# Copyright 2016 The Tulsi 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.

"""Skylark rules supporting Tulsi.

This file provides Bazel aspects used to obtain information about a given
project and pass it back to Tulsi.
"""

# List of all of the attributes that can link from a Tulsi-supported rule to a
# Tulsi-supported dependency of that rule.
# For instance, an ios_application's "binary" attribute might link to an
# objc_binary rule which in turn might have objc_library's in its "deps"
# attribute.
_TULSI_COMPILE_DEPS = [
    'binary',
    'bundles',
    'deps',
    'extensions',
    'non_propagated_deps',
    'test_bundle',
    'test_host',
    'xctest_app',
]

# List of all attributes whose contents should resolve to "support" files; files
# that are used by Bazel to build but do not need special handling in the
# generated Xcode project. For example, Info.plist and entitlements files.
_SUPPORTING_FILE_ATTRIBUTES = [
    # apple_watch1_extension
    'app_entitlements',
    'app_infoplists',
    'app_resources',
    'app_storyboards',
    'app_strings',
    'app_structured_resources',
    'ext_entitlements',
    'ext_infoplists',
    'ext_resources',
    'ext_strings',
    'ext_structured_resources',

    'entitlements',
    'infoplist',
    'infoplists',
    'resources',
    'strings',
    'structured_resources',
    'storyboards',
    'xibs',
]

# Set of rules with implicit <label>.ipa IPA outputs.
_IPA_GENERATING_RULES = set([
    'apple_watch1_extension',
    # apple_watch2_extension also generates an implicit IPA but the naming
    # cannot be derived from the target label alone so it is special cased.
    'ios_application',
    'ios_extension',
    'ios_test',
    'objc_binary',
    'tvos_application',
    '_ios_application',
    '_tvos_application',
])

# Set of rules that generate MergedInfo.plist files as part of the build.
_MERGEDINFOPLIST_GENERATING_RULES = set([
    'apple_watch1_extension',
    'apple_watch2_extension',
    'ios_application',
    'tvos_application',
    '_ios_application',
    '_tvos_application',
])

# Set of rules whose outputs should be treated as generated sources.
_SOURCE_GENERATING_RULES = set([
    'j2objc_library',
])

# Set of rules whose outputs should be treated as generated sources that do not
# use ARC.
_NON_ARC_SOURCE_GENERATING_RULES = set([
    'objc_proto_library',
])

def _dict_omitting_none(**kwargs):
  """Creates a dict from the args, dropping keys with None or [] values."""
  return {name: kwargs[name]
          for name in kwargs
          if kwargs[name] != None and kwargs[name] != []
         }


def _struct_omitting_none(**kwargs):
  """Creates a struct from the args, dropping keys with None or [] values."""
  return struct(**_dict_omitting_none(**kwargs))


def _convert_outpath_to_symlink_path(path):
  """Converts full output paths to their bazel-symlink equivalents."""
  # The path will be of the form
  # bazel-[whatever]/[platform-config]/symlink[/.*]
  first_dash = path.find('-')
  components = path.split('/')
  if (len(components) > 2 and
      first_dash >= 0 and
      first_dash < len(components[0])):
    return path[:first_dash + 1] + '/'.join(components[2:])
  return path


def _file_metadata(f):
  """Returns metadata about a given File."""
  if not f:
    return None

  if not f.is_source:
    root_path = f.root.path
    symlink_path = _convert_outpath_to_symlink_path(root_path)
    if symlink_path == root_path:
      # The root path should always be bazel-out/... and thus is expected to be
      # updated.
      print('Unexpected root path "%s". Please report.' % root_path)
      root_execution_path_fragment = root_path
    else:
      root_execution_path_fragment = symlink_path
  else:
    root_execution_path_fragment = None

