#!/usr/bin/env python
# Copyright (C) 2018 The Android Open Source Project
#
# 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.

# This tool translates a collection of BUILD.gn files into a mostly equivalent
# BUILD file for the Bazel build system. The input to the tool is a
# JSON description of the GN build definition generated with the following
# command:
#
#   gn desc out --format=json --all-toolchains "//*" > desc.json
#
# The tool is then given a list of GN labels for which to generate Bazel
# build rules.

from __future__ import print_function
import argparse
import json
import os
import re
import sys

import gn_utils

# Arguments for the GN output directory.
# host_os="linux" is to generate the right build files from Mac OS.
gn_args = ' '.join([
    'host_os="linux"',
    'is_debug=false',
    'is_perfetto_build_generator=true',
    'enable_perfetto_watchdog=true',
    'monolithic_binaries=true',
    'target_os="linux"',
])

# Default targets to translate to the blueprint file.

# These targets will be exported with public visibility in the generated BUILD.
public_targets = [
    '//src/perfetto_cmd:perfetto',
    '//src/traced/probes:traced_probes',
    '//src/traced/service:traced',
    '//src/trace_processor:trace_processor_shell',
    '//src/trace_processor:trace_processor',
    '//tools/trace_to_text:trace_to_text',
    '//tools/trace_to_text:libpprofbuilder',
]

# These targets are required by internal build rules but don't need to be
# exported publicly.
default_targets = [
    '//src/ipc:perfetto_ipc',
    '//src/ipc/protoc_plugin:ipc_plugin',
    '//src/protozero:libprotozero',
    '//src/protozero/protoc_plugin:protozero_plugin',
] + public_targets

# Root proto targets (to force discovery of intermediate proto targets).
proto_targets = [
    '//protos/perfetto/trace:merged_trace',
    '//protos/perfetto/metrics:lite',
    '//protos/perfetto/trace:lite',
    '//protos/perfetto/config:lite',
]

# The directory where the generated perfetto_build_flags.h will be copied into.
buildflags_dir = 'include/perfetto/base/build_configs/bazel'

# Internal equivalents for third-party libraries that the upstream project
# depends on.
external_deps = {
    '//gn:default_deps': [],
    '//gn:jsoncpp': ['PERFETTO_CONFIG.deps.jsoncpp'],
    '//gn:linenoise': ['PERFETTO_CONFIG.deps.linenoise'],
    '//gn:protobuf_full': ['PERFETTO_CONFIG.deps.protobuf_full'],
    '//gn:protobuf_lite': ['PERFETTO_CONFIG.deps.protobuf_lite'],
    '//gn:protoc_lib': ['PERFETTO_CONFIG.deps.protoc_lib'],
    '//gn:protoc': ['PERFETTO_CONFIG.deps.protoc'],
    '//gn:sqlite': [
        'PERFETTO_CONFIG.deps.sqlite',
        'PERFETTO_CONFIG.deps.sqlite_ext_percentile'
    ],
    '//gn:zlib': ['PERFETTO_CONFIG.deps.zlib'],
    '//gn/standalone:gen_git_revision': [],
    '//src/trace_processor/metrics:gen_merged_sql_metrics': [
        [":cc_merged_sql_metrics"]
    ]
}


def gen_sql_metrics(target):
  label = BazelLabel(get_bazel_label_name(target.name), 'genrule')
  label.srcs += [re.sub('^//', '', x) for x in target.inputs]
  label.outs += target.outputs
  label.cmd = r'$(location gen_merged_sql_metrics_py) --cpp_out=$@ $(SRCS)'
  label.tools += [':gen_merged_sql_metrics_py']
  return [label]


custom_actions = {
    '//src/trace_processor/metrics:gen_merged_sql_metrics': gen_sql_metrics,
}

# ------------------------------------------------------------------------------
# End of configuration.
# ------------------------------------------------------------------------------


class Error(Exception):
  pass


class BazelLabel(object):

  def __init__(self, name, type):
    self.comment = None
    self.name = name
    self.type = type
    self.visibility = []
    self.srcs = []
    self.hdrs = []
    self.deps = []
    self.external_deps = []
    self.tools = []
    self.outs = []

  def __str__(self):
    """Converts the object into a Bazel Starlark label."""
    res = ''
    res += ('# GN target: %s\n' % self.comment) if self.comment else ''
    res += '%s(\n' % self.type
    any_deps = len(self.deps) + len(self.external_deps) > 0
    ORD = ['name', 'srcs', 'hdrs', 'visibility', 'deps', 'outs', 'cmd', 'tools']
    key_sorter = lambda kv: ORD.index(kv[0]) if kv[0] in ORD else '99-' + kv[0]
    for k, v in sorted(self.__dict__.iteritems(), key=key_sorter):
      if k in ('type', 'comment',
               'external_deps') or v is None or (v == [] and
                                                 (k != 'deps' or not any_deps)):
        continue
      res += '    %s = ' % k
      if isinstance(v, basestring):
        res += '"%s",\n' % v
      elif isinstance(v, list):
        res += '[\n'
        if k == 'deps' and len(self.external_deps) > 1:
          indent = '           '
        else:
          indent = '    '
        for entry in v:
          res += '%s    "%s",\n' % (indent, entry)
        res += '%s]' % indent
        if k == 'deps' and self.external_deps:
          res += ' + %s' % self.external_deps[0]
          for edep in self.external_deps[1:]:
            if isinstance(edep, list):
              res += ' + [\n'
              for inner_dep in edep:
                res += '        "%s",\n' % inner_dep
              res += '    ]'
            else:
              res += ' +\n%s%s' % (indent, edep)
        res += ',\n'
      else:
        raise Error('Unsupported value %s', type(v))
    res += ')\n\n'
    return res


