pw_build/python.gni

# Copyright 2020 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("$dir_pw_build/input_group.gni")
import("$dir_pw_build/mirror_tree.gni")
import("$dir_pw_build/python_action.gni")

# Python packages provide the following targets as $target_name.$subtarget.
pw_python_package_subtargets = [
  "tests",
  "lint",
  "lint.mypy",
  "lint.pylint",
  "install",
  "wheel",
]

# Defines a Python package. GN Python packages contain several GN targets:
#
#   - $name - Provides the Python files in the build, but does not take any
#         actions. All subtargets depend on this target.
#   - $name.lint - Runs static analyis tools on the Python code. This is a group
#     of two subtargets:
#     - $name.lint.mypy - Runs mypy (if enabled).
#     - $name.lint.pylint - Runs pylint (if enabled).
#   - $name.tests - Runs all tests for this package.
#   - $name.install - Installs the package in a venv.
#   - $name.wheel - Builds a Python wheel for the package. (Not implemented.)
#
# All Python packages are instantiated with the default toolchain, regardless of
# the current toolchain.
#
# TODO(pwbug/239): Implement wheel building.
#
# Args:
#   setup: List of setup file paths (setup.py or pyproject.toml & setup.cfg),
#       which must all be in the same directory.
#   generate_setup: As an alternative to 'setup', generate setup files with the
#       keywords in this scope. 'name' is required.
#   sources: Python sources files in the package.
#   tests: Test files for this Python package.
#   python_deps: Dependencies on other pw_python_packages in the GN build.
#   python_test_deps: Test-only pw_python_package dependencies.
#   other_deps: Dependencies on GN targets that are not pw_python_packages.
#   inputs: Other files to track, such as package_data.
#   proto_library: A pw_proto_library target to embed in this Python package.
#       generate_setup is required in place of setup if proto_library is used.
#   lint: If true (default), applies mypy and pylint to the package. If false,
#       does not.
#   pylintrc: Optional path to a pylintrc configuration file to use. If not
#       provided, Pylint's default rcfile search is used. Pylint is executed
#       from the package's setup directory, so pylintrc files in that directory
#       will take precedence over others.
#   mypy_ini: Optional path to a mypy configuration file to use. If not
#       provided, mypy's default configuration file search is used. mypy is
#       executed from the package's setup directory, so mypy.ini files in that
#       directory will take precedence over others.
template("pw_python_package") {
  # The Python targets are always instantiated in the default toolchain. Use
  # fully qualified labels so that the toolchain is not lost.
  _other_deps = []
  if (defined(invoker.other_deps)) {
    foreach(dep, invoker.other_deps) {
      _other_deps += [ get_label_info(dep, "label_with_toolchain") ]
    }
  }

  _python_deps = []
  if (defined(invoker.python_deps)) {
    foreach(dep, invoker.python_deps) {
      _python_deps += [ get_label_info(dep, "label_with_toolchain") ]
    }
  }

  # pw_python_script uses pw_python_package, but with a limited set of features.
  # _pw_standalone signals that this target is actually a pw_python_script.
  _is_package = !(defined(invoker._pw_standalone) && invoker._pw_standalone)

  _generate_package = false

  # Check the generate_setup and import_protos args to determine if this package
  # is generated.
  if (_is_package) {
    assert(defined(invoker.generate_setup) != defined(invoker.setup),
           "Either 'setup' or 'generate_setup' (but not both) must provided")

    if (defined(invoker.proto_library)) {
      assert(invoker.proto_library != "", "'proto_library' cannot be empty")
      assert(defined(invoker.generate_setup),
             "Python packages that import protos with 'proto_library' must " +
                 "use 'generate_setup' instead of 'setup'")

