args = { ... }

cache = {}


settings.define("lns_client.allow_dynamic_lns_hosts", {
    description = "Allow dynamic LNS hosts",
    type = "boolean",
    default = false
})

settings.define("lns_client.lns_server", {
    description = "LNS Server Rednet ID",
    type = "number",
    default = 8
})

allow_dynamic_lns_hosts = settings.get("lns_client.allow_dynamic_lns_hosts")
lns_server_id = settings.get("lns_client.lns_server")

function load_cache()
    if fs.exists("lns_cache.db") then
        db = fs.open("lns_cache.db", "r")
        db_contents = db.readAll()
        db.close()

        cache = textutils.unserialize(db_contents)
    end
end

function save_cache()
    db = fs.open("lns_cache.db", "w")
    db.write(textutils.serialize(cache))
    db.close()
end

function lns_lookup(remote_hostname)
    local data = {
        ["action"] = "lookup",
        ["hostname"] = remote_hostname
    }

    if allow_dynamic_lns_hosts then
        lns_server_id = rednet.lookup("lns", lns_server)
        if lns_server_id == nil then
            io.write("LNS Server not found!\n")
            return nil
        end
    end

    rednet.send(lns_server_id, data)

    while true do
        id, msg = rednet.receive()
        if id == lns_server_id then
            if msg == nil then
                return nil
            else
                return msg
            end
        end
    end
end



local action = args[1]
if action == nil then
    io.write("Usage: lns <action>\n")
    return
end

if action == "lookup" then
    load_cache()

    local hostname = args[2]
    if hostname == nil then
        io.write("Usage: lns lookup <hostname>\n")
        return
    end

    if cache[hostname] ~= nil then
        io.write(cache[hostname])
        return
    end

    local result = lns_lookup(hostname)
    if result ~= nil then
        io.write(result)
        cache[hostname] = result
        save_cache()
    end

elseif action == "clear" then
    cache = {}
    save_cache()
    print("Cleared cache!")
end