common, core, light: add block age into info logs

common/format.go

@@ -38,3 +38,45 @@ func (d PrettyDuration) String() string {
 	}
 	return label
 }
+
+// PrettyAge is a pretty printed version of a time.Duration value that rounds
+// the values up to a single most significant unit, days/weeks/years included.
+type PrettyAge time.Time
+
+// ageUnits is a list of units the age pretty printing uses.
+var ageUnits = []struct {
+	Size   time.Duration
+	Symbol string
+}{
+	{12 * 30 * 24 * time.Hour, "y"},
+	{30 * 24 * time.Hour, "mo"},
+	{7 * 24 * time.Hour, "w"},
+	{24 * time.Hour, "d"},
+	{time.Hour, "h"},
+	{time.Minute, "m"},
+	{time.Second, "s"},
+}
+
+// String implements the Stringer interface, allowing pretty printing of duration
+// values rounded to the most significant time unit.
+func (t PrettyAge) String() string {
+	// Calculate the time difference and handle the 0 cornercase
+	diff := time.Since(time.Time(t))
+	if diff < time.Second {
+		return "0"
+	}
+	// Accumulate a precision of 3 components before returning
+	result, prec := "", 0
+
+	for _, unit := range ageUnits {
+		if diff > unit.Size {
+			result = fmt.Sprintf("%s%d%s", result, diff/unit.Size, unit.Symbol)
+			diff %= unit.Size
+
+			if prec += 1; prec >= 3 {
+				break
+			}
+		}
+	}
+	return result
+}