Fix renderable text files with different mimetypes (#612)

internal/git/mime.go

@@ -2,43 +2,45 @@ package git
 
 import (
 	"fmt"
+	"net/http"
 	"strings"
 
 	"github.com/gabriel-vasile/mimetype"
 )
 
 type MimeType struct {
-	ContentType string
-	extension   string
+	ContentType       string
+	extension         string
+	golangContentType string // json, m3u, etc. still renderable as text
 }
 
 func (mt MimeType) IsText() bool {
-	return strings.Contains(mt.ContentType, "text/")
+	return strings.HasPrefix(mt.ContentType, "text/") || strings.HasPrefix(mt.golangContentType, "text/")
 }
 
 func (mt MimeType) IsCSV() bool {
-	return strings.Contains(mt.ContentType, "text/csv") &&
+	return strings.HasPrefix(mt.ContentType, "text/csv") &&
 		(strings.HasSuffix(mt.extension, ".csv"))
 }
 
 func (mt MimeType) IsImage() bool {
-	return strings.Contains(mt.ContentType, "image/")
+	return strings.HasPrefix(mt.ContentType, "image/")
 }
 
 func (mt MimeType) IsSVG() bool {
-	return strings.Contains(mt.ContentType, "image/svg+xml")
+	return strings.HasPrefix(mt.ContentType, "image/svg+xml")
 }
 
 func (mt MimeType) IsPDF() bool {
-	return strings.Contains(mt.ContentType, "application/pdf")
+	return strings.HasPrefix(mt.ContentType, "application/pdf")
 }
 
 func (mt MimeType) IsAudio() bool {
-	return strings.Contains(mt.ContentType, "audio/")
+	return strings.HasPrefix(mt.ContentType, "audio/")
 }
 
 func (mt MimeType) IsVideo() bool {
-	return strings.Contains(mt.ContentType, "video/")
+	return strings.HasPrefix(mt.ContentType, "video/")
 }
 
 func (mt MimeType) CanBeHighlighted() bool {
@@ -87,5 +89,5 @@ func (mt MimeType) RenderType() string {
 }
 
 func DetectMimeType(data []byte, extension string) MimeType {
-	return MimeType{mimetype.Detect(data).String(), extension}
+	return MimeType{mimetype.Detect(data).String(), extension, http.DetectContentType(data)}
 }