"""
Program that grabs the specific lecture URLs from
the CS51A course home page
"""

from urllib.request import urlopen

COURSE_PAGE = "http://cs.pomona.edu/classes/cs51a/"


def get_lectures_urls(page):
    """
    Get the lecture URLs available from the course web page and
    return them in a list
    :param page: (str) the URL to read
    :return: (list)
    """
    web_page = urlopen(page)

    urls = []

    # all of the urls for lectures, start with "lectures/"
    search_line = "lectures/"

    for line in web_page:
        line = line.decode('ISO-8859-1').strip()
        if search_line in line:
            begin_index = line.find(search_line)
            end_index = line.find('"', begin_index)
            urls.append(page + line[begin_index:end_index])

    return urls


def write_list_to_file(some_list, output_file):
    """
    Writes out all of the contents of some_list to the output_file
    :param some_list: (list) list with data to be written to output_file
    :param output_file: (str) name of file to write some_list data to
    :return:
    """
    out = open(output_file, "w")
    out.write("Lecture notes for CS51A\n\n")

    for item in some_list:
        out.write(item + "\n")

    out.close()


def write_lectures(outfile):
    """
    Gets the lecture links from the COURSE_PAGE and writes
    :param outfile: (str) the output file to write the lecture links to
    :return: (None)
    """
    # get the lecture urls
    lecture_urls = get_lectures_urls(COURSE_PAGE)
    # print them out to the file
    write_list_to_file(lecture_urls, outfile)