# Copyright 2019 The Pigweed Authors
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.

import("//build_overrides/pigweed.gni")

import("$dir_pw_build/python_action.gni")
import("$dir_pw_build/target_types.gni")

declare_args() {
  # Path to a test runner to automatically run unit tests after they are built.
  #
  # If set, a ``pw_test`` target's ``<target_name>.run`` action will invoke the
  # test runner specified by this argument, passing the path to the unit test to
  # run. If this is unset, the ``pw_test`` target's ``<target_name>.run`` step
  # will do nothing.
  #
  # Targets that don't support parallelized execution of tests (e.g. a on-device
  # test runner that must flash a device and run the test in serial) should
  # set pw_unit_test_POOL_DEPTH to 1.
  #
  # Type: string (name of an executable on the PATH, or path to an executable)
  # Usage: toolchain-controlled only
  pw_unit_test_AUTOMATIC_RUNNER = ""

  # Additional dependencies required by all unit test targets. (For example, if
  # using a different test library like Googletest.)
  #
  # Type: list of strings (list of dependencies as GN paths)
  # Usage: toolchain-controlled only
  pw_unit_test_PUBLIC_DEPS = []

  # Implementation of a main function for ``pw_test`` unit test binaries.
  #
  # Type: string (GN path to a source set)
  # Usage: toolchain-controlled only
  pw_unit_test_MAIN = "$dir_pw_unit_test:simple_printing_main"

  # The maximum number of unit tests that may be run concurrently for the
  # current toolchain. Setting this to 0 disables usage of a pool, allowing
  # unlimited parallelization.
  #
  # Note: A single target with two toolchain configurations (e.g. release/debug)
  #       will use two separate test runner pools by default. Set
  #       pw_unit_test_POOL_TOOLCHAIN to the same toolchain for both targets to
  #       merge the pools and force serialization.
  #
  # Type: integer
  # Usage: toolchain-controlled only
  pw_unit_test_POOL_DEPTH = 0

  # The toolchain to use when referring to the pw_unit_test runner pool. When
  # this is disabled, the current toolchain is used. This means that every
  # toolchain will use its own pool definition. If two toolchains should share
  # the same pool, this argument should be by one of the toolchains to the GN
  # path of the other toolchain.
  #
  # Type: string (GN path to a toolchain)
  # Usage: toolchain-controlled only
  pw_unit_test_POOL_TOOLCHAIN = ""
}

# Defines a target if enable_if is true. Otherwise, it defines that target as
# <target_name>.DISABLED and creates an empty <target_name> group. This can be
# used to conditionally create targets without having to conditionally add them
# to groups. This results in simpler BUILD.gn files.
template("_pw_disableable_target") {
  assert(defined(invoker.enable_if),
         "`enable_if` is required for _pw_disableable_target")
  assert(defined(invoker.target_type),
         "`target_type` is required for _pw_disableable_target")

  if (invoker.enable_if) {
    _actual_target_name = target_name
  } else {
    _actual_target_name = target_name + ".DISABLED"

    # If the target is disabled, create an empty target in its place. Use an
    # action with the original target's sources as inputs to ensure that
    # the source files exist (even if they don't compile).
    pw_python_action(target_name) {
      script = "$dir_pw_build/py/pw_build/nop.py"
      stamp = true

      inputs = []
      if (defined(invoker.sources)) {
        inputs += invoker.sources
      }
      if (defined(invoker.public)) {
        inputs += invoker.public
      }
    }
  }

  target(invoker.target_type, _actual_target_name) {
    forward_variables_from(invoker,
                           "*",
                           [
                             "enable_if",
                             "target_type",
                           ])

    # Remove "" from dependencies. This allows disabling targets if a variable
    # (e.g. a backend) is empty.
    if (defined(public_deps)) {
      public_deps += [ "" ]
      public_deps -= [ "" ]
    }
    if (defined(deps)) {
      deps += [ "" ]
      deps -= [ "" ]
    }
  }
}