  # TODO(abaire): Remove once Skylark File objects can reference directories.
  # At the moment (Oct. 2016), Bazel disallows most files without extensions.
  # As a temporary hack, Tulsi treats File instances pointing at extension-less
  # paths as directories. This is extremely fragile and must be replaced with
  # logic properly homed in Bazel.
  is_dir = (f.basename.find('.') == -1)

  return _struct_omitting_none(
      path=f.short_path,
      src=f.is_source,
      root=root_execution_path_fragment,
      is_dir=is_dir
  )


def _file_metadata_by_replacing_path(f, new_path, new_is_dir=None):
  """Returns a copy of the f _file_metadata struct with the given path."""
  root_path = _get_opt_attr(f, 'rootPath')
  if new_is_dir == None:
    new_is_dir = f.is_dir

  return _struct_omitting_none(
      path=new_path,
      src=f.src,
      root=root_path,
      is_dir=new_is_dir
  )


def _collect_files(obj, attr_path):
  """Returns a list of artifact_location's for the attr_path in obj."""
  return [_file_metadata(f)
          for src in _getattr_as_list(obj, attr_path)
          for f in _get_opt_attr(src, 'files')]


def _collect_first_file(obj, attr_path):
  """Returns a the first artifact_location for the attr_path in obj."""
  files = _collect_files(obj, attr_path)
  if not files:
    return None
  return files[0]


def _collect_supporting_files(rule_attr):
  """Extracts 'supporting' files from the given rule attributes."""
  all_files = []
  for attr in _SUPPORTING_FILE_ATTRIBUTES:
    all_files += _collect_files(rule_attr, attr)
  return all_files


def _collect_bundle_paths(rule_attr, bundle_attributes, bundle_ext):
  """Extracts subpaths with the given bundle_ext for the given attributes."""
  discovered_paths = set()
  bundles = []
  if not bundle_ext.endswith('/'):
    bundle_ext += '/'
  bundle_ext_len = len(bundle_ext) - 1

  for attr in bundle_attributes:
    for f in _collect_files(rule_attr, attr):
      end = f.path.find(bundle_ext)
      if end < 0:
        continue
      end += bundle_ext_len

      path = f.path[:end]
      root_path = _get_opt_attr(f, 'rootPath')
      full_path = str(root_path) + ':' + path
      if full_path in discovered_paths:
        continue
      discovered_paths += [full_path]
      # Generally Xcode treats bundles as special files so they should not be
      # flagged as directories.
      bundles.append(_file_metadata_by_replacing_path(f, path, False))
  return bundles


def _collect_asset_catalogs(rule_attr):
  """Extracts xcassets directories from the given rule attributes."""
  return _collect_bundle_paths(rule_attr,
                               ['app_asset_catalogs', 'asset_catalogs'],
                               '.xcassets')


def _collect_bundle_imports(rule_attr):
  """Extracts bundle directories from the given rule attributes."""
  return _collect_bundle_paths(rule_attr,
                               ['bundle_imports'],
                               '.bundle')


def _collect_framework_imports(rule_attr):
  """Extracts framework directories from the given rule attributes."""
  return _collect_bundle_paths(rule_attr,
                               ['framework_imports'],
                               '.framework')


def _collect_xcdatamodeld_files(obj, attr_path):
  """Returns artifact_location's for xcdatamodeld's for attr_path in obj."""
  files = _collect_files(obj, attr_path)
  if not files:
    return []
  discovered_paths = set()
  datamodelds = []
  for f in files:
    end = f.path.find('.xcdatamodel/')
    if end < 0:
      continue
    end += 12

    path = f.path[:end]
    root_path = _get_opt_attr(f, 'rootPath')
    full_path = str(root_path) + ':' + path
    if full_path in discovered_paths:
      continue
    discovered_paths += [full_path]
    datamodelds.append(_file_metadata_by_replacing_path(f, path, False))
  return datamodelds


def _collect_dependency_labels(rule, attr_list):
  """Collects Bazel labels for a list of dependency attributes.

  Args:
    rule: The Bazel rule whose dependencies should be collected.
    attr_list: List of attribute names potentially containing Bazel labels for
        dependencies of the given rule.

  Returns:
    A list of the Bazel labels of dependencies of the given rule.
  """
  rule_attrs = rule.attr
  deps = [dep
          for attribute in attr_list
          for dep in _getattr_as_list(rule_attrs, attribute)]
  return [dep.label for dep in deps if hasattr(dep, 'label')]


def _get_opt_attr(obj, attr_path):
  """Returns the value at attr_path on the given object if it is set."""
  attr_path = attr_path.split('.')
  for a in attr_path:
    if not obj or not hasattr(obj, a):
      return None
    obj = getattr(obj, a)
  return obj


def _get_label_attr(obj, attr_path):
  """Returns the value at attr_path as a label string if it is set."""
  label = _get_opt_attr(obj, attr_path)
  return str(label) if label else None


def _getattr_as_list(obj, attr_path):
  """Returns the value at attr_path as a list.

