From cca5518b1659c1aa462f4c812f10b7e22f51750e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9sar=20Izurieta?= <cesar@caih.org>
Date: Mon, 31 Oct 2016 09:10:50 +0100
Subject: [PATCH] Make weeksOfMonthByDay match weeks from the end of the month
 too

---
 moment-recur.js                   | 71 +++++++++++++++++++++----------
 tests/spec/jasmine-event-recur.js | 13 ++++++
 2 files changed, 61 insertions(+), 23 deletions(-)

diff --git a/moment-recur.js b/moment-recur.js
index af4409c..0370176 100644
--- a/moment-recur.js
+++ b/moment-recur.js
@@ -75,7 +75,7 @@
             "daysOfMonth": "date",
             "daysOfWeek": "day",
             "weeksOfMonth": "monthWeek",
-            "weeksOfMonthByDay": "monthWeekByDay",
+            "weeksOfMonthByDay": "monthWeeksByDay",
             "weeksOfYear": "week",
             "monthsOfYear": "month"
         };
@@ -85,7 +85,7 @@
             "daysOfMonth"       : { low: 1, high: 31 },
             "daysOfWeek"        : { low: 0, high: 6 },
             "weeksOfMonth"      : { low: 0, high: 4 },
-            "weeksOfMonthByDay" : { low: 0, high: 4 },
+            "weeksOfMonthByDay" : { low: -5, high: 4 },
             "weeksOfYear"       : { low: 0, high: 52 },
             "monthsOfYear"      : { low: 0, high: 11 }
         };
@@ -150,20 +150,28 @@
             var unitType = unitTypes[measure];
 
             // Get the unit based on the required measure of the date
-            var unit = date[unitType]();
+            var units = date[unitType]();
 
-            // If the unit is in our list, return true, else return false
-            if (list[unit]) {
-                return true;
+            if (units.constructor !== Array) {
+                units = [ units ];
             }
 
-            // match on end of month days
-            if (unitType === 'date' && unit == date.add(1, 'months').date(0).format('D') && unit < 31) {
-                while (unit <= 31) {
-                    if (list[unit]) {
-                        return true;
+            for (var i = 0; i < units.length; i++) {
+                var unit = units[i];
+
+                // If the unit is in our list, return true, else return false
+                if (list[unit]) {
+                    return true;
+                }
+
+                // match on end of month days
+                if (unitType === 'date' && unit == date.add(1, 'months').date(0).format('D') && unit < 31) {
+                    while (unit <= 31) {
+                        if (list[unit]) {
+                            return true;
+                        }
+                        unit++;
                     }
-                    unit++;
                 }
             }
 
@@ -706,29 +714,46 @@
         return day0.diff(week0, "weeks");
     };
 
+    // Plugin for calculating the last week of the month of a date
+    moment.fn.lastMonthWeek = function() {
+        // Last day of the last week of the month (may be first week of next month)
+        var weekL = this.clone().endOf("month").endOf("week");
+
+        // Last day of week
+        var dayL = this.clone().endOf("week");
+
+        return dayL.diff(weekL, "weeks");
+    };
+
     // Plugin for calculating the occurrence of the day of the week in the month.
     // Similar to `moment().monthWeek()`, the return value is zero-indexed.
     // A return value of 2 means the date is the 3rd occurence of that day
     // of the week in the month.
     moment.fn.monthWeekByDay = function(date) {
-        var day, week0, day0, diff;
+        var diff = this.monthWeek();
 
-        // date obj
-        day = this.clone();
+        if (this.clone().subtract(diff, "weeks").month() === this.month()) {
+            return diff;
+        }
 
-        // First day of the first week of the month
-        week0 = this.clone().startOf("month").startOf("week");
+        return diff - 1;
+    };
 
-        // First day of week
-        day0 = this.clone().startOf("week");
+    // Plugin for calculating the last occurrence of the day of the week in the month.
+    // A return value of -3 means the date is the 3rd occurence of that day
+    // of the week from the end of the month.
+    moment.fn.lastMonthWeekByDay = function() {
+        var diff = this.lastMonthWeek();
 
-        diff = day0.diff(week0, "weeks");
+        if (this.clone().subtract(diff, "weeks").month() === this.month()) {
+            return diff - 1;
+        }
 
-        if (day.subtract(diff, "weeks").month() === this.clone().month()) {
             return diff;
-        }
+    };
 
-        return diff - 1;
+    moment.fn.monthWeeksByDay = function() {
+        return [ this.monthWeekByDay(), this.lastMonthWeekByDay() ];
     };
 
     // Plugin for removing all time information from a given date
diff --git a/tests/spec/jasmine-event-recur.js b/tests/spec/jasmine-event-recur.js
index 9a2b73a..a2eb4c0 100755
--- a/tests/spec/jasmine-event-recur.js
+++ b/tests/spec/jasmine-event-recur.js
@@ -284,6 +284,19 @@ describe("weeksOfMonthByDay()", function() {
         expect(recurrence.matches(moment(startDate).date(31))).toBe(true);
     });
 
+    it("can recur on the last and 3rd last Sundays of the month", function() {
+        var recurrence;
+        recurrence = moment.recur()
+            .every(["Sunday"]).daysOfWeek()
+            .every([-1, -3]).weeksOfMonthByDay();
+        expect(recurrence.matches(moment(startDate))).toBe(false);
+        expect(recurrence.matches(moment(startDate).date(6))).toBe(false);
+        expect(recurrence.matches(moment(startDate).date(8))).toBe(false);
+        expect(recurrence.matches(moment(startDate).date(13))).toBe(true);
+        expect(recurrence.matches(moment(startDate).date(20))).toBe(false);
+        expect(recurrence.matches(moment(startDate).date(27))).toBe(true);
+    });
+
     it("will throw an error if used without daysOfWeek()", function() {
         var recurrence, caught = { message: false };
         try {