text: # Copyright 2017 The Closure Rules Authors. All rights reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #    http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  def _filegroup_external(ctx):
      """Downloads files into filegroup rule.
  
      This rule is capable of either downloading files individually, or downloading
      tarballs which are extracted. It's also capable of downloading different URLs
      for different platforms.
      """
      strip_prefix = ctx.attr.strip_prefix
      downloaded = depset()
      basenames = depset()
      data = depset(ctx.attr.data)
      inferred_srcs = depset()
      for sha256, urls, extract in _get_downloads(ctx):
          basename = ""
          for url in urls:
              basename = url[url.rindex("/") + 1:] or basename
              if url in downloaded.to_list():
                  fail("url specified multiple times: " + url)
              downloaded = depset([url], transitive = [downloaded])
          basename = _get_match(ctx.attr.rename, urls) or basename
          if basename in basenames.to_list():
              fail("filegroup path collision: " + basename)
          basenames = depset([basename], transitive = [basenames])
          if extract:
              inferred_srcs = None
              ctx.download_and_extract(
                  urls,
                  "",
                  sha256,
                  "",
                  _get_match(ctx.attr.strip_prefix, urls),
              )
          else:
              if inferred_srcs != None:
                  inferred_srcs = depset([basename], transitive = [inferred_srcs])
              ctx.download(
                  urls,
                  basename,
                  sha256,
                  _has_match(ctx.attr.executable, urls),
              )
      if ctx.attr.srcs:
          srcs = ctx.attr.srcs
      else:
          srcs = inferred_srcs
      lines = ["# DO NOT EDIT: generated by filegroup_external()", ""]
      if ctx.attr.default_visibility:
          lines.append("package(default_visibility = %s)" % (
              _repr_list(ctx.attr.default_visibility, indent = "")
          ))
          lines.append("")
      lines.append("licenses(%s)" % _repr_list(ctx.attr.licenses, indent = ""))
      lines.append("")
      lines.append("filegroup(")
      lines.append("    name = %s," % repr(
          ctx.attr.generated_rule_name or ctx.name,
      ))
      if ctx.attr.testonly_:
          lines.append("    testonly = 1,")
      if srcs == None:
          lines.append("    srcs = glob(")
          lines.append("        [\"**\"],")
          lines.append("        exclude = [")
          lines.append("            \"BUILD\",")
          lines.append("            \"WORKSPACE\",")
          lines.append("        ],")
          lines.append("    ),")
      else:
          lines.append("    srcs = %s," % _repr_list(srcs.to_list()))
      if data:
          lines.append("    data = %s," % _repr_list(data.to_list()))
      if ctx.attr.path:
          lines.append("    path = %s," % repr(ctx.attr.path))
      if ctx.attr.visibility:
          lines.append("    visibility = %s," %
                       _repr_list(ctx.attr.visibility))
      lines.append(")")
      lines.append("")
      extra = ctx.attr.extra_build_file_content
      if extra:
          lines.append(extra)
          if not extra.endswith("\n"):
              lines.append("")
      ctx.file("BUILD", "\n".join(lines))
  
  def _linux_arch_value(repository_ctx):
      """Returns the name of the Linux arch.
  
      Args:
        repository_ctx: The repository context.
  
      Returns:
        A string containing the name of the Linux arch.
      """
      os_name = repository_ctx.os.name.lower()
      if (os_name.startswith("mac os") or os_name.find("windows") != -1):
          return ""
      result = repository_ctx.execute(["uname", "-m"])
      return result.stdout.strip()
  
  def _get_downloads(ctx):
      os_name = ctx.os.name.lower()
      if (os_name.startswith("mac os") and
          (ctx.attr.sha256_urls_macos or
           ctx.attr.sha256_urls_extract_macos)):
          return _merge(
              ctx.attr.sha256_urls_macos,
              ctx.attr.sha256_urls_extract_macos,
          )
      elif (os_name.find("windows") != -1 and
            (ctx.attr.sha256_urls_windows or
             ctx.attr.sha256_urls_extract_windows)):
          return _merge(
              ctx.attr.sha256_urls_windows,
              ctx.attr.sha256_urls_extract_windows,
          )
      else:
          arch = _linux_arch_value(ctx)
          if (arch == "ppc64le" and
              (ctx.attr.sha256_urls_ppc64le or
               ctx.attr.sha256_urls_extract_ppc64le)):
              return _merge(
                  ctx.attr.sha256_urls_ppc64le,
                  ctx.attr.sha256_urls_extract_ppc64le,
              )
          elif (ctx.attr.sha256_urls or
                ctx.attr.sha256_urls_extract):
              return _merge(
                  ctx.attr.sha256_urls,
                  ctx.attr.sha256_urls_extract,
              )
          else:
              fail("No URLs are available for downloading %s" % ctx.name)
  
  def _merge(file_urls, archive_urls):
      result = []
      for dict_list, extract in (
          (file_urls, False),
          (archive_urls, True),
      ):
          for sha256, urls in dict_list.items():
              result.append((sha256, urls, extract))
      return result
  
  def _has_match(string_list, urls):
      for url in urls:
          if url in string_list or url[url.rindex("/") + 1:] in string_list:
              return True
      return False
  
  def _get_match(string_dict, urls):
      for url in urls:
          result = string_dict.get(url[url.rindex("/") + 1:], None)
          if result:
              return result
          result = string_dict.get(url, None)
          if result:
              return result
      return ""
  
  def _repr_list(items, indent = "    "):
      items = sorted(items)
      if not items:
          return "[]"
      if len(items) == 1:
          return repr(items)
      parts = [repr(item) for item in items]
      return (("[\n%s    " % indent) +
              (",\n%s    " % indent).join(parts) +
              (",\n%s]" % indent))
  
  filegroup_external = repository_rule(
      implementation = _filegroup_external,
      attrs = {
          "sha256_urls": attr.string_list_dict(),
          "sha256_urls_macos": attr.string_list_dict(),
          "sha256_urls_windows": attr.string_list_dict(),
          "sha256_urls_ppc64le": attr.string_list_dict(),
          "sha256_urls_extract": attr.string_list_dict(),
          "sha256_urls_extract_macos": attr.string_list_dict(),
          "sha256_urls_extract_windows": attr.string_list_dict(),
          "sha256_urls_extract_ppc64le": attr.string_list_dict(),
          "strip_prefix": attr.string_dict(),
          "rename": attr.string_dict(),
          "executable": attr.string_list(),
          "licenses": attr.string_list(mandatory = True, allow_empty = False),
          "srcs": attr.string_list(),
          "data": attr.string_list(),
          "path": attr.string(),
          "testonly_": attr.bool(),
          "generated_rule_name": attr.string(),
          "default_visibility": attr.string_list(default = ["//visibility:public"]),
          "extra_build_file_content": attr.string(),
      },
  )
  