Add support for YAML frontmatters

adapter/markdown/markdown.go

@@ -2,12 +2,15 @@ package markdown
 
 import (
 	"bufio"
+	"regexp"
 	"strings"
 
 	"github.com/mickael-menu/zk/core/note"
 	"github.com/mickael-menu/zk/util/opt"
 	"github.com/yuin/goldmark"
+	meta "github.com/yuin/goldmark-meta"
 	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
 	"github.com/yuin/goldmark/text"
 )
 
@@ -19,7 +22,11 @@ type Parser struct {
 // NewParser creates a new Markdown Parser.
 func NewParser() *Parser {
 	return &Parser{
-		md: goldmark.New(),
+		md: goldmark.New(
+			goldmark.WithExtensions(
+				meta.Meta,
+			),
+		),
 	}
 }
 
@@ -28,22 +35,37 @@ func (p *Parser) Parse(source string) (note.Content, error) {
 	out := note.Content{}
 
 	bytes := []byte(source)
-	root := p.md.Parser().Parse(text.NewReader(bytes))
 
-	title, titleNode, err := parseTitle(root, bytes)
+	context := parser.NewContext()
+	root := p.md.Parser().Parse(
+		text.NewReader(bytes),
+		parser.WithContext(context),
+	)
+
+	frontmatter, err := parseFrontmatter(context, bytes)
+	if err != nil {
+		return out, err
+	}
+
+	title, bodyStart, err := parseTitle(frontmatter, root, bytes)
 	if err != nil {
 		return out, err
 	}
 
 	out.Title = title
-	out.Body = parseBody(titleNode, bytes)
+	out.Body = parseBody(bodyStart, bytes)
 	out.Lead = parseLead(out.Body)
 
 	return out, nil
 }
 
 // parseTitle extracts the note title with its node.
-func parseTitle(root ast.Node, source []byte) (title opt.String, node ast.Node, err error) {
+func parseTitle(frontmatter frontmatter, root ast.Node, source []byte) (title opt.String, bodyStart int, err error) {
+	if title = frontmatter.getString("title", "Title"); !title.IsNull() {
+		bodyStart = frontmatter.end
+		return
+	}
+
 	var titleNode *ast.Heading
 	err = ast.Walk(root, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
 		if heading, ok := n.(*ast.Heading); ok && entering &&
@@ -62,24 +84,20 @@ func parseTitle(root ast.Node, source []byte) (title opt.String, node ast.Node,
 	}
 
 	if titleNode != nil {
-		node = titleNode
 		title = opt.NewNotEmptyString(string(titleNode.Text(source)))
-	}
-	return
-}
 
-// parseBody extracts the whole content after the title.
-func parseBody(titleNode ast.Node, source []byte) opt.String {
-	start := 0
-	if titleNode != nil {
 		if lines := titleNode.Lines(); lines.Len() > 0 {
-			start = lines.At(lines.Len() - 1).Stop
+			bodyStart = lines.At(lines.Len() - 1).Stop
 		}
 	}
+	return
+}
 
+// parseBody extracts the whole content after the title.
+func parseBody(startIndex int, source []byte) opt.String {
 	return opt.NewNotEmptyString(
 		strings.TrimSpace(
-			string(source[start:]),
+			string(source[startIndex:]),
 		),
 	)
 }
@@ -97,3 +115,38 @@ func parseLead(body opt.String) opt.String {
 
 	return opt.NewNotEmptyString(strings.TrimSpace(lead))
 }
+
+// frontmatter contains metadata parsed from a YAML frontmatter.
+type frontmatter struct {
+	values map[string]interface{}
+	start  int
+	end    int
+}
+
+var frontmatterRegex = regexp.MustCompile(`(?ms)^\s*-+\s*$.*?^\s*-+\s*$`)
+
+func parseFrontmatter(context parser.Context, source []byte) (front frontmatter, err error) {
+	index := frontmatterRegex.FindIndex(source)
+	if index != nil {
+		front.start = index[0]
+		front.end = index[1]
+		front.values, err = meta.TryGet(context)
+	}
+	return
+}
+
+// getString returns the first string value found for any of the given keys.
+func (m frontmatter) getString(keys ...string) opt.String {
+	if m.values == nil {
+		return opt.NullString
+	}
+
+	for _, key := range keys {
+		if val, ok := m.values[key]; ok {
+			if val, ok := val.(string); ok {
+				return opt.NewNotEmptyString(val)
+			}
+		}
+	}
+	return opt.NullString
+}