# Creates a library and an executable target for a unit test.
#
# <target_name>.lib contains the provided test sources as a library, which can
# then be linked into a test executable.
# <target_name> is a standalone executable which contains only the test sources
# specified in the pw_unit_test_template.
#
# If the pw_unit_test_AUTOMATIC_RUNNER variable is set, this template also creates a
# "${test_name}.run" target which runs the unit test executable after building
# it.
#
# Args:
#   - enable_if: (optional) Conditionally enables or disables this test. The test
#         target and *.run target do nothing when the test is disabled. The
#         disabled test can still be built and run with the
#         <target_name>.DISABLED and <target_name>.DISABLED.run targets.
#         Defaults to true (enable_if).
#   - All of the regular "executable" target args are accepted.
template("pw_test") {
  # This is required in order to reference the pw_test template's target name
  # within the test_metadata of the metadata group below. The group() definition
  # creates a new scope where the "target_name" variable is set to its target,
  # shadowing the one in this scope.
  _test_target_name = target_name

  _test_is_enabled = !defined(invoker.enable_if) || invoker.enable_if

  # Always set the output_dir as pigweed is not compatible with shared
  # bin directories for tests.
  _test_output_dir = "${target_out_dir}/test"
  if (defined(invoker.output_dir)) {
    _test_output_dir = invoker.output_dir
  }

  _test_main = pw_unit_test_MAIN
  if (defined(invoker.test_main)) {
    _test_main = invoker.test_main
  }

  # The unit test code as a source_set.
  _pw_disableable_target("$target_name.lib") {
    target_type = "pw_source_set"
    enable_if = _test_is_enabled
    forward_variables_from(invoker, "*", [ "metadata" ])

    if (!defined(public_deps)) {
      public_deps = []
    }
    public_deps += pw_unit_test_PUBLIC_DEPS + [ dir_pw_unit_test ]
  }

  _pw_disableable_target(_test_target_name) {
    target_type = "pw_executable"
    enable_if = _test_is_enabled

    # Metadata for this test when used as part of a pw_test_group target.
    metadata = {
      tests = [
        {
          type = "test"
          test_name = _test_target_name
          test_directory = rebase_path(_test_output_dir, root_build_dir)
        },
      ]
    }

    deps = [ ":$_test_target_name.lib" ]
    if (_test_main != "") {
      deps += [ _test_main ]
    }

    output_dir = _test_output_dir
  }

  if (pw_unit_test_AUTOMATIC_RUNNER != "") {
    # When the automatic runner is set, create an action which runs the unit
    # test executable using the test runner script.
    if (_test_is_enabled) {
      _test_to_run = _test_target_name
    } else {
      # Create a run target for the .DISABLED version of the test.
      _test_to_run = _test_target_name + ".DISABLED"

      # Create a placeholder _run target for the regular version of the test.
      group(_test_target_name + ".run") {
        deps = [ ":$_test_target_name" ]
      }
    }

    pw_python_action(_test_to_run + ".run") {
      # Optionally limit max test runner concurrency.
      if (pw_unit_test_POOL_DEPTH != 0) {
        _pool_toolchain = current_toolchain
        if (pw_unit_test_POOL_TOOLCHAIN != "") {
          _pool_toolchain = pw_unit_test_POOL_TOOLCHAIN
        }
        pool = "$dir_pw_unit_test:unit_test_pool($_pool_toolchain)"
      }

      deps = [ ":$_test_target_name" ]
      inputs = [ pw_unit_test_AUTOMATIC_RUNNER ]
      script = "$dir_pw_unit_test/py/pw_unit_test/test_runner.py"
      python_deps = [ "$dir_pw_cli/py" ]
      args = [
        "--runner",
        rebase_path(pw_unit_test_AUTOMATIC_RUNNER, root_build_dir),
        "--test",
        "<TARGET_FILE(:$_test_to_run)>",
      ]
      stamp = true
    }

