Shorten processed image filenames

Fixes #12688
Fixes #12656

resources/image.go

@@ -490,36 +490,16 @@ func (i *imageResource) relTargetPathFromConfig(conf images.ImageConfig) interna
 	if conf.TargetFormat != i.Format {
 		p2 = conf.TargetFormat.DefaultExtension()
 	}
-
-	h := i.hash()
-	idStr := fmt.Sprintf("_hu%d_%d", h, i.size())
-
-	// Do not change for no good reason.
-	const md5Threshold = 100
-
-	key := conf.GetKey(i.Format)
-
-	// It is useful to have the key in clear text, but when nesting transforms, it
-	// can easily be too long to read, and maybe even too long
-	// for the different OSes to handle.
-	if len(p1)+len(idStr)+len(p2) > md5Threshold {
-		key = hashing.MD5FromStringHexEncoded(p1 + key + p2)
-		huIdx := strings.Index(p1, "_hu")
-		if huIdx != -1 {
-			p1 = p1[:huIdx]
-		} else {
-			// This started out as a very long file name. Making it even longer
-			// could melt ice in the Arctic.
-			p1 = ""
-		}
-	} else if strings.Contains(p1, idStr) {
-		// On scaling an already scaled image, we get the file info from the original.
-		// Repeating the same info in the filename makes it stuttery for no good reason.
-		idStr = ""
+	const prefix = "_hu"
+	huIdx := strings.LastIndex(p1, prefix)
+	incomingID := "i"
+	if huIdx > -1 {
+		incomingID = p1[huIdx+len(prefix):]
+		p1 = p1[:huIdx]
 	}
-
+	hash := hashing.HashUint64(incomingID, i.hash(), conf.GetKey(i.Format))
 	rp := i.getResourcePaths()
-	rp.File = fmt.Sprintf("%s%s_%s%s", p1, idStr, key, p2)
+	rp.File = fmt.Sprintf("%s%s%d%s", p1, prefix, hash, p2)
 
 	return rp
 }