#!/usr/bin/env python

# Copyright (c) 2012 Google Inc. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Utility functions for Windows builds.

These functions are executed via gyp-win-tool when using the ninja generator.
"""

from __future__ import print_function

import os
import re
import shutil
import subprocess
import stat
import string
import sys

BASE_DIR = os.path.dirname(os.path.abspath(__file__))
PY3 = bytes != str

# A regex matching an argument corresponding to the output filename passed to
# link.exe.
_LINK_EXE_OUT_ARG = re.compile('/OUT:(?P<out>.+)$', re.IGNORECASE)

def main(args):
  executor = WinTool()
  exit_code = executor.Dispatch(args)
  if exit_code is not None:
    sys.exit(exit_code)


class WinTool(object):
  """This class performs all the Windows tooling steps. The methods can either
  be executed directly, or dispatched from an argument list."""

  def _UseSeparateMspdbsrv(self, env, args):
    """Allows to use a unique instance of mspdbsrv.exe per linker instead of a
    shared one."""
    if len(args) < 1:
      raise Exception("Not enough arguments")

    if args[0] != 'link.exe':
      return

    # Use the output filename passed to the linker to generate an endpoint name
    # for mspdbsrv.exe.
    endpoint_name = None
    for arg in args:
      m = _LINK_EXE_OUT_ARG.match(arg)
      if m:
        endpoint_name = re.sub(r'\W+', '',
            '%s_%d' % (m.group('out'), os.getpid()))
        break

    if endpoint_name is None:
      return

    # Adds the appropriate environment variable. This will be read by link.exe
    # to know which instance of mspdbsrv.exe it should connect to (if it's
    # not set then the default endpoint is used).
    env['_MSPDBSRV_ENDPOINT_'] = endpoint_name

  def Dispatch(self, args):
    """Dispatches a string command to a method."""
    if len(args) < 1:
      raise Exception("Not enough arguments")

    method = "Exec%s" % self._CommandifyName(args[0])
    return getattr(self, method)(*args[1:])

  def _CommandifyName(self, name_string):
    """Transforms a tool name like recursive-mirror to RecursiveMirror."""
    return name_string.title().replace('-', '')

  def _GetEnv(self, arch):
    """Gets the saved environment from a file for a given architecture."""
    # The environment is saved as an "environment block" (see CreateProcess
    # and msvs_emulation for details). We convert to a dict here.
    # Drop last 2 NULs, one for list terminator, one for trailing vs. separator.
    pairs = open(arch).read()[:-2].split('\0')
    kvs = [item.split('=', 1) for item in pairs]
    return dict(kvs)

  def ExecStamp(self, path):
    """Simple stamp command."""
    open(path, 'w').close()

  def ExecRecursiveMirror(self, source, dest):
    """Emulation of rm -rf out && cp -af in out."""
    if os.path.exists(dest):
      if os.path.isdir(dest):
        def _on_error(fn, path, excinfo):
          # The operation failed, possibly because the file is set to
          # read-only. If that's why, make it writable and try the op again.
          if not os.access(path, os.W_OK):
            os.chmod(path, stat.S_IWRITE)
          fn(path)
        shutil.rmtree(dest, onerror=_on_error)
      else:
        if not os.access(dest, os.W_OK):
          # Attempt to make the file writable before deleting it.
          os.chmod(dest, stat.S_IWRITE)
        os.unlink(dest)

    if os.path.isdir(source):
      shutil.copytree(source, dest)
    else:
      shutil.copy2(source, dest)

