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

declare_args() {
  # The OS build is running on.
  OS = ""

  # Specifies pkg-config program to retrieve information about packages.
  pkg_config = ""

  # The logical root directory for headers and libraries.
  # Trailing slash should not be added (except root path).
  sysroot = ""

  # The libdir of the target board. e.g. /usr/lib64
  libdir = ""

  # The path to the directory where build artifacts are located.
  build_root = ""

  # The path to src/platform2.
  platform2_root = ""

  # Libbase revision number read from BASE_VER variable or file.
  libbase_ver = ""

  # Set true to allow C++ code to use exceptions.
  enable_exceptions = false

  # Set true if clang is used for C compiler.
  clang_cc = false

  # Set true if clang is used for C++ compiler.
  clang_cxx = false

  # Additional flags for C compiler.
  external_cflags = []

  # Additional flags for C++ compiler.
  external_cxxflags = []

  # Additional flags for C and C++ preprocessor.
  external_cppflags = []

  # Additional flags for C and C++ linker.
  external_ldflags = []

  # Whether to link against libstdc++fs. Set this to true if the compiler
  # version requires -lstdc++fs to use std::filesystem. Useful when compiling
  # common-mk projects outside Chrome OS where there are many compiler
  # variations.
  link_stdcppfs = false

  # Set this to true if you want to activate the debug mode.
  is_debug = false

  # Subdir in platform2 where the package is located.
  # TODO(oka): This value is public because it is used in ap/ package for common
  # targets to use different default flags based on the package to be built.
  # This is hacky, so remove such usages and move this variable back to
  # gn_root/BUILD.gn .
  platform_subdir = ""
}
import("//common-mk/use.gni")

assert(pkg_config != "", "pkg-config script path must be set")
assert(libbase_ver != -1, "libbase_ver must be set")
assert(libdir != "", "libdir must be set")

if (target_os == "") {
  target_os = host_os
}
if (target_cpu == "") {
  target_cpu = host_cpu
}
if (current_cpu == "") {
  current_cpu = target_cpu
}
if (current_os == "") {
  current_os = target_os
}

# Practically sysroot is used as a prefix of paths, e.g.
# "${sysroot}/usr/include". If sysroot is root (= "/"), it will be
# "//usr/include". However, in GN, paths starting with "//" represents the path
# to the GN root, rather than the file system root, which is unexpected.
# To support that case, replace sysroot with "/.", if sysroot is "/".
if (sysroot == "/") {
  sysroot = "/."
}

# All binary targets will get this list of configs by default.
_binary_target_configs = [ "//common-mk:compiler_defaults" ]

if (!enable_exceptions) {
  _binary_target_configs += [ "//common-mk:no_exceptions" ]
}

if (!clang_cc) {
  _binary_target_configs += [ "//common-mk:gcc_cflags_c" ]
}
if (!clang_cxx) {
  _binary_target_configs += [ "//common-mk:gcc_cflags_cc" ]
}

set_defaults("executable") {
  configs = _binary_target_configs
  configs += [ "//common-mk:pie" ]
}

set_defaults("static_library") {
  configs = _binary_target_configs
  configs += [
    "//common-mk:pie",
    "//common-mk:use_thin_archive",
  ]
}

set_defaults("shared_library") {
  configs = _binary_target_configs
  configs += [ "//common-mk:pic" ]
}

set_defaults("source_set") {
  configs = _binary_target_configs
}

set_default_toolchain("//common-mk/toolchain")

# In Chrome OS, pkg-config is commonly and widely used.
# It is not natively supported by GN. Instead, here a few special fields are
# injected to the executable, shared_library source_set, and static_library
# targets to support pkg-config.
# src_install and src_test settings are also written in the same way.
#
# install_path exports metadata for installing the file built by the target.
# For example,
# - executable("my_executable")  # template invocation
# is expanded to:
# - executable("my_executable")  # GN built-in function invocation
# - install_config("my_executable-install_config")
# In this case ":my_executable" is usually joined to the dependency chain from
# the root (":all") by the BUILD.gn that uses this template. However, the
# ":my_executable-install_config" is not. So we chain it by adding to deps.
# ":all" --> ":my_executable" -(add this dep)-> ":my_executable-install_config"
#
# Args:
#   pkg_deps(optional): A list of package names to be depend.
#     A corresponding config is created, and then injected to |configs|.
#   public_pkg_deps(optional): Similart to pkg_deps, but injected to
#     |public_configs| instead.
#   all_dependent_pkg_deps(optional): Similar to pkg_deps, but injected to
#     |all_dependent_configs|.
#   run_test(optional): A boolean if this is a unittest program that should be
#     automatically run. A corresponding metadata is injected to itself.
#   test_config(optional): A scope of configs for tests.
#     A corresponding metadata is injected to itself.
#   install_path(optional): A path to install into.
#     A corresponding group is created, and then injected to |deps|.

