# Copyright 2021 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("$dir_pw_toolchain/arm_gcc/toolchains.gni")
import("$dir_pw_toolchain/generate_toolchain.gni")
import("$dir_pw_toolchain/host_clang/toolchains.gni")
import("$dir_pw_toolchain/host_gcc/toolchains.gni")
import("backend.gni")
import("freertos_backends.gni")
import("stl_backends.gni")

# This scope is essentially an enum for pw_system_target's `cpu` selection.
PW_SYSTEM_CPU = {
  CORTEX_M4F = "cortex-m4f"

  # Native builds for the host CPU.
  NATIVE = "native"
}

# This scope is essentially an enum for pw_system_target's `scheduler`
# selection.
PW_SYSTEM_SCHEDULER = {
  FREERTOS = "freertos"

  # Native uses the host OS's native scheduler and OS primitives as provided
  # through the Standard Template Library.
  NATIVE = "native"
}

# Defines a target toolchain, automatically setting many required build
# arguments to simplify instantiation of a target.
#
# Args:
#  cpu: (required) The architecture to target.
#    Supported choices: PW_SYSTEM_CPU.CORTEX_M4F, PW_SYSTEM_CPU.NATIVE
#  scheduler: (required) The scheduler implementation and API to use for this
#    target.
#    Supported choices: PW_SYSTEM_SCHEDULER.FREERTOS, PW_SYSTEM_SCHEDULER.NATIVE
#  use_pw_malloc: Whether or not to replace the default malloc implementation
#    with pw_malloc. Defaults enabled for supported targets.
#  link_deps: Additional link-time dependencies required for all executables.
#    This is a list of source sets.
#  build_args: Additional overrides for GN build arguments.
template("pw_system_target") {
  _OPTIMIZATION_LEVELS = {
    SIZE_OPTIMIZED = "size_optimized"
    SPEED_OPTIMIZED = "speed_optimized"
    DEBUG = "debug"
  }

  # Generic defaults.
  _default_configs = [ "$dir_pw_build:extra_strict_warnings" ]
  _link_deps = [
    "$dir_pw_assert:impl",
    "$dir_pw_log:impl",
  ]
  if (defined(invoker.link_deps)) {
    _link_deps += invoker.link_deps
  }
  _final_binary_extension = ""

  _default_build_args = {
    pw_system_IO_BACKEND = "$dir_pw_system:sys_io_target_io"

    # TODO(amontanez): This should be set to pw_assert_log ASAP.
    pw_assert_BACKEND = dir_pw_assert_basic

    # TODO(amontanez): This should be set to pw_log_tokenized when support
    # is added.
    pw_log_BACKEND = dir_pw_log_basic

    pw_rpc_CONFIG = "$dir_pw_rpc:use_global_mutex"

    # TODO(amontanez): This should be set to a "$dir_pw_unit_test:rpc_main"
    # when RPC is working.
    pw_unit_test_MAIN = "$dir_pw_unit_test:logging_main"
  }

  # Populate architecture-specific build args.
  assert(
      defined(invoker.cpu),
      "Please select a `cpu` for $target_name. Options: PW_SYSTEM_CPU.CORTEX_M4F, PW_SYSTEM_CPU.NATIVE")
  if (invoker.cpu == PW_SYSTEM_CPU.CORTEX_M4F) {
    _current_cpu = "arm"
    _default_configs += [ "$dir_pw_toolchain/arm_gcc:enable_float_printf" ]
    _arch_build_args = {
      pw_bloat_BLOATY_CONFIG = "$dir_pw_boot_cortex_m/bloaty_config.bloaty"
      pw_boot_BACKEND = "$dir_pw_boot_cortex_m:armv7m"
      pw_interrupt_CONTEXT_BACKEND = "$dir_pw_interrupt_cortex_m:context_armv7m"
    }

    _final_binary_extension = ".elf"

    _toolchains = [
      {
        toolchain_base = pw_toolchain_arm_gcc.cortex_m4f_debug
        level_name = _OPTIMIZATION_LEVELS.DEBUG
      },
      {
        toolchain_base = pw_toolchain_arm_gcc.cortex_m4f_size_optimized
        level_name = _OPTIMIZATION_LEVELS.SIZE_OPTIMIZED
      },
      {
        toolchain_base = pw_toolchain_arm_gcc.cortex_m4f_speed_optimized
        level_name = _OPTIMIZATION_LEVELS.SPEED_OPTIMIZED
      },
    ]
  } else if (invoker.cpu == PW_SYSTEM_CPU.NATIVE) {
    _current_cpu = host_cpu
    _arch_build_args = {
      pw_sys_io_BACKEND = "$dir_pw_sys_io_stdio"

