#!/usr/bin/env python3

import subprocess
import sys
import os
import requests

s = requests.Session()
# auth should be in a file called '.canvas_auth' in the same dir
# should be of the form 'Bearer <auth code>'
with open(os.path.dirname(os.path.realpath(__file__)) + '/.canvas_auth') as f:
    s.headers.update({"Authorization": f.read().strip()})

def do_update():
    courses = s.get("https://canvas.wpi.edu/api/v1/courses",
                    params={'enrollment_state': 'active'}).json()

    did_change = False
    for course in courses:
        assignments = s.get(
            f"https://canvas.wpi.edu/api/v1/courses/{course['id']}/assignments",
            params={'bucket': 'future'}).json()
        for assignment in assignments:
            if assignment['due_at'] is not None:
                course_code = course['course_code'].split('-')[0]
                date_str = assignment['due_at'][:10] # just take %Y-%m-%d
                todo_string = f"(B) +hw class:{course_code} {assignment['name']} due:{date_str}"

                command = ["todo.sh", "listall", todo_string]
                lines = subprocess.check_output(command).decode(encoding='UTF-8').split('\n')[:-5]
                if len(lines) < 1: # doesn't exist in todo.txt yet
                    subprocess.call(["todo.sh", "add", todo_string])
                    did_change = True

    if not did_change:
        print("No changes to make")

if __name__ == '__main__':
    if len(sys.argv) == 2 and sys.argv[1] == "usage":
        print("    canvasUpdate\n"
              "      Adds all assignments from canvas that do not already exist")
        exit(0)

    if len(sys.argv) >= 3:
        print("Too many arguments!")
        exit(-1)
    else:
        do_update()