# Copyright 2018 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# First, import the gni files that define the names of the other toolchains, and
# the "is_<foo>_toolchain" variables that are used throughout this file.
import("//build/fidl/toolchain.gni")
import("//build/go/toolchain.gni")
import("//build/testing/host_test_data.gni")

# NOTE: The imports of this gni file are dependent on the language used, as
# there is no need to import the templates for the other languages when
# processing this file in a given language's toolchain.  They are done only
# within the scopes as needed below.

# Declares a FIDL library.
#
# Supported backends: rust, hlcpp, llcpp, banjo_{c,cpp,rust}, bindlib,
# go, and zither.
#
# Subtargets:
#  * `${target_name}`: available only in the FIDL toolchain
#  * `${target_name}_go`: available only in the go toolchain
#  * `${target_name}_${backend_name}`: available in every toolchain but go
#  * `${target_name}_host_test_data`: available on host toolchain
#
# Parameters
#
#   sources (required)
#     List of paths to library source files.
#
#   name (optional)
#     Name of the library.
#     Defaults to the target's name.
#
#   sdk_category (optional)
#     Publication level of the library in SDKs.
#     See //build/sdk/sdk_atom.gni.
#
#   sdk_area (optional)
#     [string] The API area responsible for maintaining this FIDL library.
#     See //build/sdk/sdk_atom.gni.
#
#   api (optional)
#     Path to the file representing the API of this library.
#     This file is used to ensure modifications to the library's API are
#     explicitly acknowledged. It is mandatory for publication categories of
#     "partner" or "public".
#     Defaults to "<target name>.api".
#
#   excluded_checks (optional)
#     A list of fidl-lint check IDs to ignore (by passing the command line flag
#     "-e some-check-id" for each value).
#
#   experimental_checks (optional)
#     A list of fidl-lint check IDs to include (by passing the command line flag
#     "-x some-check-id" for each value).
#
#   ${backend_name} (optional)
#     A scope giving private, backend-specific parameters.
#     Currently supported backends: zither
#
#   fuzzers (optional)
#     Protocol/methods for which to generate LibFuzzer fuzz targets. Example:
#       [
#         {
#           # Required:
#           protocol = "fully.qualified.FIDLProtocolName"
#           # Optional. Default: All methods in protocol.
#           methods = [ "MethodName1", "MethodName2", ... ]
#         },
#         ...
#       ]
#
#   golden_fuzzer (optional)
#     Boolean flag to generate a LibFuzzer fuzz target for all protocols, used
#     to ensure fuzzers for golden libraries compile successfully.
#
#   versioned (optional)
#     A string of the form PLATFORM or PLATFORM:VERSION. Validates that the
#     library is versioned under PLATFORM and added at VERSION (if provided).
#     The library's actual platform is determined as follows:
#       * If there are no @available attributes, the platform is "unversioned".
#       * The platform can be explicit with @available(platform="PLATFORM").
#       * Otherwise, the platform is the first component of the library name.
#     Defaults to "fuchsia" when the library name starts with "fuchsia." and
#     sdk_category is "cts", "partner_internal", "partner", or "public".
#     Defaults to "unversioned" for testonly libraries. Otherwise, no default.
#     TODO(https://fxbug.dev/325669391): Expand enforcement by ensuring that
#     there is always a default value.
#
#   available (optional)
#     A list of strings of the form PLATFORM:VERSION. This is needed when using
#     @available annotations for platforms other than "fuchsia". For more
#     information, look for --available in `fidlc --help`.
#     Warning: All dependencies must specify the same value for `available`,
#     otherwise bindings will be inconsistent. Since this is easy to misuse,
#     this parameter is only allowed on testonly libraries.
#
#   experimental_flags (optional)
#     A list of experimental fidlc features to enable.
#
#   goldens_dir (optional, default "//sdk/history")
#     The directory containing golden files for this FIDL API, per API level.
#     Should not contain a trailing slash. This is only used if the API is
#     publishable in an SDK.
#
#   non_fidl_deps (optional)
#     A list of non-FIDL dependency targets, i.e. targets that don't contribute
#     FIDL artifacts, but should be built before this target regardless. This is
#     typically used when `sources` contains files generated by another target.
#
#   contains_drivers (optional, boolean, default false)
#     Indicates if any of the FIDL files contain the driver transport or
#     references to the driver transport.
#
#   enable_cpp (optional flag, default to true)
#     Set to false to disable the new C++ bindings for this library
#
#   enable_rust (optional flag, default to true)
#     Set to false to disable Rust bindings for this library
#
#   enable_bindlib (optional flag, default to true)
#     Set to false to disable bindlib bindings for this library
#
#   enable_hlcpp (optional flag, default to false)
#     Set to true to enable legacy HLCPP bindings for this library
#
#   enable_banjo (optional flag, default to false)
#     Set to true to enable Banjo bindings for this library.
#
#   enable_zither (optional flag, default to false)
#     Set to true to enable Zither bindings for this library.
#     See //zircon/tools/zither/README.md for details.
#
#   applicable_licenses
#   public_deps
#   testonly
#   visibility
#
# Metadata
#
#   fidl_ir_info (`${target_name}_host_test_data` only)
#     Exactly one scope including the name of the library and the source IR JSON
#     path (relative to root_build_dir).
template("fidl") {
  assert(defined(invoker.sources), "A FIDL library requires some sources.")
  assert(!defined(invoker.deps),
         "All FIDL dependencies are inherently " +
             "public, use 'public_deps' instead of 'deps'.")