  def ExecLinkWrapper(self, arch, use_separate_mspdbsrv, *args):
    """Filter diagnostic output from link that looks like:
    '   Creating library ui.dll.lib and object ui.dll.exp'
    This happens when there are exports from the dll or exe.
    """
    env = self._GetEnv(arch)
    if use_separate_mspdbsrv == 'True':
      self._UseSeparateMspdbsrv(env, args)
    if sys.platform == 'win32':
      args = list(args)  # *args is a tuple by default, which is read-only.
      args[0] = args[0].replace('/', '\\')
    # https://docs.python.org/2/library/subprocess.html:
    # "On Unix with shell=True [...] if args is a sequence, the first item
    # specifies the command string, and any additional items will be treated as
    # additional arguments to the shell itself.  That is to say, Popen does the
    # equivalent of:
    #   Popen(['/bin/sh', '-c', args[0], args[1], ...])"
    # For that reason, since going through the shell doesn't seem necessary on
    # non-Windows don't do that there.
    link = subprocess.Popen(args, shell=sys.platform == 'win32', env=env,
                            stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    out, _ = link.communicate()
    if PY3:
      out = out.decode('utf-8')
    for line in out.splitlines():
      if (not line.startswith('   Creating library ') and
          not line.startswith('Generating code') and
          not line.startswith('Finished generating code')):
        print(line)
    return link.returncode

  def ExecLinkWithManifests(self, arch, embed_manifest, out, ldcmd, resname,
                            mt, rc, intermediate_manifest, *manifests):
    """A wrapper for handling creating a manifest resource and then executing
    a link command."""
    # The 'normal' way to do manifests is to have link generate a manifest
    # based on gathering dependencies from the object files, then merge that
    # manifest with other manifests supplied as sources, convert the merged
    # manifest to a resource, and then *relink*, including the compiled
    # version of the manifest resource. This breaks incremental linking, and
    # is generally overly complicated. Instead, we merge all the manifests
    # provided (along with one that includes what would normally be in the
    # linker-generated one, see msvs_emulation.py), and include that into the
    # first and only link. We still tell link to generate a manifest, but we
    # only use that to assert that our simpler process did not miss anything.
    variables = {
      'python': sys.executable,
      'arch': arch,
      'out': out,
      'ldcmd': ldcmd,
      'resname': resname,
      'mt': mt,
      'rc': rc,
      'intermediate_manifest': intermediate_manifest,
      'manifests': ' '.join(manifests),
    }
    add_to_ld = ''
    if manifests:
      subprocess.check_call(
          '%(python)s gyp-win-tool manifest-wrapper %(arch)s %(mt)s -nologo '
          '-manifest %(manifests)s -out:%(out)s.manifest' % variables)
      if embed_manifest == 'True':
        subprocess.check_call(
            '%(python)s gyp-win-tool manifest-to-rc %(arch)s %(out)s.manifest'
          ' %(out)s.manifest.rc %(resname)s' % variables)
        subprocess.check_call(
            '%(python)s gyp-win-tool rc-wrapper %(arch)s %(rc)s '
            '%(out)s.manifest.rc' % variables)
        add_to_ld = ' %(out)s.manifest.res' % variables
    subprocess.check_call(ldcmd + add_to_ld)

    # Run mt.exe on the theoretically complete manifest we generated, merging
    # it with the one the linker generated to confirm that the linker
    # generated one does not add anything. This is strictly unnecessary for
    # correctness, it's only to verify that e.g. /MANIFESTDEPENDENCY was not
    # used in a #pragma comment.
    if manifests:
      # Merge the intermediate one with ours to .assert.manifest, then check
      # that .assert.manifest is identical to ours.
      subprocess.check_call(
          '%(python)s gyp-win-tool manifest-wrapper %(arch)s %(mt)s -nologo '
          '-manifest %(out)s.manifest %(intermediate_manifest)s '
          '-out:%(out)s.assert.manifest' % variables)
      assert_manifest = '%(out)s.assert.manifest' % variables
      our_manifest = '%(out)s.manifest' % variables
      # Load and normalize the manifests. mt.exe sometimes removes whitespace,
      # and sometimes doesn't unfortunately.
      with open(our_manifest, 'rb') as our_f:
        with open(assert_manifest, 'rb') as assert_f:
          our_data = our_f.read().translate(None, string.whitespace)
          assert_data = assert_f.read().translate(None, string.whitespace)
      if our_data != assert_data:
        os.unlink(out)