Reformat local numbers that are placing calls in Singapore to not show
the country code.

Due to local regulations and recommendations about only showing the +65
country code when being called by international numbers as a means to
combat international spam calls.

This change also restructures the check so that other countries can be
added if needed later on.

Flag: telephony.remove_country_code_from_local_singapore_calls

Bug: 284416645
Test: atest PhoneNumberUtilsTest, atest PhoneNumberUtilsTest#testFormatSingaporeInternational, atest PhoneNumberUtilsTest#testFormatSingaporeNational
Test2: manual validity checks on call/sms/data

Change-Id: I065709ecb77764e7c838f365f98dc70bbcf7d6cf
diff --git a/telephony/java/android/telephony/PhoneNumberUtils.java b/telephony/java/android/telephony/PhoneNumberUtils.java
index f161f31..0ecafc7 100644
--- a/telephony/java/android/telephony/PhoneNumberUtils.java
+++ b/telephony/java/android/telephony/PhoneNumberUtils.java
@@ -1283,6 +1283,8 @@
 
     private static final String JAPAN_ISO_COUNTRY_CODE = "JP";
 
+    private static final String SINGAPORE_ISO_COUNTRY_CODE = "SG";
+
     /**
      * Breaks the given number down and formats it according to the rules
      * for the country the number is from.
@@ -1669,6 +1671,17 @@
                  * dialing format.
                  */
                 result = util.format(pn, PhoneNumberUtil.PhoneNumberFormat.NATIONAL);
+            } else if (Flags.removeCountryCodeFromLocalSingaporeCalls() &&
+                    (SINGAPORE_ISO_COUNTRY_CODE.equalsIgnoreCase(defaultCountryIso) &&
+                            pn.getCountryCode() ==
+                                    util.getCountryCodeForRegion(SINGAPORE_ISO_COUNTRY_CODE) &&
+                            (pn.getCountryCodeSource() ==
+                                    PhoneNumber.CountryCodeSource.FROM_NUMBER_WITH_PLUS_SIGN))) {
+                /*
+                 * Need to reformat Singaporean phone numbers (when the user is in Singapore)
+                 * with the country code (+65) removed to comply with Singaporean regulations.
+                 */
+                result = util.format(pn, PhoneNumberUtil.PhoneNumberFormat.NATIONAL);
             } else {
                 result = util.formatInOriginalFormat(pn, defaultCountryIso);
             }