From 0bea641eb0447236939676ad7ab25c1c2bf1640d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20M=C3=BCller?= <sebastian.mueller@freiheit.com>
Date: Wed, 17 Jun 2020 15:23:24 +0200
Subject: [PATCH] Add number of months instead of weeks if they exceed a
 certain amount

* default is 2 months as until that a timespan in weeks is sufficient (totally based on my personal gut feeling)
* calculates with a rough average of 365 / 12 = 30.42 days per month
---
 README.md                      | 20 ++++++++++++++++++++
 lib/src/duration.dart          | 27 ++++++++++++++++++++-------
 lib/src/time_const.dart        |  4 ++++
 test/pretty_duration_test.dart | 23 +++++++++++++++++++++++
 4 files changed, 67 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index f51792b..8cfe15b 100644
--- a/README.md
+++ b/README.md
@@ -104,3 +104,23 @@ main() {
   );
 }
 ```
+
+## Months instead of weeks
+
+If a duration spans more than two months it will be formatted as 'x months' instead of 'y weeks'.
+To override the amount of months use `minNumberMonths`.
+
+```dart
+main() {
+  // => 8 weeks 4 days
+  printDuration(
+    Duration(days: 60)
+  );
+  
+  // => 1 month 30 days
+  printDuration(
+    Duration(days: 60),
+    minNumberMonths: 1
+  );
+}
+```
diff --git a/lib/src/duration.dart b/lib/src/duration.dart
index fbce795..ff7b32e 100644
--- a/lib/src/duration.dart
+++ b/lib/src/duration.dart
@@ -1,3 +1,5 @@
+import 'package:duration/src/time_const.dart';
+
 import 'locale/locale.dart';
 import 'tersity.dart';
 
@@ -35,7 +37,8 @@ String prettyDuration(Duration duration,
     String delimiter,
     String conjunction,
     bool abbreviated = false,
-    bool first = false}) {
+    bool first = false,
+    int minNumberMonths = 2}) {
   if (abbreviated && delimiter == null) {
     delimiter = ', ';
     spacer = '';
@@ -55,14 +58,22 @@ String prettyDuration(Duration duration,
     return sb.toString();
   };
 
-  final int weeks = (duration.inDays / 7).floor();
+  final int months = (duration.inDays / avgDaysPerMonth).floor();
+  int daysCounted = 0;
 
-  if (weeks > 0) {
-    out.add(partFmt(weeks, locale.week));
+  if (months >= minNumberMonths) {
+    out.add(partFmt(months, locale.month));
+    daysCounted = (months * avgDaysPerMonth).floor();
+  } else {
+    final int weeks = (duration.inDays / 7).floor();
+    if (weeks > 0) {
+      out.add(partFmt(weeks, locale.week));
+      daysCounted = weeks * 7;
+    }
   }
 
   if (tersity >= DurationTersity.day) {
-    final int days = duration.inDays - (weeks * 7);
+    final int days = duration.inDays - daysCounted;
     if (days > 0) out.add(partFmt(days, locale.day));
 
     if (tersity >= DurationTersity.hour) {
@@ -126,14 +137,16 @@ String printDuration(Duration duration,
     String spacer,
     String delimiter,
     String conjugation,
-    bool abbreviated = false}) {
+    bool abbreviated = false,
+    int minNumberMonths = 2}) {
   final String fmt = prettyDuration(duration,
       tersity: tersity,
       locale: locale,
       spacer: spacer,
       delimiter: delimiter,
       conjunction: conjugation,
-      abbreviated: abbreviated);
+      abbreviated: abbreviated,
+      minNumberMonths: minNumberMonths);
   print(fmt);
   return fmt;
 }
diff --git a/lib/src/time_const.dart b/lib/src/time_const.dart
index faa9aff..20f4e58 100644
--- a/lib/src/time_const.dart
+++ b/lib/src/time_const.dart
@@ -36,3 +36,7 @@ Duration hours(int hours) => Duration(hours: hours);
 
 // Creates a [Duration] with given [days]
 Duration days(int days) => Duration(days: days);
+
+// Average number of days per month (365 / 12)
+// Obviously a bit off on leap years.
+const double avgDaysPerMonth = 30.42;
diff --git a/test/pretty_duration_test.dart b/test/pretty_duration_test.dart
index 3f0f3dc..e6ea47a 100644
--- a/test/pretty_duration_test.dart
+++ b/test/pretty_duration_test.dart
@@ -97,6 +97,19 @@ void main() {
         final dur = Duration(days: 14);
         expect(prettyDuration(dur), '2 weeks');
       }
+
+      {
+        final dur = Duration(days: 60);
+        expect(prettyDuration(dur), '8 weeks 4 days');
+      }
+      {
+        final dur = Duration(days: 61);
+        expect(prettyDuration(dur), '2 months 1 day');
+      }
+      {
+        final dur = Duration(days: 60);
+        expect(prettyDuration(dur, minNumberMonths: 1), '1 month 30 days');
+      }
     });
 
     test('Abbreviated', () {
@@ -204,6 +217,16 @@ void main() {
         final dur = Duration(days: 14);
         expect(prettyDuration(dur, abbreviated: true), '2w');
       }
+
+      {
+        final dur = Duration(days: 60);
+        expect(prettyDuration(dur, abbreviated: true), '8w, 4d');
+      }
+
+      {
+        final dur = Duration(days: 61);
+        expect(prettyDuration(dur, abbreviated: true), '2mon, 1d');
+      }
     });
 
     test('Delimiter', () {