Potato Harvest

chests = {
    "quark:oak_chest",
    "charm:oak_chest",
}
fuel = {
    "minecraft:coal_block",
    "actuallyadditions:block_misc",
    "quark:charcoal_block",
}

function checkAge()
    isBlock, data = turtle.inspect()
    if (data['state']['age'] == 7)
    then
        isgrown = true
    elseif (data['state']['age'] ~= 7)
    then
        isgrown = false
    end
end

function waitForGrowth()
    checkAge()
    while isgrown == false do
        sleep(20)
        checkAge()
    end
end

function getFuelIndex()
    for slotNum = 1, 16, 1 do
        local Item = turtle.getItemDetail(slotNum)
        if(Item ~=nil) then
            for fuelIndex =1, #fuel, 1 do
                if(Item.name == fuel[fuelIndex]) then
                return slotNum
                end
            end
        end
    end
end

function refuel()
    if(turtle.getFuelLevel() < 400) then
    local Index = getFuelIndex()
      if(Index ~= nil) then
      turtle.select(Index)
      turtle.refuel(2)
      end
    end
end

function getPotatoIndex()
    for slotNum = 1, 16, 1 do
        local item = turtle.getItemDetail(slotNum)
        if(item ~=nil) then
            if(item["name"] == "minecraft:potato") then
                return slotNum
            end
        end
    end
end

function harvest()
    checkAge()
    if isgrown == true then
        turtle.dig()
        turtle.suck()
        local index = getPotatoIndex()
        turtle.select(index)
        turtle.place()
        local potatoNum = turtle.getItemCount()
        turtle.dropDown(potatoNum - 1)
        goLeft()
    elseif isgrown == false then
        goLeft()
    end
end

function goLeft()
    turtle.turnLeft()
    local isBlock = turtle.detect()
    if isBlock == true then
        state, tags = turtle.inspect()
        for chestIndex = 1, #chests, 1 do
            if(tags.name == chests[chestIndex]) then
                refuel()
                getFuelIndex()
                local coalBlocks = turtle.getItemCount()
                if coalBlocks <= 4 then
                    turtle.suck(30)
                    turtle.suck(30)
                    turtle.turnLeft()
                    waitForGrowth()
                elseif coalBlocks > 4 then
                    turtle.turnLeft()
                    waitForGrowth()
                    harvest()
                end
            elseif (tags.name ~= chests[chestIndex]) == false then
                turtle.forward()
                turtle.turnRight()
            end
        end
    elseif isBlock ~= true then
        turtle.forward()
        turtle.turnRight()
        end
end


while true do
    harvest()
end