import requests


def reformat_cal(url):
    print(url)
    req = requests.get(url)
    if (req.status_code != 200):
            raise ValueError()

    if req.text == "" or req.text == None:
        raise ValueError()

    cal = req.text.split("\n")

    for counter, line in enumerate(cal):
        if "BEGIN:VEVENT" in line:
            summary = None
            desc = None

        if "SUMMARY" in line:
            summary = counter 
            continue

        if "DESCRIPTION" in line:
            desc = counter
            continue

        if "UID" in line:
            cal[counter] = ""

        if "END:VEVENT" in line:
            course_code = cal[desc].split("_")[0].split(":")[1]
            imsummary = cal[summary].split(',') 
            imsummary[0] = "SUMMARY:" + course_code
            cal[summary] = ','.join(imsummary)

    cal = "\n".join(cal)
    return cal