# Copyright 2023 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/compiler.gni")
import("//build/python/python_action.gni")
import("//build/sdk/config.gni")
import("//build/toolchain/rbe.gni")
import("//sdk/config.gni")

# Create a GN directory, and build an `sdk_collection` target for a particular
# target_cpu and api_level by calling `gn gen` and then `ninja` in that
# directory.
template("_subbuild") {
  assert(defined(invoker.sdk_collection))
  assert(defined(invoker.target_cpu))
  assert(defined(invoker.api_level))
  assert(defined(invoker.extra_deps))

  _build_dir = root_build_dir + "/build-${target_name}"
  _build_dir_stamp = _build_dir + ".stamp"

  _sdk_collection_dir = get_label_info(invoker.sdk_collection, "dir")
  _sdk_collection_name = get_label_info(invoker.sdk_collection, "name")
  _sdk_collection = "${_sdk_collection_dir}:${_sdk_collection_name}"

  _collection_dir = _build_dir + "/sdk/exported/${_sdk_collection_name}"
  _collection_dir_manifest = "${_collection_dir}/meta/manifest.json"

  action(target_name) {
    script = "//build/sdk/subbuild.py"
    outputs = [
      _build_dir_stamp,
      _collection_dir_manifest,
    ]

    # //sdk:idk_build_tools contains the host tools that must be used in the
    # subbuilds. Make sure those (and any extra deps) are built first.
    deps = [ "//sdk:idk_build_tools" ] + invoker.extra_deps

    args = [
      "--stamp-file",
      rebase_path(_build_dir_stamp, root_build_dir),
      "--sdk-id",
      sdk_id,
      "--output-build-dir",
      rebase_path(_build_dir, root_build_dir),

      "--sdk-collection-label",
      _sdk_collection,
      "--target-cpu",
      invoker.target_cpu,
      "--api-level",
      invoker.api_level,

      "--fuchsia-dir",
      rebase_path("//", root_build_dir),
      "--prebuilt-host-tools-dir",
      rebase_path("$root_build_dir/sdk/idk_build_tools", _build_dir),
      "--compress-debuginfo",
      compress_debuginfo,
    ]

    if (sdk_sub_build_parallelism != "") {
      args += [
        "--parallelism",
        "${sdk_sub_build_parallelism}",
      ]
    }
    if (sdk_sub_build_max_load_average != "") {
      args += [
        "--max-load-average",
        "${sdk_sub_build_max_load_average}",
      ]
    }
    if (sdk_sub_build_verbose) {
      args += [ "--verbose" ]
    }

    if (cxx_rbe_enable) {
      args += [ "--cxx-rbe-enable" ]
    }
    if (rust_rbe_enable) {
      args += [ "--rust-rbe-enable" ]
    }

    pool = "//sdk:subbuild_pool"

    # This script cannot be hermetic.
    hermetic_deps = false

    forward_variables_from(invoker,
                           [
                             "testonly",
                             "visibility",
                           ])
  }
}

# Generate a IDK directory, which combines outputs from different arch-specific
# sub-builds into a single one. The generated directory will include prebuilts
# for all the given `target_cpus`. On a host Linux machine, the generated
# archive will have host tools for both Linux/x64 and Linux/arm64.
#
# The generated directory will go into
# $root_build_dir/sdk/exported/{output_name}
#
# Arguments:
#    target_cpus: (required)
#      List of target cpu names. This must include the default target_cpu
#      value for the current build configuration.
#
#    api_levels: (required)
#      List of API levels, as integers, to build prebuilts for, in addition to
#      the current (HEAD) one.
#
#    sdk_collection_label: (required)
#      A single label for an sdk_collection() GN target that will be built
#      multiple times and merged into the final directory.
#
#    output_name: (optional)
#      Name of the directory. Default is target_name
#
#    testonly, visibility
#      Usual GN meaning.
#
template("idk") {
  assert(defined(invoker.target_cpus),
         "target_cpus must be defined for $target_name")
  assert(defined(invoker.api_levels),
         "api_levels must be defined for $target_name")
  assert(defined(invoker.sdk_collection_label),
         "sdk_collection_label must be defined for $target_name")

  # Default output name.
  _output_name = target_name
  if (defined(invoker.output_name)) {
    _output_name = invoker.output_name
  }

  _non_current_cpus = invoker.target_cpus + [ current_cpu ] - [ current_cpu ]

  assert(
      invoker.target_cpus != _non_current_cpus,
      "The target_cpus argument must include the current target_cpu ($target_cpu): ${invoker.target_cpus}")

  # Do the current CPU first. This may not be necessary, but it's what the old
  # script did and I want a null-diff.
  _target_cpus = [ current_cpu ] + _non_current_cpus