  This handles normalization of attributes containing a single value for use in
  methods expecting a list of values.

  Args:
    obj: The struct whose attributes should be parsed.
    attr_path: Dotted path of attributes whose value should be returned in
        list form.

  Returns:
    A list of values for obj at attr_path or [] if the struct has
    no such attribute.
  """
  val = _get_opt_attr(obj, attr_path)
  if not val:
    return []

  if type(val) == 'list':
    return val
  return [val]


def _extract_defines_from_option_list(lst):
  """Extracts preprocessor defines from a list of -D strings."""
  defines = []
  for item in lst:
    if item.startswith('-D'):
      defines.append(item[2:])
  return defines


def _extract_compiler_defines(ctx):
  """Extracts preprocessor defines from compiler fragments."""
  defines = []

  cpp_fragment = _get_opt_attr(ctx.fragments, 'cpp')
  if cpp_fragment:
    c_options = _get_opt_attr(cpp_fragment, 'c_options')
    defines += _extract_defines_from_option_list(c_options)

    compiler_options = cpp_fragment.compiler_options([])
    defines += _extract_defines_from_option_list(compiler_options)

    unfiltered = cpp_fragment.unfiltered_compiler_options([])
    defines += _extract_defines_from_option_list(unfiltered)

    cxx = cpp_fragment.cxx_options([])
    defines += _extract_defines_from_option_list(cxx)

  objc_fragment = _get_opt_attr(ctx.fragments, 'objc')
  if objc_fragment:
    objc_copts = _get_opt_attr(objc_fragment, 'copts')
    defines += _extract_defines_from_option_list(objc_copts)

  return defines


def _collect_secondary_artifacts(target, ctx):
  """Returns a list of file metadatas for implicit outputs of 'rule'."""
  artifacts = []
  rule = ctx.rule
  if rule.kind in _MERGEDINFOPLIST_GENERATING_RULES:
    bin_dir = _convert_outpath_to_symlink_path(ctx.bin_dir.path)
    package = target.label.package
    basename = target.label.name
    artifacts.append(_struct_omitting_none(
        path='%s/%s-MergedInfo.plist' % (package, basename),
        src=False,
        root=bin_dir
    ))

  return artifacts


def _extract_generated_sources_and_includes(target):
  """Returns (source_metadatas, includes) generated by the given target."""
  file_metadatas = []
  includes = []
  objc_provider = _get_opt_attr(target, 'objc')
  if hasattr(objc_provider, 'source') and hasattr(objc_provider, 'header'):
    all_files = set(objc_provider.source)
    all_files += objc_provider.header
    file_metadatas = [_file_metadata(f) for f in all_files]

  if hasattr(objc_provider, 'include'):
    includes = [_convert_outpath_to_symlink_path(x)
                for x in objc_provider.include]
  return file_metadatas, includes


def _extract_minimum_os_for_platform(ctx, platform):
  """Extracts the minimum OS version for the given apple_common.platform."""
  apple_frag = _get_opt_attr(ctx.fragments, 'apple')
  min_os = apple_frag.minimum_os_for_platform_type(platform)

  if not min_os:
    return None

  # Convert the DottedVersion to a string suitable for inclusion in a struct.
  return str(min_os)


def _extract_swift_language_version(ctx):
  """Returns the Swift version set by the xcode_toolchain option for ctx."""
  swift_toolchain = _get_opt_attr(ctx, 'fragments.apple.xcode_toolchain')
  if swift_toolchain == 'com.apple.dt.toolchain.Swift_2_3':
    return ('2.3', swift_toolchain)
  elif swift_toolchain:
    # TODO(abaire): Adjust as necessary once versions > 3.0 come out.
    return ('3.0', swift_toolchain)

