Use confidence to fix whitelist

With this the most obvious problem is fixed. However there
are two remaining items : we should still enforce whitelist
when there are no close candidates at all, and we should
start in confident mode when pressing the globe key.

Bug: 18063142
Bug: 18130489
Bug: 18132240
Bug: 18136721
Bug: 18200415
Change-Id: Ibc0571ae35fc28f8d13760aa86b25db1163d3e31

java/src/com/android/inputmethod/latin/DictionaryFacilitator.java

@@ -63,6 +63,9 @@ public class DictionaryFacilitator {
     // HACK: This threshold is being used when adding a capitalized entry in the User History
     // dictionary.
     private static final int CAPITALIZED_FORM_MAX_PROBABILITY_FOR_INSERT = 140;
+    // How many words we need to type in a row ({@see mConfidenceInMostProbableLanguage}) to
+    // declare we are confident the user is typing in the most probable language.
+    private static final int CONFIDENCE_THRESHOLD = 3;
 
     private DictionaryGroup[] mDictionaryGroups = new DictionaryGroup[] { new DictionaryGroup() };
     private DictionaryGroup mMostProbableDictionaryGroup = mDictionaryGroups[0];
@@ -293,6 +296,14 @@ public class DictionaryFacilitator {
         }
     }
 
+    public boolean isConfidentAboutCurrentLanguageBeing(final Locale mLocale) {
+        final DictionaryGroup mostProbableDictionaryGroup = mMostProbableDictionaryGroup;
+        if (!mostProbableDictionaryGroup.mLocale.equals(mLocale)) {
+            return false;
+        }
+        return mostProbableDictionaryGroup.mConfidence >= CONFIDENCE_THRESHOLD;
+    }
+
     @Nullable
     private static ExpandableBinaryDictionary getSubDict(final String dictType,
             final Context context, final Locale locale, final File dictFile,
@@ -634,7 +645,8 @@ public class DictionaryFacilitator {
             final int timeStampInSeconds, final boolean blockPotentiallyOffensive) {
         final ExpandableBinaryDictionary userHistoryDictionary =
                 dictionaryGroup.getSubDict(Dictionary.TYPE_USER_HISTORY);
-        if (userHistoryDictionary == null) {
+        if (userHistoryDictionary == null
+                || !isConfidentAboutCurrentLanguageBeing(userHistoryDictionary.mLocale)) {
             return;
         }
         final int maxFreq = getFrequency(word);

java/src/com/android/inputmethod/latin/Suggest.java

@@ -32,6 +32,7 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Locale;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 /**
@@ -117,7 +118,8 @@ public final class Suggest {
         return suggestionsContainer;
     }
 
-    private static String getWhitelistedWordOrNull(final ArrayList<SuggestedWordInfo> suggestions) {
+    private static SuggestedWordInfo getWhitelistedWordInfoOrNull(
+            @Nonnull final ArrayList<SuggestedWordInfo> suggestions) {
         if (suggestions.isEmpty()) {
             return null;
         }
@@ -125,7 +127,7 @@ public final class Suggest {
         if (!firstSuggestedWordInfo.isKindOf(SuggestedWordInfo.KIND_WHITELIST)) {
             return null;
         }
-        return firstSuggestedWordInfo.mWord;
+        return firstSuggestedWordInfo;
     }
 
     // Retrieves suggestions for non-batch input (typing, recorrection, predictions...)
@@ -156,7 +158,18 @@ public final class Suggest {
                 SuggestedWordInfo.removeDupsAndReturnSourceOfTypedWord(wordComposer.getTypedWord(),
                         mostProbableLocale /* preferredLocale */, suggestionsContainer);
 
-        final String whitelistedWord = getWhitelistedWordOrNull(suggestionsContainer);
+        final SuggestedWordInfo whitelistedWordInfo =
+                getWhitelistedWordInfoOrNull(suggestionsContainer);
+        final String whitelistedWord;
+        if (null != whitelistedWordInfo &&
+                mDictionaryFacilitator.isConfidentAboutCurrentLanguageBeing(
+                        whitelistedWordInfo.mSourceDict.mLocale)) {
+            whitelistedWord = whitelistedWordInfo.mWord;
+        } else {
+            // Even if we have a whitelist candidate, we don't use it unless we are confident
+            // the user is typing in the language this whitelist candidate comes from.
+            whitelistedWord = null;
+        }
         final boolean resultsArePredictions = !wordComposer.isComposingWord();
 
         // We allow auto-correction if we have a whitelisted word, or if the word had more than