[feature] Emojify spoiler and content in web templates (#785)

* Emojify spoiler and content in web templates

* Use more performance emojify code (thanks NyaaaWhatsUpDoc!)

1 files changed, 52 insertions, 0 deletions

diff --git a/internal/router/template.go b/internal/router/template.go
index ebd8629e8..a9d5726ea 100644
--- a/internal/router/template.go
+++ b/internal/router/template.go
@@ -19,7 +19,9 @@
 package router
 
 import (
+	"bytes"
 	"fmt"
+	"html"
 	"html/template"
 	"os"
 	"path/filepath"
@@ -28,6 +30,7 @@ import (
 	"github.com/gin-gonic/gin"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
+	"github.com/superseriousbusiness/gotosocial/internal/regexes"
 )
 
 // LoadTemplates loads html templates for use by the given engine
@@ -57,6 +60,11 @@ func oddOrEven(n int) string {
 	return "odd"
 }
 
+func escape(str string) template.HTML {
+	/* #nosec G203 */
+	return template.HTML(template.HTMLEscapeString(str))
+}
+
 func noescape(str string) template.HTML {
 	/* #nosec G203 */
 	return template.HTML(str)
@@ -97,12 +105,56 @@ func visibilityIcon(visibility model.Visibility) template.HTML {
 	return template.HTML(fmt.Sprintf(`<i aria-label="Visibility: %v" class="fa fa-%v"></i>`, icon.label, icon.faIcon))
 }
 
+// replaces shortcodes in `text` with the emoji in `emojis`
+// text is a template.HTML to affirm that the input of this function is already escaped
+func emojify(emojis []model.Emoji, text template.HTML) template.HTML {
+	emojisMap := make(map[string]model.Emoji, len(emojis))
+
+	for _, emoji := range emojis {
+		shortcode := ":" + emoji.Shortcode + ":"
+		emojisMap[shortcode] = emoji
+	}
+
+	out := regexes.ReplaceAllStringFunc(
+		regexes.EmojiFinder,
+		string(text),
+		func(shortcode string, buf *bytes.Buffer) string {
+			// Look for emoji according to this shortcode
+			emoji, ok := emojisMap[shortcode]
+			if !ok {
+				return shortcode
+			}
+
+			// Escape raw emoji content
+			safeURL := html.EscapeString(emoji.URL)
+			safeCode := html.EscapeString(emoji.Shortcode)
+
+			// Write HTML emoji repr to buffer
+			buf.WriteString(`<img src="`)
+			buf.WriteString(safeURL)
+			buf.WriteString(`" title=":`)
+			buf.WriteString(safeCode)
+			buf.WriteString(`:" alt=":`)
+			buf.WriteString(safeCode)
+			buf.WriteString(`:" class="emoji"/>`)
+
+			return buf.String()
+		},
+	)
+
+	/* #nosec G203 */
+	// (this is escaped above)
+	return template.HTML(out)
+}
+
 func LoadTemplateFunctions(engine *gin.Engine) {
 	engine.SetFuncMap(template.FuncMap{
+		"escape":         escape,
 		"noescape":       noescape,
 		"oddOrEven":      oddOrEven,
 		"visibilityIcon": visibilityIcon,
 		"timestamp":      timestamp,
 		"timestampShort": timestampShort,
+		"emojify":        emojify,
 	})
 }