# Copyright 2022 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")

declare_args() {
  # Path to the Bloaty configuration file that defines the memory layout and
  # capacities for the target binaries.
  pw_bloat_BLOATY_CONFIG = ""

  # List of toolchains to use in pw_toolchain_size_diff templates.
  #
  # Each entry is a scope containing the following variables:
  #
  #   name: Human-readable toolchain name.
  #   target: GN target that defines the toolchain.
  #   linker_script: Optional path to a linker script file to build for the
  #     toolchain's target.
  #   bloaty_config: Optional Bloaty confirugation file defining the memory
  #     layout of the binaries as specified in the linker script.
  #
  # If this list is empty, pw_toolchain_size_diff targets become no-ops.
  pw_bloat_TOOLCHAINS = []

  # Controls whether to display size reports in the build output.
  pw_bloat_SHOW_SIZE_REPORTS = false
}

# Creates a size report for a single binary.
#
# Args:
#   target: Build target for executable. Required.
#
# Example:
#   pw_size_report("foo_bloat") {
#      target = ":foo_static"
#   }
#
template("pw_size_report") {
  if (pw_bloat_BLOATY_CONFIG != "") {
    assert(defined(invoker.target),
           "Size report must defined a 'target' variable")
    _all_target_dependencies = [ invoker.target ]
    _bloat_script_args = [
      "--bloaty-config",
      rebase_path(pw_bloat_BLOATY_CONFIG, root_build_dir),
      "--out-dir",
      rebase_path(target_gen_dir, root_build_dir),
      "--target",
      target_name,
      "--single-target",
      "<TARGET_FILE(${invoker.target})>",
    ]

    if (defined(invoker.source_filter)) {
      _bloat_script_args += [
        "--source-filter",
        invoker.source_filter,
      ]
    }

    _doc_rst_output = "$target_gen_dir/${target_name}"

    if (host_os == "win") {
      # Bloaty is not yet packaged for Windows systems; display a message
      # indicating this.
      not_needed("*")
      not_needed(invoker, "*")

      pw_python_action(target_name) {
        metadata = {
          pw_doc_sources = rebase_path([ _doc_rst_output ], root_build_dir)
        }
        script = "$dir_pw_bloat/py/pw_bloat/no_bloaty.py"
        python_deps = [ "$dir_pw_bloat/py" ]
        args = [ rebase_path(_doc_rst_output, root_build_dir) ]
        outputs = [ _doc_rst_output ]
      }

      group(target_name + "_UNUSED_DEPS") {
        deps = _all_target_dependencies
      }
    } else {
      # Create an action which runs the size report script on the provided
      # targets.
      pw_python_action(target_name) {
        metadata = {
          pw_doc_sources = rebase_path([ _doc_rst_output ], root_build_dir)
        }
        script = "$dir_pw_bloat/py/pw_bloat/bloat.py"
        python_deps = [ "$dir_pw_bloat/py" ]
        inputs = [ pw_bloat_BLOATY_CONFIG ]
        outputs = [
          "${_doc_rst_output}.txt",
          _doc_rst_output,
        ]
        deps = _all_target_dependencies
        args = _bloat_script_args

        # Print size reports to stdout when they are generated, if requested.
        capture_output = !pw_bloat_SHOW_SIZE_REPORTS
      }
    }
  } else {
    not_needed(invoker, "*")
    group(target_name) {
    }
  }
}

# Creates a target which runs a size report diff on a set of executables.
#
# Args:
#   base: The default base executable target to run the diff against. May be
#     omitted if all binaries provide their own base.
#   binaries: List of executables to compare in the diff.
#     Each binary in the list is a scope containing up to three variables:
#       label: Descriptive name for the executable. Required.
#       target: Build target for the executable. Required.
#       base: Optional base diff target. Overrides global base argument.
#   source_filter: Optional regex to filter data source names in Bloaty.
#   title: Optional title string to display with the size report.
#   full_report: Optional boolean flag indicating whether to produce a full
#     symbol size breakdown or a summary.
#
# Example:
#   pw_size_diff("foo_bloat") {
#     base = ":foo_base"
#     binaries = [
#       {
#         target = ":foo_static"
#         label = "Static"
#       },
#       {
#         target = ":foo_dynamic"
#         label = "Dynamic"
#       },
#     ]
#     title = "static vs. dynamic foo"
#   }
#
template("pw_size_diff") {
  if (pw_bloat_BLOATY_CONFIG != "") {
    if (defined(invoker.base)) {
      _global_base = invoker.base
      _all_target_dependencies = [ _global_base ]
    } else {
      _all_target_dependencies = []
    }

    if (defined(invoker.title)) {
      _title = invoker.title
    } else {
      _title = target_name
    }

    # This template creates an action which invokes a Python script to run a
    # size report on each of the provided targets. Each of the targets is listed
    # as a dependency of the action so that the report gets updated when
    # anything is changed. Most of the code below builds the command-line
    # arguments to pass each of the targets into the script.

