import sys
import re

def extract(source_file, destination_file, encoding="utf-8"):
    source = open(source_file, mode='r', encoding=encoding)
    with open(destination_file, mode='w') as destination:
        while True:
            line = source.readline()
            if line == "":
                break
            if str.startswith(line, "Dialogue: "):
                destination.write(re.sub("{.*}", "", line.split(",")[9]))

def main():
    if(str.endswith(sys.argv[0], "extractor.py")):
        sys.argv.remove(sys.argv[0])

    arglen = len(sys.argv)
    if arglen == 2:
        extract(sys.argv[0], sys.argv[1])
    elif arglen == 3:
        extract(sys.argv[0], sys.argv[1], sys.argv[2])
    elif arglen == 1 and (sys.argv[0] == "-h" or sys.argv[0] == "--help"):
        print("Usage: extractor <source file> <output file> [encoding]")
    else:
        print("Malformed input. Type 'extractor -h' for the expected form of input.")

main()