#!/usr/bin/env python3

import base64
import json
import logging
from random import randint
import socket

from board_config import LoraBoardDraguino
import RPi.GPIO as GPIO


logging.basicConfig(level=logging.DEBUG)

# TODO: Move these to a settings file
GATEWAY_SEND_ENABLED = False
GATEWAY_HOST = "router.eu.thethings.network"
GATEWAY_PORT = 1700


def log_packet(self, board, packet):
    print("[{}] [receive] freq: {}, crc: {}, signal-noise-ratio: {}, signal strength: {} (packet: {}), {}".format(
        payload['datetime'].isoformat(),
        board.frequency,
        payload.get('crc'),
        payload.get('pkt_snr'),
        payload.get('rssi'),
        payload.get('pkt_rssi'),
        payload['payload'].hex()
    ))


def construct_semtec_udp(board, payload):
    # https://github.com/Lora-net/packet_forwarder/blob/d0226eae6e7b6bbaec6117d0d2372bf17819c438/PROTOCOL.TXT#L99
    frame = bytearray()
    frame.append(2)  # Protocol version = 2
    frame.extend([randint(0, 255), randint(0, 255)])  # Random numbers
    frame.extend([
        0x80, 0xFA, 0x5C, 0xFF,
        0xFF, 0x69, 0x33, 0xBB
    ])  # TODO: construct from hardware

    data = {
        "rxpk":
            {
                "time": payload['datetime'].isoformat(),
                "freq": board.frequency / 1000 / 1000,
                "stat": 1 if payload['crc'] is True else -1,
                "modu": "LORA",
                "datr": "SF7BW125",  # TODO: configurable
                "codr": "4/5",
                "rssi": payload['pkt_rssi'],
                "lsnr": payload['pkt_snr'],
                "size": len(payload['payload']),
                "data": base64.standard_b64encode(payload['payload'])
                        .decode("utf-8")
            }
    }

    frame.extend(map(ord, json.dumps(data)))

    return bytes(frame)


if __name__ == "__main__":
    sock = None
    if GATEWAY_SEND_ENABLED:
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # UDP
    
    with LoraBoardDraguino(433300000, 7) as board:
        board.set_mode_rx()
        print("Listening at SF{} on {} MHz".format(
            board.sf,
            board.frequency / 1000000
        ))
        
        while True:
            if GPIO.input(board._pin_dio0) != 1:
                continue
            
            payload = board.receive_package()
            
            if GATEWAY_SEND_ENABLED:
                semtec_udp = construct_semtec_udp(board, payload)
                sock.sendto(semtec_udp, (GATEWAY_HOST, GATEWAY_PORT))
                logging.info(semtec_udp)
            
            
            log_packet(board, payload)