import csv
import re
import sys


def write_to_csv(output_file, warning_messages):
    with open(output_file, 'a') as csvfile:
        writer = csv.writer(csvfile, delimiter=',',
                                quotechar='"', quoting=csv.QUOTE_MINIMAL)
        writer.writerows(warning_messages)


def get_warnings(filename):
    upc = filename.split('_')[0]
    with open(filename, 'r') as log_file:
        pattern = re.compile(r'<main>\s+WARN:\s*WARNING\s*(.*$)')
        warnings = []
        for line in log_file:
            warning_messages = pattern.search(line)
            if warning_messages != None:
                warnings.append([upc, warning_messages.group(1)])
        write_to_csv('output.csv', warnings)


# run the program
if __name__ == "__main__":
    for file in sys.argv[1:]:
        get_warnings(file)