# Copyright 2013 The Flutter 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("//build/compiled_action.gni")
import("//flutter/impeller/tools/args.gni")

# Dispatches to the build or prebuilt impellerc depending on the value of
# the `impeller_use_prebuilt_impellerc` argument.
# * When the `single_invocation` argument is false, all variables are
#   forwarded to `compiled_action_foreach` or `action_foreach`, which will
#   invoke `impellerc` separately for each source.
# * When the `single_invocation` argument is true, `impellerc` is only
#   invoked once via `compiled_action` or `action`.
template("_impellerc") {
  if (invoker.single_invocation) {
    compiled_action(target_name) {
      forward_variables_from(invoker, "*")
      tool = "//flutter/impeller/compiler:impellerc"
    }
  } else {
    compiled_action_foreach(target_name) {
      forward_variables_from(invoker, "*")
      tool = "//flutter/impeller/compiler:impellerc"
    }
  }
}

# Required: shaders                 The list of shaders inputs to compile.
# Required: shader_target_flags     The target flag(s) to append. Valid options:
#                                       --sksl
#                                       --metal-ios
#                                       --metal-desktop
#                                       --opengl-es
#                                       --opengl-desktop
#                                       --vulkan
#                                       --runtime-stage-metal
#                                       --runtime-stage-gles
#                                       --runtime-stage-vulkan
#                                   Not required for --shader_bundle mode.
# Required: sl_file_extension       The file extension to use for output files.
#                                   Not required for --shader_bundle mode.
# Optional: iplr                    Causes --sl output to be in iplr/runtime
#                                   stage flatbuffer format.
# Optional: shader_bundle           Specifies a Flutter GPU shader bundle
#                                   configuration.
#   Required: shader_bundle_output  Specifies the output filename of the shader
#                                   bundle. This is only required if
#                                   shader_bundle is supplied.
# Optional: defines                 Specifies a list of valueless macro
#                                   definitions.
# Optional: intermediates_subdir    Specifies the subdirectory in which to put
#                                   intermediates.
# Optional: json                    Causes output format to be JSON instead of
#                                   flatbuffer.
template("impellerc") {
  assert(defined(invoker.shaders), "Impeller shaders must be specified.")
  assert(defined(invoker.shader_target_flags) || defined(invoker.shader_bundle),
         "The flag to impellerc for target selection must be specified.")
  assert(defined(invoker.sl_file_extension) || defined(invoker.shader_bundle),
         "The extension of the SL file must be specified (metal, glsl, etc..).")
  if (defined(invoker.shader_bundle)) {
    assert(
        defined(invoker.shader_bundle_output),
        "When shader_bundle is specified, shader_bundle_output must also be specified.")
  }

  if (defined(invoker.shader_target_flags)) {
    shader_target_flags = invoker.shader_target_flags
  } else {
    shader_target_flags = []
  }

  sksl = false
  foreach(shader_target_flag, shader_target_flags) {
    sksl = shader_target_flag == "--sksl"
  }
  iplr = false
  if (defined(invoker.iplr) && invoker.iplr) {
    iplr = invoker.iplr
  }
  json = false
  if (defined(invoker.json) && invoker.json) {
    json = invoker.json
  }

  # Not needed on every path.
  not_needed([
               "iplr",
               "sksl",
               "shader_bundle",
               "shader_bundle_output",
             ])

  _impellerc(target_name) {
    pool = "//build/toolchain:toolchain_pool"
    shader_bundle = defined(invoker.shader_bundle)

    # When single_invocation is true, impellerc will be invoked exactly once. When it's
    # false, impellerc be invoked for each of the source file entries (invoker.shaders).
    single_invocation = shader_bundle

    if (defined(invoker.intermediates_subdir)) {
      subdir = invoker.intermediates_subdir
      generated_dir = "$target_gen_dir/$subdir"
    } else {
      generated_dir = "$target_gen_dir"
    }

    shader_lib_dir = rebase_path("//flutter/impeller/compiler/shader_lib")
    args = [ "--include=$shader_lib_dir" ] + shader_target_flags

