#!/usr/bin/env python3

from datetime import date, datetime, timedelta
import argparse
import os

def get_current_date():
    return date.today().strftime("%Y-%m-%d")

def get_timefile_line(date, time, desc):
    return date + " " + time + " " + desc + "\n"

def get_total(filename):
    with open(filename, 'r') as time_file:
        total_time = timedelta()

        for line in time_file:
            date_time_description = line.split(" ", 2)
            
            hours, minutes = date_time_description[1].split(':', 1)
            
            # Parse the time to integers
            hours_int = int(hours)
            minutes_int = int(minutes)
            
            # Make sure that both the hours and the minutes are negative if there's a "-" before the time
            if hours_int < 0: minutes_int *= -1
            
            delta = timedelta(hours=hours_int, minutes=minutes_int)
            
            total_time += delta

        return total_time

# Parse command line arguments
parser = argparse.ArgumentParser(prog='time.txt', description="simple plain-text time tracking.")
subparsers = parser.add_subparsers(help='Commands', dest='mode')
 
parser.add_argument("-f", "--file", help="a file in the time.txt format. default: ./time.txt")

# create the parser for the "a" command
parser_total = subparsers.add_parser('total', help='print the total unbilled time. (default)')

# create the parser for the "b" command
parser_add = subparsers.add_parser('add', help='add a time entry.')
parser_add.add_argument("date", nargs='?', default=get_current_date(), help="date in the format 2020-12-30. defaults to the current date.")
parser_add.add_argument("time", help="time in the format 19:20.")
parser_add.add_argument("description", help="short description of how the time was spent.")

parser_bill = subparsers.add_parser('bill', help='add a bill entry (a negative time entry).')
parser_bill.add_argument("date", nargs='?', default=get_current_date(), help="date in the format 2020-12-30. defaults to the current date.")
parser_bill.add_argument("time", help="time in the format 19:20.")
parser_bill.add_argument("description", help="short description of how the time was spent.")

parser_create = subparsers.add_parser('create', help='create a new time.txt file.')

args = parser.parse_args()

filename = args.file if args.file else 'time.txt'

if not args.mode or args.mode == "total":
    print("Total time:", get_total(filename))

elif args.mode == "add":
    with open(filename, 'a') as time_file:
        # TODO: Validate date and time
        time_file.write(get_timefile_line(args.date, args.time, args.description))
        
    print("New total:", get_total(filename))

elif args.mode == "bill":
    with open(filename, 'a') as time_file:
        # TODO: Validate date and time
        time_file.write(get_timefile_line(args.date, "-" + args.time, args.description))
        
    print("New total:", get_total(filename))

elif args.mode == "create":
    if (os.path.exists(filename)):
        print("Error: File", filename, "already exists, can't create a new one!")
    else:
        with open(filename, 'w') as time_file:
            time_file.write(get_timefile_line(get_current_date(), "00:01", "Setup time.txt"))