plant.lua

local tArgs = { ... }
local rows = nil
local length = nil
if #tArgs < 1 then
    print( "Usage: farm [number:rows] [number:length]" )
    return
else
    rows = tonumber(tArgs[1])
    length = tonumber(tArgs[2])
end

local function check_fuel(required)
    -- Always assumes the turtle is currently at the
    -- bread creation place

    if turtle.getFuelLevel() == 'unlimited' or turtle.getFuelLevel() > required + 1 then
        return
    end

    -- Not enough fuel
    -- Try to refuel through inventory
    turtle.select(16)
    if turtle.refuel() then
        return
    end

    -- Turn right and check the chest for fuel
    turtle.turnRight()

    -- We need an additional action now (turn left)
    -- so increment required
    required = required + 1

    empty_spots = {}

    -- Suck it all up and call refuel on every item
    for s = 1, 16 do
        if turtle.getItemCount(s) == 0 then
            empty_spots[s] = 1
            turtle.suck()
            turtle.refuel()
            if turtle.getFuelLevel() > required + 1 then
                return
            end
        else
            empty_spots[s] = 0
        end
    end
    for s = 1, 16 do
        if empty_spots[s] == 1 then
            turtle.drop()
        end
    end

    -- Ask for fuel
    turtle.select(16)
    print("Need fuel!")

    -- Will be reduced by 3 at the destination
    redstone.setAnalogOutput("bottom", 14)
    while not turtle.refuel() or turtle.getFuelLevel() < required + 1 do
        os.pullEvent( "turtle_inventory")
    end
    redstone.setOutput("bottom", false)
    print("Got fuel!")

    turtle.turnLeft()
end

local function faces_chest()
    local success, data = turtle.inspect()
    if not success then
        return false
    end
    if data.name == "minecraft:chest" or data.name == "IronChest:BlockIronChest" then
        return true
    else
        return false
    end
end

local function is_at_start()
    turtle.turnLeft()
    if not faces_chest() then
        turtle.turnRight()
        return false
    end

    turtle.turnLeft()
    if not faces_chest() then
        turtle.turnRight()
        turtle.turnRight()
        return false
    end

    turtle.turnLeft()
    if not faces_chest() then
        turtle.turnRight()
        turtle.turnRight()
        turtle.turnRight()
        return false
    end


    turtle.turnLeft()
    return true
end


local function move(dir, amount)
    if dir == "fw" then
        for t = 1, amount do
            turtle.forward()
        end
    elseif dir == "bw" then
        for t = 1, amount do
            turtle.back()
        end
    elseif dir == "up" then
        for t = 1, amount do
            turtle.up()
        end
    elseif dir == "down" then
        for t = 1, amount do
            turtle.down()
        end
    end
end

local function initial_farm_path()
    -- check_fuel(12)

    move("fw", 1)
    turtle.turnLeft()
    move("fw", 6)
    move("up", 4)
    turtle.turnLeft()
end

local function selected_is_wheat()
    if turtle.getItemCount() == 0 then
        return false
    end
    if turtle.getItemDetail().name == "minecraft:wheat" then
        return true
    else
        return false
    end
end

local function selected_is_seeds()
    if turtle.getItemCount() == 0 then
        return false
    end
    if turtle.getItemDetail().name == "minecraft:wheat_seeds" then
        return true
    else
        return false
    end
end

local row_offset = 0

local function find_seeds()
    for s = 1, 15 do
        turtle.select(s)
        if selected_is_seeds() then
            return true
        end
    end
    return false
end

local function place_seed()
    if not find_seeds() then
        return false
    end
    turtle.digDown()
    turtle.placeDown()
    return true
end

local function return_from_row(len_traveled)
    turtle.turnLeft()
    turtle.turnLeft()

    for t = 0, len_traveled do
        move("down", 1)
        if t == len_traveled then
            move("fw", 8)
        else
            move("fw", 7)
        end
    end

    turtle.turnLeft()
    turtle.turnLeft()
end

local function farm_single_row()
    -- check_fuel((length * 16) + 1)

