# Copyright 2018 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("//build/sdk/sdk_atom.gni")
import("//build/sdk/sdk_atom_alias.gni")

# A shared library that can be exported to an SDK in binary form.
#
# Parameters
#
#   category (required)
#     Publication level of the library in SDKs.
#     See //build/sdk/sdk_atom.gni.
#
#   no_headers (optional)
#     Whether to include the library's headers in the SDK.
#     Defaults to false.
#
#   sdk_name (optional)
#     Name of the library in the SDK.
#     Defaults to the library's output name.
#
#   include_base (optional)
#     Path to the root directory for includes.
#     Defaults to ".".
#
#   runtime_deps (optional)
#     List of labels representing the library's runtime dependencies. This is
#     only needed for runtime dependencies inherited from private dependencies.
#     Note that these labels should represent SDK targets.

# The defaults for a prebuilt_shared_library should match that of a shared_library.
set_defaults("prebuilt_shared_library") {
  configs = default_shared_library_configs
}

template("prebuilt_shared_library") {
  assert(defined(invoker.category), "Must define an SDK category")

  main_target_name = target_name
  metadata_target_name = "${target_name}_sdk_metadata"
  manifest_target_name = "${target_name}_sdk_manifest"
  sdk_target_name = "${target_name}_sdk"

  shared_library(main_target_name) {
    forward_variables_from(invoker,
                           "*",
                           [
                             "category",
                             "include_base",
                             "no_headers",
                             "runtime_deps",
                             "sdk_name",
                           ])

    if (defined(visibility)) {
      visibility += [ ":$manifest_target_name" ]
    }

    # Prebuilt shared libraries are eligible for inclusion in the SDK. We do not
    # want to dynamically link against libc++.so because we let clients bring
    # their own toolchain, which might have a different C++ Standard Library or
    # a different C++ ABI entirely.
    #
    # Adding this linker flag keeps us honest about not commiting to a specific
    # C++ ABI. If this flag is causing your library to not to compile, consider
    # whether your library really ought to be in the SDK. If so, consider
    # including your library in the SDK as source rather than precompiled. If
    # you do require precompilation, you probably need to find a way not to
    # depend on dynamically linking C++ symbols because C++ does not have a
    # sufficiently stable ABI for the purposes of our SDK.
    #
    # Once TC-46 is fixed, we'll be able to offer the option to statically link
    # against libc++.
    if (!defined(ldflags)) {
      ldflags = []
    }
    ldflags += [ "-nostdlib++" ]

    # Request that the runtime deps be written out to a file. This file will be
    # used later to verify that all runtime deps are available in the SDK.
    write_runtime_deps = "$target_out_dir/$target_name.runtime_deps"
  }

  output_name = target_name
  if (defined(invoker.output_name)) {
    output_name = invoker.output_name
  }

  if (defined(invoker.sdk_name)) {
    atom_name = invoker.sdk_name
  } else {
    atom_name = output_name
  }

  no_headers = defined(invoker.no_headers) && invoker.no_headers
  # Base path for source files of this library in SDKs.
  file_base = "pkg/$atom_name"
  # Base path for binaries of this library in SDKs.
  prebuilt_base = "arch/$target_cpu"

  # Identify dependencies and their metadata files.
  sdk_deps = []
  sdk_metas = []
  # If a prebuilt library is only provided for packaging purposes (by not
  # exposing headers) then its dependencies need not be included in an SDK.
  if (defined(invoker.public_deps) && !no_headers) {
    foreach(dep, invoker.public_deps) {
      full_label = get_label_info(dep, "label_no_toolchain")
      sdk_dep = "${full_label}_sdk"
      sdk_deps += [ sdk_dep ]
    }
  }
  # Runtime deps are already SDK targets.
  if (defined(invoker.runtime_deps)) {
    sdk_deps += invoker.runtime_deps
  }
  foreach(sdk_dep, sdk_deps) {
    gen_dir = get_label_info(sdk_dep, "target_gen_dir")
    name = get_label_info(sdk_dep, "name")
    sdk_metas += [ rebase_path("$gen_dir/$name.meta.json") ]
  }

  # Process headers.
  all_headers = []
  if ((defined(invoker.public) || defined(invoker.sources)) && !no_headers) {
    if (defined(invoker.public)) {
      all_headers += invoker.public
    } else {
      foreach(source_file, invoker.sources) {
        extension = get_path_info(source_file, "extension")
        if (extension == "h") {
          all_headers += [ source_file ]
        }
      }
    }
  }
  sdk_headers = []
  sdk_files = []
  new_sdk_files = []
  foreach(header, all_headers) {
    include_base = "include"
    if (defined(invoker.include_base)) {
      include_base = invoker.include_base
    }
    destination = rebase_path(header, include_base)
    header_dest = "$file_base/include/$destination"
    sdk_headers += [ header_dest ]
    sdk_files += [
      {
        source = header
        dest = "include/$destination"
      },
    ]
    new_sdk_files += [
      {
        source = header
        dest = header_dest
      }
    ]
  }

