mc_oc_eeeprom.lua

--
-- https://oc.cil.li/index.php?/topic/468-drone-follow-script/
--
local PORT_FOLLOW = 0xbf01
local MAX_DIST = 100

local drone = component.proxy(component.list("drone")())
local modem = component.proxy(component.list("modem")())
local nav = component.proxy(component.list("navigation")())

modem.open(PORT_FOLLOW)

local function findClient()
    while true do
        local evt,_,sender,port,dist,msg = computer.pullSignal()
        if evt == "modem_message" and port == PORT_FOLLOW and dist < MAX_DIST and msg == "FOLLOW_REQUEST_LINK" then
            drone.setStatusText("Linked: "..sender:sub(1,3))
            modem.send(sender,port,"FOLLOW_LINK")
            return sender
        end
    end
end

local function getNearbyNodes(justLabels)
    local waypoints = nav.findWaypoints(MAX_DIST)
    local nodes = {}
    for i = 1,waypoints.n do
        if justLabels then
            nodes[i] = waypoints[i].label
        else
            local wp = waypoints[i]
            nodes[wp.label] = wp.position
        end
    end
    return nodes
end

local client,nodes,noResponse = findClient(),getNearbyNodes()
local timeout = computer.uptime() + 10

while true do
    local evt,_,sender,port,dist,msg,label,ox,oy,oz = computer.pullSignal(timeout - computer.uptime())
    if moving and drone.getOffset() < 0.5 then
        moving = false
        nodes = getNearbyNodes()
    end
    if not evt then
        if noResponse then
            return
        end
        noResponse = true;
        modem.send(client,PORT_FOLLOW,"HEARTBEAT_REQUEST")
        timeout = timeout + 1
    elseif evt == "modem_message" and sender == client and port == PORT_FOLLOW and dist < MAX_DIST then
        if msg == "HEARTBEAT_RESPONSE" then
            noResponse = false
        elseif msg == "HEARTBEAT_REQUEST" then
            modem.send(sender,port,"HEARTBEAT_RESPONSE")
        elseif msg == "POS_UPDATE" and not moving then
            local node = nodes[label]
            if not node then
                modem.send(sender,port,"UPDATE_NODES",label,table.unpack(getNearbyNodes(true)))
            else
                drone.move(node[1] - ox, node[2] - oy, node[3] - oz)
                moving = true
                modem.send(sender,port,"OK")
            end
        end
        timeout = computer.uptime() + 10
    end
end