    local len_traveled = 0

    local do_cancel = false
    for l = 1, length do
        local local_len = 7
        if l == 1 then
            -- First row is 1 longer
            local_len = 8
        else
            move("up", 1)
        end

        if do_cancel then
            break
        end

        len_traveled = len_traveled + 1

        for f = 1, local_len do
            move("fw", 1)
            if not place_seed() then
                -- No more seeds, cancel after this row
                do_cancel = true
            end
        end
    end

    return_from_row(len_traveled)
end

local function farm_double_row()
    -- check_fuel((length * 23) + 1)

    local len_traveled = 0

    local do_cancel = false
    for l = 1, length do
        local local_len = 7
        if l == 1 then
            -- First row is 1 longer
            local_len = 8
        else
            move("up", 1)
        end

        if do_cancel then
            break
        end

        len_traveled = len_traveled + 1

        for f = 1, local_len / 2 do
            move("fw", 1)
            if not place_seed() then
                -- No more seeds, cancel after this row
                do_cancel = true
            end
            turtle.turnRight()
            move("fw", 1)
            if not place_seed() then
                -- No more seeds, cancel after this row
                do_cancel = true
            end
            turtle.turnLeft()
            move("fw", 1)
            if not place_seed() then
                -- No more seeds, cancel after this row
                do_cancel = true
            end
            turtle.turnLeft()
            move("fw", 1)
            if not place_seed() then
                -- No more seeds, cancel after this row
                do_cancel = true
            end
            turtle.turnRight()
        end
        if local_len % 2 > 0 then
            move("fw", 1)
            if not place_seed() then
                -- No more seeds, cancel after this row
                do_cancel = true
            end
            turtle.turnRight()
            move("fw", 1)
            if not place_seed() then
                -- No more seeds, cancel after this row
                do_cancel = true
            end
            turtle.turnLeft()
            turtle.turnLeft()
            move("fw", 1)
            turtle.turnRight()
        end
    end

    return_from_row(len_traveled)
end

local function go_home()
    -- check_fuel(row_offset + 12)

    turtle.turnLeft()
    move("fw", row_offset)
    move("fw", 4)
    move("down", 4)
    move("fw", 2)
    turtle.turnRight()
    move("fw", 1)
    turtle.turnLeft()
    turtle.turnLeft()
end

local function dump_excess()
    check_fuel(6)

    move("up", 1)
    turtle.turnRight()
    move("fw", 2)
    for s = 1, 15 do
        turtle.select(s)
        turtle.drop(64)
    end

    turtle.turnLeft()
    turtle.turnLeft()
    move("fw", 2)
    turtle.turnRight()
    move("down", 1)
end

local function next_row(doubled)
    local amount = nil
    if doubled then
        amount = 3
    else
        amount = 2
    end

    -- check_fuel(amount)

    row_offset = row_offset + amount
    turtle.turnRight()
    move("fw", amount)
    turtle.turnLeft()
end

local function pick_up_seeds()
    turtle.turnLeft()
    for s = 1, 15 do
        turtle.select(s)
        turtle.suck(64)
    end
    turtle.turnRight()
end

local function farm()
    if rows < 3 then
        check_fuel(12 + (((length * 16) + 1) * rows) + ((rows - 1) * 4) + 12)
    else
        check_fuel(12 + 12 + 4 + 4 + ((((length * 23) + 1) + 3 + 3) * (rows - 2)) +
            (((length * 16) + 1) * 2) + (8))
    end

    pick_up_seeds()
    initial_farm_path()

    if rows < 1 then
        print("Amount of rows is set to lower than 1")
        return
    end

    farm_single_row()
    for r = 0, rows - 2 do
        if r == 0 then
            next_row()
        else
            next_row(true)
        end
        farm_double_row()
    end
    if rows > 1 then
        if rows > 2 then
            next_row(true)
        else
            next_row()
        end
        farm_single_row()
    end

    go_home()
    dump_excess()
end

local function init()
    -- Check fuel first
    check_fuel(1)
    print("Fuel remaining: ", turtle.getFuelLevel())

    farm()
end

init()