Add js.Build asset bundling

Fixes #7321

tpl/js/js.go

@@ -0,0 +1,90 @@
+// 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 provides functions for building JavaScript resources
+package js
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/gohugoio/hugo/common/maps"
+	"github.com/gohugoio/hugo/deps"
+	"github.com/gohugoio/hugo/resources"
+	"github.com/gohugoio/hugo/resources/resource"
+	"github.com/gohugoio/hugo/resources/resource_transformers/js"
+	_errors "github.com/pkg/errors"
+)
+
+// New returns a new instance of the js-namespaced template functions.
+func New(deps *deps.Deps) *Namespace {
+	return &Namespace{
+		client: js.New(deps.BaseFs.Assets, deps.ResourceSpec),
+	}
+}
+
+// Namespace provides template functions for the "js" namespace.
+type Namespace struct {
+	deps   *deps.Deps
+	client *js.Client
+}
+
+// Build processes the given Resource with ESBuild.
+func (ns *Namespace) Build(args ...interface{}) (resource.Resource, error) {
+	r, m, err := ns.resolveArgs(args)
+	if err != nil {
+		return nil, err
+	}
+	var options js.Options
+	if m != nil {
+		options, err = js.DecodeOptions(m)
+
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return ns.client.Process(r, options)
+
+}
+
+// This roundabout way of doing it is needed to get both pipeline behaviour and options as arguments.
+// This is a copy of tpl/resources/resolveArgs
+func (ns *Namespace) resolveArgs(args []interface{}) (resources.ResourceTransformer, map[string]interface{}, error) {
+	if len(args) == 0 {
+		return nil, nil, errors.New("no Resource provided in transformation")
+	}
+
+	if len(args) == 1 {
+		r, ok := args[0].(resources.ResourceTransformer)
+		if !ok {
+			return nil, nil, fmt.Errorf("type %T not supported in Resource transformations", args[0])
+		}
+		return r, nil, nil
+	}
+
+	r, ok := args[1].(resources.ResourceTransformer)
+	if !ok {
+		if _, ok := args[1].(map[string]interface{}); !ok {
+			return nil, nil, fmt.Errorf("no Resource provided in transformation")
+		}
+		return nil, nil, fmt.Errorf("type %T not supported in Resource transformations", args[0])
+	}
+
+	m, err := maps.ToStringMapE(args[0])
+	if err != nil {
+		return nil, nil, _errors.Wrap(err, "invalid options type")
+	}
+
+	return r, m, nil
+}