#!/usr/bin/env python3

import argparse
import datetime
import json
import os
import sys

def load_log(file_path):
    if not os.path.exists(file_path):
        return []
    with open(file_path, 'r') as file:
        try:
            return json.load(file)
        except json.JSONDecodeError:
            print("\033[91mError: Invalid log file format.\033[0m")
            sys.exit(1)

def save_log(log, file_path):
    with open(file_path, 'w') as file:
        json.dump(log, file, indent=4)

def start_session(log, description):
    session = {
        'description': description,
        'start_time': datetime.datetime.now().isoformat()
    }
    log.append(session)
    save_log(log, 'chronokeep.log')
    print(f"\033[92mSession started: {description}\033[0m")

def stop_session(log):
    if not log:
        print("\033[91mError: No active session.\033[0m")
        return
    last_session = log[-1]
    if 'end_time' in last_session:
        print("\033[91mError: Session already stopped.\033[0m")
        return
    last_session['end_time'] = datetime.datetime.now().isoformat()
    save_log(log, 'chronokeep.log')
    print(f"\033[92mSession stopped: {last_session['description']}\033[0m")

def list_sessions(log):
    if not log:
        print("\033[91mNo sessions logged.\033[0m")
        return
    print("\033[94mSession Log:\033[0m")
    for i, session in enumerate(log):
        start_time = datetime.datetime.fromisoformat(session['start_time'])
        if 'end_time' in session:
            end_time = datetime.datetime.fromisoformat(session['end_time'])
            duration = end_time - start_time
            print(f"{i+1}. {session['description']} - {start_time.strftime('%Y-%m-%d %H:%M')} to {end_time.strftime('%Y-%m-%d %H:%M')} ({duration})")
        else:
            print(f"{i+1}. {session['description']} - {start_time.strftime('%Y-%m-%d %H:%M')} (active)")

def main():
    parser = argparse.ArgumentParser(description='Chronokeep - A terminal-based time tracking and logging tool')
    subparsers = parser.add_subparsers(dest='command')

    start_parser = subparsers.add_parser('start', help='Start a new session')
    start_parser.add_argument('description', help='Session description')

    stop_parser = subparsers.add_parser('stop', help='Stop the current session')

    list_parser = subparsers.add_parser('list', help='List all sessions')

    args = parser.parse_args()

    log = load_log('chronokeep.log')

    if args.command == 'start':
        start_session(log, args.description)
    elif args.command == 'stop':
        stop_session(log)
    elif args.command == 'list':
        list_sessions(log)
    else:
        parser.print_help()

if __name__ == '__main__':
    main()