1 files changed, 121 insertions, 0 deletions
diff --git a/resource/resource_factories/bundler/bundler.go b/resource/resource_factories/bundler/bundler.go
new file mode 100644
index 000000000..70b8ee536
--- /dev/null
+++ b/resource/resource_factories/bundler/bundler.go
@@ -0,0 +1,121 @@
+// 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 bundler contains functions for concatenation etc. of Resource objects.
+package bundler
+
+import (
+	"fmt"
+	"io"
+	"path/filepath"
+
+	"github.com/gohugoio/hugo/common/hugio"
+	"github.com/gohugoio/hugo/media"
+	"github.com/gohugoio/hugo/resource"
+)
+
+// Client contains methods perform concatenation and other bundling related
+// tasks to Resource objects.
+type Client struct {
+	rs *resource.Spec
+}
+
+// New creates a new Client with the given specification.
+func New(rs *resource.Spec) *Client {
+	return &Client{rs: rs}
+}
+
+type multiReadSeekCloser struct {
+	mr      io.Reader
+	sources []hugio.ReadSeekCloser
+}
+
+func (r *multiReadSeekCloser) Read(p []byte) (n int, err error) {
+	return r.mr.Read(p)
+}
+
+func (r *multiReadSeekCloser) Seek(offset int64, whence int) (newOffset int64, err error) {
+	for _, s := range r.sources {
+		newOffset, err = s.Seek(offset, whence)
+		if err != nil {
+			return
+		}
+	}
+	return
+}
+
+func (r *multiReadSeekCloser) Close() error {
+	for _, s := range r.sources {
+		s.Close()
+	}
+	return nil
+}
+
+// Concat concatenates the list of Resource objects.
+func (c *Client) Concat(targetPath string, resources resource.Resources) (resource.Resource, error) {
+	// The CACHE_OTHER will make sure this will be re-created and published on rebuilds.
+	return c.rs.ResourceCache.GetOrCreate(resource.CACHE_OTHER, targetPath, func() (resource.Resource, error) {
+		var resolvedm media.Type
+
+		// The given set of resources must be of the same Media Type.
+		// We may improve on that in the future, but then we need to know more.
+		for i, r := range resources {
+			if i > 0 && r.MediaType().Type() != resolvedm.Type() {
+				return nil, fmt.Errorf("resources in Concat must be of the same Media Type, got %q and %q", r.MediaType().Type(), resolvedm.Type())
+			}
+			resolvedm = r.MediaType()
+		}
+
+		concatr := func() (hugio.ReadSeekCloser, error) {
+			var rcsources []hugio.ReadSeekCloser
+			for _, s := range resources {
+				rcr, ok := s.(resource.ReadSeekCloserResource)
+				if !ok {
+					return nil, fmt.Errorf("resource %T does not implement resource.ReadSeekerCloserResource", s)
+				}
+				rc, err := rcr.ReadSeekCloser()
+				if err != nil {
+					// Close the already opened.
+					for _, rcs := range rcsources {
+						rcs.Close()
+					}
+					return nil, err
+				}
+				rcsources = append(rcsources, rc)
+			}
+
+			readers := make([]io.Reader, len(rcsources))
+			for i := 0; i < len(rcsources); i++ {
+				readers[i] = rcsources[i]
+			}
+
+			mr := io.MultiReader(readers...)
+
+			return &multiReadSeekCloser{mr: mr, sources: rcsources}, nil
+		}
+
+		composite, err := c.rs.NewForFs(
+			c.rs.FileCaches.AssetsCache().Fs,
+			resource.ResourceSourceDescriptor{
+				LazyPublish:        true,
+				OpenReadSeekCloser: concatr,
+				RelTargetFilename:  filepath.Clean(targetPath)})
+
+		if err != nil {
+			return nil, err
+		}
+
+		return composite, nil
+	})
+
+}