#!/usr/bin/python3
# written by andrewt@unsw.edu.au as a COMP(2041|9044) lecture example

# Report cases where there are 5 or more people
# of the same first name enrolled in a course
# implemented using a dict of dicts

import re
import sys

REPORT_MORE_THAN_STUDENTS = 5
ENROLLMENTS_FILE = "enrollments.txt"

# enrollments.txt contains synthetic course enrollments
# with fields separated by | e.g.:
# COMP1911|5218563|Syed, Hugh Ali|3707/1|COMPAS|090.667|22T2|20010419|M

course_first_name_count = {}
with open(ENROLLMENTS_FILE, encoding="utf-8") as f:
    for line in f:
        course_code, _, full_name = line.split("|")[0:3]

        if m := re.match(r".*,\s+(\S+)", full_name):
            first_name = m.group(1)
        else:
            print("Warning could not parse line", line.strip(), file=sys.stderr)
            continue

        if course_code not in course_first_name_count:
            course_first_name_count[course_code] = {}

        if first_name not in course_first_name_count[course_code]:
            course_first_name_count[course_code][first_name] = 0

        course_first_name_count[course_code][first_name] += 1


for course in sorted(course_first_name_count.keys()):
    for (first_name, count) in course_first_name_count[course].items():
        if count >= REPORT_MORE_THAN_STUDENTS:
            print(course, "has", count, "students named", first_name)