resources: Move resource interfaces into its own package

3 files changed, 314 insertions, 0 deletions

diff --git a/resources/resource_transformers/tocss/scss/client.go b/resources/resource_transformers/tocss/scss/client.go
new file mode 100644
index 000000000..41ff67433
--- /dev/null
+++ b/resources/resource_transformers/tocss/scss/client.go
@@ -0,0 +1,111 @@
+// 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 scss
+
+import (
+	"github.com/bep/go-tocss/scss"
+	"github.com/gohugoio/hugo/helpers"
+	"github.com/gohugoio/hugo/hugolib/filesystems"
+	"github.com/gohugoio/hugo/resources"
+	"github.com/gohugoio/hugo/resources/resource"
+
+	"github.com/mitchellh/mapstructure"
+)
+
+type Client struct {
+	rs     *resources.Spec
+	sfs    *filesystems.SourceFilesystem
+	workFs *filesystems.SourceFilesystem
+}
+
+func New(fs *filesystems.SourceFilesystem, rs *resources.Spec) (*Client, error) {
+	return &Client{sfs: fs, workFs: rs.BaseFs.Work, rs: rs}, nil
+}
+
+type Options struct {
+
+	// Hugo, will by default, just replace the extension of the source
+	// to .css, e.g. "scss/main.scss" becomes "scss/main.css". You can
+	// control this by setting this, e.g. "styles/main.css" will create
+	// a Resource with that as a base for RelPermalink etc.
+	TargetPath string
+
+	// Hugo automatically adds the entry directories (where the main.scss lives)
+	// for project and themes to the list of include paths sent to LibSASS.
+	// Any paths set in this setting will be appended. Note that these will be
+	// treated as relative to the working dir, i.e. no include paths outside the
+	// project/themes.
+	IncludePaths []string
+
+	// Default is nested.
+	// One of nested, expanded, compact, compressed.
+	OutputStyle string
+
+	// Precision of floating point math.
+	Precision int
+
+	// When enabled, Hugo will generate a source map.
+	EnableSourceMap bool
+}
+
+type options struct {
+	// The options we receive from the end user.
+	from Options
+
+	// The options we send to the SCSS library.
+	to scss.Options
+}
+
+func (c *Client) ToCSS(res resource.Resource, opts Options) (resource.Resource, error) {
+	internalOptions := options{
+		from: opts,
+	}
+
+	// Transfer values from client.
+	internalOptions.to.Precision = opts.Precision
+	internalOptions.to.OutputStyle = scss.OutputStyleFromString(opts.OutputStyle)
+
+	if internalOptions.to.Precision == 0 {
+		// bootstrap-sass requires 8 digits precision. The libsass default is 5.
+		// https://github.com/twbs/bootstrap-sass/blob/master/README.md#sass-number-precision
+		internalOptions.to.Precision = 8
+	}
+
+	return c.rs.Transform(
+		res,
+		&toCSSTransformation{c: c, options: internalOptions},
+	)
+}
+
+type toCSSTransformation struct {
+	c       *Client
+	options options
+}
+
+func (t *toCSSTransformation) Key() resources.ResourceTransformationKey {
+	return resources.NewResourceTransformationKey("tocss", t.options.from)
+}
+
+func DecodeOptions(m map[string]interface{}) (opts Options, err error) {
+	if m == nil {
+		return
+	}
+	err = mapstructure.WeakDecode(m, &opts)
+
+	if opts.TargetPath != "" {
+		opts.TargetPath = helpers.ToSlashTrimLeading(opts.TargetPath)
+	}
+
+	return
+}
diff --git a/resources/resource_transformers/tocss/scss/tocss.go b/resources/resource_transformers/tocss/scss/tocss.go
new file mode 100644
index 000000000..17c32ea8e
--- /dev/null
+++ b/resources/resource_transformers/tocss/scss/tocss.go
@@ -0,0 +1,173 @@
+// 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.
+
+// +build extended
+
+package scss
+
+import (
+	"fmt"
+	"io"
+	"path"
+	"path/filepath"
+	"strings"
+
+	"github.com/bep/go-tocss/scss"
+	"github.com/bep/go-tocss/scss/libsass"
+	"github.com/bep/go-tocss/tocss"
+	"github.com/gohugoio/hugo/helpers"
+	"github.com/gohugoio/hugo/hugofs"
+	"github.com/gohugoio/hugo/media"
+	"github.com/gohugoio/hugo/resources"
+	"github.com/pkg/errors"
+)
+
+// Used in tests. This feature requires Hugo to be built with the extended tag.
+func Supports() bool {
+	return true
+}
+
+func (t *toCSSTransformation) Transform(ctx *resources.ResourceTransformationCtx) error {
+	ctx.OutMediaType = media.CSSType
+
+	var outName string
+	if t.options.from.TargetPath != "" {
+		ctx.OutPath = t.options.from.TargetPath
+	} else {
+		ctx.ReplaceOutPathExtension(".css")
+	}
+
+	outName = path.Base(ctx.OutPath)
+
+	options := t.options
+	baseDir := path.Dir(ctx.SourcePath)
+	options.to.IncludePaths = t.c.sfs.RealDirs(baseDir)
+
+	// Append any workDir relative include paths
+	for _, ip := range options.from.IncludePaths {
+		options.to.IncludePaths = append(options.to.IncludePaths, t.c.workFs.RealDirs(filepath.Clean(ip))...)
