fleet_agent

-- FLEET AGENT v1.0
-- CC:Tweaked
-- Install on each turtle.
-- Change SLOT to 1 through 6.

local SLOT = 1
local PROTOCOL = "mountain_fleet_v1"
local DEPLOY_DISTANCE = 3
local HOME_FILE = "fleet_home.dat"

local id = os.getComputerID()
local state = {
    slot = SLOT,
    status = "STARTING",
    steps = 0,
    home = nil,
    error = nil
}

-- Open wireless modem
local modemName = nil

for _, name in ipairs(peripheral.getNames()) do
    if peripheral.hasType(name, "modem") then
        local modem = peripheral.wrap(name)
        if modem.isWireless() then
            modemName = name
            break
        end
    end
end

if not modemName then
    error("Wireless modem not found")
end

rednet.open(modemName)

-- Persistent state
local function saveHome()
    local f = fs.open(HOME_FILE, "w")
    f.write(textutils.serialize({
        home = state.home,
        steps = state.steps
    }))
    f.close()
end

local function loadHome()
    if not fs.exists(HOME_FILE) then
        return false
    end

    local f = fs.open(HOME_FILE, "r")
    local contents = f.readAll()
    f.close()

    local data = textutils.unserialize(contents)

    if type(data) ~= "table"
       or type(data.home) ~= "table"
       or type(data.steps) ~= "number" then
        return false
    end

    state.home = data.home
    state.steps = data.steps
    return true
end

local function locate()
    local x, y, z = gps.locate(2)

    if not x then
        return nil
    end

    return {
        x = math.floor(x + 0.5),
        y = math.floor(y + 0.5),
        z = math.floor(z + 0.5)
    }
end

local function sendStatus()
    local position = locate()

    rednet.broadcast({
        type = "status",
        slot = SLOT,
        id = id,
        status = state.status,
        position = position,
        home = state.home,
        steps = state.steps,
        fuel = turtle.getFuelLevel(),
        error = state.error
    }, PROTOCOL)
end

-- Initialize the dock record.
if not loadHome() then
    local position = locate()

    if not position then
        error("GPS unavailable. Dock not saved.")
    end

    state.home = position
    state.steps = 0
    saveHome()
end

if state.steps == 0 then
    state.status = "DOCKED"
else
    state.status = "ACTIVE"
end

local function deploy()
    if state.steps > 0 then
        state.error = "Already deployed"
        sendStatus()
        return
    end

    local current = locate()

    if not current or not state.home
       or current.x ~= state.home.x
       or current.y ~= state.home.y
       or current.z ~= state.home.z then
        state.status = "ERROR"
        state.error = "Dock position mismatch"
        sendStatus()
        return
    end

    state.status = "DEPLOYING"
    state.error = nil
    sendStatus()

    while state.steps < DEPLOY_DISTANCE do
        if turtle.forward() then
            state.steps = state.steps + 1
            saveHome()
            sendStatus()
        else
            state.status = "BLOCKED"
            state.error = "Forward path blocked"
            sendStatus()
            return
        end
    end

    state.status = "ACTIVE"
    sendStatus()
end

local function recall()
    state.error = nil

    if state.steps == 0 then
        state.status = "DOCKED"
        sendStatus()
        return
    end

    state.status = "RETURNING"
    sendStatus()

    while state.steps > 0 do
        if turtle.back() then
            state.steps = state.steps - 1
            saveHome()
            sendStatus()
        else
            state.status = "BLOCKED"
            state.error = "Return path blocked"
            sendStatus()
            return
        end
    end

    local current = locate()
    local home = state.home

    if current and home
       and current.x == home.x
       and current.y == home.y
       and current.z == home.z then
        state.status = "DOCKED"
    else
        state.status = "ERROR"
        state.error = "Dock GPS verification failed"
    end

    sendStatus()
end

-- Start communications
print("Fleet Turtle " .. SLOT)
print("Computer ID: " .. id)
print("Modem: " .. modemName)
print("GPS home registered")

sendStatus()

local heartbeat = os.startTimer(3)

while true do
    local event, a, b, c = os.pullEvent()

    if event == "timer" and a == heartbeat then
        sendStatus()
        heartbeat = os.startTimer(3)

    elseif event == "rednet_message" then
        local sender = a
        local message = b
        local protocol = c

        if protocol == PROTOCOL
           and type(message) == "table"
           and message.type == "command"
           and message.slot == SLOT then

            if message.action == "deploy" then
                deploy()

            elseif message.action == "recall" then
                recall()

            elseif message.action == "ping" then
                sendStatus()
            end
        end
    end
end