server5.py

#Written By:
#Hayagreevan Sriran
#hs3387@columbia.edu
#Columbia University


from flask import Flask, request, Response
import threading
import paho.mqtt.client as mqtt
import json
import os
import time

app = Flask(__name__)

# File paths for storing data
http_output_file = "http_info.json"
mqtt_output_file = "mqtt_info.json"
map_output_file = "map_info.json"

# MQTT Broker details
MQTT_BROKER = "nam1.cloud.thethings.network"
MQTT_PORT = 1883
##MQTT_USERNAME = ##Removed for publication
##MQTT_PASSWORD = ##Removed for publication
MQTT_TOPIC = "#"

#buffer
latest_http = ""
latest_mqtt = ""
prev_http = ""
prev_mqtt = ""

# Function to read JSON data from a file
def read_json_file(file_path):
    if os.path.exists(file_path):
        with open(file_path, 'r') as file:
            try:
                return json.load(file)
            except json.JSONDecodeError:
                return []
    else:
        return []

# Function to write JSON data to a file
def write_json_file(file_path, data):
    with open(file_path, 'w') as file:
        json.dump(data, file, indent=4)

# Function to append new data to JSON file for HTTP stream
def append_to_json_file(file_path, new_data):
    data = read_json_file(file_path)
    data.append(new_data)
    write_json_file(file_path, data)

# Function to append new data to JSON file for MQTT stream, with duplicate check
def mqtt_append_with_check(file_path, new_data):
    data = read_json_file(file_path)
    if not data or data[-1] != new_data:
        data.append(new_data)
    write_json_file(file_path, data)

# MQTT Client Setup
def on_connect(client, userdata, flags, rc):
    print("MQTT Connected with result code " + str(rc))
    client.subscribe(MQTT_TOPIC)

def on_message(client, userdata, msg):
    global prev_mqtt, latest_mqtt
    
    message = msg.payload.decode()
    new_data = json.loads(message)
    
    prev_mqtt = latest_mqtt
    latest_mqtt = new_data
    
    mqtt_append_with_check(mqtt_output_file, new_data)
    print("New MQTT message")

mqtt_client = mqtt.Client()
mqtt_client.on_connect = on_connect
mqtt_client.on_message = on_message
mqtt_client.username_pw_set(MQTT_USERNAME, MQTT_PASSWORD)

# Function to start the MQTT client
def start_mqtt_client():
    mqtt_client.connect(MQTT_BROKER, MQTT_PORT, 60)
    mqtt_client.loop_forever()

# Start MQTT client in a separate thread
threading.Thread(target=start_mqtt_client, daemon=True).start()

# Flask route for handling HTTP POST requests
@app.route('/', methods=['POST'])
def handle_post_request():
    global prev_http, latest_http
    
    data = json.loads(request.data.decode('utf-8'))
    append_to_json_file(http_output_file, data)
    print("New HTTP message")
    
    prev_http = latest_http
    latest_http = data
    
    # Call Process mapping asynchronously so as to not block new streams
    threading.Thread(target=process_and_print_result, args=(data,)).start()
    
    return Response(status=200)

# Flask route for handling HTTP GET requests
@app.route('/', methods=['GET'])
def handle_get_request():
    try:
        with open(map_output_file, 'r') as file:
            content = file.read()
        return Response(content, status=200, content_type='application/json')
    except FileNotFoundError:
        return "File not found", 404

def process_and_print_result(data):

    print("Mapping Started")
    #sleep a few seconds to allow for lags in the mqtt processing
    time.sleep(3) 
    result = process_gateway_data()
    print(f"\n\nMapping Process Result: {result}\n\n")

def process_gateway_data():
    global prev_http, latest_mqtt

    # Check if previous HTTP data and latest MQTT data are available
    if not prev_http or not latest_mqtt:
        return "Data not available for mapping"

    # Initialize the result JSON object
    result = {}

    # Extract latitude, longitude, altitude, and time from the HTTP data
    result['latitude'] = prev_http.get('latitude')
    result['longitude'] = prev_http.get('longitude')
    result['altitude'] = prev_http.get('altitude')
    result['time'] = prev_http.get('time')

    # Extract uplink data from HTTP gateways
    uplink_data = []
    for gateway in prev_http.get('gateways', []):
        gtw_data = {
            'gtw_id': gateway.get('gtw_id'),
            'rssi': gateway.get('rssi'),
            'snr': gateway.get('snr')
        }
        uplink_data.append(gtw_data)
    result['uplink'] = uplink_data

    # Extract downlink data from the MQTT message
    mqtt_payload = latest_mqtt.get('uplink_message', {}).get('decoded_payload', {})
    downlink_data = {
        'flags': mqtt_payload.get('flags'),
        'rssi': mqtt_payload.get('rssi'),
        'snr': mqtt_payload.get('snr')
    }
    result['downlink'] = downlink_data

    # Return the mapped result
    #print(json.dumps(result, indent=4)) ##DEBUG
    
    append_to_json_file(map_output_file, result)
    
    return "mapped"


if __name__ == '__main__':
    #app.run(host='172.17.0.1', debug=True) ##DEBUG
    app.run(host='172.17.0.1')