feat: format renewal duration

cmd/cmd_renew.go

@@ -7,9 +7,11 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"math"
 	"math/rand"
 	"os"
 	"slices"
+	"strings"
 	"time"
 
 	"github.com/go-acme/lego/v5/acme/api"
@@ -435,7 +437,7 @@ func needRenewalDynamic(x509Cert *x509.Certificate, domain string, now time.Time
 	}
 
 	log.Infof(log.LazySprintf("Skip renewal: The certificate expires at %s, the renewal can be performed in %s.",
-		x509Cert.NotAfter.Format(time.RFC3339), dueDate.Sub(now)), log.DomainAttr(domain))
+		x509Cert.NotAfter.Format(time.RFC3339), FormattableDuration(dueDate.Sub(now))), log.DomainAttr(domain))
 
 	return false
 }
@@ -496,3 +498,39 @@ func merge(prevDomains, nextDomains []string) []string {
 
 	return prevDomains
 }
+
+type FormattableDuration time.Duration
+
+func (f FormattableDuration) String() string {
+	d := time.Duration(f)
+
+	days := int(math.Trunc(d.Hours() / 24))
+	hours := int(d.Hours()) % 24
+	minutes := int(d.Minutes()) % 60
+	seconds := int(d.Seconds()) % 60
+	ns := int(d.Nanoseconds()) % int(time.Second)
+
+	var s strings.Builder
+
+	if days > 0 {
+		s.WriteString(fmt.Sprintf("%dd", days))
+	}
+
+	if hours > 0 {
+		s.WriteString(fmt.Sprintf("%dh", hours))
+	}
+
+	if minutes > 0 {
+		s.WriteString(fmt.Sprintf("%dm", minutes))
+	}
+
+	if seconds > 0 {
+		s.WriteString(fmt.Sprintf("%ds", seconds))
+	}
+
+	if ns > 0 {
+		s.WriteString(fmt.Sprintf("%dns", ns))
+	}
+
+	return s.String()
+}

cmd/cmd_renew_test.go

@@ -167,3 +167,56 @@ func Test_needRenewalDynamic(t *testing.T) {
 		})
 	}
 }
+
+func TestFormattableDuration(t *testing.T) {
+	testCases := []struct {
+		desc     string
+		date     time.Time
+		duration time.Duration
+		expected string
+	}{
+		{
+			desc:     "all",
+			duration: 47*time.Hour + 3*time.Minute + 8*time.Second + 1234567890*time.Nanosecond,
+			expected: "1d23h3m9s234567890ns",
+		},
+		{
+			desc:     "without nanoseconds",
+			duration: 47*time.Hour + 3*time.Minute + 8*time.Second,
+			expected: "1d23h3m8s",
+		},
+		{
+			desc:     "without seconds",
+			duration: 47*time.Hour + 3*time.Minute + 2*time.Nanosecond,
+			expected: "1d23h3m2ns",
+		},
+		{
+			desc:     "without minutes",
+			duration: 47*time.Hour + 8*time.Second + 2*time.Nanosecond,
+			expected: "1d23h8s2ns",
+		},
+		{
+			desc:     "without hours",
+			duration: 3*time.Minute + 8*time.Second + 2*time.Nanosecond,
+			expected: "3m8s2ns",
+		},
+		{
+			desc:     "only hours",
+			duration: 23 * time.Hour,
+			expected: "23h",
+		},
+		{
+			desc:     "only days",
+			duration: 48 * time.Hour,
+			expected: "2d",
+		},
+	}
+
+	for _, test := range testCases {
+		t.Run(test.desc, func(t *testing.T) {
+			t.Parallel()
+
+			assert.Equal(t, test.expected, FormattableDuration(test.duration).String())
+		})
+	}
+}