#!/usr/bin/python
# -*- coding:utf-8 -*-
import RPi.GPIO as GPIO
import serial
import time
import os
import csv
from datetime import datetime
import pynmea2

# GPIO configuration
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

ser = serial.Serial('/dev/ttyUSB3', 115200)
ser.flushInput()

myhost = os.uname()[1]

# CSV file settings
csv_filename = f"gps_data_{myhost}.csv"
csv_headers = ["Timestamp", "Latitude", "Longitude"]

def parse_gps_data(gps_string):
    try:
        msg = pynmea2.parse(gps_string)
        if isinstance(msg, pynmea2.GGA):
            if msg.latitude and msg.longitude:
                return f"{msg.latitude:.6f}", f"{msg.longitude:.6f}"
    except pynmea2.ParseError as e:
        print(f"Parse error: {e}")
    return None, None

def write_to_csv(lat, lon):
    timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
    with open(csv_filename, mode='a', newline='') as file:
        writer = csv.writer(file)
        writer.writerow([timestamp, lat, lon])
    time.sleep(12)

def send_at(command, back, timeout):
    ser.write((command + '\r\n').encode())
    time.sleep(timeout)
    if ser.inWaiting():
        time.sleep(0.01)
        rec_buff = ser.read(ser.inWaiting()).decode()
        if back not in rec_buff:
            print(command + ' ERROR')
            print(command + ' back:\t' + rec_buff)
            return 0
        else:
            print("Raw GPS data:", rec_buff)
            gps_sentences = rec_buff.split('\r\n')
            for sentence in gps_sentences:
                if sentence.startswith('$'):
                    lat, lon = parse_gps_data(sentence)
                    if lat and lon:
                        print(f"Parsed GPS data: {lat}, {lon}")
                        write_to_csv(lat, lon)
                        return 1
            print('No valid GPS data found')
            return 0
    else:
        print('GPS is not ready')
        return 0

def get_gps_position():
    print('Starting GPS')
    send_at('AT+CGPS=1,1', 'OK', 1)
    time.sleep(2)
    
    while True:
        answer = send_at('AT+CGPSINFO', '+CGPSINFO: ', 1)
        if answer == 1:
            break
        else:
            print('Waiting for GPS fix...')
        time.sleep(2)

# Create CSV file with headers if it doesn't exist
if not os.path.exists(csv_filename):
    with open(csv_filename, mode='w', newline='') as file:
        writer = csv.writer(file)
        writer.writerow(csv_headers)

try:
    get_gps_position()
except Exception as e:
    print(f"Error: {e}")
finally:
    if ser:
        ser.close()
    GPIO.cleanup()