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

# 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"]

# Global flag for graceful exit
running = True

def signal_handler(sig, frame):
    global running
    print('You pressed Ctrl+C! Stopping GPS tracking...')
    running = False

signal.signal(signal.SIGINT, signal_handler)

def parse_gps_data(gps_string):
    parts = gps_string.split(',')
    if len(parts) < 4 or not parts[0] or not parts[2]:
        return None
    
    try:
        lat = float(parts[0][:2]) + float(parts[0][2:]) / 60
        if parts[1] == 'S':
            lat = -lat
        
        lon = float(parts[2][:3]) + float(parts[2][3:]) / 60
        if parts[3] == 'W':
            lon = -lon
        
        return f"{lat:.6f}", f"{lon:.6f}"
    except ValueError:
        return 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])

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 in rec_buff:
            gps_data = rec_buff.split('+CGPSINFO: ')[1].split('\r\n')[0]
            parsed_data = parse_gps_data(gps_data)
            if parsed_data:
                lat, lon = parsed_data
                print(f"GPS: Lat: {lat}, Lon: {lon}")
                write_to_csv(lat, lon)
                return 1
            else:
                print("Invalid GPS data received")
        else:
            print("Unexpected response from GPS module")
    else:
        print("No data received from GPS module")
    return 0

def get_gps_position():
    send_at('AT+CGPSINFO', '+CGPSINFO:', 1)

def initialize_gps():
    print('Starting GPS')
    send_at('AT+CGPS=1,1', 'OK', 1)
    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)

initialize_gps()
print("Starting continuous GPS tracking. Press Ctrl+C to stop.")

while running:
    get_gps_position()
    time.sleep(2)  # Wait for 10 seconds before the next reading

ser.close()
GPIO.cleanup()
print("GPS tracking stopped. Goodbye!")