Fix Resource output in multihost setups

In Hugo 0.46 we made the output of what you get from resources.Get and similar static, i.e. language agnostic. This makes total sense, as it is wasteful and time-consuming to do SASS/SCSS/PostCSS processing for lots of languages when the output is lots of duplicates with different filenames.

But since we now output the result once only, this had a negative side effect for multihost setups: We publish the resource once only to the root folder (i.e. not to the language "domain folder").

This commit removes the language code from the processed image keys. This creates less duplication in the file cache, but it means that you should do a `hugo --gc` to clean up stale files.

Fixes #5058

5 files changed, 86 insertions, 36 deletions

diff --git a/resource/image.go b/resource/image.go
index 57da4f93d..fd8aea376 100644
--- a/resource/image.go
+++ b/resource/image.go
@@ -268,7 +268,7 @@ func (i *Image) doWithImageConfig(action, spec string, f func(src image.Image, c
 		ci.config = image.Config{Width: b.Max.X, Height: b.Max.Y}
 		ci.configLoaded = true
 
-		return ci, i.encodeToDestinations(converted, conf, resourceCacheFilename, ci.targetFilename())
+		return ci, i.encodeToDestinations(converted, conf, resourceCacheFilename, ci.targetFilenames()...)
 	})
 
 }
@@ -447,13 +447,21 @@ func (i *Image) decodeSource() (image.Image, error) {
 func (i *Image) copyToDestination(src string) error {
 	var res error
 	i.copyToDestinationInit.Do(func() {
-		target := i.targetFilename()
+		targetFilenames := i.targetFilenames()
+		var changedFilenames []string
 
 		// Fast path:
 		// This is a processed version of the original.
 		// If it exists on destination with the same filename and file size, it is
 		// the same file, so no need to transfer it again.
-		if fi, err := i.spec.BaseFs.PublishFs.Stat(target); err == nil && fi.Size() == i.osFileInfo.Size() {
+		for _, targetFilename := range targetFilenames {
+			if fi, err := i.spec.BaseFs.PublishFs.Stat(targetFilename); err == nil && fi.Size() == i.osFileInfo.Size() {
+				continue
+			}
+			changedFilenames = append(changedFilenames, targetFilename)
+		}
+
+		if len(changedFilenames) == 0 {
 			return
 		}
 
@@ -464,7 +472,7 @@ func (i *Image) copyToDestination(src string) error {
 		}
 		defer in.Close()
 
-		out, err := helpers.OpenFileForWriting(i.spec.BaseFs.PublishFs, target)
+		out, err := helpers.OpenFilesForWriting(i.spec.BaseFs.PublishFs, changedFilenames...)
 
 		if err != nil {
 			res = err
@@ -485,9 +493,9 @@ func (i *Image) copyToDestination(src string) error {
 	return nil
 }
 
-func (i *Image) encodeToDestinations(img image.Image, conf imageConfig, resourceCacheFilename, targetFilename string) error {
+func (i *Image) encodeToDestinations(img image.Image, conf imageConfig, resourceCacheFilename string, targetFilenames ...string) error {
 
-	file1, err := helpers.OpenFileForWriting(i.spec.BaseFs.PublishFs, targetFilename)
+	file1, err := helpers.OpenFilesForWriting(i.spec.BaseFs.PublishFs, targetFilenames...)
 	if err != nil {
 		return err
 	}
diff --git a/resource/image_cache.go b/resource/image_cache.go
index fb2996c9d..470c24c99 100644
--- a/resource/image_cache.go
+++ b/resource/image_cache.go
@@ -69,7 +69,7 @@ func (c *imageCache) getOrCreate(
 	parent *Image, conf imageConfig, create func(resourceCacheFilename string) (*Image, error)) (*Image, error) {
 
 	relTarget := parent.relTargetPathFromConfig(conf)
-	key := parent.relTargetPathForRel(relTarget.path(), false)
+	key := parent.relTargetPathForRel(relTarget.path(), false, false)
 
 	// First check the in-memory store, then the disk.
 	c.mu.RLock()
diff --git a/resource/resource.go b/resource/resource.go
index a1e29c52f..01e66078b 100644
--- a/resource/resource.go
+++ b/resource/resource.go
@@ -16,6 +16,7 @@ package resource
 import (
 	"errors"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"mime"
 	"os"
@@ -62,8 +63,8 @@ type Source interface {
 type permalinker interface {
 	relPermalinkFor(target string) string
 	permalinkFor(target string) string
-	relTargetPathFor(target string) string
-	relTargetPath() string
+	relTargetPathsFor(target string) []string
+	relTargetPaths() []string
 	targetPath() string
 }
 