+	}
+
+	// To allow for overrides of SCSS files anywhere in the project/theme hierarchy, we need
+	// to help libsass revolve the filename by looking in the composite filesystem first.
+	// We add the entry directories for both project and themes to the include paths list, but
+	// that only work for overrides on the top level.
+	options.to.ImportResolver = func(url string, prev string) (newUrl string, body string, resolved bool) {
+		// We get URL paths from LibSASS, but we need file paths.
+		url = filepath.FromSlash(url)
+		prev = filepath.FromSlash(prev)
+
+		var basePath string
+		urlDir := filepath.Dir(url)
+		var prevDir string
+		if prev == "stdin" {
+			prevDir = baseDir
+		} else {
+			prevDir = t.c.sfs.MakePathRelative(filepath.Dir(prev))
+			if prevDir == "" {
+				// Not a member of this filesystem. Let LibSASS handle it.
+				return "", "", false
+			}
+		}
+
+		basePath = filepath.Join(prevDir, urlDir)
+		name := filepath.Base(url)
+
+		// Libsass throws an error in cases where you have several possible candidates.
+		// We make this simpler and pick the first match.
+		var namePatterns []string
+		if strings.Contains(name, ".") {
+			namePatterns = []string{"_%s", "%s"}
+		} else if strings.HasPrefix(name, "_") {
+			namePatterns = []string{"_%s.scss", "_%s.sass"}
+		} else {
+			namePatterns = []string{"_%s.scss", "%s.scss", "_%s.sass", "%s.sass"}
+		}
+
+		name = strings.TrimPrefix(name, "_")
+
+		for _, namePattern := range namePatterns {
+			filenameToCheck := filepath.Join(basePath, fmt.Sprintf(namePattern, name))
+			fi, err := t.c.sfs.Fs.Stat(filenameToCheck)
+			if err == nil {
+				if fir, ok := fi.(hugofs.RealFilenameInfo); ok {
+					return fir.RealFilename(), "", true
+				}
+			}
+		}
+
+		// Not found, let LibSASS handle it
+		return "", "", false
+	}
+
+	if ctx.InMediaType.SubType == media.SASSType.SubType {
+		options.to.SassSyntax = true
+	}
+
+	if options.from.EnableSourceMap {
+
+		options.to.SourceMapFilename = outName + ".map"
+		options.to.SourceMapRoot = t.c.rs.WorkingDir
+
+		// Setting this to the relative input filename will get the source map
+		// more correct for the main entry path (main.scss typically), but
+		// it will mess up the import mappings. As a workaround, we do a replacement
+		// in the source map itself (see below).
+		//options.InputPath = inputPath
+		options.to.OutputPath = outName
+		options.to.SourceMapContents = true
+		options.to.OmitSourceMapURL = false
+		options.to.EnableEmbeddedSourceMap = false
+	}
+
+	res, err := t.c.toCSS(options.to, ctx.To, ctx.From)
+	if err != nil {
+		return err
+	}
+
+	if options.from.EnableSourceMap && res.SourceMapContent != "" {
+		sourcePath := t.c.sfs.RealFilename(ctx.SourcePath)
+
+		if strings.HasPrefix(sourcePath, t.c.rs.WorkingDir) {
+			sourcePath = strings.TrimPrefix(sourcePath, t.c.rs.WorkingDir+helpers.FilePathSeparator)
+		}
+
+		// This needs to be Unix-style slashes, even on Windows.
+		// See https://github.com/gohugoio/hugo/issues/4968
+		sourcePath = filepath.ToSlash(sourcePath)
+
+		// This is a workaround for what looks like a bug in Libsass. But
+		// getting this resolution correct in tools like Chrome Workspaces
+		// is important enough to go this extra mile.
+		mapContent := strings.Replace(res.SourceMapContent, `stdin",`, fmt.Sprintf("%s\",", sourcePath), 1)
+
+		return ctx.PublishSourceMap(mapContent)
+	}
+	return nil
+}
+
+func (c *Client) toCSS(options scss.Options, dst io.Writer, src io.Reader) (tocss.Result, error) {
+	var res tocss.Result
+
+	transpiler, err := libsass.New(options)
+	if err != nil {
+		return res, err
+	}
+
+	res, err = transpiler.Execute(dst, src)
+	if err != nil {
+		return res, errors.Wrap(err, "SCSS processing failed")
+	}
+
+	return res, nil
+}
diff --git a/resources/resource_transformers/tocss/scss/tocss_notavailable.go b/resources/resource_transformers/tocss/scss/tocss_notavailable.go
new file mode 100644
index 000000000..ad6b42b98
--- /dev/null
+++ b/resources/resource_transformers/tocss/scss/tocss_notavailable.go
@@ -0,0 +1,30 @@
+// 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.
+
+// +build !extended
+
+package scss
+
+import (
+	"github.com/gohugoio/hugo/common/herrors"
+	"github.com/gohugoio/hugo/resources"
+)
+
+// Used in tests.
+func Supports() bool {
+	return false
+}
+
+func (t *toCSSTransformation) Transform(ctx *resources.ResourceTransformationCtx) error {
+	return herrors.ErrFeatureNotAvailable
+}