import("//common-mk/install_config.gni")
import("//common-mk/pkg_config.gni")

template("_generate_config_rule") {
  if (defined(invoker.pkg_deps) && invoker.pkg_deps != []) {
    _pkg_deps_name = "_${target_name}-pkg_deps-config"
    pkg_config(_pkg_deps_name) {
      pkg_deps = invoker.pkg_deps
    }
  }
  if (defined(invoker.public_pkg_deps) && invoker.public_pkg_deps != []) {
    _public_pkg_deps_name = "_${target_name}-public_pkg_deps-config"
    pkg_config(_public_pkg_deps_name) {
      pkg_deps = invoker.public_pkg_deps
    }
  }
  if (defined(invoker.all_dependent_pkg_deps) &&
      invoker.all_dependent_pkg_deps != []) {
    _all_dependent_pkg_deps_name =
        "_${target_name}-all_dependent_pkg_deps-config"
    pkg_config(_all_dependent_pkg_deps_name) {
      pkg_deps = invoker.all_dependent_pkg_deps
    }
  }

  if (defined(invoker.install_path)) {
    _install_config_name = "_${target_name}-install_config"
    source_name = invoker.target_name
    if (defined(invoker.output_name)) {
      source_name = invoker.output_name
    }
    source_dir = invoker.root_build_dir
    if (defined(invoker.output_dir)) {
      source_dir = invoker.output_dir
    }
    install_config(_install_config_name) {
      if (defined(invoker.target_type)) {
        type = invoker.target_type
      }
      if (invoker.target_type == "shared_library") {
        sources = [ "${source_dir}/lib/${source_name}.so" ]
      } else if (invoker.target_type == "static_library") {
        sources = [ "${source_dir}/${source_name}.a" ]
      } else {
        sources = [ "${source_dir}/${source_name}" ]
      }
      install_path = invoker.install_path
    }
  }

  target(invoker.target_type, target_name) {
    forward_variables_from(invoker,
                           "*",
                           [
                             "all_dependent_pkg_deps",
                             "install_path",
                             "metadata",
                             "pkg_deps",
                             "public_pkg_deps",
                             "run_test",
                             "target_type",
                             "test_config",
                           ])
    if (defined(_pkg_deps_name)) {
      if (!defined(configs)) {
        configs = []
      }
      configs += [ ":${_pkg_deps_name}" ]
    }
    if (defined(_public_pkg_deps_name)) {
      if (!defined(public_configs)) {
        public_configs = []
      }
      public_configs += [ ":${_public_pkg_deps_name}" ]
    }
    if (defined(_all_dependent_pkg_deps_name)) {
      if (!defined(all_dependent_configs)) {
        all_dependent_configs = []
      }
      all_dependent_configs += [ ":${_all_dependent_pkg_deps_name}" ]
    }
    if (defined(_install_config_name)) {
      # Add deps to have install_config rule joined to the dependency chain.
      # The dependency direction is opposite to the real information flow, but
      # it does not matter here because the installation is done in the
      # src_install ebuild phase after all build is finished.
      if (!defined(deps)) {
        deps = []
      }
      deps += [ ":${_install_config_name}" ]
    }
    _run_test = defined(invoker.run_test) && invoker.run_test
    if (defined(invoker.metadata) || _run_test) {
      metadata = {
        if (defined(invoker.metadata)) {
          forward_variables_from(invoker.metadata, "*")
        }
        if (_run_test) {
          _run_test = [ true ]
          if (defined(invoker.test_config)) {
            _test_config = [ invoker.test_config ]
          }
        }
      }
    }
  }
}

# Add variables for exporting install configs of files generated by action targets.
#
# install_configs:
#   Optional list of scopes that specify installation configuration.
#   Each scope can contain these values:
#     path: Install destination.
#     files: Optional list of files to be installed.
#            This should be a subset of outputs.
#            When this is omitted, the enclosing install_configs can have only
#            one item, and all the files in the outputs are installed.
#     options: Optional string. Specifies the insopts.
template("action") {
  if (defined(invoker.install_configs)) {
    _installs = []
    _i = 0
    _all_files = false
    foreach(c, invoker.install_configs) {
      _install_config_name = "_${target_name}-${_i}-install_config"
      install_config(_install_config_name) {
        if (defined(c.files)) {
          sources = c.files
        } else {
          sources = invoker.outputs
        }
        install_path = c.path
        if (defined(c.options)) {
          options = c.options
        }
      }
      _installs += [ ":${_install_config_name}" ]
      _i = _i + 1
      if (!defined(c.files)) {
        _all_files = true
      }
    }

    # _i here is the length of invoker.intall_configs.
    # Note that GN does not provide a function to get a list length.
    assert(
        _i == 1 || !_all_files,
        "|install_configs| should have only one entry when |files| is omitted inside it.")
  }
  action(target_name) {
    forward_variables_from(invoker, "*", [ "install_configs" ])
    if (defined(_installs)) {
      # Add deps so that data export is added to the dependency chain.
      # See the comments in _generate_config_rule.
      if (!defined(deps)) {
        deps = []
      }
      deps += _installs
    }
  }
}

template("executable") {
  _generate_config_rule(target_name) {
    forward_variables_from(invoker, "*")
    target_type = "executable"
  }
}

template("shared_library") {
  _generate_config_rule(target_name) {
    forward_variables_from(invoker, "*")
    target_type = "shared_library"
  }
}

template("source_set") {
  _generate_config_rule(target_name) {
    forward_variables_from(invoker, "*")
    target_type = "source_set"
  }
}

template("static_library") {
  _generate_config_rule(target_name) {
    forward_variables_from(invoker, "*")
    target_type = "static_library"
  }
}