CC Hilbert Potato Farm

--
-- This script farms potatoes (other crops if you modify singleHarvest()) in the pattern of
-- a Hilbert curve of the second order.
--
-- It looks like this:
-- x: air with water for the farm undearneath
-- <: the starting position of the turtle (facing into the cobblestone)
-- C: a block of cobblestone as a marker for when the turtle is done with one round
--  : farmblock
--
-- xxxx  xxxx
-- x  x  x  x
-- x  x  x  x
-- x  xxxx  x
-- x        x
-- x        x
-- xxxx  xxxx
--    x  x
--    x  x
--C<xxx  xxxx
--

local function isBlock(block)
    local found_block, block_data = turtle.inspect();
    if found_block then
        if block_data["name"] == block then
            return true;
        end
    end

    return false;
end

local function tableContains(table, needle)
    for key, value in pairs(table) do
        if key == needle then
            return true;
        end
    end

    return false;
end

local function isCrop()
    local found_block, block_data = turtle.inspect();
    if found_block then
        if tableContains(block_data["tags"], "minecraft:crops") then
            return true;
        end
    end

    return false;
end

local function isGrown()
    local found_block, block_data = turtle.inspect();
    if found_block then
        if tableContains(block_data["tags"], "minecraft:crops") then
            if block_data["state"]["age"] == 7 then
                return true;
            end
        end
    end

    return false;
end

local function itemIndex(item_name)
    for i = 1, 16, 1 do
        local details = turtle.getItemDetail(i)
        if details ~= nil then
            if details["name"] == item_name then
                return i
            end
        end
    end

    return 1 -- FIXME not great, since this is an invalid return
end

local function harvestSingle()
    turtle.suck()
    if isGrown() then
        turtle.dig()
        turtle.select(itemIndex("minecraft:potato"))
        turtle.place();
    end
end

local function moveRight()
    harvestSingle();
    turtle.turnRight()
    turtle.forward()
    turtle.turnLeft()
end

local function forwardTurnLeft()
    turtle.forward()
    turtle.turnLeft()
end

local function firstHalfSmallLoop()
    for i = 1, 3, 1 do
        moveRight()
    end
    for i = 1, 2, 1 do
        forwardTurnLeft()
        for j = 1, 2, 1 do
            moveRight()
        end
    end
    turtle.turnRight()
end

local function firstHalflongStretchA()
    for i = 1, 6, 1 do
        moveRight()
    end
    turtle.turnRight()
    for i = 1, 3, 1 do
        moveRight()
    end
    turtle.turnRight()
end

local function firstHalflongStretchB()
    for i = 1, 3, 1 do
        moveRight()
    end
    turtle.turnRight()
    for i = 1, 6, 1 do
        moveRight()
    end
    turtle.turnRight()
end

local function firstHalf()
    firstHalfSmallLoop()
    firstHalflongStretchA()
    firstHalfSmallLoop()
    firstHalflongStretchB()
    firstHalfSmallLoop()
end

local function secondHalfShortLoop()
    for i = 1, 2, 1 do
        turtle.turnRight()
        for j = 1, 3, 1 do
            moveRight()
        end
    end
end

local function secondHalfLongStretchA()
    forwardTurnLeft()
    for i = 1, 5, 1 do
        moveRight()
    end
    for i = 1, 2, 1 do
        forwardTurnLeft()
        for j = 1, 2, 1 do
            moveRight()
        end
    end
end

local function secondHalfLongStretchB()
    forwardTurnLeft()
    for i = 1, 2, 1 do
        moveRight()
    end
    forwardTurnLeft()
    for i = 1, 5, 1 do
        moveRight()
    end
    forwardTurnLeft()
    for i = 1, 2, 1 do
        moveRight()
    end
end

local function secondHalf()
    secondHalfShortLoop()
    turtle.turnRight()
    for i = 1, 3, 1 do
        moveRight()
    end
    secondHalfLongStretchA()
    secondHalfShortLoop()
    secondHalfLongStretchB()
    secondHalfShortLoop()
end

local function harvest()
    term.setCursorPos(1, 4)
    term.write("Harvesting...")

    firstHalf()
    secondHalf()
    turtle.turnRight() -- Turn back to the starting block
end

local function printSleep(number)
    local seconds_remaining = number

    while seconds_remaining > 0 do
        term.setCursorPos(1, 1)
        term.clearLine()
        term.write("Sleeping for " .. seconds_remaining .. "...")

        sleep(5)
        seconds_remaining = seconds_remaining - 5
    end
    term.setCursorPos(1, 2)
    term.write("Done sleeping.")
end

local function main()
    while true do
        term.clear()
        if isBlock("minecraft:cobblestone") then
            turtle.turnRight();
            harvest();
        end
        printSleep(60)
    end
end

main()