create: Use archetype template as-is as a Go template

This commit removes the fragile front matter decoding, and takes the provided archetype file as-is and processes it as a template.

This also means that we no longer will attempt to fill in default values for `title` and `date`.

The upside is that it is now easy to create these values in a dynamic way:

```toml
+++
title = {{ .BaseFileName | title }}
date = {{ .Date }}
draft = true
+++
```

You can currently use all of Hugo's template funcs, but the data context is currently very shallow:

* `.Type` gives the archetype kind provided
* `.Name` gives the target file name without extension.
* `.Path` gives the target file name
* `.Date` gives the current time as RFC3339 formatted string

The above  will probably be extended in #1629.

Fixes #452
Updates #1629

3 files changed, 113 insertions, 94 deletions

diff --git a/create/content.go b/create/content.go
index a62227176..e29ea9ac8 100644
--- a/create/content.go
+++ b/create/content.go
@@ -19,68 +19,40 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
-	"strings"
-	"time"
 
 	"github.com/gohugoio/hugo/helpers"
 	"github.com/gohugoio/hugo/hugolib"
-	"github.com/gohugoio/hugo/parser"
-	"github.com/spf13/afero"
-	"github.com/spf13/cast"
 	jww "github.com/spf13/jwalterweatherman"
 )
 
 // NewContent creates a new content file in the content directory based upon the
 // given kind, which is used to lookup an archetype.
-func NewContent(s *hugolib.Site, kind, name string) (err error) {
-	jww.INFO.Println("attempting to create ", name, "of", kind)
+func NewContent(s *hugolib.Site, kind, targetPath string) error {
+	jww.INFO.Println("attempting to create ", targetPath, "of", kind)
 
-	location := FindArchetype(s, kind)
+	archetypeFilename := findArchetype(s, kind)
 
-	var by []byte
+	var (
+		content []byte
+		err     error
+	)
 
-	if location != "" {
-		by, err = afero.ReadFile(s.Fs.Source, location)
-		if err != nil {
-			jww.ERROR.Println(err)
-		}
-	}
-	if location == "" || err != nil {
-		by = []byte("+++\ndraft = true \n+++\n")
-	}
-
-	psr, err := parser.ReadFrom(bytes.NewReader(by))
+	content, err = executeArcheTypeAsTemplate(s, kind, targetPath, archetypeFilename)
 	if err != nil {
 		return err
 	}
 
-	metadata, err := createMetadata(psr, name)
-	if err != nil {
-		jww.ERROR.Printf("Error processing archetype file %s: %s\n", location, err)
-		return err
-	}
+	contentPath := s.PathSpec.AbsPathify(filepath.Join(s.Cfg.GetString("contentDir"), targetPath))
 
-	page, err := s.NewPage(name)
-	if err != nil {
+	if err := helpers.SafeWriteToDisk(contentPath, bytes.NewReader(content), s.Fs.Source); err != nil {
 		return err
 	}
 
-	if err = page.SetSourceMetaData(metadata, parser.FormatToLeadRune(s.Cfg.GetString("metaDataFormat"))); err != nil {
-		return
-	}
-
-	page.SetSourceContent(psr.Content())
-
-	contentPath := s.PathSpec.AbsPathify(filepath.Join(s.Cfg.GetString("contentDir"), name))
-
-	if err = page.SafeSaveSourceAs(contentPath); err != nil {
-		return
-	}
 	jww.FEEDBACK.Println(contentPath, "created")
 
 	editor := s.Cfg.GetString("newContentEditor")
 	if editor != "" {
-		jww.FEEDBACK.Printf("Editing %s with %q ...\n", name, editor)
+		jww.FEEDBACK.Printf("Editing %s with %q ...\n", targetPath, editor)
 
 		cmd := exec.Command(editor, contentPath)
 		cmd.Stdin = os.Stdin
@@ -93,59 +65,10 @@ func NewContent(s *hugolib.Site, kind, name string) (err error) {
 	return nil
 }
 
-// createMetadata generates Metadata for a new page based upon the metadata
-// found in an archetype.
-func createMetadata(archetype parser.Page, name string) (map[string]interface{}, error) {
-	archMetadata, err := archetype.Metadata()
-	if err != nil {
-		return nil, err
-	}
-
-	metadata, err := cast.ToStringMapE(archMetadata)
-	if err != nil {
-		return nil, err
-	}
-
-	var date time.Time
-
-	for k, v := range metadata {
-		if v == "" {
-			continue
-		}
-		lk := strings.ToLower(k)
-		switch lk {
-		case "date":
-			date, err = cast.ToTimeE(v)
-			if err != nil {
-				return nil, err
-			}
-		case "title":
-			// Use the archetype title as is
-			metadata[lk] = v
-		}
-	}
-
-	if metadata == nil {
-		metadata = make(map[string]interface{})
-	}
-
-	if date.IsZero() {
-		date = time.Now()
-	}
-
-	if _, ok := metadata["title"]; !ok {
-		metadata["title"] = helpers.MakeTitle(helpers.Filename(name))
-	}
-
-	metadata["date"] = date.Format(time.RFC3339)
-
-	return metadata, nil
-}
-
 // FindArchetype takes a given kind/archetype of content and returns an output
 // path for that archetype.  If no archetype is found, an empty string is
 // returned.
-func FindArchetype(s *hugolib.Site, kind string) (outpath string) {
+func findArchetype(s *hugolib.Site, kind string) (outpath string) {
 	search := []string{s.PathSpec.AbsPathify(s.Cfg.GetString("archetypeDir"))}
 
