#!/usr/bin/env python
from datetime import datetime
import os
import random
import re
import sys

try:
    from humanize import naturalday
except ImportError as e:
    naturalday = lambda x: x.strftime('%Y-%m-%d')

if sys.argv[1] == 'usage':
    print('  random')
    print('    Print a random task from your list')
    print('  random due')
    print('    Print a random task due on the first due date in your list')
    print('  random due [offset]')
    print('    Print a random task due on the [offset] due date in your list')
    print('')
    exit()

with open(os.environ['TODO_FILE'], 'r') as f:
    tasks = f.readlines()

# Add index number to each task
tasks = ['%02d %s' % task for task in enumerate(tasks, start=1)]

# When the option "due" is specified
if len(sys.argv) > 2 and sys.argv[2] == 'due':
    # Stores tuples of (str, datetime)
    taskDueDates = []
    for task in tasks:
        # match due date, e.g. due:2000-12-31
        match = re.search(r'\bdue:(\d{4}-\d{2}-\d{2})', task)
        # skip tasks with no due date
        if match is None: continue
        dueDate = datetime.strptime(match.group(1), '%Y-%m-%d')
        taskDueDates.append((task, dueDate))
    # Sort by due date ascending
    taskDueDates.sort(key=lambda x: x[1])

    # Find soonest due date
    date = taskDueDates[0][1]

    if len(sys.argv) > 3:
        # Find offset due date
        for i in range(int(sys.argv[3])):
            for task in taskDueDates:
                if task[1] > date:
                    date = task[1]
                    break

    # Filter list to only contain the right due date
    taskDueDates = [task for task in taskDueDates if task[1] == date]
    # Overwrite tasks list
    tasks = [task[0] for task in taskDueDates]
    
    if len(tasks) == 1:
        print('You have only one task due %s:' % naturalday(date))
    else:
        print('Random task due %s:' % naturalday(date))
else:
    print('Random task:')

print('  ' + random.choice(tasks), end='')