resources: Move resource interfaces into its own package

resources/resource_transformers/minifier/minify.go

@@ -0,0 +1,59 @@
+// Copyright 2018 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 minifier
+
+import (
+	"github.com/gohugoio/hugo/minifiers"
+	"github.com/gohugoio/hugo/resources"
+	"github.com/gohugoio/hugo/resources/resource"
+)
+
+// Client for minification of Resource objects. Supported minfiers are:
+// css, html, js, json, svg and xml.
+type Client struct {
+	rs *resources.Spec
+	m  minifiers.Client
+}
+
+// New creates a new Client given a specification. Note that it is the media types
+// configured for the site that is used to match files to the correct minifier.
+func New(rs *resources.Spec) *Client {
+	return &Client{rs: rs, m: minifiers.New(rs.MediaTypes, rs.OutputFormats)}
+}
+
+type minifyTransformation struct {
+	rs *resources.Spec
+	m  minifiers.Client
+}
+
+func (t *minifyTransformation) Key() resources.ResourceTransformationKey {
+	return resources.NewResourceTransformationKey("minify")
+}
+
+func (t *minifyTransformation) Transform(ctx *resources.ResourceTransformationCtx) error {
+	if err := t.m.Minify(ctx.InMediaType, ctx.To, ctx.From); err != nil {
+		return err
+	}
+	ctx.AddOutPathIdentifier(".min")
+	return nil
+}
+
+func (c *Client) Minify(res resource.Resource) (resource.Resource, error) {
+	return c.rs.Transform(
+		res,
+		&minifyTransformation{
+			rs: c.rs,
+			m:  c.m},
+	)
+}