1 files changed, 129 insertions, 0 deletions
diff --git a/resource/resource_metadata.go b/resource/resource_metadata.go
new file mode 100644
index 000000000..2c82aeaf6
--- /dev/null
+++ b/resource/resource_metadata.go
@@ -0,0 +1,129 @@
+// 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 resource
+
+import (
+	"fmt"
+	"strconv"
+
+	"github.com/spf13/cast"
+
+	"strings"
+
+	"github.com/gohugoio/hugo/common/maps"
+)
+
+var (
+	_ metaAssigner = (*genericResource)(nil)
+)
+
+// metaAssigner allows updating metadata in resources that supports it.
+type metaAssigner interface {
+	setTitle(title string)
+	setName(name string)
+	updateParams(params map[string]interface{})
+}
+
+const counterPlaceHolder = ":counter"
+
+// AssignMetadata assigns the given metadata to those resources that supports updates
+// and matching by wildcard given in `src` using `filepath.Match` with lower cased values.
+// This assignment is additive, but the most specific match needs to be first.
+// The `name` and `title` metadata field support shell-matched collection it got a match in.
+// See https://golang.org/pkg/path/#Match
+func AssignMetadata(metadata []map[string]interface{}, resources ...Resource) error {
+
+	counters := make(map[string]int)
+
+	for _, r := range resources {
+		if _, ok := r.(metaAssigner); !ok {
+			continue
+		}
+
+		var (
+			nameSet, titleSet                   bool
+			nameCounter, titleCounter           = 0, 0
+			nameCounterFound, titleCounterFound bool
+			resourceSrcKey                      = strings.ToLower(r.Name())
+		)
+
+		ma := r.(metaAssigner)
+		for _, meta := range metadata {
+			src, found := meta["src"]
+			if !found {
+				return fmt.Errorf("missing 'src' in metadata for resource")
+			}
+
+			srcKey := strings.ToLower(cast.ToString(src))
+
+			glob, err := getGlob(srcKey)
+			if err != nil {
+				return fmt.Errorf("failed to match resource with metadata: %s", err)
+			}
+
+			match := glob.Match(resourceSrcKey)
+
+			if match {
+				if !nameSet {
+					name, found := meta["name"]
+					if found {
+						name := cast.ToString(name)
+						if !nameCounterFound {
+							nameCounterFound = strings.Contains(name, counterPlaceHolder)
+						}
+						if nameCounterFound && nameCounter == 0 {
+							counterKey := "name_" + srcKey
+							nameCounter = counters[counterKey] + 1
+							counters[counterKey] = nameCounter
+						}
+
+						ma.setName(replaceResourcePlaceholders(name, nameCounter))
+						nameSet = true
+					}
+				}
+
+				if !titleSet {
+					title, found := meta["title"]
+					if found {
+						title := cast.ToString(title)
+						if !titleCounterFound {
+							titleCounterFound = strings.Contains(title, counterPlaceHolder)
+						}
+						if titleCounterFound && titleCounter == 0 {
+							counterKey := "title_" + srcKey
+							titleCounter = counters[counterKey] + 1
+							counters[counterKey] = titleCounter
+						}
+						ma.setTitle((replaceResourcePlaceholders(title, titleCounter)))
+						titleSet = true
+					}
+				}
+
+				params, found := meta["params"]
+				if found {
+					m := cast.ToStringMap(params)
+					// Needed for case insensitive fetching of params values
+					maps.ToLower(m)
+					ma.updateParams(m)
+				}
+			}
+		}
+	}
+
+	return nil
+}
+
+func replaceResourcePlaceholders(in string, counter int) string {
+	return strings.Replace(in, counterPlaceHolder, strconv.Itoa(counter), -1)
+}