  common_parameters = {
    library_name = target_name
    if (defined(invoker.name)) {
      library_name = invoker.name
    }

    fidl_target = target_name
    fidl_gen_dir = get_label_info(":$fidl_target($fidl_toolchain)",
                                  "target_gen_dir") + "/$fidl_target"

    # The FIDL IR target, to be forwarded to each backend as a dependency.
    fidl_ir_target = ":${target_name}_compile_fidlc($fidl_toolchain)"
    fidl_ir_json = get_label_info(fidl_ir_target, "target_gen_dir") +
                   "/${target_name}.fidl.json"
  }

  # These bindings are enabled by default:
  enable_bindlib = !defined(invoker.enable_bindlib) || invoker.enable_bindlib
  enable_cpp = !defined(invoker.enable_cpp) || invoker.enable_cpp
  enable_rust = !defined(invoker.enable_rust) || invoker.enable_rust

  # These bindings are not:
  enable_banjo = defined(invoker.enable_banjo) && invoker.enable_banjo
  enable_hlcpp = defined(invoker.enable_hlcpp) && invoker.enable_hlcpp
  enable_zither = defined(invoker.enable_zither) && invoker.enable_zither

  not_needed([
               "enable_bindlib",
               "enable_cpp",
               "enable_rust",
               "enable_banjo",
               "enable_hlcpp",
               "enable_zither",
             ])

  # Allow generated targets visibility to their dependant generated targets
  if (defined(invoker.visibility)) {
    invoker.visibility += [ ":*" ]
  }

  fidl_only = [
    "api",
    "sdk_area",
    "available",
    "excluded_checks",
    "experimental_checks",
    "experimental_flags",
    "goldens_dir",
    "non_fidl_deps",
    "versioned",
  ]
  if (is_fidl_toolchain) {
    # Only import the fidl_library template when in the fidl toolchain
    import("//build/fidl/fidl_library.gni")
    fidl_library(target_name) {
      forward_variables_from(invoker,
                             fidl_only + [
                                   "applicable_licenses",
                                   "testonly",
                                   "visibility",
                                   "public_deps",
                                   "sdk_category",
                                   "sources",
                                 ])
      forward_variables_from(common_parameters,
                             [
                               "library_name",
                               "fidl_ir_json",
                             ])
    }

    # Check that the IR JSON is indeed an output of the purported IR target.
    fidlc_outputs = get_target_outputs(common_parameters.fidl_ir_target)
    assert([ common_parameters.fidl_ir_json ] + fidlc_outputs - fidlc_outputs ==
           [])
  } else {
    not_needed(invoker, fidl_only)
  }

  if (is_host) {
    fidl_ir_root_target = "${target_name}_ir_root"
    fidl_ir_root_base = get_label_info(":anything($fidl_toolchain)",
                                       "root_gen_dir") + "/ir_root"
    fidl_library_name = common_parameters.library_name
    fidl_ir_root_dir = fidl_ir_root_base + "/" + fidl_library_name
    fidl_ir_root_outfile = "${fidl_ir_root_base}/${fidl_library_name}/${fidl_library_name}.fidl.json"