def get_bazel_label_name(gn_name):
  """Converts a GN target name into a Bazel label name.

  If target is in the public taraget list, returns only the GN target name,
  e.g.: //src/ipc:perfetto_ipc -> perfetto_ipc

  Otherwise, in the case of an intermediate taraget, returns a mangled path.
  e.g.:  //include/perfetto/base:base -> include_perfetto_base_base.
  """
  if gn_name in default_targets:
    return gn_utils.label_without_toolchain(gn_name).split(':')[1]
  return gn_utils.label_to_target_name_with_path(gn_name)


def gen_proto_labels(target):
  """ Generates the xx_proto_library label for proto targets.

  Bazel requires that each protobuf-related target is modeled with two labels:
  1. A plugin-dependent target (e.g. cc_library, cc_protozero_library) that has
     only a dependency on 2 and does NOT refer to any .proto sources.
  2. A plugin-agnostic target that defines only the .proto sources and their
     dependencies.
  """
  assert (target.type == 'proto_library')

  def get_sources_label(target_name):
    return re.sub('_(lite|zero)$', '',
                  get_bazel_label_name(target_name)) + '_protos'

  sources_label_name = get_sources_label(target.name)

  # Generates 1.
  if target.proto_plugin == 'proto':
    plugin_label_type = 'perfetto_cc_proto_library'
  elif target.proto_plugin == 'protozero':
    plugin_label_type = 'perfetto_cc_protozero_library'
  elif target.proto_plugin == 'ipc':
    plugin_label_type = 'perfetto_cc_ipc_library'
  else:
    raise Error('Unknown proto plugin: %s' % target.proto_plugin)
  plugin_label_name = get_bazel_label_name(target.name)
  plugin_label = BazelLabel(plugin_label_name, plugin_label_type)
  plugin_label.comment = target.name
  plugin_label.deps += [':' + sources_label_name]

  # Generates 2.
  sources_label = BazelLabel(sources_label_name, 'perfetto_proto_library')
  sources_label.comment = target.name
  assert (all(x.startswith('//') for x in target.sources))
  assert (all(x.endswith('.proto') for x in target.sources))
  sources_label.srcs = sorted([x[2:] for x in target.sources])  # Strip //.
  deps = [':' + get_sources_label(x) for x in target.proto_deps]
  sources_label.deps = sorted(deps)

  return [plugin_label, sources_label]


def gen_target(gn_target):
  if gn_target.type == 'proto_library':
    return gen_proto_labels(gn_target)
  elif gn_target.type == 'action':
    if gn_target.name in custom_actions:
      return custom_actions[gn_target.name](gn_target)
    return []
  elif gn_target.type == 'group':
    return []
  elif gn_target.type == 'executable':
    bazel_type = 'perfetto_cc_binary'
  elif gn_target.type == 'shared_library':
    bazel_type = 'perfetto_cc_binary'
    vars['linkshared'] = True
  elif gn_target.type == 'static_library':
    bazel_type = 'perfetto_cc_library'
  elif gn_target.type == 'source_set':
    bazel_type = 'filegroup'
  else:
    raise Error('target type not supported: %s' % gn_target.type)

  label = BazelLabel(get_bazel_label_name(gn_target.name), bazel_type)
  label.comment = gn_target.name
  label.srcs = [x[2:] for x in gn_target.sources]

  if gn_target.name in public_targets:
    label.visibility = ['//visibility:public']

  if gn_target.type in gn_utils.LINKER_UNIT_TYPES:
    # |source_sets| contains the transitive set of source_set deps.
    for trans_dep in gn_target.source_set_deps:
      name = ':' + get_bazel_label_name(trans_dep)
      if name.startswith(
          ':include_perfetto_') and gn_target.type != 'executable':
        label.hdrs += [name]
      else:
        label.srcs += [name]
    for dep in gn_target.deps:
      if dep.startswith('//gn:'):
        assert (dep in external_deps), dep
      if dep in external_deps:
        assert (isinstance(external_deps[dep], list))
        label.external_deps += external_deps[dep]
      else:
        label.deps += [':' + get_bazel_label_name(dep)]
    label.deps += [':' + get_bazel_label_name(x) for x in gn_target.proto_deps]

