#!/usr/bin/env python3
#
# playready_experiment.py - Example of SmoothStreaming PlayReady authentication
#
# Copyright (C) 2016  Antonio Ospite <ao2@ao2.it>
#
# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation, either version 3 of the License, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program.  If not, see <http://www.gnu.org/licenses/>.
#
#
# Experiment on how to use the ProtectionHeader element in SmoothSTreaming
# manifest files.
#
# The code is just a demonstration of how to decode the ProtectionHeader element
# content, it is not supposed to do nothing actually useful.
#
# Based on the PlayReady Header Object specification:
# http://download.microsoft.com/download/1/4/7/1475C862-6B67-44B2-AF31-ABC83EA68292/PlayReady%20Header%20Object%20(7-2-2012).docx

import base64
import struct
import sys
import xml.etree.ElementTree as etree

from pysimplesoap.client import SoapClient
from pysimplesoap.simplexml import SimpleXMLElement


def get_right_management_header(protection_header_text):
    play_ready_header_objects = base64.b64decode(protection_header_text)

    offset = 0

    field_size = 4
    total_size = struct.unpack("<L", play_ready_header_objects[offset:offset + field_size])[0]
    offset += field_size

    if total_size != len(play_ready_header_objects):
        sys.stderr.write("Error, unexpected size.\n")
        sys.exit(1)

    field_size = 2
    count = struct.unpack("<H", play_ready_header_objects[offset:offset + field_size])[0]
    offset += field_size

    for i in range(count):
        field_size = 2
        record_type = struct.unpack("<H", play_ready_header_objects[offset:offset + field_size])[0]
        offset += field_size

        field_size = 2
        record_length = struct.unpack("<H", play_ready_header_objects[offset:offset + field_size])[0]
        offset += field_size

        if record_type == 1:
            right_management_header = play_ready_header_objects[offset:offset + record_length].decode("UTF-16")
            return right_management_header
        else:
            sys.stderr.write("Error, unsupported record type. Skipping.\n")
            offset += record_length


def main():
    if len(sys.argv) != 2:
        sys.stderr.write("usage: %s <manifest>\n" % sys.argv[0])
        sys.exit(1)

    manifest_filename = sys.argv[1]

    manifest = etree.parse(manifest_filename)
    protection_header = manifest.find(".//Protection/ProtectionHeader")

    challenge = get_right_management_header(protection_header.text)

    challenge_xml = etree.fromstring(challenge)
    la_url = challenge_xml.find(".//{http://schemas.microsoft.com/DRM/2007/03/PlayReadyHeader}LA_URL").text

    client = SoapClient(
        location=la_url,
        action='http://schemas.microsoft.com/DRM/2007/03/protocols/',
        soap_ns='soap', trace=True, ns=False)

    params = SimpleXMLElement("""<AcquireLicense xmlns="http://schemas.microsoft.com/DRM/2007/03/protocols"><challenge>""" +
                              challenge + 
                              """</challenge></AcquireLicense>""")

    response = client.call('AcquireLicense', params)
    print(response)

if __name__ == "__main__":
    main()