-- John Longworth   December 2017
-- This program displays the time from a SNTP Server on a 128x 64 LCD OLED
-- Uses i2c, rtctime, sntptime, u8g & u8g.font_6x10 modules

days = {"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"}
months = {"January","February","March","April","May","June","July",
        "August","September","October","November","December"}

function init_i2c_display()
  id, sda, scl, device = 0, 3, 4, 0x3C
  i2c.setup(id, sda, scl, i2c.SLOW)
  disp = u8g.ssd1306_128x64_i2c(device)
  disp:setFont(u8g.font_6x10) 
end

function getTime()
sntp.sync("uk.pool.ntp.org", function(sec, usec, server, info)
  --print('Time Received ', sec, usec, server)
  tm = rtctime.epoch2cal(rtctime.get())
  tf = (string.format("%02d:%02d:%02d",tm["hour"], tm["min"], tm["sec"]))
  print("\n The time is ",tf)
  print("  The day is ", days[tm["wday"]])
  print(" The date is ", tm["day"].." ".. months[tm["mon"]].." ".. tm["year"])
  disp:firstPage()  -- Write to OLED display
  repeat
    updateOLED()
  until disp:nextPage() == false
end, function()
  print("Failed to Update!")
end)
end

function updateOLED()
  line1 = "Today is "..days[tm["wday"]] 
  line2 = tm["day"].." ".. months[tm["mon"]].." ".. tm["year"]
  line3 = "Time is "..tf
  disp:drawFrame(0,0,128,64) 
  --Centre text on the display
  disp:drawStr((128 - #line1 * 6) / 2, 16, line1)
  disp:drawStr((128 - #line2 * 6) / 2, 36, line2)   
  disp:drawStr((128 - #line3 * 6) / 2, 56, line3)   
end    

init_i2c_display() 
-- NOTE: The program needs the time delay to allow it to 
-- connect and get the information fron the SNTP server
tmr.alarm(1,10000,1,function()
  getTime()  -- Update display every 10 seconds
end)