Add proper Media Type handling in js.Build

See #732

3 files changed, 100 insertions, 93 deletions

diff --git a/tpl/internal/resourcehelpers/helpers.go b/tpl/internal/resourcehelpers/helpers.go
new file mode 100644
index 000000000..4f8b7539a
--- /dev/null
+++ b/tpl/internal/resourcehelpers/helpers.go
@@ -0,0 +1,71 @@
+// Copyright 2020 The Hugo Authors. All rights reserved.
+//
+// Portions Copyright The Go Authors.
+
+// 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 resourcehelpers
+
+import (
+	"errors"
+	"fmt"
+
+	_errors "github.com/pkg/errors"
+
+	"github.com/gohugoio/hugo/common/maps"
+	"github.com/gohugoio/hugo/resources"
+)
+
+// We allow string or a map as the first argument in some cases.
+func ResolveIfFirstArgIsString(args []interface{}) (resources.ResourceTransformer, string, bool) {
+	if len(args) != 2 {
+		return nil, "", false
+	}
+
+	v1, ok1 := args[0].(string)
+	if !ok1 {
+		return nil, "", false
+	}
+	v2, ok2 := args[1].(resources.ResourceTransformer)
+
+	return v2, v1, ok2
+}
+
+// This roundabout way of doing it is needed to get both pipeline behaviour and options as arguments.
+func 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
+}
diff --git a/tpl/js/js.go b/tpl/js/js.go
index d8ba35a76..4dc97a707 100644
--- a/tpl/js/js.go
+++ b/tpl/js/js.go
@@ -15,15 +15,12 @@
 package js
 
 import (
-	"errors"
-	"fmt"
-
-	"github.com/gohugoio/hugo/common/maps"
 	"github.com/gohugoio/hugo/deps"
+	"github.com/gohugoio/hugo/helpers"
 	"github.com/gohugoio/hugo/resources"
 	"github.com/gohugoio/hugo/resources/resource"
 	"github.com/gohugoio/hugo/resources/resource_transformers/js"
-	_errors "github.com/pkg/errors"
+	"github.com/gohugoio/hugo/tpl/internal/resourcehelpers"
 )
 
 // New returns a new instance of the js-namespaced template functions.
@@ -41,50 +38,33 @@ type Namespace struct {
 
 // 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)
+	var (
+		r          resources.ResourceTransformer
+		m          map[string]interface{}
+		targetPath string
+		err        error
+		ok         bool
+	)
+
+	r, targetPath, ok = resourcehelpers.ResolveIfFirstArgIsString(args)
 
+	if !ok {
+		r, m, err = resourcehelpers.ResolveArgs(args)
 		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")
+	var options js.Options
+	if targetPath != "" {
+		options.TargetPath = helpers.ToSlashTrimLeading(targetPath)
+	} else if m != nil {
+		options, err = js.DecodeOptions(m)
+		if err != nil {
+			return nil, err
 		}
-		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 ns.client.Process(r, options)
 
-	return r, m, nil
 }
diff --git a/tpl/resources/resources.go b/tpl/resources/resources.go
index 6625702ab..cdde6bd5d 100644
--- a/tpl/resources/resources.go
+++ b/tpl/resources/resources.go
@@ -19,13 +19,14 @@ import (
 	"fmt"
 	"path/filepath"
 
+	"github.com/gohugoio/hugo/tpl/internal/resourcehelpers"
+
+	"github.com/gohugoio/hugo/helpers"
 	"github.com/gohugoio/hugo/resources/postpub"
 
-	"github.com/gohugoio/hugo/common/maps"
 	"github.com/gohugoio/hugo/deps"
 	"github.com/gohugoio/hugo/resources"
 	"github.com/gohugoio/hugo/resources/resource"
-	_errors "github.com/pkg/errors"
 
 	"github.com/gohugoio/hugo/resources/resource_factories/bundler"
 	"github.com/gohugoio/hugo/resources/resource_factories/create"
@@ -239,10 +240,10 @@ func (ns *Namespace) ToCSS(args ...interface{}) (resource.Resource, error) {
 		ok         bool
 	)
 
-	r, targetPath, ok = ns.resolveIfFirstArgIsString(args)
+	r, targetPath, ok = resourcehelpers.ResolveIfFirstArgIsString(args)
 
 	if !ok {
-		r, m, err = ns.resolveArgs(args)
+		r, m, err = resourcehelpers.ResolveArgs(args)
 		if err != nil {
 			return nil, err
 		}
@@ -250,7 +251,7 @@ func (ns *Namespace) ToCSS(args ...interface{}) (resource.Resource, error) {
 
 	var options scss.Options
 	if targetPath != "" {
-		options.TargetPath = targetPath
+		options.TargetPath = helpers.ToSlashTrimLeading(targetPath)
 	} else if m != nil {
 		options, err = scss.DecodeOptions(m)
 		if err != nil {
@@ -263,7 +264,7 @@ func (ns *Namespace) ToCSS(args ...interface{}) (resource.Resource, error) {
 
 // PostCSS processes the given Resource with PostCSS
 func (ns *Namespace) PostCSS(args ...interface{}) (resource.Resource, error) {
-	r, m, err := ns.resolveArgs(args)
+	r, m, err := resourcehelpers.ResolveArgs(args)
 	if err != nil {
 		return nil, err
 	}
@@ -285,7 +286,7 @@ func (ns *Namespace) PostProcess(r resource.Resource) (postpub.PostPublishedReso
 
 // Babel processes the given Resource with Babel.
 func (ns *Namespace) Babel(args ...interface{}) (resource.Resource, error) {
-	r, m, err := ns.resolveArgs(args)
+	r, m, err := resourcehelpers.ResolveArgs(args)
 	if err != nil {
 		return nil, err
 	}
@@ -301,48 +302,3 @@ func (ns *Namespace) Babel(args ...interface{}) (resource.Resource, error) {
 	return ns.babelClient.Process(r, options)
 
 }
-
-// We allow string or a map as the first argument in some cases.
-func (ns *Namespace) resolveIfFirstArgIsString(args []interface{}) (resources.ResourceTransformer, string, bool) {
-	if len(args) != 2 {
-		return nil, "", false
-	}
-
-	v1, ok1 := args[0].(string)
-	if !ok1 {
-		return nil, "", false
-	}
-	v2, ok2 := args[1].(resources.ResourceTransformer)
-
-	return v2, v1, ok2
-}
-
-// This roundabout way of doing it is needed to get both pipeline behaviour and options as arguments.
-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
-}