--[[
Unitary Navigational System v0

This basic script attempts to consolidate a GPS constellation into a single computer. Because using 4 is plain wasteful!
It was made out of project "GLONASS Tower" I wrote back in 2022 after first discovering CC

TODO: Bring back cool logging!
]]

local UNS_VERSION = 0
local UNS_HOST_ID = "lavender-1"

-- Modems declaration. Edit this!
local modems = {
    {
        id = "modem_id",
        pos = {
            1,  -- x
            1,  -- y
            1   -- z
        },
        primary = true,  -- The modem that does listening
        modem = nil,  -- Declared below, leave as nil
    }
}

-- Simple logging. It's not ideal but will do as a "temporary" solution
local function log(message)
    term.write(message)
    term.setCursorPos(1, select(2, term.getCursorPos()) + 1)
    if select(2, term.getCursorPos()) >= select(2, term.getSize()) then
        term.scroll(1)
        term.setCursorPos(1, select(2, term.getCursorPos()) - 1)
    end
end
term.clear()
term.setCursorPos(1, 1)
log("UNS v" .. UNS_VERSION)

-- Prepare all modems
local primary_modem = nil
for i, modem in ipairs(modems) do
    modems[i].modem = peripheral.wrap(modems[i].id)
    if modems[i].primary then
        primary_modem = modems[i].modem
    end
    log("load <" .. modem.id .. "> pos - " .. textutils.serialise(modem.pos))
end
if primary_modem == nil then
    primary_modem = modems[0].modem
end
primary_modem.open(gps.CHANNEL_GPS)  -- Only *listen* on 1 modem to avoid repeats

while true do
    -- Wait for a request on channel
    local event, side, channel, replyChannel, message, distance
    repeat
        event, side, channel, replyChannel, message, distance = os.pullEvent("modem_message")
    until channel == gps.CHANNEL_GPS

    if message == "PING" then  -- Normal location request
        log("Recieved location request, d-" .. distance)
        for _, modem in ipairs(modems) do
            modem.modem.transmit(channel, replyChannel, modem.pos)
            log("Modem <" .. modem.id .. "> transmitted location")
        end
    elseif message == "INFO" then  -- Host query
        log("Recieved info request, d-" .. distance)
        primary_modem.transmit(channel, replyChannel, {version = UNS_VERSION, host = UNS_HOST_ID, modems = modems})
    elseif distance > 30 then  -- TODO: How do I and *should* I even ensure I don't recieve my own messages?
        log("Recieved broken request, d-" .. distance)
    end
end