function char_to_pchar(c)
    return string.format("%%%02X", c:byte(1,1))
end
function encodeURI(str)
    return (str:gsub("[^%;%,%/%?%:%@%&%=%+%$%w%-%_%.%!%~%*%'%(%)%#]", char_to_pchar))
end
function encodeURIComponent(str)
    return (str:gsub("[^%w%-_%.%!%~%*%'%(%)]", char_to_pchar))
end

function _(hex) return string.char(tonumber(hex, 16)) end

function decodeURI(str)
    str = string.gsub(str, '%%(%x%x)', _)
    return str
end

function generateSasToken(resourceUri, signingKey, expiresInMinutes)
    resourceUri = string.lower(encodeURIComponent(string.lower(resourceUri)));
    -- Set expiration
    sec, usec = rtctime.get()
    expires = math.ceil(sec + expiresInMinutes * 60)
    toSign = resourceUri.."\n"..expires
    -- add the password
    decodedPassword = encoder.fromBase64(signingKey)
    base64signature = crypto.toBase64(crypto.hmac("SHA256", toSign, decodedPassword))
    base64UriEncoded = encodeURIComponent(base64signature)
    -- construct the authorization string
    token = "SharedAccessSignature sr="..resourceUri.."&sig="..base64UriEncoded.."&se="..expires;
    token = token.."&skn="
    return token    
end

sntp_connect_status_codes = {
    [1] = "DNS lookup failed",
    [2] = "Memory allocation failure",
    [3] = "UDP send failed",
    [4] = "Timeout, no NTP response received"
}

-- sync the clock via NTP
sntp.sync('pool.ntp.org',
  function(sec, usec, server)
    print("Clock Synced: "..sec..", "..usec..", "..server)
    end,
  function(error_code)
    print("Clock Sync Failed: "..sntp_connect_status_codes[error_code])
  end
)

-- Diagnostic Information
print('init.lua ver 1.2') 
wifi.setmode(wifi.STATION)
print('set mode=STATION (mode='..wifi.getmode()..')')
print('MAC: '..wifi.sta.getmac())
print('chip: '..node.chipid())
print('heap: '..node.heap())

-- Connect to Wifi
wifi.sta.config("SSID", "PASSWORD")

wifi_status_codes = {
    [0] = "Idle",
    [1] = "Connecting",
    [2] = "Wrong Password",
    [3] = "No AP Found",
    [4] = "Connection Failed",
    [5] = "Got IP"
}

-- Wait for wifi to get connected, fail if it doesn't
tmr.alarm(1,1000, 1, function() 
    if wifi.sta.getip()==nil then 
        print("Waiting for IP address! (Status: "..wifi_status_codes[wifi.sta.status()]..")") 
    else 
        print("New IP address is "..wifi.sta.getip()) 
        tmr.stop(1) 
    end 
  end
)

-- Launch Next Startup File
tmr.alarm(0, 5000, 0, function() -- Zero as third parameter. Call once the file.
   dofile('startup.lua')
end)

--
-- LAB 04: Sending Device-to-Cloud (D2C) Messages
--
-- This program sends the telemetry (light, temperature and humidity) and sends it to the cloud.
--

-- Configuration to connect to the MQTT broker.
DEVICE = "DEVICE ID" 
IOTHUB = "IOTHUB DNS NAME"   
IOTHUB_DEVICE_CONNECTION_KEY = "DEVICE CONNECTION KEY"

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

-- Pin Assignment Variables from the previous Labs
ADCPIN = 0
LEDPIN = 3
DHTPIN = 6
MAXLIGHT = 1024

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

-- MQTT topics to subscribe
telemetry_topic="devices/"..DEVICE.."/messages/events/"
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 setup()    
    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)
    
        -- Turn the LED off
        gpio.write(LEDPIN, gpio.HIGH)
    end
end