    # This is intended as an alternative easily-searchable setup to all_fidl_json.txt
    # The only caveat is that this will fail if there are FIDL libraries with duplicate names as
    # dependencies. A future step may be to create this directory structure in a given package's
    # gen dir rather than the root FIDL gen dir.
    action(fidl_ir_root_target) {
      forward_variables_from(invoker,
                             [
                               "testonly",
                               "visibility",
                             ])
      sources = [ common_parameters.fidl_ir_json ]
      script = "//build/fidl/gen_ir_root_out.py"
      args = [
        "--root-dir",
        rebase_path(fidl_ir_root_base, root_build_dir),
        "--ir-path",
        rebase_path(common_parameters.fidl_ir_json, fidl_ir_root_dir),
        "--library-name",
        fidl_library_name,
      ]
      outputs = [ fidl_ir_root_outfile ]
      deps = [ ":${common_parameters.fidl_target}($fidl_toolchain)" ]
    }

    # Use SDK category markers to enable detection of host targets that use FIDL
    # libraries in nonpermissible categories.
    marker_category = "unknown"
    if (defined(invoker.sdk_category)) {
      marker_category = invoker.sdk_category
    }

    host_test_data("_${target_name}_host_test_data") {
      forward_variables_from(invoker,
                             [
                               "applicable_licenses",
                               "visibility",
                             ])
      sources = [
        common_parameters.fidl_ir_json,
        fidl_ir_root_outfile,
      ]

      # Explicitly set `testonly` to false for SDK inclusion.
      # host_test_data()'s default for `testonly` is true so we can't simply
      # forward `invoker.testonly` as that's most likely unset for fidl()
      # targets.
      testonly = false
      if (defined(invoker.testonly)) {
        testonly = invoker.testonly
      }

      # It's only necessary to depend on fidl_ir_target got get the FIDL IR json
      # file, but without depending on fidl_target, there is no entry in
      # all_fidl_json.txt, which at the moment is the main source for finding
      # the list of current FIDL IR json files.
      # TODO(b/295190178): append all_fidl_json.txt with inclusion of
      # fidl_ir_target target.
      deps = [
        ":${common_parameters.fidl_target}($fidl_toolchain)",
        ":${fidl_ir_root_target}",
      ]

      # Add SDK category markers as FIDL-IR host data is used for host tests
      # that use Fuchsia Controller.
      # Check for allowed marker before adding category.
      import("//src/testing/end_to_end/host_test_allowlist.gni")
      label_name = get_label_info(":${common_parameters.fidl_target}",
                                  "label_no_toolchain")
      is_allowed_for_host_test = host_test_fidl_allowlist + [ label_name ] -
                                 [ label_name ] != host_test_fidl_allowlist
      if (is_allowed_for_host_test) {
        marker_category = "allowed-for-host-test"
      }
      deps += [ "//sdk:marker-${marker_category}" ]
    }

    group("${target_name}_host_test_data") {
      forward_variables_from(invoker, [ "testonly" ])
      deps = [ ":_${target_name}" ]
      if (defined(invoker.public_deps)) {
        foreach(pdep, invoker.public_deps) {
          label = get_label_info(pdep, "label_no_toolchain")
          deps += [ "${label}_host_test_data" ]
        }
      }

      metadata = {
        fidl_ir_info = [
          {
            library_name = fidl_library_name
            source = rebase_path(fidl_ir_root_outfile, root_build_dir)
          },
        ]
      }
    }
  }

  not_needed(invoker, [ "sources" ])

  if (is_go_toolchain) {
    # Only import the fidl_go() template when in the Go toolchain.
    import("//build/go/fidl_go.gni")

    # Define the Go bindings
    fidl_go("${target_name}_go") {
      forward_variables_from(invoker,
                             [
                               "applicable_licenses",
                               "testonly",
                               "visibility",
                               "public_deps",
                             ])
      forward_variables_from(common_parameters, "*", [ "fidl_target" ])
      fidl_gen_dir += "/go"
    }
    not_needed(invoker,
               [
                 "sdk_category",
                 "sdk_area",
                 "sources",
               ])
  }

  non_go_only = [
    "contains_drivers",
    "fuzzers",
    "golden_fuzzer",
  ]
  if (is_fidl_toolchain || toolchain_variant.supports_cpp ||
      toolchain_variant.supports_rust) {
    # The C, C++, and Rust bindings are compiled in their own toolchain, from
    # sources generated in the FIDL toolchain, so this section of the template
    # is processed in the FIDL toolchain as well as the binary toolchain(s).