      _import_protos = [ invoker.proto_library ]
    } else if (defined(invoker.generate_setup)) {
      _import_protos = []
    }

    if (defined(invoker.generate_setup)) {
      _generate_package = true
      _setup_dir = "$target_gen_dir/$target_name.generated_python_package"

      if (defined(invoker.strip_prefix)) {
        _source_root = invoker.strip_prefix
      } else {
        _source_root = "."
      }
    } else {
      # Non-generated packages with sources provided need an __init__.py.
      assert(!defined(invoker.sources) || invoker.sources == [] ||
                 filter_include(invoker.sources, [ "*\b__init__.py" ]) != [],
             "Python packages must have at least one __init__.py file")

      # Get the directories of the setup files. All must be in the same dir.
      _setup_dirs = get_path_info(invoker.setup, "dir")
      _setup_dir = _setup_dirs[0]

      foreach(dir, _setup_dirs) {
        assert(dir == _setup_dir,
               "All files in 'setup' must be in the same directory")
      }

      assert(!defined(invoker.strip_prefix),
             "'strip_prefix' may only be given if 'generate_setup' is provided")
    }
  }

  # Process arguments defaults and set defaults.

  # Argument: lint (bool); default = true.
  if (defined(invoker.lint)) {
    _should_lint = invoker.lint
  } else {
    _should_lint = true
  }

  # Argument: sources (list)
  _sources = []
  if (defined(invoker.sources)) {
    if (_generate_package) {
      foreach(source, rebase_path(invoker.sources, _source_root)) {
        _sources += [ "$_setup_dir/$source" ]
      }
    } else {
      _sources += invoker.sources
    }
  }

  # Argument: tests (list)
  _test_sources = []
  if (defined(invoker.tests)) {
    if (_generate_package) {
      foreach(source, rebase_path(invoker.tests, _source_root)) {
        _test_sources += [ "$_setup_dir/$source" ]
      }
    } else {
      _test_sources += invoker.tests
    }
  }

  # Argument: setup (list)
  _setup_sources = []
  if (defined(invoker.setup)) {
    _setup_sources = invoker.setup
  } else if (_generate_package) {
    _setup_sources = [ "$_setup_dir/setup.py" ]
  }

  # Argument: python_test_deps (list)
  _python_test_deps = _python_deps  # include all deps in test deps
  if (defined(invoker.python_test_deps)) {
    foreach(dep, invoker.python_test_deps) {
      _python_test_deps += [ get_label_info(dep, "label_with_toolchain") ]
    }
  }

  if (_test_sources == []) {
    assert(!defined(invoker.python_test_deps),
           "python_test_deps was provided, but there are no tests in " +
               get_label_info(":$target_name", "label_no_toolchain"))
    not_needed([ "_python_test_deps" ])
  }

  _all_py_files = _sources + _test_sources + _setup_sources

  # The pw_python_package subtargets are only instantiated in the default
  # toolchain. Other toolchains just refer to targets in the default toolchain.
  if (current_toolchain == default_toolchain) {
    # Declare the main Python package group. This represents the Python files,
    # but does not take any actions. GN targets can depend on the package name
    # to run when any files in the package change.
    if (_generate_package) {
      # If this package is generated, mirror the sources to the final directory.
      pw_mirror_tree("$target_name._mirror_sources_to_out_dir") {
        directory = _setup_dir

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

        source_root = _source_root
        public_deps = _python_deps + _other_deps
      }

      # Depend on the proto's _gen targets (from the default toolchain).
      _gen_protos = []
      foreach(proto, _import_protos) {
        _gen_protos +=
            [ get_label_info(proto, "label_no_toolchain") + ".python._gen" ]
      }

      generated_file("$target_name._protos") {
        deps = _gen_protos
        data_keys = [ "protoc_outputs" ]
        outputs = [ "$_setup_dir/protos.txt" ]
      }

      _protos_file = get_target_outputs(":${invoker.target_name}._protos")

      generated_file("$target_name._protos_root") {
        deps = _gen_protos
        data_keys = [ "root" ]
        outputs = [ "$_setup_dir/proto_root.txt" ]
      }

      _root_file = get_target_outputs(":${invoker.target_name}._protos_root")

