-- Configuration Settings
local serverUrl = "wss://://yourdomain.com" 
local token = "your_secure_secret_token"    
local FUEL_LIMIT = 400                      
local FORWARD_BUFFER = 4                    -- Blocks to travel forward safely BEFORE mining starts

-- Operational & Spatial State Tracking
local turtleId = tostring(os.computerID())
local idNum = os.computerID() 
local ws = nil
local stopRequested = false
local lastHeartbeat = os.epoch("utc")

-- Saved State for Resumption
local jobActive = false
local targetX, targetY, targetZ = 0, 0, 0
local savedX, savedY, savedZ = 1, 1, 1

-- Relative Position Tracking Matrix
local currentX, currentY, currentZ = 0, 0, 0
local currentDir = 0 -- 0=Forward (+X), 1=Right (+Y), 2=Back (-X), 3=Left (-Y)

local function getFullSlots()
    local fullCount = 0
    for i = 1, 16 do if turtle.getItemCount(i) > 0 then fullCount = fullCount + 1 end end
    return fullCount
end

local function getTelemetry(currentStatus)
    return {
        fuel = turtle.getFuelLevel(),
        maxFuel = turtle.getFuelLimit(),
        inventorySlots = getFullSlots(),
        status = currentStatus or "Idle",
        pos = {x = currentX, y = currentY, z = currentZ}
    }
end

local function sendUpdate(status, logMessage)
    if ws then
        pcall(function()
            ws.send(textutils.serializeJSON({
                type = "telemetry",
                turtleId = turtleId,
                data = getTelemetry(status),
                logMessage = logMessage
            }))
        end)
    end
end

-- NEW & IMPROVED: Constant Automatic Refueling Hook
local function autoRefuel()
    if turtle.getFuelLevel() == "unlimited" then return end
    
    -- Only consume items if we are below our maximum fuel capacity limit
    if turtle.getFuelLevel() < turtle.getFuelLimit() then
        local currentFuel = turtle.getFuelLevel()
        
        for i = 1, 16 do
            turtle.select(i)
            -- Check if slot has a fuel item without consuming it yet
            if turtle.refuel(0) then 
                -- If we are critically low, eat everything. 
                -- Otherwise, only eat if we have room so we don't waste fuel points.
                if currentFuel < FUEL_LIMIT or (turtle.getFuelLevel() < (turtle.getFuelLimit() - 80)) then
                    local before = turtle.getFuelLevel()
                    turtle.refuel(turtle.getItemCount(i)) -- Eat the stack!
                    local gained = turtle.getFuelLevel() - before
                    sendUpdate(nil, "Auto-Refuel: Consumed items from slot " .. i .. ". Added +" .. gained .. " fuel.")
                end
            end
        end
        turtle.select(1) -- Always default selection box back to slot 1
    end
end

-- Navigation Wrappers
local function trackTurnRight()
    turtle.turnRight()
    currentDir = (currentDir + 1) % 4
end

local function trackTurnLeft()
    turtle.turnLeft()
    currentDir = (currentDir - 1) % 4
end

local function trackForward()
    while turtle.detect() do 
        turtle.dig() 
        os.sleep(0.4)
    end
    if turtle.forward() then
        if currentDir == 0 then currentX = currentX + 1
        elseif currentDir == 1 then currentY = currentY + 1
        elseif currentDir == 2 then currentX = currentX - 1
        elseif currentDir == 3 then currentY = currentY - 1
        end
        autoRefuel() -- Automatically scan and eat any fuel mined up or collected immediately
        return true
    end
    return false
end

local function trackDown()
    while turtle.detectDown() do turtle.digDown() end
    if turtle.down() then
        currentZ = currentZ - 1
        autoRefuel()
        return true
    end
    return false
end

local function trackUp()
    while turtle.detectUp() do turtle.digUp() end
    if turtle.up() then
        currentZ = currentZ + 1
        autoRefuel()
        return true
    end
    return false
end

local function navigateHome()
    sendUpdate("Returning Home", "Initiating return path tracking sequence to base dock.")
    while currentZ < 0 do trackUp() end
    while currentZ > 0 do trackDown() end
    
    if currentY > 0 then
        while currentDir ~= 3 do trackTurnRight() end
        while currentY > 0 do trackForward() end
    elseif currentY < 0 then
        while currentDir ~= 1 do trackTurnRight() end
        while currentY < 0 do trackForward() end
    end
    
    if currentX > 0 then
        while currentDir ~= 2 do trackTurnRight() end
        while currentX > 0 do trackForward() end
    end
    
    while currentDir ~= 0 do trackTurnRight() end
    sendUpdate("Idle", "Successfully docked at home station.")
    jobActive = false
end

local function checkFuelSafety()
    if turtle.getFuelLevel() == "unlimited" then return true end
    