  # All items starting with : need to be sorted to the end of the list.
  # However, Python makes specifying a comparator function hard so cheat
  # instead and make everything start with : sort as if it started with |
  # As | > all other normal ASCII characters, this will lead to all : targets
  # starting with : to be sorted to the end.
  label.srcs = sorted(label.srcs, key=lambda x: x.replace(':', '|'))

  label.deps = sorted(label.deps)
  label.hdrs = sorted(label.hdrs)
  return [label]


def gen_target_str(gn_target):
  return ''.join(str(x) for x in gen_target(gn_target))


def generate_build(gn_desc, targets, extras):
  gn = gn_utils.GnParser(gn_desc)
  res = '''
# Copyright (C) 2019 The Android Open Source Project
#
# 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.
#
# This file is automatically generated by {}. Do not edit.

load("@perfetto_cfg//:perfetto_cfg.bzl", "PERFETTO_CONFIG")
load(
    "@perfetto//bazel:rules.bzl",
    "perfetto_cc_binary",
    "perfetto_cc_ipc_library",
    "perfetto_cc_library",
    "perfetto_cc_proto_library",
    "perfetto_cc_protozero_library",
    "perfetto_java_proto_library",
    "perfetto_proto_library",
    "perfetto_py_binary",
    "perfetto_gensignature_internal_only",
)

package(default_visibility = ["//visibility:private"])

licenses(["notice"])  # Apache 2.0

exports_files(["NOTICE"])
'''.format(__file__).lstrip()

  # Public targets need to be computed at the beginning (to figure out the
  # intermediate deps) but printed at the end (because declaration order matters
  # in Bazel).
  public_str = ''
  for target_name in sorted(public_targets):
    target = gn.get_target(target_name)
    public_str += gen_target_str(target)

  res += '''
# ##############################################################################
# Internal targets
# ##############################################################################

'''.lstrip()
  # Generate the other non-public targets.
  for target_name in sorted(set(default_targets) - set(public_targets)):
    target = gn.get_target(target_name)
    res += gen_target_str(target)

  # Generate all the intermediate targets.
  for target in sorted(gn.all_targets.itervalues(), key=lambda x: x.name):
    if target.name in default_targets or target.name in gn.proto_libs:
      continue
    res += gen_target_str(target)

  res += '''
# ##############################################################################
# Proto libraries
# ##############################################################################

'''.lstrip()
  # Force discovery of explicilty listed root proto targets.
  for target_name in proto_targets:
    gn.get_target(target_name)

  # Generate targets for the transitive set of proto targets.
  # TODO explain deduping here.
  labels = {}
  for target in gn.proto_libs.itervalues():
    for label in gen_target(target):
      labels[label.name] = label

  res += ''.join(str(x) for x in labels.itervalues())

  res += '''
# ##############################################################################
# Public targets
# ##############################################################################

'''.lstrip()
  res += public_str
  res += '# Content from BUILD.extras\n\n'
  res += extras
  return res


def main():
  parser = argparse.ArgumentParser(
      description='Generate BUILD from a GN description.')
  parser.add_argument(
      '--check-only',
      help='Don\'t keep the generated files',
      action='store_true')
  parser.add_argument(
      '--desc',
      help='GN description ' +
      '(e.g., gn desc out --format=json --all-toolchains "//*"')
  parser.add_argument(
      '--repo-root',
      help='Standalone Perfetto repository to generate a GN description',
      default=gn_utils.repo_root(),
  )
  parser.add_argument(
      '--extras',
      help='Extra targets to include at the end of the BUILD file',
      default=os.path.join(gn_utils.repo_root(), 'BUILD.extras'),
  )
  parser.add_argument(
      '--output',
      help='BUILD file to create',
      default=os.path.join(gn_utils.repo_root(), 'BUILD'),
  )
  parser.add_argument(
      '--output-proto',
      help='Proto BUILD file to create',
      default=os.path.join(gn_utils.repo_root(), 'protos', 'BUILD'),
  )
  parser.add_argument(
      'targets',
      nargs=argparse.REMAINDER,
      help='Targets to include in the BUILD file (e.g., "//:perfetto_tests")')
  args = parser.parse_args()

  if args.desc:
    with open(args.desc) as f:
      desc = json.load(f)
  else:
    desc = gn_utils.create_build_description(gn_args, args.repo_root)

  out_files = []

  # Generate the main BUILD file.
  with open(args.extras, 'r') as extra_f:
    extras = extra_f.read()

  contents = generate_build(desc, args.targets or default_targets, extras)
  out_files.append(args.output + '.swp')
  with open(out_files[-1], 'w') as out_f:
    out_f.write(contents)

  # Generate the build flags file.
  out_files.append(os.path.join(buildflags_dir, 'perfetto_build_flags.h.swp'))
  gn_utils.gen_buildflags(gn_args, out_files[-1])

  return gn_utils.check_or_commit_generated_files(out_files, args.check_only)


if __name__ == '__main__':
  sys.exit(main())