feat(master): suggest newer version tags for third-party images (#11) (#31)

internal/master/web/views.go

@@ -12,6 +12,7 @@ import (
 	"github.com/shcizo/package-updater/internal/master/jobs"
 	"github.com/shcizo/package-updater/internal/master/model"
 	"github.com/shcizo/package-updater/internal/master/poller"
+	"github.com/shcizo/package-updater/internal/master/tagver"
 	"github.com/shcizo/package-updater/internal/master/web/icons"
 	"github.com/shcizo/package-updater/internal/protocol"
 )
@@ -45,6 +46,7 @@ type serviceRow struct {
 	Tag          string // ":tag", or ""
 	Digest       string // "@sha256:<12 hex>…" when the image has no tag, else ""
 	AvailableTag string // the tag of AvailableRef, or ""
+	NewerTag     string // the tag of NewerRef while it is still newer than the followed tag, or ""
 	Icon         string // Simple Icons slug; "" when there is no icon
 	Letter       string // shown instead of an icon
 	LetterClass  string // lc-0 .. lc-3
@@ -66,6 +68,7 @@ func newServiceRow(s model.Service, autoBlocked string) serviceRow {
 	}
 	r.Repo, r.Tag, r.Digest = imageParts(s.ActualRef)
 	r.AvailableTag = imageref.Parse(s.AvailableRef).Tag
+	r.NewerTag = newerTag(s)
 	r.Icon = icons.ForImage(s.ActualRef)
 	r.Letter = "?"
 	if first, _ := utf8.DecodeRuneInString(r.Name); first != utf8.RuneError {
@@ -243,6 +246,26 @@ func followsNoTag(svc model.Service) bool {
 	return jobs.FollowedRef(svc.ActualRef) == ""
 }
 
+// newerTag returns the tag of the service's newer-tag suggestion, or "" when
+// there is none or it no longer holds. The poller writes the suggestion once
+// per cycle, so after the service moved to another tag the stored value can
+// be stale until the next cycle; checking again here hides it meanwhile. A
+// suggestion from another repo than the service follows now is hidden too.
+func newerTag(s model.Service) string {
+	if s.RemovedAt != nil || s.NewerRef == "" {
+		return ""
+	}
+	newer := imageref.Parse(s.NewerRef)
+	repo, followed := poller.Followed(s)
+	if newer.Repo != repo {
+		return ""
+	}
+	if _, ok := tagver.Newer(followed, []string{newer.Tag}); !ok {
+		return ""
+	}
+	return newer.Tag
+}
+
 // versionRow is an image version as shown on the service page.
 type versionRow struct {
 	model.ImageVersion