#!/usr/bin/env python3

# Copyright 2018 Abdulkadir Furkan Şanlı

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


import sqlite3
import time


def connect_database(file):
    """
    Creates and returns Connection object.
    :param file: database file
    """
    conn = sqlite3.connect(file)
    return conn


def get_lower_weekday():
    """
    Returns current weekday's name as lowercase string.
    """
    day = time.strftime("%A")
    lower_day = day.lower()
    return lower_day


def check_id(conn, id):
    """
    Returns True if existing ID, False if not.
    :param conn: Connection object
    :param id: ID of student, int
    """
    cur = conn.cursor()
    cur.execute("SELECT id FROM students")
    ids = cur.fetchall()

    for x in ids:
        if id == x[0]:
            return True
    else:
        return False


def select_final_time(conn, day, id):
    """
    Returns ending time of final lesson student must attend, or None.
    :param conn: Connection object
    :param day: current weekday, lowercase str
    :param id: ID of student, int
    """
    cur = conn.cursor()
    cur.execute("""
        SELECT end_time
        FROM timetable
            INNER JOIN students ON g1 = lesson_id
                OR g2 = lesson_id
                OR g3 = lesson_id
                OR g4 = lesson_id
                OR g5 = lesson_id
                OR g6 = lesson_id
                OR lesson_id = 'gu'
                OR lesson_id = 'tok'
        WHERE id = ? AND day = ?
        ORDER BY end_time DESC
        LIMIT 1
        """, (id, day))
    finish = cur.fetchone()
    if str(type(finish)) == "<class 'tuple'>":
        return finish[0]
    else:
        return finish


def parse_time_string(timestring):
    """
    Parses given 24h time string of format "HH:MM" into time_struct.
    :param timestring: time string "HH:MM"
    """
    timestruct = time.strptime(timestring, "%H:%M")
    return timestruct


def main():
    print("ib-clearance")
    print("============")
    db = input(
        "Please enter name of database (in same folder as program): ")
    conn = connect_database(db)

    y = "y"
    while y == "y":
        id = int(input("Please input the student ID number: "))

        if check_id(conn, id):
            day = get_lower_weekday()
            raw_time = select_final_time(conn, day, id)
            # if raw_time is None, student has no lessons today
            if raw_time != None:
                final_time = parse_time_string(raw_time)
                current_time = parse_time_string(time.strftime("%H:%M"))
                if current_time > final_time:
                    print("Clear to leave.")
                else:
                    print("Student does not have clearance.")
            elif raw_time == None:
                print("Clear to leave.")
        else:
            print("Student does not exist in the database. Please try again.")

        y = input("Press y key followed by enter to run again.")


if __name__ == "__main__":
    main()