1 files changed, 71 insertions, 1 deletions
diff --git a/src/com/android/datetimepicker/Utils.java b/src/com/android/datetimepicker/Utils.java
index 8772fb8..9bc5952 100644
--- a/src/com/android/datetimepicker/Utils.java
+++ b/src/com/android/datetimepicker/Utils.java
@@ -17,9 +17,79 @@
 package com.android.datetimepicker;
 
 import android.os.Build;
+import android.text.format.Time;
 
+import java.util.Calendar;
+
+/**
+ * Utility helper functions for time and date pickers.
+ */
 public class Utils {
+
+    public static final int MONDAY_BEFORE_JULIAN_EPOCH = Time.EPOCH_JULIAN_DAY - 3;
+
+    static final String SHARED_PREFS_NAME = "com.android.calendar_preferences";
+
     public static boolean isJellybeanOrLater() {
-        return Build.VERSION.SDK_INT >= 16;
+      return Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN;
+    }
+
+    public static int getDaysInMonth(int month, int year) {
+        switch (month) {
+            case Calendar.JANUARY:
+            case Calendar.MARCH:
+            case Calendar.MAY:
+            case Calendar.JULY:
+            case Calendar.AUGUST:
+            case Calendar.OCTOBER:
+            case Calendar.DECEMBER:
+                return 31;
+            case Calendar.APRIL:
+            case Calendar.JUNE:
+            case Calendar.SEPTEMBER:
+            case Calendar.NOVEMBER:
+                return 30;
+            case Calendar.FEBRUARY:
+                return (year % 4 == 0) ? 29 : 28;
+            default:
+                throw new IllegalArgumentException("Invalid Month");
+        }
+    }
+
+    /**
+     * Takes a number of weeks since the epoch and calculates the Julian day of
+     * the Monday for that week.
+     *
+     * This assumes that the week containing the {@link Time#EPOCH_JULIAN_DAY}
+     * is considered week 0. It returns the Julian day for the Monday
+     * {@code week} weeks after the Monday of the week containing the epoch.
+     *
+     * @param week Number of weeks since the epoch
+     * @return The julian day for the Monday of the given week since the epoch
+     */
+    public static int getJulianMondayFromWeeksSinceEpoch(int week) {
+        return MONDAY_BEFORE_JULIAN_EPOCH + week * 7;
+    }
+
+    /**
+     * Returns the week since {@link Time#EPOCH_JULIAN_DAY} (Jan 1, 1970)
+     * adjusted for first day of week.
+     *
+     * This takes a julian day and the week start day and calculates which
+     * week since {@link Time#EPOCH_JULIAN_DAY} that day occurs in, starting
+     * at 0. *Do not* use this to compute the ISO week number for the year.
+     *
+     * @param julianDay The julian day to calculate the week number for
+     * @param firstDayOfWeek Which week day is the first day of the week,
+     *          see {@link Time#SUNDAY}
+     * @return Weeks since the epoch
+     */
+    public static int getWeeksSinceEpochFromJulianDay(int julianDay, int firstDayOfWeek) {
+        int diff = Time.THURSDAY - firstDayOfWeek;
+        if (diff < 0) {
+            diff += 7;
+        }
+        int refDay = Time.EPOCH_JULIAN_DAY - diff;
+        return (julianDay - refDay) / 7;
     }
 }