  # TODO(abaire): Remove the fallback check for swift_library once
  #               xcode_toolchain is available everywhere.
  if ctx.rule.kind == 'swift_library':
    return ('3.0', 'com.apple.dt.toolchain.XcodeDefault')

  return (None, None)


def _tulsi_sources_aspect(target, ctx):
  """Extracts information from a given rule, emitting it as a JSON struct."""
  rule = ctx.rule
  target_kind = rule.kind
  rule_attr = _get_opt_attr(rule, 'attr')

  tulsi_info_files = set()
  transitive_attributes = dict()
  for attr_name in _TULSI_COMPILE_DEPS:
    deps = _getattr_as_list(rule_attr, attr_name)
    for dep in deps:
      if hasattr(dep, 'tulsi_info_files'):
        tulsi_info_files += dep.tulsi_info_files
      if hasattr(dep, 'transitive_attributes'):
        transitive_attributes += dep.transitive_attributes

  artifacts = _get_opt_attr(target, 'files')
  if artifacts:
    # Ignore any generated Xcode projects as they are not useful to Tulsi.
    artifacts = [_file_metadata(f)
                 for f in artifacts
                 if not f.short_path.endswith('project.pbxproj')]
  else:
    # artifacts may be an empty set type, in which case it must be explicitly
    # set to None to allow Skylark's serialization to work.
    artifacts = None

  srcs = (_collect_files(rule, 'attr.srcs') +
          _collect_files(rule, 'attr.hdrs') +
          _collect_files(rule, 'attr.textual_hdrs'))
  generated_files = []
  generated_non_arc_files = []
  generated_includes = []
  if target_kind in _SOURCE_GENERATING_RULES:
    generated_files, generated_includes = (
        _extract_generated_sources_and_includes(target))
  elif target_kind in _NON_ARC_SOURCE_GENERATING_RULES:
    generated_non_arc_files, generated_includes = (
        _extract_generated_sources_and_includes(target))

  raw_swift_transitive_modules = _getattr_as_list(target,
                                                  'swift.transitive_modules')
  swift_transitive_modules = [_file_metadata(f)
                              for f in raw_swift_transitive_modules]

  # Collect ObjC module maps dependencies for Swift targets.
  objc_module_maps = set()
  if hasattr(target, 'swift'):
    for module_maps in _getattr_as_list(target, 'objc.module_map'):
      objc_module_maps += set([_file_metadata(f) for f in module_maps])

  # Collect the dependencies of this rule, dropping any .jar files (which may be
  # created as artifacts of java/j2objc rules).
  dep_labels = _collect_dependency_labels(rule, _TULSI_COMPILE_DEPS)
  compile_deps = [str(l) for l in dep_labels if not l.name.endswith('.jar')]

  binary_rule = _get_opt_attr(rule_attr, 'binary')
  if binary_rule and type(binary_rule) == 'list':
    binary_rule = binary_rule[0]

  supporting_files = (_collect_supporting_files(rule_attr) +
                      _collect_asset_catalogs(rule_attr) +
                      _collect_bundle_imports(rule_attr))

  # Keys for attribute and inheritable_attributes keys must be kept in sync
  # with defines in Tulsi's RuleEntry.
  attributes = _dict_omitting_none(
      binary=_get_label_attr(binary_rule, 'label'),
      copts=_get_opt_attr(rule_attr, 'copts'),
      datamodels=_collect_xcdatamodeld_files(rule_attr, 'datamodels'),
      supporting_files=supporting_files,
      xctest=_get_opt_attr(rule_attr, 'xctest'),
      xctest_app=_get_label_attr(rule_attr, 'xctest_app.label'),
      test_host=_get_label_attr(rule_attr, 'test_host.label'),
  )

  # Inheritable attributes are pulled up through dependencies of type 'binary'
  # to simplify handling in Tulsi (so it appears as though bridging_header is
  # defined on an ios_application rather than its associated objc_binary, for
  # example).
  inheritable_attributes = _dict_omitting_none(
      bridging_header=_collect_first_file(rule_attr, 'bridging_header'),
      compiler_defines=_extract_compiler_defines(ctx),
      defines=_getattr_as_list(rule_attr, 'defines'),
      enable_modules=_get_opt_attr(rule_attr, 'enable_modules'),
      includes=_getattr_as_list(rule_attr, 'includes'),
      launch_storyboard=_collect_first_file(rule_attr, 'launch_storyboard'),
      pch=_collect_first_file(rule_attr, 'pch'),
  )

  # Merge any attributes on the "binary" dependency into this container rule.
  binary_attributes = _get_opt_attr(binary_rule, 'inheritable_attributes')
  if binary_attributes:
    inheritable_attributes = binary_attributes + inheritable_attributes

  ipa_output_label = None
  if target_kind == 'apple_watch2_extension':
    # watch2 extensions need to use the IPA produced for the app_name attribute.
    ipa_name = _get_opt_attr(rule_attr, 'app_name') + '.ipa'
    ipa_output_label = '//' + target.label.package + ':' + ipa_name
  elif target_kind in _IPA_GENERATING_RULES:
    ipa_output_label = str(target.label) + '.ipa'

  extensions = [str(t.label) for t in _getattr_as_list(rule_attr, 'extensions')]

  bundle_id = _get_opt_attr(rule_attr, 'bundle_id')
  if not bundle_id:
    bundle_id = _get_opt_attr(rule_attr, 'app_bundle_id')

