sos port main

-- Portable Computer: tracker.lua
-- By Gemini

-- CONFIGURATION --
-- Set the ID of the stationary computer you want to send coordinates to.
local serverId = 1 -- IMPORTANT: Change this to the ID of your stationary computer!

-- Set how often (in seconds) to send the coordinates.
local sendInterval = 5 -- 5 seconds

-- -- -- -- -- -- --

-- First, make sure the ender modem is open on the correct side.
-- Replace "top" with the side your ender modem is attached to.
rednet.open("back")

if not gps then
    error("GPS API not available. Is this an advanced portable computer?")
end

print("Tracker started. Sending coordinates to server ID: " .. serverId)
print("Press CTRL+T to terminate.")

while true do
    -- Get the GPS coordinates. This requires the computer to have a clear view of the sky.
    local x, y, z = gps.locate()

    if x then
        -- Package the coordinates into a Lua table.
        local coordinates = {x = x, y = y, z = z}

        -- Serialize the table into a string to send it over rednet.
        local message = textutils.serialize(coordinates)

        -- Send the message to the server.
        rednet.send(serverId, message, "gps_coords")
        print(string.format("Sent coordinates: %d, %d, %d", x, y, z))
    else
        print("Could not get a GPS lock. Make sure you are outdoors.")
    end

    -- Wait for the specified interval before looping again.
    os.sleep(sendInterval)
end