--
-- LAB 05: Receiving Cloud-to-Device (C2D) Messages
--
-- This program receives commands from the cloud and executes them.
--

-- Configuration to connect to the MQTT broker.
DEVICE = "ThingLabs-esp8266"
IOTHUB = "ThingLabsIoTHub.azure-devices.net"  
IOTHUB_DEVICE_CONNECTION_KEY = "5AohmbYte0vuQtkpUCxTRjcnQOe5bmU2zaotv9hUS/k="

-- Standard variables for connecting via MQTT to IoTHUB Do Not Change
PORT   = 8883
USER   = IOTHUB.."/"..DEVICE

-- Pin Assignment Variables from the previous Labs
REDLED   = 1
GREENLED = 2
BLUELED  = 5
ADCPIN = 0
LEDPIN = 3
DHTPIN = 6
MAXLIGHT = 1024

-- Generate a SAS Token for Azure IoTHub
PASSWD = generateSasToken(IOTHUB..'/devices/'..DEVICE, IOTHUB_DEVICE_CONNECTION_KEY, 'device', 7 * 24 * 60)

-- MQTT topics to subscribe
telemetry_topic="devices/"..DEVICE.."/messages/events/"
command_topic="devices/"..DEVICE.."/messages/devicebound/#"
connected = false

-- Create an MQTT Client
esp8266 = mqtt.Client(DEVICE, 240, USER, PASSWD)

-- Connect to IoTHub via MQTT
print "Connecting to MQTT broker. Please wait..."
esp8266:connect(IOTHUB, PORT, 1, 0, 
    -- Callback for a successful connection
    function(client)
        print("Connected to MQTT: "..IOTHUB..":"..PORT.." as "..DEVICE)
        connected = true
        setup()        
    end,
    -- Error callback, if connection fails
    function(client, reason)
        print("Error Connecting: "..reason)
    end
)

function led(r, g, b)
    pwm.setduty(REDLED, r)
    pwm.setduty(GREENLED, g)
    pwm.setduty(BLUELED, b)
end

function setup()    
    esp8266:subscribe(command_topic, 0, function(client)
        connected = true
        print("Subscribed to command and control topic.")
    end)

    tmr.alarm(2, 1000, tmr.ALARM_AUTO, publish_data)

    -- If we get disconnected a callback informs us
    esp8266:on("offline", function(client)
        print("MQTT Disconnected.")
        connected = false
    end)
end

-- Sample publish functions:
function publish_data()
    if connected == true then
        -- Turn the LED on
        gpio.write(LEDPIN, gpio.LOW)
        light = MAXLIGHT - adc.read(ADCPIN)
        
        status, temperature, humidity, temperature_dec, humidity_dec = dht.read(DHTPIN)
        if status == dht.OK then
            -- Integer firmware using this example
            -- print(string.format("DHT Temperature:%d.%03d;Humidity:%d.%03d\r\n",
            --       math.floor(temperature),
            --       temperature_dec,
            --       math.floor(humidity),
            --       humidity_dec
            -- ))
            
            -- Float firmware using this example
            -- print("DHT Temperature: "..temperature.."; ".."Humidity: "..humidity)
            print("Light: "..light.." Temperature: "..temperature.." ".."Humidity: "..humidity)
        elseif status == dht.ERROR_CHECKSUM then
            print( "DHT Checksum error." )
        elseif status == dht.ERROR_TIMEOUT then
            print( "DHT timed out." )
        end
        
        -- Construct the payload of data
        payload =  
            "{ \"deviceId\" : \""..DEVICE.."\","..
            "\"location\" : \"Instructor ESP8266 Virtual Weather Station\""..","..
            "\"celsius\" :"..temperature..","..
            "\"relativeHumidity\" :"..humidity..","..
            "\"lightLevel\" :"..light.."}"
    
        -- Send it to the cloud via mqtt
        esp8266:publish(telemetry_topic, payload, 1, 0, function(client)
            print("Data published successfully.")
        end)

        -- Set the LED Brightness
        led(light, light, light)
    
        -- Turn the LED off
        gpio.write(LEDPIN, gpio.HIGH)
    end
end