    if (enable_cpp || enable_hlcpp) {
      # Only import fidl_cpp_family() if in a cpp toolchain and cpp bindings are
      # enabled, as this can be particularly slow to import.
      import("//build/cpp/fidl_cpp.gni")

      # Define the cpp bindings.
      fidl_cpp_family(target_name) {
        forward_variables_from(invoker,
                               non_go_only + [
                                     "applicable_licenses",
                                     "testonly",
                                     "visibility",
                                     "public_deps",
                                     "sdk_category",
                                   ])
        forward_variables_from(common_parameters, "*")
        enable_hlcpp = enable_hlcpp
        enable_cpp = enable_cpp
      }
    } else {
      not_needed([ "non_go_only" ])
    }

    if (enable_rust && (is_fidl_toolchain || toolchain_variant.supports_rust)) {
      # Only import the fidl_rust() template if in a rust-capable toolchain and
      # rust bindings are to be defined.
      import("//build/rust/fidl_rust.gni")

      # Define the Rust bindings.
      fidl_rust("${target_name}_rust") {
        forward_variables_from(invoker,
                               [
                                 "applicable_licenses",
                                 "testonly",
                                 "visibility",
                                 "public_deps",
                                 "disable_rustdoc",
                               ])
        forward_variables_from(common_parameters, "*", [ "fidl_target" ])
        deps = []
        if (is_host) {
          # Add SDK category markers as Rust is used for ffx host tools.
          # Check for allowed marker before adding category.
          import("//src/developer/ffx/build/ffx_subtool_allowlist.gni")
          label_name = get_label_info(":${common_parameters.fidl_target}",
                                      "label_no_toolchain")
          is_allowed_for_ffx = ffx_subtool_fidl_allowlist + [ label_name ] -
                               [ label_name ] != ffx_subtool_fidl_allowlist
          if (is_allowed_for_ffx) {
            marker_category = "allowed-for-ffx-subtool"
          }
          deps += [ "//sdk:marker-${marker_category}" ]
        }
        fidl_gen_dir += "/rust"
      }
    } else {
      not_needed(invoker, [ "disable_rustdoc" ])
    }

    if (enable_bindlib) {
      # Only import the fidl_bind_library() template if bindlib is enabled.
      import("//build/bind/fidl_bind_library.gni")

      # Define the bindlib bindings.
      fidl_bind_library("${target_name}_bindlib") {
        forward_variables_from(invoker,
                               [
                                 "applicable_licenses",
                                 "testonly",
                                 "visibility",
                               ])
        forward_variables_from(common_parameters, "*", [ "fidl_target" ])
        fidl_gen_dir += "/bindlib"
      }
    }

    if (enable_banjo) {
      # Only import fidl_banjo() if banjo is enabled.
      import("//build/banjo/fidl_banjo.gni")

      # Define the banjo bindings.
      fidl_banjo("${target_name}_banjo") {
        forward_variables_from(invoker,
                               [
                                 "testonly",
                                 "visibility",
                                 "public_deps",
                               ])
        forward_variables_from(common_parameters, "*")
        fidl_gen_dir += "/banjo"
      }
    }

    if (enable_zither) {
      # Only import zither_library() if zither is enabled.
      import("//zircon/tools/zither/zither_library.gni")

      # Define the zither bindings.
      zither_library("${target_name}_zither") {
        forward_variables_from(invoker,
                               [
                                 "testonly",
                                 "visibility",
                                 "sources",
                               ])
        forward_variables_from(common_parameters, "*")
        if (defined(invoker.zither)) {
          forward_variables_from(invoker.zither, "*")
        }
        fidl_gen_dir += "/zither"
      }
    } else {
      not_needed(invoker, [ "sources" ])
    }
  } else {
    not_needed(invoker,
               non_go_only + [
                     "sources",
                     "disable_rustdoc",
                   ])
  }
}