 	if s.Cfg.GetString("theme") != "" {
diff --git a/create/content_template_handler.go b/create/content_template_handler.go
new file mode 100644
index 000000000..9903c3dec
--- /dev/null
+++ b/create/content_template_handler.go
@@ -0,0 +1,94 @@
+// Copyright 2017 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 create
+
+import (
+	"bytes"
+	"fmt"
+	"time"
+
+	"github.com/gohugoio/hugo/source"
+
+	"github.com/gohugoio/hugo/hugolib"
+	"github.com/gohugoio/hugo/tpl"
+	"github.com/spf13/afero"
+)
+
+const (
+	archetypeTemplateTemplate = `+++
+title = "{{ replace .BaseFileName "-" " " | title }}"
+date = {{ .Date }}
+draft = true
++++`
+)
+
+func executeArcheTypeAsTemplate(s *hugolib.Site, kind, targetPath, archetypeFilename string) ([]byte, error) {
+
+	var (
+		archetypeContent  []byte
+		archetypeTemplate []byte
+		err               error
+	)
+
+	sp := source.NewSourceSpec(s.Deps.Cfg, s.Deps.Fs)
+	f := sp.NewFile(targetPath)
+
+	data := struct {
+		Type string
+		Date string
+		*source.File
+	}{
+		Type: kind,
+		Date: time.Now().Format(time.RFC3339),
+		File: f,
+	}
+
+	if archetypeFilename == "" {
+		// TODO(bep) archetype revive the issue about wrong tpl funcs arg order
+		archetypeTemplate = []byte(archetypeTemplateTemplate)
+	} else {
+		archetypeTemplate, err = afero.ReadFile(s.Fs.Source, archetypeFilename)
+		if err != nil {
+			return nil, fmt.Errorf("Failed to read archetype file %q: %s", archetypeFilename, err)
+		}
+
+	}
+
+	// Reuse the Hugo template setup to get the template funcs properly set up.
+	templateHandler := s.Deps.Tmpl.(tpl.TemplateHandler)
+	if err := templateHandler.AddTemplate("_text/archetype", string(archetypeTemplate)); err != nil {
+		return nil, fmt.Errorf("Failed to parse archetype file %q: %s", archetypeFilename, err)
+	}
+
+	templ := templateHandler.Lookup("_text/archetype")
+
+	var buff bytes.Buffer
+	if err := templ.Execute(&buff, data); err != nil {
+		return nil, fmt.Errorf("Failed to process archetype file %q: %s", archetypeFilename, err)
+	}
+
+	archetypeContent = buff.Bytes()
+
+	if !bytes.Contains(archetypeContent, []byte("date")) || !bytes.Contains(archetypeContent, []byte("title")) {
+		// TODO(bep) remove some time in the future.
+		s.Log.FEEDBACK.Println(fmt.Sprintf(`WARNING: date and/or title missing from archetype file %q. 
+From Hugo 0.24 this must be provided in the archetype file itself, if needed. Example:
+%s
+`, archetypeFilename, archetypeTemplateTemplate))
+
+	}
+
+	return archetypeContent, nil
+
+}
diff --git a/create/content_test.go b/create/content_test.go
index 8eaaf7bf5..aa7ed3fcf 100644
--- a/create/content_test.go
+++ b/create/content_test.go
@@ -45,9 +45,9 @@ func TestNewContent(t *testing.T) {
 	}{
 		{"post", "post/sample-1.md", []string{`title = "Post Arch title"`, `test = "test1"`, "date = \"2015-01-12T19:20:04-07:00\""}},
 		{"emptydate", "post/sample-ed.md", []string{`title = "Empty Date Arch title"`, `test = "test1"`}},
-		{"stump", "stump/sample-2.md", []string{`title = "sample 2"`}},     // no archetype file
-		{"", "sample-3.md", []string{`title = "sample 3"`}},                // no archetype
-		{"product", "product/sample-4.md", []string{`title = "sample 4"`}}, // empty archetype front matter
+		{"stump", "stump/sample-2.md", []string{`title = "Sample 2"`}},     // no archetype file
+		{"", "sample-3.md", []string{`title = "Sample 3"`}},                // no archetype
+		{"product", "product/sample-4.md", []string{`title = "SAMPLE-4"`}}, // empty archetype front matter
 	}
 
 	for _, c := range cases {
@@ -108,8 +108,10 @@ func initFs(fs *hugofs.Fs) error {
 			content: "+++\ndate = \"2015-01-12T19:20:04-07:00\"\ntitle = \"Post Arch title\"\ntest = \"test1\"\n+++\n",
 		},
 		{
-			path:    filepath.Join("archetypes", "product.md"),
-			content: "+++\n+++\n",
+			path: filepath.Join("archetypes", "product.md"),
+			content: `+++
+title = "{{ .BaseFileName  | upper }}"
++++`,
 		},
 		{
 			path:    filepath.Join("archetypes", "emptydate.md"),