adapter/markdown/markdown_test.go

@@ -25,6 +25,22 @@ func TestParseTitle(t *testing.T) {
 	test("# Heading 1\n## Heading 1.a\n# Heading 2", "Heading 1")
 	test("## Small Heading\n# Bigger Heading", "Bigger Heading")
 	test("# A **title** with [formatting](http://stripped)", "A title with formatting")
+
+	// From a YAML frontmatter
+	test(`---
+Title:     A title
+Tags:
+    - tag1
+    - tag2
+---
+
+# Heading
+`, "A title")
+	test(`---
+title: lowercase key
+---
+Paragraph
+`, "lowercase key")
 }
 
 func TestParseBody(t *testing.T) {
@@ -63,6 +79,12 @@ Paragraph:
 * item1
 * item2`,
 	)
+	test(`---
+title: A title
+---
+
+Paragraph
+`, "Paragraph")
 }
 
 func TestParseLead(t *testing.T) {

go.mod

@@ -25,6 +25,7 @@ require (
 	github.com/tebeka/strftime v0.1.5 // indirect
 	github.com/tj/go-naturaldate v1.3.0
 	github.com/yuin/goldmark v1.3.1
+	github.com/yuin/goldmark-meta v1.0.0
 	golang.org/x/sys v0.0.0-20210113181707-4bcb84eeeb78 // indirect
 	gopkg.in/djherbis/times.v1 v1.2.0
 	gopkg.in/yaml.v2 v2.4.0 // indirect

go.sum

@@ -165,8 +165,11 @@ github.com/tj/assert v0.0.0-20190920132354-ee03d75cd160/go.mod h1:mZ9/Rh9oLWpLLD
 github.com/tj/go-naturaldate v1.3.0 h1:OgJIPkR/Jk4bFMBLbxZ8w+QUxwjqSvzd9x+yXocY4RI=
 github.com/tj/go-naturaldate v1.3.0/go.mod h1:rpUbjivDKiS1BlfMGc2qUKNZ/yxgthOfmytQs8d8hKk=
 github.com/vmihailenco/msgpack v3.3.3+incompatible/go.mod h1:fy3FlTQTDXWkZ7Bh6AcGMlsjHatGryHQYUTf1ShIgkk=
+github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.3.1 h1:eVwehsLsZlCJCwXyGLgg+Q4iFWE/eTIMG0e8waCmm/I=
 github.com/yuin/goldmark v1.3.1/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
+github.com/yuin/goldmark-meta v1.0.0 h1:ScsatUIT2gFS6azqzLGUjgOnELsBOxMXerM3ogdJhAM=
+github.com/yuin/goldmark-meta v1.0.0/go.mod h1:zsNNOrZ4nLuyHAJeLQEZcQat8dm70SmB2kHbls092Gc=
 github.com/zclconf/go-cty v1.2.0 h1:sPHsy7ADcIZQP3vILvTjrh74ZA175TFP5vqiNK1UmlI=
 github.com/zclconf/go-cty v1.2.0/go.mod h1:hOPWgoHbaTUnI5k4D2ld+GRpFJSCe6bCM7m1q/N4PQ8=
 github.com/zenazn/goji v0.9.0/go.mod h1:7S9M489iMyHBNxwZnk9/EHS098H4/F6TATF2mIxtB1Q=
@@ -238,5 +241,6 @@ gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/inconshreveable/log15.v2 v2.0.0-20180818164646-67afb5ed74ec/go.mod h1:aPpfJ7XW+gOuirDoZ8gHhLh3kZ1B08FtV2bbmy7Jv3s=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.7/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=