# 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/config/clang/clang.gni")
import("//build/toolchain/goma.gni")

_zircon_variants = []
foreach(selector, select_variant) {
  if (selector == "$selector") {
    _zircon_variants += [ selector ]
  }
}

declare_args() {
  # [Zircon GN build arguments](../../../zircon/docs/gen/build_arguments.md).
  # This is included in the default value of [`zircon_args`](#zircon_args) so
  # you can set this to add things there without wiping out the defaults.
  # When you set `zircon_args` directly, then this has no effect at all.
  # Arguments you set here override any arguments in the default
  # `zircon_args`.  There is no way to append to a value from the defaults.
  # Note that for just setting simple (string-only) values in Zircon GN's
  # [`variants`](../../../zircon/docs/gen/build_arguments.md#variants), the
  # default [`zircon_args`](#zircon_args) uses a `variants` value derived from
  # [`select_variant`](#select_variant) so for simple cases there is no need
  # to explicitly set Zircon's `variants` here.
  zircon_extra_args = {
  }

  # Whether to include various features (non-shipping, insecure, etc.) in the
  # kernel build.
  zircon_enable_kernel_debugging_features = false
}

declare_args() {
  # [Zircon GN build arguments](../../../zircon/docs/gen/build_arguments.md).
  # The default passes through GOMA settings and
  # [`select_variant`](#select_variant) shorthand selectors.
  # **Only set this if you want to wipe out all the defaults that
  # propagate from Fuchsia GN to Zircon GN.**  The default value
  # folds in [`zircon_extra_args`](#zircon_extra_args), so usually
  # it's better to just set `zircon_extra_args` and leave `zircon_args` alone.
  # Any individual Zircon build argument set in `zircon_extra_args` will
  # silently clobber the default value shown here.
  zircon_args = {
    use_goma = use_goma
    goma_dir = goma_dir
    if (clang_prefix != default_clang_prefix) {
      # Propagate a custom value to override Zircon's default.  But don't
      # propagate the default because Zircon has proper incremental build
      # dependencies on toolchain updates only if it knows it's using the
      # prebuilt.
      clang_tool_dir = clang_prefix
    }
    variants = _zircon_variants
    default_deps = [ ":legacy-$target_cpu" ]
    enable_kernel_debugging_features = zircon_enable_kernel_debugging_features
    forward_variables_from(zircon_extra_args, "*")
  }
}

# This is $root_build_dir in the Zircon GN build.
# **NOTE!** This is not a subdirectory of $root_build_dir because that
# makes GN insist that it understand where all files in there come from.
# We instead require that users (or `fx build`) run ninja in
# $zircon_root_build_dir before running ninja in $root_build_dir.
zircon_root_build_dir = "${root_build_dir}.zircon"

# The Zircon GN is completely a puppet of this build.  This gen runs that gen.
if (current_toolchain == default_toolchain) {
  # First run Zircon's `gn gen`.  By GN evaluation order this is roughly
  # the first thing that happens at all and it's synchronous so after this
  # point we can read in files written by this gen step.
  exec_script(
      "//buildtools/gn",
      [
        "gen",
        "-q",
        "--root=" + rebase_path("//zircon", root_build_dir),
        "--args=# THIS FILE IS CLOBBERED.  DO NOT EDIT!$0x0a" +
            "# Instead, edit $root_build_dir/args.gn to add$0x0a" +
            "# zircon_args = { ... } to replace the defaults above.$0x0a" +
            "forward_variables_from($zircon_args, \"*\")",
        rebase_path(zircon_root_build_dir, root_build_dir),
      ])

  exec_script("//build/zircon/populate_zircon_public.py",
              [ rebase_path("$zircon_root_build_dir/legacy_dirs.json") ],
              "",
              [ "$zircon_root_build_dir/legacy_dirs.json" ])
}

# The top-level `tools` Ninja target in Zircon puts the tool binaries here.
zircon_tools_dir = "$zircon_root_build_dir/tools"

# The `gn gen` stage of the Zircon GN build writes these files.
# See //build/zircon/template.gn for how they're used.
zircon_legacy_targets =
    read_file("$zircon_root_build_dir/legacy-$target_cpu.json", "json")

# See //zircon/public/sysroot/BUILD.gn and //build/config/fuchsia/BUILD.gn.
zircon_legacy_sysroot =
    read_file("$zircon_root_build_dir/legacy_sysroot-$target_cpu.json", "json")

# The `gn gen` stage of the Zircon GN build writes this file.
# It's a list of {name=... path=... type=...} scopes.
zircon_images = read_file("$zircon_root_build_dir/legacy_images.json", "json")

foreach(image, zircon_images) {
  if (image.name == "kernel" && image.type == "zbi" &&
      image.cpu == target_cpu) {
    zircon_kernel_zbi = "$zircon_root_build_dir/${image.path}"
  }
}

# Template for running a Zircon host tool as part of the build.
# This is a thin wrapper to define an `action()` target.
#
# Parameters
#
#     tool (required)
#         [string] The name of the tool, like "mkbootfs".
#
#     args (required)
#         [list of strings] The arguments to pass the tool.
#         The tool runs with `root_build_dir` as its current directory,
#         so any file names should be made either absolute or relative
#         to `root_build_dir` using `rebase_path()`.
#
# All other parameters are exactly as for `action()`, except
# that `script` is replaced with `tool`.
#
template("zircon_tool_action") {
  assert(defined(invoker.tool), "zircon_tool_action() requires `tool`")
  assert(defined(invoker.args), "zircon_tool_action() requires `args`")
  _tool = "$zircon_tools_dir/${invoker.tool}"
  action(target_name) {
    inputs = []
    forward_variables_from(invoker,
                           [
                             "testonly",
                             "visibility",
                           ])
    forward_variables_from(invoker,
                           "*",
                           [
                             "args",
                             "script",
                             "tool",
                             "testonly",
                             "visibility",
                           ])
    script = "//build/gn_run_binary.sh"
    inputs += [ _tool ]
    args = [
             clang_prefix,
             rebase_path(_tool, root_build_dir),
           ] + invoker.args
  }
}