  _exported_dir = root_build_dir + "/sdk/exported/${_output_name}"
  _exported_dir_manifest = "${_exported_dir}/meta/manifest.json"
  _exported_dir_stamp = _exported_dir + ".stamp"

  _sdk_collection_name = get_label_info(invoker.sdk_collection_label, "name")
  _relative_collection_build_manifest = "sdk/manifest/${_sdk_collection_name}"

  # Targets that must be built before producing the final IDK.
  _subbuild_targets = []

  # Build directories for each subbuilds that contribute to the IDK, including
  # the main build. Note that the contents of the IDK are sensitive to the order
  # of this list.
  _subbuild_dirs = []

  # First, do subbuilds for the default API level.
  foreach(target_cpu, _target_cpus) {
    if (target_cpu == current_cpu) {
      # Don't do a subbuild for the current CPU - just depend on the
      # `sdk_collection` in the current build.
      _subbuild_targets += [ invoker.sdk_collection_label ]
      _subbuild_dirs += [ root_build_dir ]
    } else {
      _subbuild_name = "${target_name}.subbuild-${target_cpu}"

      _subbuild(_subbuild_name) {
        sdk_collection = invoker.sdk_collection_label
        target_cpu = target_cpu
        api_level = "PLATFORM"

        # Each subbuild depends on the `sdk_collection` in the main build, so
        # that when a change happens that would cause the `sdk_collection` to be
        # rebuilt, that also triggers the subbuilds to be rerun.
        extra_deps = [ invoker.sdk_collection_label ]

        forward_variables_from(invoker,
                               [
                                 "testonly",
                                 "visibility",
                               ])
      }
      _subbuild_targets += [ ":$_subbuild_name" ]
      _subbuild_dirs += [ "${root_build_dir}/build-${_subbuild_name}" ]
    }
  }

  # Now do them for individual API levels.
  foreach(api_level, invoker.api_levels) {
    foreach(target_cpu, _target_cpus) {
      _subbuild_name = "${target_name}.subbuild-api${api_level}-${target_cpu}"

      _subbuild(_subbuild_name) {
        sdk_collection = invoker.sdk_collection_label
        target_cpu = target_cpu
        api_level = "$api_level"

        # Each subbuild depends on the `sdk_collection` in the main build, so
        # that when a change happens that would cause the `sdk_collection` to be
        # rebuilt, that also triggers the subbuilds to be rerun.
        extra_deps = [ invoker.sdk_collection_label ]

        forward_variables_from(invoker,
                               [
                                 "testonly",
                                 "visibility",
                               ])
      }

      _subbuild_targets += [ ":$_subbuild_name" ]
      _subbuild_dirs += [ "${root_build_dir}/build-${_subbuild_name}" ]
    }
  }

  if (host_cpu == "x64") {
    host_triple_cpu = "x86_64"
  } else if (host_cpu == "arm64") {
    host_triple_cpu = "aarch64"
  } else {
    assert(false, "Unrecognized host CPU: $host_cpu")
  }
  if (host_os == "linux") {
    host_triple_os = "linux-gnu"
  } else if (host_os == "mac") {
    host_triple_os = "apple-darwin"
  } else if (host_os == "fuchsia") {
    host_triple_os = "fuchsia"
  } else {
    assert(false, "Unrecognized host OS: $host_os")
  }
  host_triple = "$host_triple_cpu-$host_triple_os"

  # Combine all the individual sdk_collection subbuilds and put the result in
  # the exported directory.
  python_action(target_name) {
    binary_label = "//build/sdk/generate_idk"

    deps = _subbuild_targets
    outputs = [
      _exported_dir_manifest,
      _exported_dir_stamp,
    ]

    # The exported dir is fully under our control and gets deleted by every
    # invocation of this build rule.
    hermetic_action_ignored_prefixes = [ _exported_dir ]

    depfile = "${target_gen_dir}/${target_name}.d"

    args = []

    foreach(dir, _subbuild_dirs) {
      args += [
        "--subbuild-directory",
        rebase_path(dir, root_build_dir),
      ]
    }
    args += [
      "--relative-manifest",
      _relative_collection_build_manifest,
      "--output-directory",
      rebase_path(_exported_dir, root_build_dir),
      "--stamp-file",
      rebase_path(_exported_dir_stamp, root_build_dir),
      "--depfile",
      rebase_path(depfile, root_build_dir),
      "--host-arch",
      host_triple,
      "--release-version",
      sdk_id,
    ]

    foreach(cpu, invoker.target_cpus) {
      args += [
        "--target-arch",
        cpu,
      ]
    }

    forward_variables_from(invoker,
                           [
                             "testonly",
                             "visibility",
                           ])
  }
}