# Copyright 2021 The Bazel Authors. All rights reserved.
#
# 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
#
#    http://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.

"""A Starlark implementation of the proto_lang_toolchain rule."""

load(":common/proto/proto_common.bzl", "ProtoLangToolchainInfo", "toolchains", proto_common = "proto_common_do_not_use")
load(":common/proto/proto_semantics.bzl", "semantics")

ProtoInfo = _builtins.toplevel.ProtoInfo

def _rule_impl(ctx):
    provided_proto_sources = depset(transitive = [bp[ProtoInfo].transitive_proto_sources() for bp in ctx.attr.blacklisted_protos]).to_list()

    flag = ctx.attr.command_line
    if flag.find("$(PLUGIN_OUT)") > -1:
        fail("in attribute 'command_line': Placeholder '$(PLUGIN_OUT)' is not supported.")
    flag = flag.replace("$(OUT)", "%s")

    plugin = None
    if ctx.attr.plugin != None:
        plugin = ctx.attr.plugin[DefaultInfo].files_to_run

    if proto_common.INCOMPATIBLE_ENABLE_PROTO_TOOLCHAIN_RESOLUTION:
        proto_compiler = ctx.toolchains[semantics.PROTO_TOOLCHAIN].proto.proto_compiler
        protoc_opts = ctx.toolchains[semantics.PROTO_TOOLCHAIN].proto.protoc_opts
    else:
        proto_compiler = ctx.attr._proto_compiler.files_to_run
        protoc_opts = ctx.fragments.proto.experimental_protoc_opts

    proto_lang_toolchain_info = ProtoLangToolchainInfo(
        out_replacement_format_flag = flag,
        output_files = ctx.attr.output_files,
        plugin_format_flag = ctx.attr.plugin_format_flag,
        plugin = plugin,
        runtime = ctx.attr.runtime,
        provided_proto_sources = provided_proto_sources,
        proto_compiler = proto_compiler,
        protoc_opts = protoc_opts,
        progress_message = ctx.attr.progress_message,
        mnemonic = ctx.attr.mnemonic,
        toolchain_type = ctx.attr.toolchain_type.label if ctx.attr.toolchain_type else None,
    )
    return [
        DefaultInfo(files = depset(), runfiles = ctx.runfiles()),
        _builtins.toplevel.platform_common.ToolchainInfo(proto = proto_lang_toolchain_info),
        # TODO(b/300592942): remove when --incompatible_enable_proto_toolchains is flipped and removed
        proto_lang_toolchain_info,
    ]

proto_lang_toolchain = rule(
    _rule_impl,
    attrs =
        {
            "progress_message": attr.string(default = "Generating proto_library %{label}"),
            "mnemonic": attr.string(default = "GenProto"),
            "command_line": attr.string(mandatory = True),
            "output_files": attr.string(values = ["single", "multiple", "legacy"], default = "legacy"),
            "plugin_format_flag": attr.string(),
            "plugin": attr.label(
                executable = True,
                cfg = "exec",
            ),
            "runtime": attr.label(),
            "blacklisted_protos": attr.label_list(
                providers = [ProtoInfo],
            ),
            "toolchain_type": attr.label(),
        } | ({} if proto_common.INCOMPATIBLE_ENABLE_PROTO_TOOLCHAIN_RESOLUTION else {
            "_proto_compiler": attr.label(
                cfg = "exec",
                executable = True,
                allow_files = True,
                default = configuration_field("proto", "proto_compiler"),
            ),
        }),
    provides = [ProtoLangToolchainInfo],
    fragments = ["proto"],
    toolchains = toolchains.use_toolchain(semantics.PROTO_TOOLCHAIN),  # Used to obtain protoc
)