Use existing analyzer module for language detection for highlighting (#13522) (#13551)

* Use existing analyzer module for language detction for highlighting

Thanks @lafriks for pointing out we can reuse existing code for more reliable language detection here.

* Update modules/highlight/highlight.go

Co-authored-by: Lauris BH <lauris@nix.lv>

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/highlight/highlight.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 	"sync"
 
+	"code.gitea.io/gitea/modules/analyze"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 	"github.com/alecthomas/chroma/formatters/html"
@@ -117,9 +118,11 @@ func File(numLines int, fileName string, code []byte) map[int]string {
 		fileName = "test." + val
 	}
 
-	lexer := lexers.Match(fileName)
+	language := analyze.GetCodeLanguage(fileName, code)
+
+	lexer := lexers.Get(language)
 	if lexer == nil {
-		lexer = lexers.Analyse(string(code))
+		lexer = lexers.Match(fileName)
 		if lexer == nil {
 			lexer = lexers.Fallback
 		}