    _binary_paths = []
    _binary_labels = []
    _bloaty_configs = []

    # Process each of the binaries, resolving their full output paths and
    # building them into a list of command-line arguments to the bloat script.
    foreach(binary, invoker.binaries) {
      assert(defined(binary.label) && defined(binary.target),
             "Size report binaries must define 'label' and 'target' variables")
      _all_target_dependencies += [ binary.target ]

      _binary_path = "<TARGET_FILE(${binary.target})>"

      # If the binary defines its own base, use that instead of the global base.
      if (defined(binary.base)) {
        _binary_base = binary.base
        _all_target_dependencies += [ _binary_base ]
      } else if (defined(_global_base)) {
        _binary_base = _global_base
      } else {
        assert(false, "pw_size_diff requires a 'base' file")
      }

      # Allow each binary to override the global bloaty config.
      if (defined(binary.bloaty_config)) {
        _bloaty_configs += [ binary.bloaty_config ]
      } else {
        _bloaty_configs += [ pw_bloat_BLOATY_CONFIG ]
      }

      _binary_path += ";" + "<TARGET_FILE($_binary_base)>"

      _binary_paths += [ _binary_path ]
      _binary_labels += [ binary.label ]
    }

    _bloat_script_args = [
      "--bloaty-config",
      string_join(";", rebase_path(_bloaty_configs, root_build_dir)),
      "--out-dir",
      rebase_path(target_gen_dir, root_build_dir),
      "--target",
      target_name,
      "--title",
      _title,
      "--labels",
      string_join(";", _binary_labels),
    ]

    if (defined(invoker.full_report) && invoker.full_report) {
      _bloat_script_args += [ "--full" ]
    }

    if (defined(invoker.source_filter)) {
      _bloat_script_args += [
        "--source-filter",
        invoker.source_filter,
      ]
    }

    _doc_rst_output = "$target_gen_dir/${target_name}"

    if (host_os == "win") {
      # Bloaty is not yet packaged for Windows systems; display a message
      # indicating this.
      not_needed("*")
      not_needed(invoker, "*")

      pw_python_action(target_name) {
        metadata = {
          pw_doc_sources = rebase_path([ _doc_rst_output ], root_build_dir)
        }
        script = "$dir_pw_bloat/py/pw_bloat/no_bloaty.py"
        python_deps = [ "$dir_pw_bloat/py" ]
        args = [ rebase_path(_doc_rst_output, root_build_dir) ]
        outputs = [ _doc_rst_output ]
      }

      group(target_name + "_UNUSED_DEPS") {
        deps = _all_target_dependencies
      }
    } else {
      # Create an action which runs the size report script on the provided
      # targets.
      pw_python_action(target_name) {
        metadata = {
          pw_doc_sources = rebase_path([ _doc_rst_output ], root_build_dir)
        }
        script = "$dir_pw_bloat/py/pw_bloat/bloat.py"
        python_deps = [ "$dir_pw_bloat/py" ]
        inputs = _bloaty_configs
        outputs = [
          "${_doc_rst_output}.txt",
          _doc_rst_output,
        ]
        deps = _all_target_dependencies
        args = _bloat_script_args + _binary_paths

        # Print size reports to stdout when they are generated, if requested.
        capture_output = !pw_bloat_SHOW_SIZE_REPORTS
      }
    }
  } else {
    not_needed(invoker, "*")
    group(target_name) {
    }
  }
}

