local P = {}
local m, topic, cid, connected
local subscriptions = {}

local function mq_client_connected(con)
  info("mqtt: connected")
  connected = true
end

local function subscribed()
  info("mqtt: subscribed")
end

local function offline()
  info("mqtt: disconnected")
  connected = false
--  m:close()
--  m = nil
end

local function on_message(client, topic, message)
  -- p("mqtt: on_message: topic="..topic..", message="..message)

  local _, _, key = string.find(topic, '/property/([%a%d-]+)/name$')
  if key then
    local filename = 'property-'..key..'-name'
    local old = read_cfg(filename, false)
    if old ~= message then
      write_cfg(filename, message)
    end
    print("msg cmd=new-property-name key="..key..", name=\""..message.."\"")
  end

  local _, _, key = string.find(topic, '/property/([%a%d-]+)/description$')
  if key then
    local filename = 'property-'..key..'-description'
    local old = read_cfg(filename, false)
    if old ~= message then
      write_cfg(filename, message)
    end
    print("msg cmd=new-property-description key="..key..", description=\""..message.."\"")
  end
end

function mq_on_timer()
  -- This crashes the module:
  -- local status = wifi.sta.status()
  -- p("mqtt: checking status, status="..status)

  info("mqtt: connecting")

  -- client id, keepalive, username, password
  m = mqtt.Client(cid, 120)
  -- m:on("connect", mq_connected)
  m:on("offline", offline)
  m:on("message", on_message)

  -- host, port, secure, auto_reconnect, function(client), ssl=8883
  m:connect("trygvis.io", 1883, 0, 1, mq_client_connected)
end

function P.init(timer_id, device_id, client_id)
  cid = client_id

  topic = "/diller/"..device_id

  -- Wait a bit to get a connection first
  tmr.alarm(timer_id, 5 * 1000, 0, mq_on_timer)
end

function P.subscribe(path)
  local subscription = subscriptions[path]
  if subscription then
    info("mqtt: subscription on "..path.." already registered, state="..tostring(subscription.state))
    return
  end

  info("mqtt: Registering subscription on "..path)

  subscriptions[path] = true

  local qos = 0
  m:subscribe(topic.."/"..path, qos, subscribed)
end

function P.publish(path, payload)
  if not m then
    info("mqtt: Not connected, dropping message to "..path)
    return false, 'not connected'
  end

  path = topic.."/"..path
  -- info("mqtt: path="..path)
  m:publish(path, payload, 0, 0)

  return true, 'ok'
end

function P.status()
  if connected then
    return 'connected'
  else
    return 'disconnected'
  end
end

return P