    # When we're in single invocation mode, we can't use source enumeration.
    if (!single_invocation) {
      depfile_path = "$generated_dir/{{source_file_part}}.d"
      depfile_intermediate_path = rebase_path(depfile_path, root_build_dir)
      depfile = depfile_path
      args += [
        "--input={{source}}",
        "--include={{source_dir}}",
        "--depfile=$depfile_intermediate_path",
      ]

      if (defined(invoker.shader_target_flag)) {
        args += [ "${invoker.shader_target_flag}" ]
      }
    }

    if (defined(invoker.gles_language_version)) {
      gles_language_version = invoker.gles_language_version
      args += [ "--gles-language-version=$gles_language_version" ]
    }

    if (defined(invoker.metal_version)) {
      assert(is_mac || is_ios)
      metal_version = invoker.metal_version
      args += [ "--metal-version=$metal_version" ]
    }

    if (defined(invoker.use_half_textures) && invoker.use_half_textures) {
      args += [ "--use-half-textures" ]
    }
    if (defined(invoker.require_framebuffer_fetch) &&
        invoker.require_framebuffer_fetch) {
      args += [ "--require-framebuffer-fetch" ]
    }

    if (json) {
      args += [ "--json" ]
    }

    if (iplr) {
      # When building in IPLR mode, the compiler may be executed twice
      args += [ "--iplr" ]
    }

    # The `sl_output` is the raw shader file output by the compiler. For --iplr
    # and --shader-bundle, this is used as the filename for the flatbuffer to
    # output.

    if (shader_bundle) {
      # When a shader bundle is specified, don't bother supplying flags for
      # the reflection state as these are ignored. In this mode, the compiler
      # is invoked multiple times and the reflection state for each shader is
      # written to the output flatbuffer.
      sl_output = "$generated_dir/${invoker.shader_bundle_output}"
      sl_output_path = rebase_path(sl_output, root_build_dir)

      args += [
        "--sl=$sl_output_path",
        "--shader-bundle=${invoker.shader_bundle}",
      ]

      outputs = [ sl_output ]
    } else if (sksl) {
      # When SkSL is selected as a `shader_target_flags`, don't generate
      # C++ reflection state. Nothing needs to use it and it's likely invalid
      # given the special cases when generating SkSL.
      # Note that this configuration is orthogonal to the "--iplr" flag
      sl_output =
          "$generated_dir/{{source_file_part}}.${invoker.sl_file_extension}"
      sl_output_path = rebase_path(sl_output, root_build_dir)

      spirv_intermediate = "$generated_dir/{{source_file_part}}.spirv"
      spirv_intermediate_path = rebase_path(spirv_intermediate, root_build_dir)
      args += [
        "--sl=$sl_output_path",
        "--spirv=$spirv_intermediate_path",
      ]

      outputs = [ sl_output ]
    } else {
      # The default branch. Here we just generate one shader along with all of
      # its C++ reflection state.

      sl_output =
          "$generated_dir/{{source_file_part}}.${invoker.sl_file_extension}"
      sl_output_path = rebase_path(sl_output, root_build_dir)

      reflection_json_intermediate = "$generated_dir/{{source_file_part}}.json"
      reflection_header_intermediate = "$generated_dir/{{source_file_part}}.h"
      reflection_cc_intermediate = "$generated_dir/{{source_file_part}}.cc"

      spirv_intermediate = "$generated_dir/{{source_file_part}}.spirv"
      spirv_intermediate_path = rebase_path(spirv_intermediate, root_build_dir)
      reflection_json_path =
          rebase_path(reflection_json_intermediate, root_build_dir)
      reflection_header_path =
          rebase_path(reflection_header_intermediate, root_build_dir)
      reflection_cc_path =
          rebase_path(reflection_cc_intermediate, root_build_dir)

      args += [
        "--sl=$sl_output_path",
        "--spirv=$spirv_intermediate_path",
        "--reflection-json=$reflection_json_path",
        "--reflection-header=$reflection_header_path",
        "--reflection-cc=$reflection_cc_path",
      ]

      outputs = [
        sl_output,
        reflection_header_intermediate,
        reflection_cc_intermediate,
      ]
    }

    if (defined(invoker.defines)) {
      foreach(def, invoker.defines) {
        args += [ "--define=$def" ]
      }
    }

    if (single_invocation) {
      inputs = invoker.shaders
    } else {
      sources = invoker.shaders
    }
  }
}

template("impellerc_reflect") {
  assert(
      defined(invoker.impellerc_invocation),
      "The target that specifies the ImpellerC invocation to reflect must be defined.")

  reflect_config = "reflect_$target_name"
  config(reflect_config) {
    include_dirs = [ get_path_info(
            get_label_info("//flutter/impeller:impeller", "target_gen_dir"),
            "dir") ]
  }

  impellerc_invocation = invoker.impellerc_invocation

  source_set(target_name) {
    public_configs = [ ":$reflect_config" ]
    public = filter_include(get_target_outputs(impellerc_invocation), [ "*.h" ])
    sources = filter_include(get_target_outputs(impellerc_invocation),
                             [
                               "*.h",
                               "*.cc",
                               "*.mm",
                             ])

    deps = [
      "//flutter/impeller/core",
      impellerc_invocation,
    ]
  }
}