Simple Mystical Agriculture Farmer (CC:Restitched)

--Setup:
--Place turtle with hoe on top of the
--crop on the bottom left corner
--of a rectangular field.
--Place fuel in the last slot.

--Config
local farmWidth = 5
local farmLength = 5
-- Do not edit past this point
-- unless you know what you are
-- doing!

local DIRECTIONS =
{
    ["FORWARD"] = 1,
    ["BACKWARD"] = 2,
    ["LEFT"] = 3,
    ["RIGHT"] = 4
}

local posX = 1
local posY = 1
local direction = DIRECTIONS.FORWARD


function refuel()
    local fuelNeeded = farmWidth * farmLength
    if fuelNeeded > turtle.getFuelLimit() then fuelneeded = turtle.getFuelLimit() end;

    while turtle.getFuelLevel() < fuelNeeded do
        turtle.select(16)
        local didRefuel = turtle.refuel()
        if not didRefuel then error("Need more fuel in the last slot!") end;
    end
end


function forward(int)
    for i=1,int do
        turtle.forward()
    end
end


function checkStatus()
    local wasSuccess, plantInfo = turtle.inspectDown()

    if type(plantInfo) == "string" then return false end;

    local plantName = plantInfo.name
    local plantAge = plantInfo.state.age

    if plantAge == 7 then return plantName end;

    return false
end


function scanInv(itemName)
    for i=1,15 do
        turtle.select(i)
        local item = turtle.getItemDetail()
        if item ~= nil and string.match(item.name, itemName) then
            return i
        end
    end

    return false
end


function harvest(plantName)
    local plantResource = string.match(plantName, ":(%S+)_")

    turtle.select(1)
    turtle.digDown()
    local slot = scanInv(":"..plantResource.."_seeds")

    if slot then
        turtle.placeDown()
    end
end


function reset()
    if direction == DIRECTIONS.FORWARD then turtle.turnLeft() end;
    if direction == DIRECTIONS.BACKWARD then turtle.turnRight() end;
    direction = DIRECTIONS.LEFT

    forward(farmWidth - 1)
    posY = 1

    if posX ~= 1 then
        turtle.turnLeft()
        forward(farmLength - 1)
        direction = DIRECTIONS.BACKWARD
    end

    if direction == DIRECTIONS.BACKWARD then
        turtle.turnLeft()
        turtle.turnLeft()
    elseif direction == DIRECTIONS.LEFT then
        turtle.turnRight()
    end

    posX = 1
    direction = DIRECTIONS.FORWARD
end


function main()
    for i=1, farmWidth do
        for j=1, farmLength do

            refuel()

            local isRipe = checkStatus()
            if isRipe then
                harvest(isRipe)
            end

            if posX < farmLength and direction == DIRECTIONS.FORWARD then
                turtle.forward()
                posX = posX + 1
            elseif posX > 1 and direction == DIRECTIONS.BACKWARD then
                turtle.forward()
                posX = posX - 1
            end
        end

        if posX == farmLength and posY ~= farmWidth then
            turtle.turnRight()
            turtle.forward()
            posY = posY + 1
            turtle.turnRight()
            direction = DIRECTIONS.BACKWARD
        elseif posX == 1 and posY ~= farmWidth then
            turtle.turnLeft()
            turtle.forward()
            posY = posY + 1
            turtle.turnLeft()
            direction = DIRECTIONS.FORWARD
        end
    end

    reset()
end

while true do
    main()
    os.sleep(60)
end