messagesnoop-main.py

### Category: Comms 
### Author: zakx <zakx@koeln.ccc.de>
### License: MIT
### Appname: Message Snoop
### Description: Have no friends? Receive other people's messages

import wifi
import mqtt
import ugfx
import pyb
import math
import time
import json

def callback(topic, msg):
    data = json.loads(msg)
    if data['type'] == 'message':
        printmsg(topic, data['sender'], data['payload'], data['ts'])

# taken from nexmo's messages app. cheers!
def zf(d):
    l=2
    if len(d) < l:
        return "0" + d
    else:
        return d

# taken from nexmo's messages app. cheers!
def timestring(tt):
    offset = 946681200
    t = tt-offset
    ts = time.localtime(t)
    timestamp = "{}:{}:{} {}/{}/{}".format(zf(str(ts[3])), zf(str(ts[4])), zf(str(ts[5])), str(ts[2]), str(ts[1]), str(ts[0]))
    return timestamp

# taken from nexmo's messages app. cheers!
def printmsg(topic, sender, text, ts):
    ugfx.clear(ugfx.WHITE)
    ugfx.set_default_font(ugfx.FONT_SMALL)
    ugfx.text(0, 0, "From: "+sender, ugfx.BLUE)
    ugfx.text(0, 15, "To: "+topic.decode("ascii"), ugfx.BLUE)
    timestamp = timestring(ts)
    ugfx.text(0, 30, "Sent at "+timestamp, ugfx.BLUE)
    linelen = 40
    lines = int(math.ceil(len(text)/linelen))
    for l in range(0, lines):
        pixels = l*25+50
        start = l*linelen
        end = l*linelen+linelen
        if end>len(text):
            end = len(text)
        linetext = text[start:end]
        ugfx.text(10,pixels,linetext,ugfx.BLACK)

def waiting_screen():
    ugfx.clear(ugfx.WHITE)
    ugfx.area(0,0,ugfx.width(),ugfx.height(),0xFFFF)
    ugfx.set_default_font(ugfx.FONT_MEDIUM_BOLD)    
    ugfx.text(0,10,"Waiting for messages.",ugfx.BLACK)
    ugfx.set_default_font(ugfx.FONT_SMALL)
    ugfx.text(0,225,"Press MENU to exit.",ugfx.BLACK)

ugfx.init()
c = None

def connect_mqtt():
    global c
    # if they don't like it, they may block our user agant
    c = mqtt.MQTTClient('snoop/2', 'badge.emf.camp')
    try:
        c.connect()
    except OSError:
        pyb.delay(200)
        connect_mqtt()
        return
    c.set_callback(callback)
    c.subscribe('/badge/#', qos=0)

def disconnect_mqtt():
    global c
    if c:
        try:
            c.disconnect()
        except:
            pass

def connect(reconnect=False):
    global c
    ugfx.clear(ugfx.RED)
    ugfx.set_default_font(ugfx.FONT_SMALL)
    ugfx.text(0, 10, "Connecting to Wifi...", ugfx.WHITE)

    if reconnect:
        disconnect_mqtt()
        wifi.nic().disconnect()

    while wifi.is_connected():
        try:
            wifi.connect(wait=True, timeout=15)
        except:
            pyb.delay(200)

    ugfx.text(0, 22, "Connecting to MQTT...", ugfx.WHITE)

    c = None
    connect_mqtt()

connect()
waiting_screen()

next_tick = 0

while True:
    if pyb.millis() > next_tick:
        if not wifi.is_connected():
            connect(reconnect=True)
        try:
            c.check_msg()
        except:
            pass
        try:
            c.sock.send(b"\xc0\0")  # ping
        except:
            connect(reconnect=True)
            waiting_screen()
        next_tick = pyb.millis() + 30000
    try:
        c.check_msg()
    except:
        pyb.delay(200)

ugfx.clear()