      # Get generated_setup scope and write it to disk ask JSON.
      _gen_setup = invoker.generate_setup
      assert(defined(_gen_setup.name), "'name' is required in generate_package")
      assert(!defined(_gen_setup.packages) && !defined(_gen_setup.package_data),
             "'packages' and 'package_data' may not be provided " +
                 "in 'generate_package'")
      write_file("$_setup_dir/setup.json", _gen_setup, "json")

      # Generate the setup.py, py.typed, and __init__.py files as needed.
      action(target_name) {
        script = "$dir_pw_build/py/pw_build/generate_python_package.py"
        args = [
                 "--label",
                 get_label_info(":$target_name", "label_no_toolchain"),
                 "--root",
                 rebase_path(_setup_dir),
                 "--setup-json",
                 rebase_path("$_setup_dir/setup.json"),
                 "--file-list",
                 rebase_path(_protos_file[0]),
                 "--file-list-root",
                 rebase_path(_root_file[0]),
               ] + rebase_path(_sources)

        if (defined(invoker._pw_module_as_package) &&
            invoker._pw_module_as_package) {
          args += [ "--module-as-package" ]
        }

        public_deps = [
          ":$target_name._mirror_sources_to_out_dir",
          ":$target_name._protos",
          ":$target_name._protos_root",
        ]

        foreach(proto, _import_protos) {
          _tgt = get_label_info(proto, "label_no_toolchain")
          _path = get_label_info("$_tgt($default_toolchain)", "target_gen_dir")
          _name = get_label_info(_tgt, "name")

          args += [
            "--proto-library=$_tgt",
            "--proto-library-file",
            rebase_path("$_path/$_name.proto_library/python_package.txt"),
          ]

          public_deps += [ "$_tgt.python._gen($default_toolchain)" ]
        }

        outputs = _setup_sources
      }
    } else {
      # If the package is not generated, use an input group for the sources.
      pw_input_group(target_name) {
        inputs = _all_py_files
        if (defined(invoker.inputs)) {
          inputs += invoker.inputs
        }

        deps = _python_deps + _other_deps
      }
    }

    if (_is_package) {
      # Install this Python package and its dependencies in the current Python
      # environment.
      pw_python_action("$target_name.install") {
        module = "pip"
        public_deps = []

        args = [ "install" ]

        # For generated packages, reinstall when any files change. For regular
        # packages, only reinstall when setup.py changes.
        if (_generate_package) {
          public_deps += [ ":${invoker.target_name}" ]
        } else {
          inputs = invoker.setup

          # Install with --editable since the complete package is in source.
          args += [ "--editable" ]
        }

        args += [ rebase_path(_setup_dir) ]

        stamp = true

        # Parallel pip installations don't work, so serialize pip invocations.
        pool = "$dir_pw_build:pip_pool"

        foreach(dep, _python_deps) {
          # We need to add a suffix to the target name, but the label is
          # formatted as "//path/to:target(toolchain)", so we can't just append
          # ".subtarget". Instead, we replace the opening parenthesis of the
          # toolchain with ".suffix(".
          public_deps += [ string_replace(dep, "(", ".install(") ]
        }
      }

      # TODO(pwbug/239): Add support for building groups of wheels. The code below
      #     is incomplete and untested.
      pw_python_action("$target_name.wheel") {
        script = "$dir_pw_build/py/pw_build/python_wheels.py"

        args = [
          "--out_dir",
          rebase_path(target_out_dir),
        ]
        args += rebase_path(_all_py_files)

        deps = [ ":${invoker.target_name}.install" ]
        stamp = true
      }
    } else {
      # If this is not a package, install or build wheels for its deps only.
      group("$target_name.install") {
        deps = []
        foreach(dep, _python_deps) {
          deps += [ string_replace(dep, "(", ".install(") ]
        }
      }
      group("$target_name.wheel") {
        deps = []
        foreach(dep, _python_deps) {
          deps += [ string_replace(dep, "(", ".wheel(") ]
        }
      }
    }