  # Add binaries.
  shared_out_dir = get_label_info(":bogus($shlib_toolchain)", "root_out_dir")
  lib_name = "lib$output_name.so"
  link_lib = "$prebuilt_base/lib/$lib_name"
  dist_lib = "$prebuilt_base/dist/$lib_name"
  debug_lib = "$prebuilt_base/debug/$lib_name"
  sdk_files += [
    {
      # TODO(TO-791): put ABI stubs under lib/, not the full thing.
      source = "$shared_out_dir/$lib_name"
      dest = "lib/$lib_name"
    },
    {
      source = "$shared_out_dir/$lib_name"
      dest = "dist/$lib_name"
      packaged = true
    },
    {
      source = "$shared_out_dir/lib.unstripped/$lib_name"
      dest = "debug/$lib_name"
    },
  ]
  new_sdk_files += [
    {
      # TODO(TO-791): put ABI stubs under lib/, not the full thing.
      source = "$shared_out_dir/$lib_name"
      dest = link_lib
    },
    {
      source = "$shared_out_dir/$lib_name"
      dest = dist_lib
    },
    {
      source = "$shared_out_dir/lib.unstripped/$lib_name"
      dest = debug_lib
    },
  ]

  metadata_file = "$target_gen_dir/$metadata_target_name.sdk_meta.json"

  action(metadata_target_name) {
    script = "//build/cpp/gen_sdk_prebuilt_meta_file.py"

    inputs = sdk_metas

    outputs = [ metadata_file ]

    args = [
      "--out",
      rebase_path(metadata_file),
      "--name",
      atom_name,
      "--root",
      file_base,
      "--include-dir",
      "$file_base/include",
      "--deps",
    ] + sdk_metas + [
      "--headers",
    ] + sdk_headers + [
      "--arch",
      target_cpu,
      "--lib-link",
      link_lib,
      "--lib-dist",
      dist_lib,
      "--lib-debug",
      debug_lib,
    ]

    deps = sdk_deps
  }

  sdk_atom(manifest_target_name) {
    forward_variables_from(invoker, [ "testonly" ])

    domain = "cpp"
    name = atom_name
    id = "sdk://pkg/$atom_name"
    tags = [ "type:compiled_shared" ]

    category = invoker.category

    meta = {
      source = metadata_file
      dest = "$file_base/meta.json"
      schema = "cc_prebuilt_library"
    }

    if (is_fuchsia) {
      tags += [ "arch:target" ]
    } else {
      tags += [ "arch:host" ]
    }

    files = sdk_files

    new_files = new_sdk_files

    deps = sdk_deps

    non_sdk_deps = [
      ":$main_target_name",
      ":$metadata_target_name",
    ]

    # Explicitly add non-public dependencies, in case some of the source files
    # are generated.
    if (defined(invoker.deps)) {
      non_sdk_deps += invoker.deps
    }
  }

  shared_gen_dir = get_label_info(":bogus($shlib_toolchain)", "target_out_dir")
  runtime_deps_file = "$shared_gen_dir/$target_name.runtime_deps"
  sdk_manifest_file = "$target_gen_dir/$manifest_target_name.sdk"
  verify_target_name = "${target_name}_verify"

  # Verify that the SDK manifest for this target includes all of the expected
  # runtime dependencies.
  # TODO(DX-340): also check that everything in there is either prebuilt or
  # headers only.
  action(verify_target_name) {
    script = "//build/cpp/verify_runtime_deps.py"

    inputs = [
      sdk_manifest_file,
      runtime_deps_file,
    ]

    stamp_file = "$target_gen_dir/$target_name.stamp"

    outputs = [
      stamp_file,
    ]

    args = [
      "--stamp",
      rebase_path(stamp_file),
      "--manifest",
      rebase_path(sdk_manifest_file),
      "--runtime-deps-file",
      rebase_path(runtime_deps_file),
      "--root-out-dir",
      rebase_path(root_out_dir),
    ]

    deps = [
      ":$main_target_name",
      ":$manifest_target_name",
    ]
  }

  sdk_atom_alias(sdk_target_name) {
    atom = ":$manifest_target_name"

    non_sdk_deps = [
      ":$verify_target_name",
    ]
  }
}