# 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/common/config.gni")
import("//flutter/testing/testing.gni")

declare_args() {
  # Whether playgrounds are enabled for unit tests.
  impeller_enable_playground = false

  # Whether Impeller is supported on the platform.
  impeller_supports_platform = true

  # Whether the Metal backend is enabled.
  impeller_enable_metal = is_mac || is_ios

  # Whether the OpenGLES backend is enabled.
  impeller_enable_opengles = is_mac || is_linux

  # Whether to use a prebuilt impellerc.
  # If this is the empty string, impellerc will be built.
  # If it is non-empty, it should be the absolute path to impellerc.
  impeller_use_prebuilt_impellerc = ""
}

declare_args() {
  # Whether Impeller shaders are supported on the platform.
  impeller_shaders_supports_platform =
      impeller_enable_metal || impeller_enable_opengles

  # Whether Impeller supports rendering on the platform.
  impeller_supports_rendering =
      impeller_enable_metal || impeller_enable_opengles
}

# ------------------------------------------------------------------------------
# @brief           Define an Impeller component. Components are different
#                  Impeller subsystems part of the umbrella framework.
#
# @param[optional] target_type  The type of the component. This can be any of
#                               the target types supported by GN. Defaults to
#                               source_set. If Impeller is not supported on the
#                               target platform, this target is a no-op.
#
template("impeller_component") {
  if (defined(invoker.testonly) && invoker.testonly && !enable_unittests) {
    group(target_name) {
      not_needed(invoker, "*")
    }
  } else if (impeller_supports_platform) {
    target_type = "source_set"
    if (defined(invoker.target_type)) {
      target_type = invoker.target_type
    }
    target(target_type, target_name) {
      forward_variables_from(invoker, "*")

      if (!defined(invoker.public_configs)) {
        public_configs = []
      }

      public_configs += [ "//flutter/impeller:impeller_public_config" ]

      if (!defined(invoker.cflags)) {
        cflags = []
      }
      cflags += [ "-Wthread-safety-analysis" ]

      if (!defined(invoker.cflags_objc)) {
        cflags_objc = []
      }

      if (is_ios || is_mac) {
        cflags_objc += flutter_cflags_objc_arc
      }

      if (!defined(invoker.cflags_objcc)) {
        cflags_objcc = []
      }

      if (is_ios || is_mac) {
        cflags_objcc += flutter_cflags_objcc_arc
      }
    }
  } else {
    group(target_name) {
      not_needed(invoker, "*")
    }
  }
}

# ------------------------------------------------------------------------------
# @brief           Build a Metal Library. The output is a single file. Use
#                  get_target_outputs to get its location on build.
#
# @param[required] name     The name of the Metal library.
#
# @param[required] sources  The GLSL (4.60) sources to compiled into the Metal
#                           library.
#
template("metal_library") {
  assert(is_ios || is_mac)
  assert(defined(invoker.name), "Metal library name must be specified.")
  assert(defined(invoker.sources), "Metal source files must be specified.")

  metal_library_name = invoker.name

  action("$target_name") {
    forward_variables_from(invoker,
                           "*",
                           [
                             "inputs",
                             "outputs",
                             "script",
                             "depfile",
                             "args",
                           ])

    inputs = invoker.sources

    metal_library_path = "$root_out_dir/shaders/$metal_library_name.metallib"

    outputs = [ metal_library_path ]

    script = "//flutter/impeller/tools/build_metal_library.py"

    depfile = "$target_gen_dir/mtl/$metal_library_name.depfile"

    args = [
      "--output",
      rebase_path(metal_library_path, root_out_dir),
      "--depfile",
      rebase_path(depfile),
    ]

    if (!is_debug) {
      args += [ "--optimize" ]
    }

    if (is_ios) {
      args += [ "--platform=ios" ]
    } else if (is_mac) {
      args += [ "--platform=mac" ]
    } else {
      assert(false, "Unsupported platform for generating Metal shaders.")
    }

    foreach(source, invoker.sources) {
      args += [
        "--source",
        rebase_path(source, root_out_dir),
      ]
    }
  }
}

template("embed_blob") {
  assert(defined(invoker.symbol_name), "The symbol name must be specified.")
  assert(defined(invoker.blob), "The blob file to embed must be specified")
  assert(defined(invoker.hdr),
         "The header file containing the symbol name must be specified.")
  assert(defined(invoker.cc),
         "The CC file containing the symbol data must be specified.")
  assert(defined(invoker.deps), "The target dependencies must be specified")

  gen_blob_target_name = "gen_blob_$target_name"
  action(gen_blob_target_name) {
    inputs = [ invoker.blob ]
    outputs = [
      invoker.hdr,
      invoker.cc,
    ]
    args = [
      "--symbol-name",
      invoker.symbol_name,
      "--output-header",
      rebase_path(invoker.hdr),
      "--output-source",
      rebase_path(invoker.cc),
      "--source",
      rebase_path(invoker.blob),
    ]
    script = "//flutter/impeller/tools/xxd.py"
    deps = invoker.deps
  }