@@ -332,10 +333,12 @@ type ResourceSourceDescriptor struct {
 	// Typically the language code if this resource should be published to its sub-folder.
 	URLBase string
 
-	// Any base path prepended to the target path. This will also typically be the
+	// Any base paths prepended to the target path. This will also typically be the
 	// language code, but setting it here means that it should not have any effect on
 	// the permalink.
-	TargetPathBase string
+	// This may be several values. In multihost mode we may publish the same resources to
+	// multiple targets.
+	TargetBasePaths []string
 
 	// Delay publishing until either Permalink or RelPermalink is called. Maybe never.
 	LazyPublish bool
@@ -373,6 +376,11 @@ func (r *Spec) newResourceForFs(sourceFs afero.Fs, fd ResourceSourceDescriptor)
 		fd.RelTargetFilename = fd.Filename()
 	}
 
+	if len(fd.TargetBasePaths) == 0 {
+		// If not set, we publish the same resource to all hosts.
+		fd.TargetBasePaths = r.MultihostTargetBasePaths
+	}
+
 	return r.newResource(sourceFs, fd)
 }
 
@@ -418,7 +426,7 @@ func (r *Spec) newResource(sourceFs afero.Fs, fd ResourceSourceDescriptor) (Reso
 		fd.LazyPublish,
 		fd.OpenReadSeekCloser,
 		fd.URLBase,
-		fd.TargetPathBase,
+		fd.TargetBasePaths,
 		fd.TargetPathBuilder,
 		fi,
 		sourceFilename,
@@ -505,8 +513,8 @@ type resourcePathDescriptor struct {
 	baseURLDir string
 
 	// This will normally be the same as above, but this will only apply to publishing
-	// of resources.
-	baseTargetPathDir string
+	// of resources. It may be mulltiple values when in multihost mode.
+	baseTargetPathDirs []string
 
 	// baseOffset is set when the output format's path has a offset, e.g. for AMP.
 	baseOffset string
@@ -688,12 +696,12 @@ func (l *genericResource) permalinkFor(target string) string {
 	return l.spec.PermalinkForBaseURL(l.relPermalinkForRel(target), l.spec.BaseURL.HostURL())
 
 }
-func (l *genericResource) relTargetPathFor(target string) string {
-	return l.relTargetPathForRel(target, false)
+func (l *genericResource) relTargetPathsFor(target string) []string {
+	return l.relTargetPathsForRel(target)
 }
 
-func (l *genericResource) relTargetPath() string {
-	return l.relTargetPathForRel(l.targetPath(), false)
+func (l *genericResource) relTargetPaths() []string {
+	return l.relTargetPathsForRel(l.targetPath())
 }
 
 func (l *genericResource) Name() string {
@@ -731,11 +739,34 @@ func (l *genericResource) updateParams(params map[string]interface{}) {
 }
 
 func (l *genericResource) relPermalinkForRel(rel string) string {
-	return l.spec.PathSpec.URLizeFilename(l.relTargetPathForRel(rel, true))
+	return l.spec.PathSpec.URLizeFilename(l.relTargetPathForRel(rel, false, true))
+}
+
+func (l *genericResource) relTargetPathsForRel(rel string) []string {
+	if len(l.baseTargetPathDirs) == 0 {
+		return []string{l.relTargetPathForRelAndBasePath(rel, "", false)}
+	}
+
+	var targetPaths = make([]string, len(l.baseTargetPathDirs))
+	for i, dir := range l.baseTargetPathDirs {
+		targetPaths[i] = l.relTargetPathForRelAndBasePath(rel, dir, false)
+	}
+	return targetPaths
 }
 
-func (l *genericResource) relTargetPathForRel(rel string, isURL bool) string {
+func (l *genericResource) relTargetPathForRel(rel string, addBaseTargetPath, isURL bool) string {
+	if addBaseTargetPath && len(l.baseTargetPathDirs) > 1 {
+		panic("multiple baseTargetPathDirs")
+	}
+	var basePath string
+	if addBaseTargetPath && len(l.baseTargetPathDirs) > 0 {
+		basePath = l.baseTargetPathDirs[0]
+	}
 
+	return l.relTargetPathForRelAndBasePath(rel, basePath, isURL)
+}
+
+func (l *genericResource) relTargetPathForRelAndBasePath(rel, basePath string, isURL bool) string {
 	if l.targetPathBuilder != nil {
 		rel = l.targetPathBuilder(rel)
 	}
@@ -744,8 +775,8 @@ func (l *genericResource) relTargetPathForRel(rel string, isURL bool) string {
 		rel = path.Join(l.baseURLDir, rel)
 	}
 
