saikyo-farmer

-- 種のあるスロット番号
firstSlot = 1

-- 種を撒く処理
function putSeed()
    for i=firstSlot, 16 do
        turtle.select(i)
        local data = turtle.getItemDetail(i)
        if data ~= nill and data.name == "minecraft:wheat_seeds" then
            if turtle.getItemCount(i) > 0 then
                firstSlot = i
                break
            end
        end
    end
    turtle.digDown()
    turtle.placeDown()
end

-- 麦を収穫する処理
function harvest()
    local success, data = turtle.inspectDown()
    if success then
        if data.name == "minecraft:wheat" and data.metadata == 7 then
            turtle.digDown()
            putSeed()
        else
          print("Block name: ", data.name)
          print("Block metadata: ", data.metadata)
        end
    end
end

-- 刈り取った麦をチェストに格納する処理
function storeWheat()
    for i=1, 16 do
        turtle.select(i)
        local data = turtle.getItemDetail(i)
        if data ~= nil and data.name == "minecraft:wheat" then
            turtle.drop(turtle.getItemCount(i))
        end
    end
end

-- 作業を終えて元の位置に戻る処理
function backHome()
    if width%2 == 0 then
        turtle.turnLeft()
        for i=1, height do turtle.forward() end
    else
        turtle.forward()
        for i=1, width do turtle.forward() end
        turtle.turnRight()
        for i=1, height do turtle.forward() end
    end
end

-- 畑の縦横に順番にチェックし収穫と種まきを行う処理
function plant()
    for i=1, width do
        turtle.forward()
        for j=1, height do
            if turtle.detectDown() == false then
                putSeed()
            else
                harvest()
            end
            turtle.forward()
        end
        if i%2 == 0 then
            turtle.turnLeft()
            turtle.forward()
            turtle.turnLeft()
        else
            turtle.turnRight()
            turtle.forward()
            turtle.turnRight()
        end
    end
end

-- メインの処理
io.write("width?")
width = io.read()
io.write("height?")
height = io.read()

turtle.up()
plant()
backHome()
turtle.down()

storeWheat()
turtle.turnRight()