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

  source_set(target_name) {
    public_configs = [ ":$embed_config" ]
    sources = get_target_outputs(":$gen_blob_target_name")
    deps = [ ":$gen_blob_target_name" ]
  }
}

# Dispatches to the build or prebuilt impellerc depending on the value of
# the impeller_use_prebuilt_impellerc argument. Forwards all variables to
# compiled_action_foreach or action_foreach as appropriate.
template("_impellerc") {
  if (impeller_use_prebuilt_impellerc == "") {
    compiled_action_foreach(target_name) {
      forward_variables_from(invoker, "*")
      tool = "//flutter/impeller/compiler:impellerc"
    }
  } else {
    action_foreach(target_name) {
      forward_variables_from(invoker, "*", [ "args" ])
      script = "//build/gn_run_binary.py"
      impellerc_path =
          rebase_path(impeller_use_prebuilt_impellerc, root_build_dir)
      args = [ impellerc_path ] + invoker.args
    }
  }
}

template("impellerc") {
  assert(defined(invoker.shaders), "Impeller shaders must be specified.")
  assert(defined(invoker.sl_file_extension),
         "The extension of the SL file must be specified (metal, glsl, etc..).")
  assert(defined(invoker.shader_target_flag),
         "The flag to impellerc for target selection must be specified.")

  # Optional: invoker.defines specifies a list of valueless macro definitions.
  # Optional: invoker.intermediates_subdir specifies the subdirectory in which
  #           to put intermediates.

  sl_file_extension = invoker.sl_file_extension

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

    shader_target_flag = invoker.shader_target_flag

    sl_intermediate = "$generated_dir/{{source_file_part}}.$sl_file_extension"
    spirv_intermediate = "$generated_dir/{{source_file_part}}.spirv"
    reflection_json_intermediate = "$generated_dir/{{source_file_part}}.json"
    reflection_header_intermediate = "$generated_dir/{{source_file_part}}.h"
    reflection_cc_intermediate = "$generated_dir/{{source_file_part}}.cc"

    outputs = [
      sl_intermediate,
      reflection_header_intermediate,
      reflection_cc_intermediate,
    ]

    depfile_path = "$generated_dir/{{source_file_part}}.d"

    sl_intermediate_path = rebase_path(sl_intermediate, root_build_dir)
    spirv_intermediate_path = rebase_path(spirv_intermediate, root_build_dir)
    depfile_intermediate_path = rebase_path(depfile_path, 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)

    depfile = depfile_path

    args = [
      "--input={{source}}",
      "--sl=$sl_intermediate_path",
      "--spirv=$spirv_intermediate_path",
      "--reflection-json=$reflection_json_path",
      "--reflection-header=$reflection_header_path",
      "--reflection-cc=$reflection_cc_path",
      "--include={{source_dir}}",
      "--depfile=$depfile_intermediate_path",
      "$shader_target_flag",
    ]
    if (defined(invoker.defines)) {
      foreach(def, invoker.defines) {
        args += [ "--define=$def" ]
      }
    }
  }
}

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/renderer",
      impellerc_invocation,
    ]
  }
}

template("impeller_shaders_metal") {
  assert(defined(invoker.shaders), "Impeller shaders must be specified.")
  assert(defined(invoker.name), "Name of the shader library must be specified.")

