
        movingUp = true
    elseif what == SWITCH_DOWN then
        movingDown = true
    end
end


function onInputReleased(what)
    if what == SWITCH_LEFT then
        movingLeft = false
    elseif what == SWITCH_RIGHT then
        movingRight = false
    elseif what == SWITCH_UP then
        movingUp = false
    elseif what == SWITCH_DOWN then
        movingDown = false
    end
end


function onOverlayUpdate()
    if movingLeft and not movingRight then
        boxX = boxX - BOX_SPEED
    elseif movingRight and not movingLeft then
        boxX = boxX + BOX_SPEED
    end

    if movingUp and not movingDown then
        boxY = boxY - BOX_SPEED
    elseif movingDown and not movingUp then
        boxY = boxY + BOX_SPEED
    end

    if boxX < 0 then
        boxX = 0
    elseif boxX > maxX then
        boxX = maxX
    end

    if boxY < 0 then
        boxY = 0
    elseif boxY > maxY then
        boxY = maxY
    end

    overlayClear()

    if movingLeft or movingRight or movingUp or movingDown then
        colorForeground(255, 220, 0)
    else
        colorForeground(80, 160, 255)
    end

    overlayBox(boxX, boxY, boxX + BOX_SIZE, boxY + BOX_SIZE)
    overlayPrint(0, 0, "x " .. boxX .. "  y " .. boxY)
    return OVERLAY_UPDATED
end