# Copyright 2019 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("$zx/public/gn/toolchain/environment_redirect.gni")

# Depend on a build host tool.
#
# This defines its target as an environment_redirect() that finds the
# actual target that host_tool_action() would use to run its tool.
#
# Parameters
#
#   tool
#     Required: See host_tool_action().
#
template("host_tool_redirect") {
  # Dispatch to a host toolchain to get the tool built.
  environment_redirect(target_name) {
    forward_variables_from(invoker,
                           [
                             "assert_no_deps",
                             "testonly",
                             "visibility",
                           ])
    environment_label = "$zx/public/gn/toolchain:host"
    cpu = host_cpu
    os = host_os
    direct = true
    deps = [
      invoker.tool,
    ]
  }
}

# Subroutine of host_tool_action() and host_tool_action_foreach().
template("_host_tool_action_target") {
  action_target = target_name
  assert(defined(invoker.tool), "tool must be defined for $target_name")
  assert(defined(invoker.outputs), "outputs must be defined for $target_name")

  tool_target = "_host_tool_action.tool.$action_target"
  rspfile_target = "_host_tool_action.rsp.$action_target"

  host_tool_redirect(tool_target) {
    forward_variables_from(invoker, [ "testonly" ])
    visibility = [
      ":$action_target",
      ":$rspfile_target",
    ]
    tool = invoker.tool
  }

  # The response file generated by host_tool() gives the files used (like
  # the executable itself), then "--", then the arguments that make up the
  # command line prefix to invoke the tool.  host_tool_action.sh consumes that.
  rspfile = "$target_gen_dir/$target_name._host_tool_action.rsp"
  generated_file(rspfile_target) {
    forward_variables_from(invoker, [ "testonly" ])
    visibility = [ ":$action_target" ]
    deps = [
      ":$tool_target",
    ]
    outputs = [
      rspfile,
    ]
    data_keys = [ "host_tool_rspfile" ]
    walk_keys = [ "host_tool_barrier" ]
  }

  target(invoker._target_type, action_target) {
    forward_variables_from(invoker,
                           [
                             "assert_no_deps",
                             "data_deps",
                             "deps",
                             "inputs",
                             "outputs",
                             "public_deps",
                             "sources",
                             "testonly",
                             "visibility",
                           ])
    if (!defined(deps)) {
      deps = []
    }
    if (!defined(inputs)) {
      inputs = []
    }
    deps += [
      ":$rspfile_target",
      ":$tool_target",
    ]
    inputs += [ rspfile ]

    depfile =
        "$target_out_dir/$target_name.{{source_file_part}}._host_tool_action.d"
    if (defined(invoker.depfile)) {
      orig_depfile = rebase_path(invoker.depfile, root_build_dir)
    } else {
      orig_depfile = "-"
    }

    script = "$zx/public/gn/host_tool_action.sh"
    args = rebase_path([
                         rspfile,
                         outputs[0],
                         depfile,
                       ],
                       root_build_dir) + [ orig_depfile ]
    if (defined(invoker.args)) {
      args += invoker.args
    }

    metadata = {
      # This can be used to prune metadata walks that want to treat
      # any sort of action target as an opaque atom.
      action_barrier = []

      # Never follow the deps to find link outputs from invoker.tool.
      # TODO: Maybe should still follow invoker.deps?
      link_barrier = []
      if (defined(invoker.metadata)) {
        forward_variables_from(invoker.metadata, "*")
      }
    }
  }
}

# Run an action() using a host_tool() compiled for the build host.
#
# This takes all the same parameters as action() except that $script is
# replaced by $tool.  See also host_tool_action_foreach().
#
# Parameters
#
#   tool
#     Required: Label (without toolchain) of a host_tool() target.
#     The tool will be built for the build host if necessary, and
#     then run with the $args list just like $script runs in action().
#     Type: label_no_toolchain
#
# Other parameters are as for action().
template("host_tool_action") {
  _host_tool_action_target(target_name) {
    _target_type = "action"
    forward_variables_from(invoker, "*")
  }
}

# Run an action_foreach() using a host_tool() compiled for the build host.
#
# This takes all the same parameters as action_foreach() except that
# $script is replaced by $tool.  host_tool_action_foreach() is to as
# action_foreach() as host_tool_action() is to action().
#
# Parameters
#
#   tool
#     Required: Label (without toolchain) of a host_tool() target.
#     The tool will be built for the build host if necessary, and
#     then run with the $args list just like $script runs in action().
#     Type: label_no_toolchain
#
# Other parameters are as for action_foreach().
template("host_tool_action_foreach") {
  _host_tool_action_target(target_name) {
    _target_type = "action_foreach"
    forward_variables_from(invoker, "*")
  }
}