templates: Change functions, add front matter support, better markdown

1 files changed, 100 insertions, 0 deletions

diff --git a/modules/caddyhttp/templates/frontmatter.go b/modules/caddyhttp/templates/frontmatter.go
new file mode 100644
index 0000000..730cfd1
--- /dev/null
+++ b/modules/caddyhttp/templates/frontmatter.go
@@ -0,0 +1,100 @@
+package templates
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"unicode"
+
+	"github.com/naoina/toml"
+	"gopkg.in/yaml.v2"
+)
+
+func extractFrontMatter(input string) (map[string]interface{}, string, error) {
+	// get the bounds of the first non-empty line
+	var firstLineStart, firstLineEnd int
+	lineEmpty := true
+	for i, b := range input {
+		if b == '\n' {
+			firstLineStart = firstLineEnd
+			if firstLineStart > 0 {
+				firstLineStart++ // skip newline character
+			}
+			firstLineEnd = i
+			if !lineEmpty {
+				break
+			}
+			continue
+		}
+		lineEmpty = lineEmpty && unicode.IsSpace(b)
+	}
+	firstLine := input[firstLineStart:firstLineEnd]
+
+	// see what kind of front matter there is, if any
+	var closingFence string
+	var fmParser func([]byte) (map[string]interface{}, error)
+	switch string(firstLine) {
+	case yamlFrontMatterFenceOpen:
+		fmParser = yamlFrontMatter
+		closingFence = yamlFrontMatterFenceClose
+	case tomlFrontMatterFenceOpen:
+		fmParser = tomlFrontMatter
+		closingFence = tomlFrontMatterFenceClose
+	case jsonFrontMatterFenceOpen:
+		fmParser = jsonFrontMatter
+		closingFence = jsonFrontMatterFenceClose
+	default:
+		// no recognized front matter; whole document is body
+		return nil, input, nil
+	}
+
+	// find end of front matter
+	fmEndFenceStart := strings.Index(input[firstLineEnd:], "\n"+closingFence)
+	if fmEndFenceStart < 0 {
+		return nil, "", fmt.Errorf("unterminated front matter")
+	}
+	fmEndFenceStart += firstLineEnd + 1 // add 1 to account for newline
+
+	// extract and parse front matter
+	frontMatter := input[firstLineEnd:fmEndFenceStart]
+	fm, err := fmParser([]byte(frontMatter))
+	if err != nil {
+		return nil, "", err
+	}
+
+	// the rest is the body
+	body := input[fmEndFenceStart+len(closingFence):]
+
+	return fm, body, nil
+}
+
+func yamlFrontMatter(input []byte) (map[string]interface{}, error) {
+	m := make(map[string]interface{})
+	err := yaml.Unmarshal(input, &m)
+	return m, err
+}
+
+func tomlFrontMatter(input []byte) (map[string]interface{}, error) {
+	m := make(map[string]interface{})
+	err := toml.Unmarshal(input, &m)
+	return m, err
+}
+
+func jsonFrontMatter(input []byte) (map[string]interface{}, error) {
+	input = append([]byte{'{'}, input...)
+	input = append(input, '}')
+	m := make(map[string]interface{})
+	err := json.Unmarshal(input, &m)
+	return m, err
+}
+
+type parsedMarkdownDoc struct {
+	Meta map[string]interface{} `json:"meta,omitempty"`
+	Body string                 `json:"body,omitempty"`
+}
+
+const (
+	yamlFrontMatterFenceOpen, yamlFrontMatterFenceClose = "---", "---"
+	tomlFrontMatterFenceOpen, tomlFrontMatterFenceClose = "+++", "+++"
+	jsonFrontMatterFenceOpen, jsonFrontMatterFenceClose = "{", "}"
+)