# Creates a report card comparing the sizes of the same binary compiled with
# different toolchains. The toolchains to use are listed in the build variable
# pw_bloat_TOOLCHAINS.
#
# Args:
#   base_executable: Scope containing a list of variables defining an executable
#     target for the size report base.
#   diff_executable: Scope containing a list of variables defining an executable
#     target for the size report comparison.
#
# Outputs:
#   $target_gen_dir/$target_name.txt
#   $target_gen_dir/$target_name.rst
#
# Example:
#
#   pw_toolchain_size_diff("my_size_report") {
#     base_executable = {
#       sources = [ "base.cc" ]
#     }
#
#     diff_executable = {
#       sources = [ "base_with_libfoo.cc" ]
#       deps = [ ":libfoo" ]
#     }
#   }
#
template("pw_toolchain_size_diff") {
  assert(defined(invoker.base_executable),
         "pw_toolchain_size_diff requires a base_executable")
  assert(defined(invoker.diff_executable),
         "pw_toolchain_size_diff requires a diff_executable")

  _size_report_binaries = []

  # Multiple build targets are created for each toolchain, which all need unique
  # target names, so throw a counter in there.
  i = 0

  # Create a base and diff executable for each toolchain, adding the toolchain's
  # linker script to the link flags for the executable, and add them all to a
  # list of binaries for the pw_size_diff template.
  foreach(_toolchain, pw_bloat_TOOLCHAINS) {
    _prefix = "_${target_name}_${i}_pw_size"

    # Create a config which adds the toolchain's linker script as a linker flag
    # if the toolchain provides one.
    _linker_script_target_name = "${_prefix}_linker_script"
    config(_linker_script_target_name) {
      if (defined(_toolchain.linker_script)) {
        ldflags =
            [ "-T" + rebase_path(_toolchain.linker_script, root_build_dir) ]
        inputs = [ _toolchain.linker_script ]
      } else {
        ldflags = []
      }
    }

    # Create a group which forces the linker script config its dependents.
    _linker_group_target_name = "${_prefix}_linker_group"
    group(_linker_group_target_name) {
      public_configs = [ ":$_linker_script_target_name" ]
    }

    # Define the size report base executable with the toolchain's linker script.
    _base_target_name = "${_prefix}_base"
    executable(_base_target_name) {
      forward_variables_from(invoker.base_executable, "*")
      if (!defined(deps)) {
        deps = []
      }
      deps += [ ":$_linker_group_target_name" ]
    }

    # Define the size report diff executable with the toolchain's linker script.
    _diff_target_name = "${_prefix}_diff"
    executable(_diff_target_name) {
      forward_variables_from(invoker.diff_executable, "*")
      if (!defined(deps)) {
        deps = []
      }
      deps += [ ":$_linker_group_target_name" ]
    }

    # Force compilation with the toolchain.
    _base_label = get_label_info(":$_base_target_name", "label_no_toolchain")
    _base_with_toolchain = "$_base_label(${_toolchain.target})"
    _diff_label = get_label_info(":$_diff_target_name", "label_no_toolchain")
    _diff_with_toolchain = "$_diff_label(${_toolchain.target})"

    # Append a pw_size_diff binary scope to the list comparing the toolchain's
    # diff and base executables.
    _size_report_binaries += [
      {
        base = _base_with_toolchain
        target = _diff_with_toolchain
        label = _toolchain.name

        if (defined(_toolchain.bloaty_config)) {
          bloaty_config = _toolchain.bloaty_config
        }
      },
    ]

    i += 1
  }

  # TODO(frolv): Have a way of indicating that a toolchain should build docs.
  if (current_toolchain == default_toolchain && _size_report_binaries != []) {
    # Create the size report which runs on the binaries.
    pw_size_diff(target_name) {
      forward_variables_from(invoker, [ "title" ])
      binaries = _size_report_binaries
    }
  } else {
    # If no toolchains are listed in pw_bloat_TOOLCHAINS, prevent GN from
    # complaining about unused variables and run a script that outputs a ReST
    # warning to the size report file.
    not_needed("*")
    not_needed(invoker, "*")

    _doc_rst_output = "$target_gen_dir/$target_name"
    pw_python_action(target_name) {
      metadata = {
        pw_doc_sources = rebase_path([ _doc_rst_output ], root_build_dir)
      }
      script = "$dir_pw_bloat/py/pw_bloat/no_toolchains.py"
      python_deps = [ "$dir_pw_bloat/py" ]
      args = [ rebase_path(_doc_rst_output, root_build_dir) ]
      outputs = [ _doc_rst_output ]
    }
  }
}

# A base_executable for the pw_toolchain_size_diff template which contains a
# main() function that loads the bloat_this_binary library and does nothing
# else.
pw_bloat_empty_base = {
  deps = [
    "$dir_pw_bloat:base_main",
    "$dir_pw_bloat:bloat_this_binary",
  ]
}