  # Build up any local transitive attributes and apply them.
  swift_language_version, swift_toolchain = _extract_swift_language_version(ctx)
  if swift_language_version:
    transitive_attributes['swift_language_version'] = swift_language_version
    transitive_attributes['has_swift_dependency'] = True
  if swift_toolchain:
    transitive_attributes['swift_toolchain'] = swift_toolchain
    transitive_attributes['has_swift_dependency'] = True

  all_attributes = attributes + inheritable_attributes + transitive_attributes
  info = _struct_omitting_none(
      artifacts=artifacts,
      attr=_struct_omitting_none(**all_attributes),
      build_file=ctx.build_file_path,
      bundle_id=bundle_id,
      deps=compile_deps,
      ext_bundle_id=_get_opt_attr(rule_attr, 'ext_bundle_id'),
      extensions=extensions,
      framework_imports=_collect_framework_imports(rule_attr),
      generated_files=generated_files,
      generated_non_arc_files=generated_non_arc_files,
      generated_includes=generated_includes,
      ipa_output_label=ipa_output_label,
      iphoneos_deployment_target=_extract_minimum_os_for_platform(
          ctx, apple_common.platform_type.ios),
      # TODO(abaire): Uncomment if/when Bazel supports macOS.
      # macos_deployment_target=_extract_minimum_os_for_platform(
      #     ctx, apple_common.platform_type.macosx),
      tvos_deployment_target=_extract_minimum_os_for_platform(
          ctx, apple_common.platform_type.tvos),
      watchos_deployment_target=_extract_minimum_os_for_platform(
          ctx, apple_common.platform_type.watchos),
      label=str(target.label),
      non_arc_srcs=_collect_files(rule, 'attr.non_arc_srcs'),
      secondary_product_artifacts=_collect_secondary_artifacts(target, ctx),
      srcs=srcs,
      swift_transitive_modules=swift_transitive_modules,
      objc_module_maps=list(objc_module_maps),
      type=target_kind,
  )

  # Create an action to write out this target's info.
  output = ctx.new_file(target.label.name + '.tulsiinfo')
  ctx.file_action(output, info.to_json())
  tulsi_info_files += set([output])

  return struct(
      # Matches the --output_groups on the bazel commandline.
      output_groups={
          'tulsi-info': tulsi_info_files,
      },
      # The file actions used to save this rule's info and that of all of its
      # transitive dependencies.
      tulsi_info_files=tulsi_info_files,
      # The inheritable attributes of this rule, expressed as a dict instead of
      # a struct to allow easy joining.
      inheritable_attributes=inheritable_attributes,
      # Transitive info that should be applied to every rule that depends on
      # this rule.
      transitive_attributes=transitive_attributes,
  )

def _tulsi_outputs_aspect(target, ctx):
  """Collects outputs of each build invocation."""

  # TODO(b/35322727): Move apple_watch2_extension into _IPA_GENERATING_RULES
  # when dynamic outputs is the default strategy and it does need to be
  # special-cased above.
  if ctx.rule.kind not in _IPA_GENERATING_RULES + ['apple_watch2_extension']:
    return

  # An IPA output is guaranteed to exist for rules in _IPA_GENERATING_RULES
  ipa_output = [x.path for x in target.files if x.path.endswith('.ipa')][0]
  info = _struct_omitting_none(ipa=ipa_output)

  output = ctx.new_file(target.label.name + '.tulsiouts')
  ctx.file_action(output, info.to_json())

  return struct(
      output_groups={
          'tulsi-outputs': [output],
      },
  )


tulsi_sources_aspect = aspect(
    implementation=_tulsi_sources_aspect,
    attr_aspects=_TULSI_COMPILE_DEPS,
    fragments=['apple', 'cpp', 'objc'],
)


# This aspect does not propagate past the top-level target because we only need
# the IPA, which is at top level.
tulsi_outputs_aspect = aspect(
    implementation=_tulsi_outputs_aspect,
)