-	if !isURL && l.baseTargetPathDir != "" {
-		rel = path.Join(l.baseTargetPathDir, rel)
+	if basePath != "" {
+		rel = path.Join(basePath, rel)
 	}
 
 	if l.baseOffset != "" {
@@ -772,12 +803,19 @@ func (l *genericResource) String() string {
 }
 
 func (l *genericResource) Publish() error {
-	f, err := l.ReadSeekCloser()
+	fr, err := l.ReadSeekCloser()
 	if err != nil {
 		return err
 	}
-	defer f.Close()
-	return helpers.WriteToDisk(l.targetFilename(), f, l.spec.BaseFs.PublishFs)
+	defer fr.Close()
+	fw, err := helpers.OpenFilesForWriting(l.spec.BaseFs.PublishFs, l.targetFilenames()...)
+	if err != nil {
+		return err
+	}
+	defer fw.Close()
+
+	_, err = io.Copy(fw, fr)
+	return err
 }
 
 // Path is stored with Unix style slashes.
@@ -785,8 +823,12 @@ func (l *genericResource) targetPath() string {
 	return l.relTargetDirFile.path()
 }
 
-func (l *genericResource) targetFilename() string {
-	return filepath.Clean(l.relTargetPath())
+func (l *genericResource) targetFilenames() []string {
+	paths := l.relTargetPaths()
+	for i, p := range paths {
+		paths[i] = filepath.Clean(p)
+	}
+	return paths
 }
 
 // TODO(bep) clean up below
@@ -801,7 +843,7 @@ func (r *Spec) newGenericResource(sourceFs afero.Fs,
 		false,
 		nil,
 		"",
-		"",
+		nil,
 		targetPathBuilder,
 		osFileInfo,
 		sourceFilename,
@@ -816,7 +858,7 @@ func (r *Spec) newGenericResourceWithBase(
 	lazyPublish bool,
 	openReadSeekerCloser OpenReadSeekCloser,
 	urlBaseDir string,
-	targetPathBaseDir string,
+	targetPathBaseDirs []string,
 	targetPathBuilder func(base string) string,
 	osFileInfo os.FileInfo,
 	sourceFilename,
@@ -836,10 +878,10 @@ func (r *Spec) newGenericResourceWithBase(
 	}
 
 	pathDescriptor := resourcePathDescriptor{
-		baseURLDir:        urlBaseDir,
-		baseTargetPathDir: targetPathBaseDir,
-		targetPathBuilder: targetPathBuilder,
-		relTargetDirFile:  dirFile{dir: fpath, file: fname},
+		baseURLDir:         urlBaseDir,
+		baseTargetPathDirs: targetPathBaseDirs,
+		targetPathBuilder:  targetPathBuilder,
+		relTargetDirFile:   dirFile{dir: fpath, file: fname},
 	}
 
 	var po *publishOnce
diff --git a/resource/resource_test.go b/resource/resource_test.go
index e699e6f3f..b76f0a604 100644
--- a/resource/resource_test.go
+++ b/resource/resource_test.go
@@ -93,7 +93,7 @@ func TestNewResourceFromFilenameSubPathInBaseURL(t *testing.T) {
 	assert.Equal("/docs/a/b/logo.png", r.RelPermalink())
 	assert.Equal("https://example.com/docs/a/b/logo.png", r.Permalink())
 	img := r.(*Image)
-	assert.Equal(filepath.FromSlash("/a/b/logo.png"), img.targetFilename())
+	assert.Equal(filepath.FromSlash("/a/b/logo.png"), img.targetFilenames()[0])
 
 }
 
diff --git a/resource/transform.go b/resource/transform.go
index c61a9771e..dd9cd143b 100644
--- a/resource/transform.go
+++ b/resource/transform.go
@@ -267,7 +267,7 @@ func (r *transformedResource) initContent() error {
 func (r *transformedResource) transform(setContent bool) (err error) {
 
 	openPublishFileForWriting := func(relTargetPath string) (io.WriteCloser, error) {
-		return helpers.OpenFileForWriting(r.cache.rs.PublishFs, r.linker.relTargetPathFor(relTargetPath))
+		return helpers.OpenFilesForWriting(r.cache.rs.PublishFs, r.linker.relTargetPathsFor(relTargetPath)...)
 	}
 
 	// This can be the last resource in a chain.
@@ -299,7 +299,7 @@ func (r *transformedResource) transform(setContent bool) (err error) {
 			key = key + "_" + v.transformation.Key().key()
 		case permalinker:
 			r.linker = v
-			p := v.relTargetPath()
+			p := v.targetPath()
 			if p == "" {
 				panic("target path needed for key creation")
 			}