      # Don't use pw_sys_io, as stdio isn't great for RPC interaction on a host.
      # TODO(amontanez): This should be a socket stream.
      pw_system_IO_BACKEND = "$dir_pw_system:sys_io_target_io"
    }

    if (host_os != "win") {
      _toolchains = [
        {
          toolchain_base = pw_toolchain_host_clang.debug
          level_name = _OPTIMIZATION_LEVELS.DEBUG
        },
        {
          toolchain_base = pw_toolchain_host_clang.size_optimized
          level_name = _OPTIMIZATION_LEVELS.SIZE_OPTIMIZED
        },
        {
          toolchain_base = pw_toolchain_host_clang.speed_optimized
          level_name = _OPTIMIZATION_LEVELS.SPEED_OPTIMIZED
        },
      ]
    } else {
      _toolchains = [
        {
          toolchain_base = pw_toolchain_host_gcc.debug
          level_name = _OPTIMIZATION_LEVELS.DEBUG
        },
        {
          toolchain_base = pw_toolchain_host_gcc.size_optimized
          level_name = _OPTIMIZATION_LEVELS.SIZE_OPTIMIZED
        },
        {
          toolchain_base = pw_toolchain_host_gcc.speed_optimized
          level_name = _OPTIMIZATION_LEVELS.SPEED_OPTIMIZED
        },
      ]
    }
  }
  assert(defined(_arch_build_args),
         "Unknown cpu choice for $target_name: `${invoker.cpu}`")

  # Populate OS-specific build args.
  assert(
      defined(invoker.scheduler),
      "Please select an `scheduler` for $target_name. Options: PW_SYSTEM_SCHEDULER.FREERTOS, PW_SYSTEM_SCHEDULER.NATIVE")
  if (invoker.scheduler == PW_SYSTEM_SCHEDULER.FREERTOS) {
    _current_os = "freertos"
    _os_build_args = PW_SYSTEM_FREERTOS_BACKENDS
  } else if (invoker.scheduler == PW_SYSTEM_SCHEDULER.NATIVE) {
    _current_os = host_os
    _os_build_args = PW_SYSTEM_STL_BACKENDS
  }
  assert(defined(_os_build_args),
         "Unknown scheduler choice for $target_name: `${invoker.scheduler}`")

  # Configure malloc defaults.
  _use_pw_malloc = false
  if (defined(invoker.use_pw_malloc)) {
    _use_pw_malloc = invoker.use_pw_malloc
  } else if (invoker.cpu != PW_SYSTEM_CPU.NATIVE) {
    _use_pw_malloc = true
  }

  if (_use_pw_malloc) {
    _default_configs += [ "$dir_pw_malloc:pw_malloc_wrapper_config" ]
    _link_deps += [ dir_pw_malloc ]
    _malloc_build_args = {
      pw_malloc_BACKEND = dir_pw_malloc_freelist
    }
  } else {
    _malloc_build_args = {
    }
  }

  foreach(toolchain_and_level, _toolchains) {
    # Clear from previous iteration.
    _base = {
    }
    _base = toolchain_and_level.toolchain_base

    generate_toolchain("${target_name}.${toolchain_and_level.level_name}") {
      forward_variables_from(_base,
                             "*",
                             [
                               "defaults",
                               "name",
                             ])
      final_binary_extension = _final_binary_extension
      defaults = {
        current_os = _current_os
        current_cpu = _current_cpu
        forward_variables_from(_base.defaults, "*")
        forward_variables_from(_default_build_args, "*")
        forward_variables_from(_arch_build_args, "*")
        forward_variables_from(_os_build_args, "*")
        forward_variables_from(_malloc_build_args, "*")
        default_configs += _default_configs
        if (!defined(pw_build_LINK_DEPS)) {
          pw_build_LINK_DEPS = []
        }
        pw_build_LINK_DEPS += _link_deps

        if (defined(invoker.build_args)) {
          forward_variables_from(invoker.build_args, "*")
        }
      }
    }
  }
}