    # Define the static analysis targets for this package.
    group("$target_name.lint") {
      deps = [
        ":${invoker.target_name}.lint.mypy",
        ":${invoker.target_name}.lint.pylint",
      ]
    }

    if (_should_lint || _test_sources != []) {
      # All packages to install for either general use or test running.
      _test_install_deps = [ ":$target_name.install" ]
      foreach(dep, _python_test_deps + [ "$dir_pw_build:python_lint" ]) {
        _test_install_deps += [ string_replace(dep, "(", ".install(") ]
      }
    }

    # For packages that are not generated, create targets to run mypy and pylint.
    if (_should_lint) {
      # Run lint tools from the setup or target directory so that the tools detect
      # config files (e.g. pylintrc or mypy.ini) in that directory. Config files
      # may be explicitly specified with the pylintrc or mypy_ini arguments.
      if (defined(_setup_dir)) {
        _lint_directory = rebase_path(_setup_dir)
      } else {
        _lint_directory = rebase_path(".")
      }

      pw_python_action("$target_name.lint.mypy") {
        module = "mypy"
        args = [
          "--pretty",
          "--show-error-codes",
        ]

        if (defined(invoker.mypy_ini)) {
          args += [ "--config-file=" + rebase_path(invoker.mypy_ini) ]
          inputs = [ invoker.mypy_ini ]
        }

        args += rebase_path(_all_py_files)

        # Use this environment variable to force mypy to colorize output.
        # See https://github.com/python/mypy/issues/7771
        environment = [ "MYPY_FORCE_COLOR=1" ]

        directory = _lint_directory
        stamp = true

        deps = _test_install_deps

        foreach(dep, _python_test_deps) {
          deps += [ string_replace(dep, "(", ".lint.mypy(") ]
        }
      }

      # Create a target to run pylint on each of the Python files in this
      # package and its dependencies.
      pw_python_action_foreach("$target_name.lint.pylint") {
        module = "pylint"
        args = [
          rebase_path(".") + "/{{source_target_relative}}",
          "--jobs=1",
          "--output-format=colorized",
        ]

        if (defined(invoker.pylintrc)) {
          args += [ "--rcfile=" + rebase_path(invoker.pylintrc) ]
          inputs = [ invoker.pylintrc ]
        }

        if (host_os == "win") {
          # Allow CRLF on Windows, in case Git is set to switch line endings.
          args += [ "--disable=unexpected-line-ending-format" ]
        }

        sources = _all_py_files

        directory = _lint_directory
        stamp = "$target_gen_dir/{{source_target_relative}}.pylint.passed"

        public_deps = _test_install_deps

        foreach(dep, _python_test_deps) {
          public_deps += [ string_replace(dep, "(", ".lint.pylint(") ]
        }
      }
    } else {
      pw_input_group("$target_name.lint.mypy") {
        if (defined(invoker.pylintrc)) {
          inputs = [ invoker.pylintrc ]
        }
      }
      pw_input_group("$target_name.lint.pylint") {
        if (defined(invoker.mypy_ini)) {
          inputs = [ invoker.mypy_ini ]
        }
      }
    }
  } else {
    # Create groups with the public target names ($target_name, $target_name.lint,
    # $target_name.install, etc.). These are actually wrappers around internal
    # Python actions instantiated with the default toolchain. This ensures there
    # is only a single copy of each Python action in the build.
    #
    # The $target_name.tests group is created separately below.
    group("$target_name") {
      deps = [ ":$target_name($default_toolchain)" ]
    }

    foreach(subtarget, pw_python_package_subtargets - [ "tests" ]) {
      group("$target_name.$subtarget") {
        deps = [ ":${invoker.target_name}.$subtarget($default_toolchain)" ]
      }
    }

    # Everything Python-related is only instantiated in the default toolchain.
    # Silence not-needed warnings except for in the default toolchain.
    not_needed("*")
    not_needed(invoker, "*")
  }

