Baze rule for 99designs/gqlgen

gqlgen.bzl

load("@bazel_skylib//lib:paths.bzl", "paths")
load(
    "@io_bazel_rules_go//go:def.bzl",
    _go_context = "go_context",
    _go_rule = "go_rule",
)

_CONFIG = """
schema:
    {schemas}

exec:
    filename: {exec}
    package: {exec_package}

model:
    filename: {model}
    package: {model_package}

resolver:
    filename: {resolver}
    package: {resolver_package}
    type: Resolver

autobind:
    - {autobind}
"""

def _extract_go_package(file, ctx):
    segments = paths.dirname(file.basename).split("/")
    if len(segments) == 0 or len(segments[0]) == 0:
        return ctx.attr.default_package
    return segments[-1]

def _gqlgen_impl(ctx):
    go = _go_context(ctx)

    schemas = []
    for s in ctx.attr.schemas:
        schemas.append("- {}".format(s.label.name))
    schemas = "\n".join(schemas)

    config_file = ctx.actions.declare_file(ctx.label.name + ".yml")
    ctx.actions.write(
        content = _CONFIG.format(
            schemas = schemas,
            exec = ctx.outputs.parser.basename,
            exec_package = _extract_go_package(ctx.outputs.parser, ctx),
            model = ctx.outputs.model.basename,
            model_package = _extract_go_package(ctx.outputs.model, ctx),
            resolver = ctx.outputs.resolver.basename,
            resolver_package = _extract_go_package(ctx.outputs.resolver, ctx),
            autobind = ctx.attr.autobind,
        ),
        output = config_file,
    )

    out_files = [ctx.outputs.parser, ctx.outputs.model, ctx.outputs.resolver]
    inputs = [config_file]
    for s in ctx.attr.schemas:
        inputs.extend(s.files.to_list())

    env = {
        "GOCACHE": "/tmp",
        "GOPACKAGESPRINTGOLISTERRORS": "1",
        "GOPACKAGESDEBUG": "1",
    }
    env.update(go.env)
    env["PATH"] = go.env["PATH"] + ":{}/bin".format(go.env["GOROOT"])
    ctx.actions.run(
        tools = [go.go],
        inputs = inputs,
        outputs = out_files,
        arguments = ["--config", config_file.path],
        executable = ctx.executable._gqlgen,
        env = env,
    )

_gqlgen = _go_rule(
    implementation = _gqlgen_impl,
    attrs = {
        "autobind": attr.string(
            doc = "The directory containing Go files that bind to GraphQL types",
        ),
        "default_package": attr.string(
            doc = "The default package for the generated files",
            mandatory = True,
        ),
        "model": attr.output(
            doc = "The generated model file",
            mandatory = True,
        ),
        "parser": attr.output(
            doc = "The generated parser",
            mandatory = True,
        ),
        "resolver": attr.output(
            doc = "The resolver code skeleton",
            mandatory = True,
        ),
        "schemas": attr.label_list(
            allow_files = [".graphql"],
            doc = "The schema files from which to generate Go code",
            mandatory = True,
        ),
        "_gqlgen": attr.label(
            default = "@com_github_99designs_gqlgen//:gqlgen",
            cfg = "host",
            executable = True,
        ),
    },
)

def gqlgen(**kwargs):
    tags = kwargs.get("tags", [])
    if "manual" not in tags:
        tags.append("manual")
        kwargs["tags"] = tags
    _gqlgen(**kwargs)

WORKSPACE

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

rules_go_version = "0.19.1"

http_archive(
    name = "io_bazel_rules_go",
    sha256 = "8df59f11fb697743cbb3f26cfb8750395f30471e9eabde0d174c3aebc7a1cd39",
    urls = [
        "https://storage.googleapis.com/bazel-mirror/github.com/bazelbuild/rules_go/releases/download/{}/rules_go-{}.tar.gz".format(rules_go_version, rules_go_version),
        "https://github.com/bazelbuild/rules_go/releases/download/{}/rules_go-{}.tar.gz".format(rules_go_version, rules_go_version),
    ],
)

load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_dependencies")

go_rules_dependencies()

go_register_toolchain()

go_repository(
    name = "com_github_99designs_gqlgen",
    importpath = "github.com/99designs/gqlgen",
    sum = "h1:sYL+xoM+PeMyh7RWwikT+1G+6GVtFur5ZJ1V73ra1w4=",
    version = "v0.9.2",
)