RPiLCD_Web_Service.py

#
# RPiLCD Web Service
#  Brent Petit - 2015
#
# take in messages via a Web Service and update the 
# Raspberry Pi LCD screen.
#
from flask import Flask, jsonify, abort, request, Response
from functools import wraps
import json
import threading
import RPiLCD_Driver

# Use flask for Web Services
app = Flask(__name__)

def check_auth(username, password):
    global auth_info
    # Check that user and password are expected
    return username == auth_info['username'] and password == auth_info['password']

def authenticate():
    # Sen 401 error to trigger authentication
    return Response('Authentication Required', 401,
    {'WWW-Authenticate': 'Basic realm="Login Required"'})

def requires_auth(f):
    @wraps(f)
    def decorated(*args, **kwargs):
        auth = request.authorization
        if not auth or not check_auth(auth.username, auth.password):
            return authenticate()
        return f(*args, **kwargs)
    return decorated 

#
# initAuth
#  read up password file
#
def initAuth():
   global auth_info
   with open('.passwd.json') as auth_file:    
      auth_info = json.load(auth_file)

#
# sendEntry handler
#  This is THE web service call for updating the LCD screen
#   The arguments for this web service are
#   type = what type of messsage? (receive, transmit, digi, gate)
#   call = what was the call sign of the station?
#   path = what AX.25 path did the packet take?
#   description = what additional info was in the packet?
#  TODO: Add authentication
@app.route('/RPiLCD_Web_Service/api/v1.0/sendEntry', methods=['POST'])
@requires_auth
def _sendEntry():
   # Do simple validation
   if not request.json or not 'call' in request.json:
      abort(400)

   type = request.json['type'] 
   call = request.json['call']
   path = request.json.get('path', "")
   description = request.json.get('description', "") 

   # Insert the data into the PiLDC_Driver message queue
   RPiLCD_Driver.lcdMessageInsert(type, call, path, description)

   return jsonify({'Message': 'Added Entry'}), 201

#
# getStatus handler
#  Return basic stats on the service
#
@app.route('/RPiLCD_Web_Service/api/v1.0/getStatus', methods=['GET'])
@requires_auth
def _getStatus():

   resp = jsonify(RPiLCD_Driver.lcdGetStats())
   resp.status_code = 200
   
   return resp

#
# 404 Handler
#
@app.errorhandler(404)
def _not_found(error):
    return make_response(jsonify({'error': 'Not found'}), 404)

#
# Web service helpers
#

#
# Threads
#
def start_LCD_thread():
   RPiLCD_Driver.lcdMessageLoop()

def start_button_thread():
   RPiLCD_Driver.lcdButtonLoop()

#
# Main Task: Fire up threads and start Flask service
#
if __name__ == '__main__':
   print "Starting LCD Update Thread..."
   lcd = threading.Thread(target=start_LCD_thread)
   lcd.setDaemon(True)
   lcd.start()
   print "LCD Update Thread Started"

   print "Starting Button Handler Thread..."
   buttons = threading.Thread(target=start_button_thread)
   buttons.setDaemon(True)
   buttons.start()
   print "Button Handler Thread Started"

   initAuth()

   print "Entering Web Service Loop"
   app.run(host='0.0.0.0')
   print "Exiting..."