-- LUA from https://nodemcu-build.com/  (SSL True, module crypto, file,gpio, 
-- http, net, node, tmr, uart, websocket, wifi, tls)

-- for access to local wifi:
local SSID = "xxxx"
local SSID_PASSWORD = "xxxxxxxxxxxxxxxxxx"

-- email provider data:
local email_subject = ""
local email_body = ""
local count = 0
local MY_EMAIL = "mail@xxxx.de"
local EMAIL_PASSWORD = "xxxxxxxxx"
local mail_to = "mail@xxxx.de"

-- The SMTP server and port of the email provider:
local SMTP_SERVER = "smtp.xxx.com"
local SMTP_PORT = "465"
local smtp_socket = nil -- will be used as socket to email server

-- Connect to local wifi:
wifi.setmode(wifi.STATION)
wifi.sta.config(SSID,SSID_PASSWORD)
wifi.sta.connect()
-- wait with 1second timer until connection is ready:
tmr.alarm(1, 1000, tmr.ALARM_AUTO, function()
 	 if wifi.sta.getip() == nil then
     		print("Wifi not jet ready...")
 	 else
     		tmr.stop(1)
    	 	print("Wifi ready, IP is "..wifi.sta.getip())
   		 -- Send the email
     		send_email( "ESP8266",
                  		 "ESP8266: " .. tmr.time()/60 .."min  Uptime")
                -- never reached, deepsleep at the end of do_next()
  	end
end)


-- The do_next() function is used to send the SMTP commands to the SMTP server 
-- in the required sequence after connection to the smtp server
function do_next()
            if(count == 0)then
	                count = count+1
	                local IP_ADDRESS = wifi.sta.getip()
	                smtp_socket:send("HELO "..IP_ADDRESS.."\r\n")
            elseif(count == 1) then
	                count = count+1
	                smtp_socket:send("AUTH LOGIN\r\n")
            elseif(count == 2) then
	                count = count + 1
	                smtp_socket:send(crypto.toBase64(MY_EMAIL).."\r\n")
            elseif(count == 3) then
	                count = count + 1
	                smtp_socket:send(crypto.toBase64(EMAIL_PASSWORD).."\r\n")
            elseif(count == 4) then
	                count = count+1
	                smtp_socket:send("MAIL FROM:<" .. MY_EMAIL .. ">\r\n")
            elseif(count == 5) then
	                count = count+1
	                smtp_socket:send("RCPT TO:<" .. mail_to ..">\r\n")
            elseif(count == 6) then
	                count = count+1
	                smtp_socket:send("DATA\r\n")
            elseif(count == 7) then
	                count = count+1
                        -- no single . line in message allowed, so string.gsub( ) deletes such lines
	                local message = string.gsub( 
	               		 "From: \"".. MY_EMAIL .."\"<"..MY_EMAIL..">\r\n" ..
	               		 "To: \"".. mail_to .. "\"<".. mail_to..">\r\n"..
	               		 "Subject: ".. email_subject .. "\r\n\r\n"  ..  email_body,
    				 "\r\n.\r\n" , "")	                                
	                smtp_socket:send(message.."\r\n.\r\n")
            elseif(count == 8) then
	                count = count+1
	                smtp_socket:send("QUIT\r\n")
            elseif(count == 9) then
	                smtp_socket:close()
	                print("email send..")  
	                print("Socket Closed, goto sleep")

	                tmr.stop(0)       
	                node.dsleep(0)  --deepsleep bis Reset or CH_PD Button pressed           
	                return
            else
            end
end

-- callback functions for socket events "connection" und "receive"
-- do_next function wird alle 0.5s aufgerufen um nŠchstes smtp kommando zu senden
function connected(sck) 
	     tmr.alarm(0,500,tmr.ALARM_AUTO,do_next) 
	     print("3") 
end

-- display_received function prints die vom smtp server empfangenen Antworten
function display_received(sck,response) 
	     print(response) 
	     if(string.match(response,"%d+") == 221) then
		         gpio.mode(4, gpio.OUTPUT)
		         gpio.write(4,gpio.LOW)
	     else
		         gpio.write(4,gpio.HIGH)
	     end
end

function send_email(subject,body)
	     count = 0
	     email_subject = subject
	     email_body = body
	     --smtp_socket = tls.createConnection()
	     smtp_socket = net.createConnection(net.TCP,1)  -- creates a TCP Client for secure connection
	     print("1")
	     smtp_socket:on("connection",connected)         -- callbach function for "connection" event
	     smtp_socket:on("receive",display_received)     -- callback function for "receive"  event
	     smtp_socket:dns(SMTP_SERVER,function(conn,ip) print("dns  ".. ip) end)
	     smtp_socket:connect(SMTP_PORT,SMTP_SERVER)     -- Verbindung zum smtp server aufbauen
	     print("2")
end