    -- Always try to eat fuel right before checking safety values
    autoRefuel()
    
    local distanceHome = math.abs(currentX) + math.abs(currentY) + math.abs(currentZ)
    local absoluteMinimumNeeded = distanceHome + 5
    
    if turtle.getFuelLevel() <= absoluteMinimumNeeded then
        sendUpdate("Low Fuel Return", "Critical fuel fallback reached. Heading home.")
        navigateHome()
        return false
    end
    return true
end

-- Resumable Mining Engine Loop
local function executeMiningJob()
    stopRequested = false
    
    if savedX == 1 and savedY == 1 and savedZ == 1 then
        sendUpdate("Buffer Transit", "Moving forward past the " .. FORWARD_BUFFER .. " block safety buffer zone.")
        for i = 1, FORWARD_BUFFER do
            if not checkFuelSafety() then return end
            trackForward()
        end

        local myOffsetSequence = (idNum - 1) * targetY
        if myOffsetSequence > 0 then
            sendUpdate("Positioning", "Shifting right by " .. myOffsetSequence .. " blocks to align team row.")
            trackTurnRight()
            for i = 1, myOffsetSequence do trackForward() end
            trackTurnLeft()
        end
    end

    sendUpdate("Mining Grid Active", "Resuming/Starting sector clearing: " .. targetX .. "x" .. targetY .. "x" .. targetZ)

    for z = savedZ, targetZ do
        savedZ = z
        for y = savedY, targetY do
            savedY = y
            for x = savedX, targetX - 1 do
                savedX = x
                os.sleep(0.05)

                if not ws then
                    sendUpdate("Reconnecting", "Connection lost! Pausing mining operation until server is online...")
                    print("Lost server handshake. Freezing task loop until reconnected...")
                    while not ws do os.sleep(1) end
                    lastHeartbeat = os.epoch("utc")
                    sendUpdate("Mining Grid Active", "Connection restored! Resuming task.")
                end

                if stopRequested then
                    sendUpdate("Aborted", "Halted by backend request.")
                    navigateHome()
                    return
                end

                if getFullSlots() >= 16 then
                    sendUpdate("Returning Base", "Inventory full.")
                    navigateHome()
                    return
                end
                
                if not checkFuelSafety() then return end
                trackForward()
            end
            savedX = 1 
            
            if y < targetY then
                if y % 2 == 1 then
                    trackTurnRight()
                    trackForward()
                    trackTurnRight()
                else
                    trackTurnLeft()
                    trackForward()
                    trackTurnLeft()
                end
            end
        end
        savedY = 1 
        
        if z < targetZ then
            trackDown()
            trackTurnRight()
            trackTurnRight()
        end
    end
    
    navigateHome()
end

local function connect()
    print("Connecting to Central Control...")
    local success, socketOrErr = pcall(http.websocket, serverUrl)
    if not success or not socketOrErr then return false end

    ws = socketOrErr
    ws.send(textutils.serializeJSON({
        type = "handshake",
        token = token,
        turtleId = turtleId,
        data = getTelemetry(jobActive and "Mining Grid Active" or "Online")
    }))
    lastHeartbeat = os.epoch("utc")
    print("Connected safely.")
    return true
end

-- Global parallel handler threads
local function listenToNetwork()
    while true do
        if not ws then
            if not connect() then os.sleep(5) end
        else
            local event, url, msg = os.pullEvent()
            if event == "websocket_message" then
                lastHeartbeat = os.epoch("utc")
                local success, payload = pcall(textutils.unserializeJSON, msg)
                if success and payload then
                    if payload.command == "excavate" and not jobActive then
                        targetX = payload.args.x
                        targetY = payload.args.y
                        targetZ = payload.args.z
                        savedX, savedY, savedZ = 1, 1, 1 
                        jobActive = true
                    elseif payload.command == "stop" then
                        stopRequested = true
                    end
                end
            elseif event == "websocket_closed" then
                ws = nil
                print("WebSocket closed by proxy.")
            end
        end
    end
end

local function jobWorker()
    while true do
        if jobActive then
            executeMiningJob()
        end
        os.sleep(1)
    end
end

parallel.waitForAll(listenToNetwork, jobWorker)