feat: markdown import splits H2 leafs in Go (#26)

Drop the Python ExecFile wrapper. Conversion still does not write
Ladybug; add a dry-run fixture check for the index adapter split.

internal/mdleaves/leaf.go

@@ -0,0 +1,146 @@
+package mdleaves
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+type Leaf struct {
+	Source  string `json:"source"`
+	Repo    string `json:"repo"`
+	Heading string `json:"heading"`
+	Text    string `json:"text"`
+	Type    string `json:"type"`
+	Status  string `json:"status"`
+	Related string `json:"related"`
+}
+
+type chunk struct {
+	Heading string
+	Text    string
+}
+
+var (
+	h1 = regexp.MustCompile(`^# \S`)
+	h2 = regexp.MustCompile(`^## \S`)
+)
+
+func ExtractFrontmatter(text string) (map[string]string, string) {
+	if !strings.HasPrefix(text, "---") {
+		return map[string]string{}, text
+	}
+	end := strings.Index(text[3:], "\n---")
+	if end == -1 {
+		return map[string]string{}, text
+	}
+	fm := strings.TrimSpace(text[3 : 3+end])
+	body := text[3+end+4:]
+	meta := map[string]string{}
+	for _, line := range strings.Split(fm, "\n") {
+		key, value, ok := strings.Cut(line, ":")
+		if !ok {
+			continue
+		}
+		meta[strings.TrimSpace(key)] = strings.Trim(strings.TrimSpace(value), `"'`)
+	}
+	return meta, body
+}
+
+func SplitLeafs(meta map[string]string, body string) []chunk {
+	lines := strings.Split(body, "\n")
+	title := ""
+	type hdr struct {
+		heading string
+		start   int
+	}
+	var headers []hdr
+	for i, line := range lines {
+		switch {
+		case h1.MatchString(line):
+			title = strings.TrimSpace(strings.TrimLeft(line, "#"))
+		case h2.MatchString(line):
+			headers = append(headers, hdr{strings.TrimSpace(strings.TrimLeft(line, "#")), i})
+		}
+	}
+	if len(headers) == 0 {
+		var kept []string
+		for _, l := range lines {
+			if strings.TrimSpace(l) != "" {
+				kept = append(kept, l)
+			}
+		}
+		return []chunk{{Heading: title, Text: strings.TrimSpace(strings.Join(kept, "\n"))}}
+	}
+	out := make([]chunk, 0, len(headers))
+	for idx, h := range headers {
+		end := len(lines)
+		if idx+1 < len(headers) {
+			end = headers[idx+1].start
+		}
+		var kept []string
+		for _, l := range lines[h.start:end] {
+			if strings.TrimSpace(l) != "" {
+				kept = append(kept, l)
+			}
+		}
+		text := strings.Join(kept, "\n")
+		if idx == 0 && title != "" {
+			text = title + "\n\n" + text
+		}
+		out = append(out, chunk{Heading: h.heading, Text: strings.TrimSpace(text)})
+	}
+	return out
+}
+
+func ToAll(text, path, repo string) []Leaf {
+	meta, body := ExtractFrontmatter(text)
+	if meta["type"] == "" {
+		meta["type"] = "reference"
+	}
+	if meta["status"] == "" {
+		meta["status"] = "current"
+	}
+	chunks := SplitLeafs(meta, body)
+	out := make([]Leaf, 0, len(chunks))
+	for _, c := range chunks {
+		out = append(out, Leaf{
+			Source:  path,
+			Repo:    repo,
+			Heading: c.Heading,
+			Text:    c.Text,
+			Type:    meta["type"],
+			Status:  meta["status"],
+			Related: meta["related"],
+		})
+	}
+	return out
+}
+
+func WalkMarkdown(root string) ([]string, error) {
+	var out []string
+	err := filepath.Walk(root, func(p string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			return nil
+		}
+		ext := strings.ToLower(filepath.Ext(p))
+		if ext == ".md" || ext == ".markdown" {
+			out = append(out, p)
+		}
+		return nil
+	})
+	return out, err
+}
+
+func EncodeJSON(leafs []Leaf) (string, error) {
+	raw, err := json.MarshalIndent(leafs, "", "  ")
+	if err != nil {
+		return "", err
+	}
+	return string(raw) + "\n", nil
+}