[ui] Reshorten refs for output (#413)

* Add shortener for SHA1 refs
* Print shortened refs

internal/cli/formatters.go

@@ -4,6 +4,7 @@
 package cli
 
 import (
+	"strings"
 	"time"
 
 	"github.com/ryanuber/columnize"
@@ -34,3 +35,16 @@ func formatTime(t time.Time) string {
 func formatTimeDifference(first, second time.Time, d time.Duration) string {
 	return second.Truncate(d).Sub(first.Truncate(d)).String()
 }
+
+func formatSHA1Reference(in string) string {
+	// a SHA1 hash is 20 bytes written as a hexadecimal string (40 chars)
+	if len(in) != 40 && len(strings.Trim(strings.ToLower(in), "0123456789abcdef")) != 0 {
+		// if it can't be a sha1, return it unchanged
+		return in
+	}
+	l := 8
+	if len(in) < l {
+		l = len(in)
+	}
+	return in[:l]
+}

internal/cli/helpers.go

@@ -66,10 +66,10 @@ func registryTableRow(cachedRegistry *cache.Registry) []terminal.TableEntry {
 			Value: cachedRegistry.Name,
 		},
 		{
-			Value: cachedRegistry.Ref,
+			Value: formatSHA1Reference(cachedRegistry.Ref),
 		},
 		{
-			Value: cachedRegistry.LocalRef,
+			Value: formatSHA1Reference(cachedRegistry.LocalRef),
 		},
 		{
 			Value: cachedRegistry.Source,
@@ -85,11 +85,11 @@ func registryPackRow(cachedRegistry *cache.Registry, cachedPack *cache.Pack) []t
 		},
 		// The revision from where the registryPack was cloned
 		{
-			Value: cachedPack.Ref,
+			Value: formatSHA1Reference(cachedPack.Ref),
 		},
 		// The canonical revision from where the registryPack was cloned
 		{
-			Value: cachedRegistry.LocalRef,
+			Value: formatSHA1Reference(cachedRegistry.LocalRef),
 		},
 		// The metadata version
 		{