Add js.Build asset bundling

Fixes #7321

resources/resource_transformers/js/build.go

@@ -0,0 +1,166 @@
+// Copyright 2020 The Hugo 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.
+
+package js
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path"
+
+	"github.com/gohugoio/hugo/hugolib/filesystems"
+	"github.com/gohugoio/hugo/resources/internal"
+
+	"github.com/mitchellh/mapstructure"
+
+	"github.com/evanw/esbuild/pkg/api"
+	"github.com/gohugoio/hugo/resources"
+	"github.com/gohugoio/hugo/resources/resource"
+)
+
+type Options struct {
+	Minify      bool
+	Externals   []string
+	Target      string
+	Loader      string
+	Defines     map[string]string
+	JSXFactory  string
+	JSXFragment string
+	TSConfig    string
+}
+
+func DecodeOptions(m map[string]interface{}) (opts Options, err error) {
+	if m == nil {
+		return
+	}
+	err = mapstructure.WeakDecode(m, &opts)
+	return
+}
+
+type Client struct {
+	rs  *resources.Spec
+	sfs *filesystems.SourceFilesystem
+}
+
+func New(fs *filesystems.SourceFilesystem, rs *resources.Spec) *Client {
+	return &Client{rs: rs, sfs: fs}
+}
+
+type buildTransformation struct {
+	options Options
+	rs      *resources.Spec
+	sfs     *filesystems.SourceFilesystem
+}
+
+func (t *buildTransformation) Key() internal.ResourceTransformationKey {
+	return internal.NewResourceTransformationKey("jsbuild", t.options)
+}
+
+func (t *buildTransformation) Transform(ctx *resources.ResourceTransformationCtx) error {
+	var target api.Target
+	switch t.options.Target {
+	case "", "esnext":
+		target = api.ESNext
+	case "es6", "es2015":
+		target = api.ES2015
+	case "es2016":
+		target = api.ES2016
+	case "es2017":
+		target = api.ES2017
+	case "es2018":
+		target = api.ES2018
+	case "es2019":
+		target = api.ES2019
+	case "es2020":
+		target = api.ES2020
+	default:
+		return fmt.Errorf("invalid target: %q", t.options.Target)
+	}
+
+	var loader api.Loader
+	switch t.options.Loader {
+	case "", "js":
+		loader = api.LoaderJS
+	case "jsx":
+		loader = api.LoaderJSX
+	case "ts":
+		loader = api.LoaderTS
+	case "tsx":
+		loader = api.LoaderTSX
+	case "json":
+		loader = api.LoaderJSON
+	case "text":
+		loader = api.LoaderText
+	case "base64":
+		loader = api.LoaderBase64
+	case "dataURL":
+		loader = api.LoaderDataURL
+	case "file":
+		loader = api.LoaderFile
+	case "binary":
+		loader = api.LoaderBinary
+	default:
+		return fmt.Errorf("invalid loader: %q", t.options.Loader)
+	}
+
+	src, err := ioutil.ReadAll(ctx.From)
+	if err != nil {
+		return err
+	}
+
+	sdir, sfile := path.Split(ctx.SourcePath)
+	sdir = t.sfs.RealFilename(sdir)
+
+	buildOptions := api.BuildOptions{
+		Outfile: "",
+		Bundle:  true,
+
+		Target: target,
+
+		MinifyWhitespace:  t.options.Minify,
+		MinifyIdentifiers: t.options.Minify,
+		MinifySyntax:      t.options.Minify,
+
+		Defines: t.options.Defines,
+
+		Externals: t.options.Externals,
+
+		JSXFactory:  t.options.JSXFactory,
+		JSXFragment: t.options.JSXFragment,
+
+		Tsconfig: t.options.TSConfig,
+
+		Stdin: &api.StdinOptions{
+			Contents:   string(src),
+			Sourcefile: sfile,
+			ResolveDir: sdir,
+			Loader:     loader,
+		},
+	}
+	result := api.Build(buildOptions)
+	if len(result.Errors) > 0 {
+		return fmt.Errorf("%s", result.Errors[0].Text)
+	}
+	if len(result.OutputFiles) != 1 {
+		return fmt.Errorf("unexpected output count: %d", len(result.OutputFiles))
+	}
+
+	ctx.To.Write(result.OutputFiles[0].Contents)
+	return nil
+}
+
+func (c *Client) Process(res resources.ResourceTransformer, options Options) (resource.Resource, error) {
+	return res.Transform(
+		&buildTransformation{rs: c.rs, sfs: c.sfs, options: options},
+	)
+}