GPS/Relay Hybrid Routines - Global Builders Project

-- GPS/Relay Hybrid Computer Routines

-- Edit the below values to reflect the world coordinates
-- of the GPS computer. Format: x, y, z

local deviceLoc = {-203, 134, 136}

local centralPCChannel = 1

-- edit msgsRetained value to adjust the number of messages kept for
-- each registered device to compare for duplicates

local msgsRetained = 10

local eventTable = {}
local cID = os.getComputerID ()
local cLabel = os.getComputerID ()
local gpsChan = gps.CHANNEL_GPS
local commTable = { {1, {"000-00.000" }}, {2, {"000-00.000"}}, {gpsChan, {"0000-0000"}} }
local msgContainer = {}
local m = nil



function initDevice ()

    local periLoc = redstone.getSides()
    local periStr, wModem = "", ""

    term.clear ()
    term.setCursorPos (1, 1)

    for i = 1, 6 do
        periStr = peripheral.getType (periLoc[i])
        if periStr == "modem" then
            if m == nil then
                m = peripheral.wrap (periLoc[i])
                wModem = periLoc[i]
                print ('Wireless modem connected on '..periLoc[i]..' side.')
            else
                wModem = periLoc[i]
                print ('Rednet modem connected on '..periLoc[i]..' side.')
            end
        end
    end

    local tempStr = "GPS_Relay_"..tostring(cID)
    if (cLabel == "") or (cLabel ~= tempStr) then
        os.setComputerLabel (tempStr)
        cLabel = tempStr
    end

    print ('Device label : '..cLabel..' on channel '..tostring(cID))
    print ('Pausing for network startup.')
    sleep (1)
    msgContainer = {0, 3, cLabel, cID, cID, reqMessageID () }
    m.transmit (centralPCChannel, cID, textutils.serialize (msgContainer))
end


function reqMessageID ()

    local IDStr = tostring( os.day() )..'-'..tostring( os.time () )
    return IDStr
end


function isDupe (checkMsg)

-- To DO:
-- review and correct table format for stored channels
-- review and correct list format for msg IDs
-- NOTE: should be no duplicate checking on GPS requests

    local chChan = checkMsg[4]

    for i = 1, #commTable do
        if commTable[i][1] == chChan then
            if #commTable[i][2] == 1 then
                commTable[i][2] = { checkMsg[6] }
                return false
            else
                local chkInTab = false
                for ii = 1, #commTable[i][2] do
                    if commTable[i][2][ii] == checkMsg[6] then
                        chkInTab = true
                    end
                end
                if not chkInTab then
                    table.insert (commTable[i], checkMsg[6])
                    if #commTable[i] > msgsRetained then
                        table.remove (commTable[i], 1)
                        return false
                    end
                else
                    return true
                end
            end

        end
    end
end


function openChannels ()

    m.closeAll ()
    if not commTable == {} then
        for i = 1, #commTable do
            m.open (commTable[i][1])
        end
    end
end


function main ()

    initDevice ()
    openChannels ()

    while true do
        print ('Listening for message...')
        eventTable = { os.pullEvent () }

        if eventTable[1] == "rednet_message" then
            print ('rednet_message received.')

        elseif eventTable[1] == "modem_message" then
            if (eventTable[3] == 65534) and
                (eventTable[5] == 'PING') then
                print ('GPS request received from channel '..tostring(eventTable[4]))

                m.transmit (eventTable[4], 65534, textutils.serialize (deviceLoc))

            else
                -- check message table contents for type 4 (registered channel data)
                -- check against comm log for duplicates
                -- relay message
                msgContainer = textutils.unserialize (eventTable[5])
                print ('Received message ID '..msgContainer[6].." from channel "..tostring (msgContainer[5])..'.')
                if msgContainer[5] == cID then
                    print ('Rejected bounced origin message.')
                elseif msgContainer[1] == 4 then
                    print ('Received network channel list update.')
                    local inTab = false
                    for i = 1, #msgContainer[7] do
                        if not (msgContainer[7][i] == cID) then
                            for ii = 1, #commTable do
                                if commTable[ii][1] == msgContainer[7][i] then
                                    inTab = true
                                end
                            end
                            if not inTab then
                                table.insert (commTable, { msgContainer[7][i], {"0000-0000"} } )
                            end
                            inTab = false
                        end
                    end
                elseif isDupe(msgContainer) then
                    print ('Rejected duplicate message.')
                else
                    m.transmit (eventTable[3], cID, eventTable[5])
                    print ('Relayed message.')
                end
            end
        else write ('.')
        end
        sleep (0.5)
    end
end

main ()