-- Config & Args
local tArgs = { ... }
local returnToStart = false
for _, arg in ipairs(tArgs) do
    if arg == "-startPosition" then
        returnToStart = true
    end
end

-- Optional startup delay
local waitTime = 30
for i = 1, waitTime do
    if i == 10 then
        -- After 10 seconds, proceed unless interrupted
        break
    end
    os.sleep(1)
end

-- State
local pos = {x = 0, y = 0}
local dir = 0 -- 0=N, 1=E, 2=S, 3=W
local startPos = {x = 0, y = 0}
local startDir = 0
local depth = 0
local maxDepth = 1

-- Helpers
local function turnRight() turtle.turnRight() dir = (dir + 1) % 4 end
local function turnLeft()  turtle.turnLeft()  dir = (dir + 3) % 4 end

local function moveForward()
    if turtle.forward() then
        if dir == 0 then pos.y = pos.y + 1
        elseif dir == 1 then pos.x = pos.x + 1
        elseif dir == 2 then pos.y = pos.y - 1
        elseif dir == 3 then pos.x = pos.x - 1 end
        return true
    end
    return false
end

local function digIfKelp()
    local success, data = turtle.inspect()
    if success and data.name and data.name:lower():find("kelp") then
        turtle.dig()
        return true
    end
    return false
end

local function tryMove()
    digIfKelp()
    if not turtle.detect() then
        return moveForward()
    end
    return false
end

local function dropKelp()
    for i = 1, 16 do
        turtle.select(i)
        local item = turtle.getItemDetail()
        if item and item.name:lower():find("kelp") then
            turtle.drop()
        end
    end
end

local function refuelFromInventory()
    turtle.select(1)
    while turtle.getItemCount(1) > 0 do
        if not turtle.refuel(1) then
            return false -- Not a valid fuel item
        end
        if turtle.getFuelLevel() == "unlimited" then
            return true
        end
    end
    return turtle.getFuelLevel() > 0
end

local function waitForFuel(timeout)
    if turtle.getFuelLevel() == 0 and refuelFromInventory() then
        return true
    end
    local waited = 0
    while turtle.getFuelLevel() == 0 and waited < timeout do
        os.sleep(1)
        waited = waited + 1
        refuelFromInventory()
    end
    return turtle.getFuelLevel() > 0
end

local function stepOutward()
    turnRight()
    tryMove()
    turnLeft()
end

local function returnHome()
    -- Step back in from current depth
    while depth > 0 do
        turnLeft()
        tryMove()
        turnRight()
        depth = depth - 1
    end
    -- Return to original starting pos
    while pos.x ~= startPos.x or pos.y ~= startPos.y do
        if pos.x < startPos.x then while dir ~= 1 do turnRight() end
        elseif pos.x > startPos.x then while dir ~= 3 do turnRight() end
        elseif pos.y < startPos.y then while dir ~= 0 do turnRight() end
        elseif pos.y > startPos.y then while dir ~= 2 do turnRight() end
        end
        moveForward()
    end
    -- Face original start direction
    while dir ~= startDir do turnRight() end
end

-- MAIN LOOP
while true do
    if not waitForFuel(30) then return end

    local stepsTaken = 0
    local loopStart = {x = pos.x, y = pos.y}
    local loopDir = dir

    repeat
        turnRight()
        if not tryMove() then
            turnLeft()
            if not tryMove() then
                turnLeft()
                if not tryMove() then
                    turnLeft()
                end
            end
        else
            stepsTaken = stepsTaken + 1
            if not returnToStart then
                dropKelp()
            end
        end

        if turtle.getFuelLevel() == 0 then
            if not waitForFuel(30) then return end
        end
    until stepsTaken > 0 and pos.x == loopStart.x and pos.y == loopStart.y and dir == loopDir

    if depth < maxDepth then
        depth = depth + 1
        stepOutward()
    else
        if returnToStart then
            returnHome()
            dropKelp()
        end
        depth = 0
    end

end