From 9e2b7620b101f9b0d7352ce313eb90714f5118c5 Mon Sep 17 00:00:00 2001
From: Matt Baer <matt@write.as>
Date: Tue, 4 Apr 2023 12:09:49 -0400
Subject: [PATCH] Add funcs PostTitle, GetSlug, GetSlugFromPost

---
 go.mod         |  2 +-
 posts/parse.go | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/go.mod b/go.mod
index 5170100..1955354 100644
--- a/go.mod
+++ b/go.mod
@@ -8,7 +8,7 @@ require (
 	github.com/microcosm-cc/bluemonday v1.0.5
 	github.com/rainycape/unidecode v0.0.0-20150907023854-cb7f23ec59be // indirect
 	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
-	github.com/writeas/go-strip-markdown v2.0.1+incompatible
+	github.com/writeas/go-strip-markdown/v2 v2.1.1
 	github.com/writeas/impart v1.1.1
 	github.com/writeas/openssl-go v1.0.0
 	github.com/writeas/saturday v1.7.1
diff --git a/posts/parse.go b/posts/parse.go
index 168289f..0d61bac 100644
--- a/posts/parse.go
+++ b/posts/parse.go
@@ -2,7 +2,8 @@ package posts
 
 import (
 	"fmt"
-	stripmd "github.com/writeas/go-strip-markdown"
+	stripmd "github.com/writeas/go-strip-markdown/v2"
+	"github.com/writeas/slug"
 	"github.com/writeas/web-core/stringmanip"
 	"regexp"
 	"strings"
@@ -37,6 +38,20 @@ func ExtractTitle(content string) (title string, body string) {
 	return
 }
 
+func PostTitle(content, friendlyId string) string {
+	content = StripHTMLWithoutEscaping(content)
+
+	content = strings.TrimLeftFunc(stripmd.Strip(content), unicode.IsSpace)
+	eol := strings.IndexRune(content, '\n')
+	blankLine := strings.Index(content, "\n\n")
+	if blankLine != -1 && blankLine <= eol && blankLine <= assumedTitleLen {
+		return strings.TrimSpace(content[:blankLine])
+	} else if utf8.RuneCountInString(content) <= maxTitleLen {
+		return content
+	}
+	return friendlyId
+}
+
 func FriendlyPostTitle(content, friendlyId string) string {
 	content = StripHTMLWithoutEscaping(content)
 
@@ -163,3 +178,32 @@ func PostLede(t string, includePunc bool) string {
 
 	return t
 }
+
+func GetSlug(title, lang string) string {
+	return GetSlugFromPost("", title, lang)
+}
+
+func GetSlugFromPost(title, body, lang string) string {
+	if title == "" {
+		// Remove Markdown, so e.g. link URLs and image alt text don't make it into the slug
+		body = strings.TrimSpace(stripmd.StripOptions(body, stripmd.Options{SkipImages: true}))
+		title = PostTitle(body, body)
+	}
+	title = PostLede(title, false)
+	// Truncate lede if needed
+	title, _ = TruncToWord(title, maxTitleLen)
+	var s string
+	if lang != "" && len(lang) == 2 {
+		s = slug.MakeLang(title, lang)
+	} else {
+		s = slug.Make(title)
+	}
+
+	// Transliteration may cause the slug to expand past the limit, so truncate again
+	s, _ = TruncToWord(s, maxTitleLen)
+	return strings.TrimFunc(s, func(r rune) bool {
+		// TruncToWord doesn't respect words in a slug, since spaces are replaced
+		// with hyphens. So remove any trailing hyphens.
+		return r == '-'
+	})
+}