  shaders_base_name = string_join("",
                                  [
                                    invoker.name,
                                    "_shaders",
                                  ])
  impellerc_mtl = "impellerc_$target_name"
  impellerc(impellerc_mtl) {
    shaders = invoker.shaders
    sl_file_extension = "metal"
    shader_target_flag = ""
    defines = [ "IMPELLER_TARGET_METAL" ]
    if (is_ios) {
      shader_target_flag = "--metal-ios"
      defines += [ "IMPELLER_TARGET_METAL_IOS" ]
    } else if (is_mac) {
      shader_target_flag = "--metal-desktop"
      defines += [ "IMPELLER_TARGET_METAL_DESKTOP" ]
    } else {
      assert(false, "Metal not supported on this platform.")
    }
  }

  mtl_lib = "genlib_$target_name"
  metal_library(mtl_lib) {
    name = invoker.name
    sources =
        filter_include(get_target_outputs(":$impellerc_mtl"), [ "*.metal" ])
    deps = [ ":$impellerc_mtl" ]
  }

  reflect_mtl = "reflect_$target_name"
  impellerc_reflect(reflect_mtl) {
    impellerc_invocation = ":$impellerc_mtl"
  }

  embed_mtl_lib = "embed_$target_name"
  embed_blob(embed_mtl_lib) {
    metal_library_files = get_target_outputs(":$mtl_lib")
    symbol_name = shaders_base_name
    blob = metal_library_files[0]
    hdr = "$target_gen_dir/mtl/$shaders_base_name.h"
    cc = "$target_gen_dir/mtl/$shaders_base_name.c"
    deps = [ ":$mtl_lib" ]
  }

  group(target_name) {
    public_deps = [
      ":$embed_mtl_lib",
      ":$reflect_mtl",
    ]
  }
}

template("blobcat_library") {
  assert(defined(invoker.shaders),
         "The shaders to build the library from must be specified.")
  assert(defined(invoker.deps), "Target dependencies must be specified.")

  output_file = "$target_gen_dir/$target_name.shaderblob"
  compiled_action(target_name) {
    tool = "//flutter/impeller/blobcat"
    inputs = invoker.shaders
    outputs = [ output_file ]
    output_path_rebased = rebase_path(output_file, root_build_dir)
    args = [ "--output=$output_path_rebased" ]
    foreach(shader, invoker.shaders) {
      shader_path = rebase_path(shader, root_build_dir)
      args += [ "--input=$shader_path" ]
    }
    deps = invoker.deps
  }
}

template("impeller_shaders_gles") {
  assert(defined(invoker.shaders), "Impeller shaders must be specified.")
  assert(defined(invoker.name), "Name of the shader library must be specified.")

  shaders_base_name = string_join("",
                                  [
                                    invoker.name,
                                    "_shaders_gles",
                                  ])
  impellerc_gles = "impellerc_$target_name"
  impellerc(impellerc_gles) {
    shaders = invoker.shaders
    sl_file_extension = "gles"

    # Metal reflectors generate a superset of information.
    if (impeller_enable_metal) {
      intermediates_subdir = "gles"
    }
    if (is_mac) {
      shader_target_flag = "--opengl-desktop"
    } else {
      shader_target_flag = "--opengl-es"
    }

    defines = [ "IMPELLER_TARGET_OPENGLES" ]
  }

  gles_lib = "genlib_$target_name"
  blobcat_library(gles_lib) {
    shaders =
        filter_include(get_target_outputs(":$impellerc_gles"), [ "*.gles" ])
    deps = [ ":$impellerc_gles" ]
  }

  reflect_gles = "reflect_$target_name"
  impellerc_reflect(reflect_gles) {
    impellerc_invocation = ":$impellerc_gles"
  }

  embed_gles_lib = "embed_$target_name"
  embed_blob(embed_gles_lib) {
    gles_library_files = get_target_outputs(":$gles_lib")
    symbol_name = shaders_base_name
    blob = gles_library_files[0]
    hdr = "$target_gen_dir/gles/$shaders_base_name.h"
    cc = "$target_gen_dir/gles/$shaders_base_name.c"
    deps = [ ":$gles_lib" ]
  }

  group(target_name) {
    public_deps = [ ":$embed_gles_lib" ]

    if (!impeller_enable_metal) {
      public_deps += [ ":$reflect_gles" ]
    }
  }
}

template("impeller_shaders") {
  if (impeller_enable_metal) {
    mtl_shaders = "mtl_$target_name"
    impeller_shaders_metal(mtl_shaders) {
      name = invoker.name
      shaders = invoker.shaders
    }
  }

  if (impeller_enable_opengles) {
    gles_shaders = "gles_$target_name"
    impeller_shaders_gles(gles_shaders) {
      name = invoker.name
      shaders = invoker.shaders
    }
  }

  group(target_name) {
    public_deps = []
    if (impeller_enable_metal) {
      public_deps += [ ":$mtl_shaders" ]
    }

    if (impeller_enable_opengles) {
      public_deps += [ ":$gles_shaders" ]
    }
  }
}