From 36fc86b69c591babc0af1a27bbf0694e1bd40aee Mon Sep 17 00:00:00 2001
From: Ben Fortuna <bfortuna@odecee.com.au>
Date: Mon, 29 Jul 2019 23:07:15 +1000
Subject: [PATCH] Arithmetic fixes

---
 .../fortuna/ical4j/transform/recurrence/ByMonthDayRule.java   | 4 ++--
 .../net/fortuna/ical4j/transform/recurrence/ByWeekNoRule.java | 4 ++--
 .../fortuna/ical4j/transform/recurrence/ByYearDayRule.java    | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/main/java/net/fortuna/ical4j/transform/recurrence/ByMonthDayRule.java b/src/main/java/net/fortuna/ical4j/transform/recurrence/ByMonthDayRule.java
index 3bdf8007e..d14eca08a 100644
--- a/src/main/java/net/fortuna/ical4j/transform/recurrence/ByMonthDayRule.java
+++ b/src/main/java/net/fortuna/ical4j/transform/recurrence/ByMonthDayRule.java
@@ -68,7 +68,7 @@ public List<T> apply(T date) {
             // construct a list of possible month days..
             final int numDaysInMonth = YearMonth.of(getYear(date), getMonth(date)).lengthOfMonth();
             for (final int monthDay : monthDayList) {
-                if (monthDay == 0 || monthDay <= -numDaysInMonth || monthDay > numDaysInMonth) {
+                if (monthDay == 0 || monthDay < -numDaysInMonth || monthDay > numDaysInMonth) {
                     if (log.isTraceEnabled()) {
                         log.trace("Invalid day of month: " + monthDay);
                     }
@@ -84,7 +84,7 @@ public List<T> apply(T date) {
                     if (numDaysInMonth < -monthDay) {
                         continue;
                     }
-                    candidate = withTemporalField(date, DAY_OF_MONTH, numDaysInMonth + monthDay);
+                    candidate = withTemporalField(date, DAY_OF_MONTH, numDaysInMonth + 1 + monthDay);
                 }
                 retVal.add(candidate);
             };
diff --git a/src/main/java/net/fortuna/ical4j/transform/recurrence/ByWeekNoRule.java b/src/main/java/net/fortuna/ical4j/transform/recurrence/ByWeekNoRule.java
index e6450500c..33a7c893f 100644
--- a/src/main/java/net/fortuna/ical4j/transform/recurrence/ByWeekNoRule.java
+++ b/src/main/java/net/fortuna/ical4j/transform/recurrence/ByWeekNoRule.java
@@ -38,7 +38,7 @@ public List<T> transform(List<T> dates) {
         for (final T date : dates) {
             final int numWeeksInYear = (int) IsoFields.WEEK_OF_WEEK_BASED_YEAR.rangeRefinedBy(date).getMaximum();
             for (final Integer weekNo : weekNoList) {
-                if (weekNo == 0 || weekNo <= -numWeeksInYear || weekNo > numWeeksInYear) {
+                if (weekNo == 0 || weekNo < -numWeeksInYear || weekNo > numWeeksInYear) {
                     if (log.isTraceEnabled()) {
                         log.trace("Invalid week of year: " + weekNo);
                     }
@@ -54,7 +54,7 @@ public List<T> transform(List<T> dates) {
                     if (numWeeksInYear < -weekNo) {
                         continue;
                     }
-                    candidate = withTemporalField(date, ALIGNED_WEEK_OF_YEAR, numWeeksInYear + weekNo);
+                    candidate = withTemporalField(date, ALIGNED_WEEK_OF_YEAR, numWeeksInYear + 1 + weekNo);
                 }
                 weekNoDates.add(candidate);
             }
diff --git a/src/main/java/net/fortuna/ical4j/transform/recurrence/ByYearDayRule.java b/src/main/java/net/fortuna/ical4j/transform/recurrence/ByYearDayRule.java
index 5aa44732a..fa556c4aa 100644
--- a/src/main/java/net/fortuna/ical4j/transform/recurrence/ByYearDayRule.java
+++ b/src/main/java/net/fortuna/ical4j/transform/recurrence/ByYearDayRule.java
@@ -67,7 +67,7 @@ public List<T> apply(T date) {
             // construct a list of possible year days..
             final int numDaysInYear = Year.of(getYear(date)).length();
             for (final int yearDay : yearDayList) {
-                if (yearDay == 0 || yearDay <= -numDaysInYear || yearDay > numDaysInYear) {
+                if (yearDay == 0 || yearDay < -numDaysInYear || yearDay > numDaysInYear) {
                     if (log.isTraceEnabled()) {
                         log.trace("Invalid day of year: " + yearDay);
                     }
@@ -83,7 +83,7 @@ public List<T> apply(T date) {
                     if (numDaysInYear < -yearDay) {
                         continue;
                     }
-                    candidate = withTemporalField(date, DAY_OF_YEAR, numDaysInYear + yearDay);
+                    candidate = withTemporalField(date, DAY_OF_YEAR, numDaysInYear + 1 + yearDay);
                 }
                 retVal.add(candidate);
             }