#!/usr/bin/python
# Copyright (c) 2016 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
# TODO(svaldez): Deduplicate various annotate_test_data.

"""This script is called without any arguments to re-format all of the *.pem
files in the script's parent directory.

The main formatting change is to run "openssl asn1parse" for each of the PEM
block sections, and add that output to the comment. It also runs the command
on the OCTET STRING representing BasicOCSPResponse.

"""

import glob
import os
import re
import base64
import subprocess


def Transform(file_data):
  """Returns a transformed (formatted) version of file_data"""

  result = ''

  for block in GetPemBlocks(file_data):
    if len(result) != 0:
      result += '\n'

    # If there was a user comment (non-script-generated comment) associated
    # with the block, output it immediately before the block.
    user_comment = GetUserComment(block.comment)
    if user_comment:
      result += user_comment

    generated_comment = GenerateCommentForBlock(block.name, block.data)
    result += generated_comment + '\n'


    result += MakePemBlockString(block.name, block.data)

  return result


def GenerateCommentForBlock(block_name, block_data):
  """Returns a string describing |block_data|. The format of |block_data| is
  inferred from |block_name|, and is pretty-printed accordingly. For
  instance CERTIFICATE is understood to be an X.509 certificate and pretty
  printed using OpenSSL's x509 command. If there is no specific pretty-printer
  for the data type, it is annotated using "openssl asn1parse"."""

  # Try to pretty printing as X.509 certificate.
  if "CERTIFICATE" in block_name:
    p = subprocess.Popen(["openssl", "x509", "-text", "-noout",
                          "-inform", "DER"],
                          stdin=subprocess.PIPE,
                          stdout=subprocess.PIPE,
                          stderr=subprocess.PIPE)
    stdout_data, stderr_data = p.communicate(block_data)

    # If pretty printing succeeded, return it.
    if p.returncode == 0:
      stdout_data = stdout_data.strip()
      return '$ openssl x509 -text < [%s]\n%s' % (block_name, stdout_data)

  # Try pretty printing as OCSP Response.
  if block_name == "OCSP RESPONSE":
    tmp_file_path = "tmp_ocsp.der"
    WriteStringToFile(block_data, tmp_file_path)
    p = subprocess.Popen(["openssl", "ocsp", "-noverify", "-resp_text",
                          "-respin", tmp_file_path],
                          stdin=subprocess.PIPE,
                          stdout=subprocess.PIPE,
                          stderr=subprocess.PIPE)
    stdout_data, stderr_data = p.communicate(block_data)
    os.remove(tmp_file_path)

    # If pretty printing succeeded, return it.
    if p.returncode == 0:
      stdout_data = stdout_data.strip()
      # May contain embedded CERTIFICATE pem blocks. Escape these since
      # CERTIFICATE already has meanining in the test file.
      stdout_data = stdout_data.replace("-----", "~~~~~")
      return '$ openssl ocsp -resp_text -respin <([%s])\n%s' % (block_name,
                                                                stdout_data)
    print 'Error pretty printing OCSP response:\n',stderr_data

  # Otherwise try pretty printing using asn1parse.

  p = subprocess.Popen(['openssl', 'asn1parse', '-i', '-inform', 'DER'],
                       stdout=subprocess.PIPE, stdin=subprocess.PIPE,
                       stderr=subprocess.PIPE)
  stdout_data, stderr_data = p.communicate(input=block_data)
  generated_comment = '$ openssl asn1parse -i < [%s]\n%s' % (block_name,
                                                             stdout_data)

  # The OCTET STRING encoded BasicOCSPResponse is also parsed out using
  #'openssl asn1parse'.
  if block_name == 'OCSP RESPONSE':
    if '[HEX DUMP]:' in generated_comment:
      (generated_comment, response) = generated_comment.split('[HEX DUMP]:', 1)
      response = response.replace('\n', '')
      if len(response) % 2 != 0:
        response = '0' + response
      response = GenerateCommentForBlock('INNER', response.decode('hex'))
      response = response.split('\n', 1)[1]
      response = response.replace(': ', ':      ')
      generated_comment += '\n%s' % (response)
  return generated_comment.strip('\n')


def GetUserComment(comment):
  """Removes any script-generated lines (everything after the $ openssl line)"""

  # Consider everything after "$ openssl" to be a generated comment.
  comment = comment.split('$ openssl', 1)[0]
  if IsEntirelyWhiteSpace(comment):
    comment = ''
  elif not comment.endswith("\n\n"):
    comment += "\n\n"
  return comment


def MakePemBlockString(name, data):
  return ('-----BEGIN %s-----\n'
          '%s'
          '-----END %s-----\n') % (name, EncodeDataForPem(data), name)


def GetPemFilePaths():
  """Returns an iterable for all the paths to the PEM test files"""

  base_dir = os.path.dirname(os.path.realpath(__file__))
  return glob.iglob(os.path.join(base_dir, '*.pem'))


def ReadFileToString(path):
  with open(path, 'r') as f:
    return f.read()


def WrapTextToLineWidth(text, column_width):
  result = ''
  pos = 0
  while pos < len(text):
    result += text[pos : pos + column_width] + '\n'
    pos += column_width
  return result


def EncodeDataForPem(data):
  result = base64.b64encode(data)
  return WrapTextToLineWidth(result, 75)


class PemBlock(object):
  def __init__(self):
    self.name = None
    self.data = None
    self.comment = None


def StripAllWhitespace(text):
  pattern = re.compile(r'\s+')
  return re.sub(pattern, '', text)


def IsEntirelyWhiteSpace(text):
  return len(StripAllWhitespace(text)) == 0


def DecodePemBlockData(text):
  text = StripAllWhitespace(text)
  return base64.b64decode(text)


def GetPemBlocks(data):
  """Returns an iterable of PemBlock"""

  comment_start = 0

  regex = re.compile(r'-----BEGIN ([\w ]+)-----(.*?)-----END \1-----',
                     re.DOTALL)

  for match in regex.finditer(data):
    block = PemBlock()

    block.name = match.group(1)
    block.data = DecodePemBlockData(match.group(2))

    # Keep track of any non-PEM text above blocks
    block.comment = data[comment_start : match.start()].strip()
    comment_start = match.end()

    yield block


def WriteStringToFile(data, path):
  with open(path, "w") as f:
    f.write(data)


def main():
  for path in GetPemFilePaths():
    print "Processing %s ..." % (path)
    original_data = ReadFileToString(path)
    transformed_data = Transform(original_data)
    if original_data != transformed_data:
      WriteStringToFile(transformed_data, path)
      print "Rewrote %s" % (path)


if __name__ == "__main__":
  main()