#!/usr/bin/env python
# Copyright 2018 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.
#
# Generates a single BUILD.gn file with build targets generated using the
# manifest files in the SDK.

import json
import os
import subprocess
import sys


# Inserted at the top of the generated BUILD.gn file.
_GENERATED_PREAMBLE = """# DO NOT EDIT! This file was generated by
# //third_party/fuchsia-sdk/gen_build_defs.py.
# Any changes made to this file will be discarded.

import("//third_party/fuchsia-sdk/fuchsia_sdk_pkg.gni")

"""


def SerializeListOfStrings(strings):
  """Outputs a list of strings in GN-friendly, double-quoted format."""

  return '[' + ','.join(['"{}"'.format(s) for s in strings]) + ']'


def ConvertFidlLibrary(json):
  """Massages the manifest data to match the format required by the GN build
  and outputs a GN target for the FIDL library

  Arguments:
    json: The parsed manifest JSON.
  Returns:
    The GN target definition, represented as a string."""

  json['deps'] = SerializeListOfStrings(
      [':' + dep.split('.')[-1] for dep in json['deps']])
  json['sources'] = SerializeListOfStrings(json['sources'])

  name_tokenized = json['name'].split('.')
  json['shortname'] = name_tokenized[-1]
  json['namespace'] = '.'.join(name_tokenized[:-1])

  return """fuchsia_sdk_fidl_pkg("{shortname}") {{
    namespace = "{namespace}"
    public_deps = {deps}
    sources = {sources}
  }}""".format(**json)


def ConvertNoOp(json):
  """Null implementation of a conversion function. No output is generated."""

  return ""


"""Maps manifest type strings to relevant conversion functions."""
_CONVERSION_FUNCTION_MAP = {
  'fidl_library': ConvertFidlLibrary,

  # TODO(888753): Add conversion routines for these manifest types and migrate
  # existing dependents of //third_party/fuchsia_sdk/BUILD.gn to use the
  # generated targets instead. The migration can be executed incrementally.
  'cc_source_library': ConvertNoOp,
  'cc_prebuilt_library': ConvertNoOp,
  'host_tool': ConvertNoOp,
  'image': ConvertNoOp,
  'loadable_module': ConvertNoOp,
  'sysroot': ConvertNoOp,
}


def ConvertSdkManifests():
  sdk_base_dir = os.path.join(os.path.dirname(__file__), 'sdk')
  toplevel_meta = json.load(open(os.path.join(sdk_base_dir, 'meta',
                                              'manifest.json')))

  build_output_path = os.path.join(sdk_base_dir, 'BUILD.gn')
  with open(build_output_path, 'w') as buildfile:
    buildfile.write(_GENERATED_PREAMBLE)

    for next_part in toplevel_meta['parts']:
      parsed = json.load(open(os.path.join(sdk_base_dir, next_part)))
      if 'type' not in parsed:
        raise Exception("Couldn't find 'type' node in %s." % next_part)

      convert_function = _CONVERSION_FUNCTION_MAP.get(parsed['type'])
      if convert_function is None:
        raise Exception('Unexpected SDK artifact type %s in %s.' %
                        (parsed['type'], next_part))
      buildfile.write(convert_function(parsed))


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