  # Create a target for each test file.
  _test_targets = []

  foreach(test, _test_sources) {
    if (_is_package) {
      _name = rebase_path(test, _setup_dir)
    } else {
      _name = test
    }

    _test_target = "$target_name.tests." + string_replace(_name, "/", "_")

    if (current_toolchain == default_toolchain) {
      pw_python_action(_test_target) {
        script = test
        stamp = true

        deps = _test_install_deps

        foreach(dep, _python_test_deps) {
          deps += [ string_replace(dep, "(", ".tests(") ]
        }
      }
    } else {
      # Create a public version of each test target, so tests can be executed as
      # //path/to:package.tests.foo.py.
      group(_test_target) {
        deps = [ ":$_test_target($default_toolchain)" ]
      }
    }

    _test_targets += [ ":$_test_target" ]
  }

  group("$target_name.tests") {
    deps = _test_targets
  }
}

# Declares a group of Python packages or other Python groups. pw_python_groups
# expose the same set of subtargets as pw_python_package (e.g.
# "$group_name.lint" and "$group_name.tests"), but these apply to all packages
# in deps and their dependencies.
template("pw_python_group") {
  if (defined(invoker.python_deps)) {
    _python_deps = invoker.python_deps
  } else {
    _python_deps = []
  }

  group(target_name) {
    deps = _python_deps
  }

  foreach(subtarget, pw_python_package_subtargets) {
    group("$target_name.$subtarget") {
      deps = []
      foreach(dep, _python_deps) {
        # Split out the toolchain to support deps with a toolchain specified.
        _target = get_label_info(dep, "label_no_toolchain")
        _toolchain = get_label_info(dep, "toolchain")
        deps += [ "$_target.$subtarget($_toolchain)" ]
      }
    }
  }
}

# Declares Python scripts or tests that are not part of a Python package.
# Similar to pw_python_package, but only supports a subset of its features.
#
# pw_python_script accepts the same arguments as pw_python_package, except
# `setup` cannot be provided.
#
# pw_python_script provides the same subtargets as pw_python_package, but
# $target_name.install and $target_name.wheel only affect the python_deps of
# this GN target, not the target itself.
template("pw_python_script") {
  _supported_variables = [
    "sources",
    "tests",
    "python_deps",
    "other_deps",
    "inputs",
    "pylintrc",
  ]

  pw_python_package(target_name) {
    _pw_standalone = true
    forward_variables_from(invoker, _supported_variables)
  }
}

# Represents a list of Python requirements, as in a requirements.txt.
#
# Args:
#  files: One or more requirements.txt files.
#  requirements: A list of requirements.txt-style requirements.
template("pw_python_requirements") {
  assert(defined(invoker.files) || defined(invoker.requirements),
         "pw_python_requirements requires a list of requirements.txt files " +
             "in the 'files' arg or requirements in 'requirements'")

  _requirements_files = []

  if (defined(invoker.files)) {
    _requirements_files += invoker.files
  }

  if (defined(invoker.requirements)) {
    _requirements_file = "$target_gen_dir/$target_name.requirements.txt"
    write_file(_requirements_file, invoker.requirements)
    _requirements_files += [ _requirements_file ]
  }

  # The default target represents the requirements themselves.
  pw_input_group(target_name) {
    inputs = _requirements_files
  }

  # Use the same subtargets as pw_python_package so these targets can be listed
  # as python_deps of pw_python_packages.
  pw_python_action("$target_name.install") {
    inputs = _requirements_files

    module = "pip"
    args = [ "install" ]

    foreach(_requirements_file, inputs) {
      args += [
        "--requirement",
        rebase_path(_requirements_file),
      ]
    }

    pool = "$dir_pw_build:pip_pool"
    stamp = true
  }

  # Create stubs for the unused subtargets so that pw_python_requirements can be
  # used as python_deps.
  foreach(subtarget, pw_python_package_subtargets - [ "install" ]) {
    group("$target_name.$subtarget") {
    }
  }
}