    # TODO(frolv): Alias for the deprecated _run target. Remove when projects
    # are migrated.
    group(_test_to_run + "_run") {
      public_deps = [ ":$_test_to_run.run" ]
    }
  } else {
    group(_test_target_name + ".run") {
    }
  }
}

# Defines a related collection of unit tests.
#
# pw_test_group targets output a JSON metadata file for the Pigweed test runner.
#
# Args:
#   - tests: List of pw_test targets for each of the tests in the group.
#   - group_deps: (optional) pw_test_group targets on which this group depends.
#   - enable_if: (optional) Conditionally enables or disables this test group.
#         If false, an empty group is created. Defaults to true.
template("pw_test_group") {
  _group_target = target_name
  _group_deps_metadata = []
  if (defined(invoker.tests)) {
    _deps = invoker.tests
  } else {
    _deps = []
  }

  _group_is_enabled = !defined(invoker.enable_if) || invoker.enable_if

  if (_group_is_enabled) {
    if (defined(invoker.group_deps)) {
      # If the group specified any other group dependencies, create a metadata
      # entry for each of them indicating that they are another group and a
      # group target to collect that metadata.
      foreach(dep, invoker.group_deps) {
        _group_deps_metadata += [
          {
            type = "dep"
            group = get_label_info(dep, "label_no_toolchain")
          },
        ]
      }

      _deps += invoker.group_deps
    }

    group(_group_target + ".lib") {
      deps = []
      foreach(_target, _deps) {
        _dep_target = get_label_info(_target, "label_no_toolchain")
        _dep_toolchain = get_label_info(_target, "toolchain")
        deps += [ "$_dep_target.lib($_dep_toolchain)" ]
      }
    }

    _metadata_group_target = "${target_name}_pw_test_group_metadata"
    group(_metadata_group_target) {
      metadata = {
        group_deps = _group_deps_metadata
        self = [
          {
            type = "self"
            name = get_label_info(":$_group_target", "label_no_toolchain")
          },
        ]

        # Metadata from the group's own unit test targets is forwarded through
        # the group dependencies group. This entry is listed as a "walk_key" in
        # the generated file so that only test targets' metadata (not group
        # targets) appear in the output.
        if (defined(invoker.tests)) {
          propagate_metadata_from = invoker.tests
        }
      }
      deps = _deps
    }

    _test_group_deps = [ ":$_metadata_group_target" ]

    generated_file(_group_target) {
      outputs = [ "$target_out_dir/$target_name.testinfo.json" ]
      data_keys = [
        "group_deps",
        "self",
        "tests",
      ]
      walk_keys = [ "propagate_metadata_from" ]
      output_conversion = "json"
      deps = _test_group_deps
    }

    # If automatic test running is enabled, create a *.run group that collects
    # all of the individual *.run targets and groups.
    if (pw_unit_test_AUTOMATIC_RUNNER != "") {
      group(_group_target + ".run") {
        deps = [ ":$_group_target" ]
        foreach(_target, _deps) {
          _dep_target = get_label_info(_target, "label_no_toolchain")
          _dep_toolchain = get_label_info(_target, "toolchain")
          deps += [ "$_dep_target.run($_dep_toolchain)" ]
        }
      }

      # TODO(frolv): Remove this deprecated alias.
      group(_group_target + "_run") {
        deps = [ ":$_group_target.run" ]
      }
    }
  } else {  # _group_is_enabled
    # Create empty groups for the tests to avoid pulling in any dependencies.
    group(_group_target) {
    }
    group(_group_target + ".lib") {
    }

    if (pw_unit_test_AUTOMATIC_RUNNER != "") {
      group(_group_target + ".run") {
      }

      # TODO(frolv): Remove this deprecated alias.
      group(_group_target + "_run") {
      }
    }

    not_needed("*")
    not_needed(invoker, "*")
  }

  # All of the tests in this group and its dependencies bundled into a single
  # test binary.
  pw_test(_group_target + ".bundle") {
    deps = [ ":$_group_target.lib" ]
    enable_if = _group_is_enabled
  }
}