import os
import schedule
import shutil
import subprocess
import time

from datetime import datetime, timedelta
from dotenv import load_dotenv
from pathlib import Path

# Example .env file:
# SOURCE_DIRECTORIES=DATA-DRIVE:\A;DDATA-DRIVE:\B;DATA-DRIVE:\C
# DESTINATION_PATHS=\\NETWORK-SHARE\A;\\NETWORK-SHARE\B;\\NETWORK-SHARE\C
# USERNAME=CHANGE-ME
# PASSWORD=CHANGE-ME
load_dotenv()

def connect_to_network_drive(network_path, username, password):
    # Only one connection can be made to a network drive at a time, so attempt a disconnect first.
    # Use only the network drive name in the disconnect command, or else it won't work.
    network_drive = network_path.split('\\')[1]
    disconnect_cmd = f'net use \\\\{network_drive} /delete'
    subprocess.run(disconnect_cmd, shell=True)

    connect_cmd = f'net use {network_path} /user:{username} {password}'
    result = subprocess.run(connect_cmd, shell=True, capture_output=True)
    if result.returncode != 0:
        raise ConnectionError(f'Failed to connect to network drive: {result.stderr.decode()}')

def file_has_changed(source_file, destination_file):
    if not os.path.exists(destination_file):
        return True
    return os.path.getmtime(source_file) != os.path.getmtime(destination_file)

def copy_files(source_directory, destination_directory):
    for root, directories, files in os.walk(source_directory, followlinks=True):
        for file in files:
            source_file = Path(root) / file
            destination_file = Path(destination_directory) / Path(root).relative_to(source_directory) / file
            print(f'Checking: {source_file}')

            if file_has_changed(source_file, destination_file):
                destination_file.parent.mkdir(parents=True, exist_ok=True)
                shutil.copy2(source_file, destination_file)
                print(f'Copied: {source_file} to {destination_file}')

def sync_directories(source_directory, destination_path):
    username = os.getenv('USERNAME')
    password = os.getenv('PASSWORD')

    connect_to_network_drive(destination_path, username, password)
    copy_files(source_directory, destination_path)

def schedule_syncs(start_hour, start_minute, interval_minutes):
    source_directories = os.getenv('SOURCE_DIRECTORIES').split(';')
    destination_paths = os.getenv('DESTINATION_PATHS').split(';')

    start_time = datetime.now().replace(hour=start_hour, minute=start_minute, second=0, microsecond=0)
    
    for i, (source_directory, destination_path) in enumerate(zip(source_directories, destination_paths)):
        schedule_time = start_time + timedelta(minutes=i * interval_minutes)
        schedule_time_string = schedule_time.strftime('%H:%M')
        schedule.every().day.at(schedule_time_string, 'America/Los_Angeles').do(sync_directories, source_directory, destination_path)
        print(f'Scheduled sync for {source_directory} to {destination_path} at {schedule_time_string}.')

if __name__ == '__main__':
    # Schedules sync jobs starting at 3:00 AM PT, 30 minutes apart from one another.
    schedule_syncs(3, 0, 30)
    while True:
        schedule.run_pending()
        time.sleep(60) # Seconds.