turtle shearer

local delay = 180

local function itemBelow()
    local ok, item = turtle.inspectDown()
    if ok then
        if item["name"] == "minecraft:chest" or item["name"] == "ironchest:iron_chest" then
            return "chest"
        else
            return "other"
        end
    else
        return "none"
    end
end

local function tryFindChest(maxDistance)
    local dx = 0
    for i=1,maxDistance do
        if itemBelow() == "chest" then
            return true
        end
        if turtle.forward() then
            dx = dx + 1
        else
            break
        end
    end
    -- no luck, return back
    turtle.turnRight()
    turtle.turnRight()
    for i=1,dx do
        while not turtle.forward() do
            sleep(0.5)
        end
    end
    return false
end

local function unload()
    local total = 0
    for i=1,16 do
        if turtle.getItemCount(i) > 0 then
            total = total + turtle.getItemCount(i)
            turtle.select(i)
            if not turtle.dropDown() then
                print("No space in the chest")
                fs.delete("startup")
                return false
            end
            sleep(0.5)
        end
    end
    print("Time: "..os.time().." items: "..total.." fuel: "..turtle.getFuelLevel())
    return true
end

-- enable autorun
local s = "shell.run(\"shear\")"
local f = fs.open("/startup", "w")
f.write(s)
f.close()

-- find chest
if itemBelow() ~= "chest" then
    print("Chest not found")
    return
end

if not unload() then
    return
end

while true do
    -- check fuel
    if turtle.getFuelLevel() < 100 then
        print("Low fuel")
        return
    end

    -- sanity check
    if itemBelow() ~= "chest" then
        print("Chest not found")
        return
    end

    -- harvest
    local dx = 0
    while true do
        if turtle.forward() then
            dx = dx + 1
        else
            break
        end

        local item = itemBelow()
        if item == "none" then
            repeat
                local sheared = turtle.attackDown()
            until not sheared
        elseif item ~= "none" then
            break
        end
    end

    -- return back
    turtle.turnRight()
    turtle.turnRight()
    for i=1,dx do
        while not turtle.forward() do
            sleep(0.5)
        end
    end
    turtle.turnRight()
    turtle.turnRight()

    -- unload
    if not unload() then
        return
    end

    sleep(delay)
end