refactor(exporters): replace deprecated strings.Title with cases.Title

The `strings.Title` function is deprecated because it does not handle Unicode punctuation correctly.

This change replaces its usage in the DOCX, HTML, and Markdown exporters with the recommended `golang.org/x/text/cases` package. This ensures more robust and accurate title-casing for item headings.

Author: kjanat

go.mod

@@ -2,7 +2,10 @@ module github.com/kjanat/articulate-parser
 
 go 1.24.0
 
-require github.com/fumiama/go-docx v0.0.0-20250506085032-0c30fd09304b
+require (
+	github.com/fumiama/go-docx v0.0.0-20250506085032-0c30fd09304b
+	golang.org/x/text v0.30.0
+)
 
 require (
 	github.com/fumiama/imgsz v0.0.4 // indirect

go.sum

@@ -4,3 +4,5 @@ github.com/fumiama/imgsz v0.0.4 h1:Lsasu2hdSSFS+vnD+nvR1UkiRMK7hcpyYCC0FzgSMFI=
 github.com/fumiama/imgsz v0.0.4/go.mod h1:bISOQVTlw9sRytPwe8ir7tAaEmyz9hSNj9n8mXMBG0E=
 golang.org/x/image v0.32.0 h1:6lZQWq75h7L5IWNk0r+SCpUJ6tUVd3v4ZHnbRKLkUDQ=
 golang.org/x/image v0.32.0/go.mod h1:/R37rrQmKXtO6tYXAjtDLwQgFLHmhW+V6ayXlxzP2Pc=
+golang.org/x/text v0.30.0 h1:yznKA/E9zq54KzlzBEAWn1NXSQ8DIp/NYMy88xJjl4k=
+golang.org/x/text v0.30.0/go.mod h1:yDdHFIX9t+tORqspjENWgzaCVXgk0yYnYuSZ8UzzBVM=

internal/exporters/docx.go

@@ -11,6 +11,8 @@ import (
 	"github.com/kjanat/articulate-parser/internal/interfaces"
 	"github.com/kjanat/articulate-parser/internal/models"
 	"github.com/kjanat/articulate-parser/internal/services"
+	"golang.org/x/text/cases"
+	"golang.org/x/text/language"
 )
 
 // DocxExporter implements the Exporter interface for DOCX format.
@@ -119,7 +121,8 @@ func (e *DocxExporter) exportItem(doc *docx.Docx, item *models.Item) {
 	// Add item type as heading
 	if item.Type != "" {
 		itemPara := doc.AddParagraph()
-		itemPara.AddText(strings.Title(item.Type)).Size("24").Bold()
+		caser := cases.Title(language.English)
+		itemPara.AddText(caser.String(item.Type)).Size("24").Bold()
 	}
 
 	// Add sub-items

internal/exporters/html.go

@@ -12,6 +12,8 @@ import (
 	"github.com/kjanat/articulate-parser/internal/interfaces"
 	"github.com/kjanat/articulate-parser/internal/models"
 	"github.com/kjanat/articulate-parser/internal/services"
+	"golang.org/x/text/cases"
+	"golang.org/x/text/language"
 )
 
 // HTMLExporter implements the Exporter interface for HTML format.
@@ -441,7 +443,8 @@ func (e *HTMLExporter) processDividerItem(buf *bytes.Buffer) {
 func (e *HTMLExporter) processUnknownItem(buf *bytes.Buffer, item models.Item) {
 	if len(item.Items) > 0 {
 		buf.WriteString("        <div class=\"item unknown-item\">\n")
-		buf.WriteString(fmt.Sprintf("            <h4>%s Content</h4>\n", strings.Title(item.Type)))
+		caser := cases.Title(language.English)
+		buf.WriteString(fmt.Sprintf("            <h4>%s Content</h4>\n", caser.String(item.Type)))
 		for _, subItem := range item.Items {
 			e.processGenericSubItem(buf, subItem)
 		}

internal/exporters/markdown.go

@@ -11,6 +11,8 @@ import (
 	"github.com/kjanat/articulate-parser/internal/interfaces"
 	"github.com/kjanat/articulate-parser/internal/models"
 	"github.com/kjanat/articulate-parser/internal/services"
+	"golang.org/x/text/cases"
+	"golang.org/x/text/language"
 )
 
 // MarkdownExporter implements the Exporter interface for Markdown format.
@@ -269,7 +271,8 @@ func (e *MarkdownExporter) processDividerItem(buf *bytes.Buffer) {
 // processUnknownItem handles unknown or unsupported item types
 func (e *MarkdownExporter) processUnknownItem(buf *bytes.Buffer, item models.Item, headingPrefix string) {
 	if len(item.Items) > 0 {
-		buf.WriteString(fmt.Sprintf("%s %s Content\n\n", headingPrefix, strings.Title(item.Type)))
+		caser := cases.Title(language.English)
+		buf.WriteString(fmt.Sprintf("%s %s Content\n\n", headingPrefix, caser.String(item.Type)))
 		for _, subItem := range item.Items {
 			e.processGenericSubItem(buf, subItem)
 		}