InputLogic.java

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.inputmethod.latin.inputlogic;

import android.graphics.Color;
import android.os.SystemClock;
import android.text.SpannableString;
import android.text.Spanned;
import android.text.TextUtils;
import android.text.style.BackgroundColorSpan;
import android.text.style.SuggestionSpan;
import android.util.Log;
import android.view.KeyCharacterMap;
import android.view.KeyEvent;
import android.view.inputmethod.CorrectionInfo;
import android.view.inputmethod.EditorInfo;

import com.android.inputmethod.compat.SuggestionSpanUtils;
import com.android.inputmethod.event.Event;
import com.android.inputmethod.event.InputTransaction;
import com.android.inputmethod.keyboard.Keyboard;
import com.android.inputmethod.keyboard.KeyboardSwitcher;
import com.android.inputmethod.latin.Dictionary;
import com.android.inputmethod.latin.DictionaryFacilitator;
import com.android.inputmethod.latin.LastComposedWord;
import com.android.inputmethod.latin.LatinIME;
import com.android.inputmethod.latin.NgramContext;
import com.android.inputmethod.latin.RichInputConnection;
import com.android.inputmethod.latin.Suggest;
import com.android.inputmethod.latin.Suggest.OnGetSuggestedWordsCallback;
import com.android.inputmethod.latin.SuggestedWords;
import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
import com.android.inputmethod.latin.WordComposer;
import com.android.inputmethod.latin.common.Constants;
import com.android.inputmethod.latin.common.InputPointers;
import com.android.inputmethod.latin.common.StringUtils;
import com.android.inputmethod.latin.define.DebugFlags;
import com.android.inputmethod.latin.settings.SettingsValues;
import com.android.inputmethod.latin.settings.SettingsValuesForSuggestion;
import com.android.inputmethod.latin.settings.SpacingAndPunctuations;
import com.android.inputmethod.latin.suggestions.SuggestionStripViewAccessor;
import com.android.inputmethod.latin.utils.AsyncResultHolder;
import com.android.inputmethod.latin.utils.InputTypeUtils;
import com.android.inputmethod.latin.utils.RecapitalizeStatus;
import com.android.inputmethod.latin.utils.StatsUtils;
import com.android.inputmethod.latin.utils.TextRange;

import java.util.ArrayList;
import java.util.TreeSet;
import java.util.concurrent.TimeUnit;

import javax.annotation.Nonnull;

/**
 * This class manages the input logic.
 */
public final class InputLogic {
    private static final String TAG = InputLogic.class.getSimpleName();

    // TODO : Remove this member when we can.
    final LatinIME mLatinIME;
    private final SuggestionStripViewAccessor mSuggestionStripViewAccessor;

    // Never null.
    private InputLogicHandler mInputLogicHandler = InputLogicHandler.NULL_HANDLER;

    // TODO : make all these fields private as soon as possible.
    // Current space state of the input method. This can be any of the above constants.
    private int mSpaceState;
    // Never null
    public SuggestedWords mSuggestedWords = SuggestedWords.getEmptyInstance();
    public final Suggest mSuggest;
    private final DictionaryFacilitator mDictionaryFacilitator;

    public LastComposedWord mLastComposedWord = LastComposedWord.NOT_A_COMPOSED_WORD;
    // This has package visibility so it can be accessed from InputLogicHandler.
    /* package */ final WordComposer mWordComposer;
    public final RichInputConnection mConnection;
    private final RecapitalizeStatus mRecapitalizeStatus = new RecapitalizeStatus();

    private int mDeleteCount;
    private long mLastKeyTime;
    public final TreeSet<Long> mCurrentlyPressedHardwareKeys = new TreeSet<>();

    // Keeps track of most recently inserted text (multi-character key) for reverting
    private String mEnteredText;

    // TODO: This boolean is persistent state and causes large side effects at unexpected times.
    // Find a way to remove it for readability.
    private boolean mIsAutoCorrectionIndicatorOn;
    private long mDoubleSpacePeriodCountdownStart;

    /**
     * Create a new instance of the input logic.
     * @param latinIME the instance of the parent LatinIME. We should remove this when we can.
     * @param suggestionStripViewAccessor an object to access the suggestion strip view.
     * @param dictionaryFacilitator facilitator for getting suggestions and updating user history
     * dictionary.
     */
    public InputLogic(final LatinIME latinIME,
            final SuggestionStripViewAccessor suggestionStripViewAccessor,
            final DictionaryFacilitator dictionaryFacilitator) {
        mLatinIME = latinIME;
        mSuggestionStripViewAccessor = suggestionStripViewAccessor;
        mWordComposer = new WordComposer();
        mConnection = new RichInputConnection(latinIME);
        mInputLogicHandler = InputLogicHandler.NULL_HANDLER;
        mSuggest = new Suggest(dictionaryFacilitator);
        mDictionaryFacilitator = dictionaryFacilitator;
    }

    /**
     * Initializes the input logic for input in an editor.
     *
     * Call this when input starts or restarts in some editor (typically, in onStartInputView).
     *
     * @param combiningSpec the combining spec string for this subtype
     * @param settingsValues the current settings values
     */
    public void startInput(final String combiningSpec, final SettingsValues settingsValues) {
        mEnteredText = null;
        if (!mWordComposer.getTypedWord().isEmpty()) {
            // For messaging apps that offer send button, the IME does not get the opportunity
            // to capture the last word. This block should capture those uncommitted words.
            // The timestamp at which it is captured is not accurate but close enough.
            StatsUtils.onWordCommitUserTyped(
                    mWordComposer.getTypedWord(), mWordComposer.isBatchMode());
        }
        mWordComposer.restartCombining(combiningSpec);
        resetComposingState(true /* alsoResetLastComposedWord */);
        mDeleteCount = 0;
        mSpaceState = SpaceState.NONE;
        mRecapitalizeStatus.disable(); // Do not perform recapitalize until the cursor is moved once
        mCurrentlyPressedHardwareKeys.clear();
        mSuggestedWords = SuggestedWords.getEmptyInstance();
        // In some cases (namely, after rotation of the device) editorInfo.initialSelStart is lying
        // so we try using some heuristics to find out about these and fix them.
        mConnection.tryFixLyingCursorPosition();
        cancelDoubleSpacePeriodCountdown();
        if (InputLogicHandler.NULL_HANDLER == mInputLogicHandler) {
            mInputLogicHandler = new InputLogicHandler(mLatinIME, this);
        } else {
            mInputLogicHandler.reset();
        }

        if (settingsValues.mShouldShowLxxSuggestionUi) {
            mConnection.requestCursorUpdates(true /* enableMonitor */,
                    true /* requestImmediateCallback */);
        }
    }

    /**
     * Call this when the subtype changes.
     * @param combiningSpec the spec string for the combining rules
     * @param settingsValues the current settings values
     */
    public void onSubtypeChanged(final String combiningSpec, final SettingsValues settingsValues) {
        finishInput();
        startInput(combiningSpec, settingsValues);
    }

    /**
     * Call this when the orientation changes.
     * @param settingsValues the current values of the settings.
     */
    public void onOrientationChange(final SettingsValues settingsValues) {
        // If !isComposingWord, #commitTyped() is a no-op, but still, it's better to avoid
        // the useless IPC of {begin,end}BatchEdit.
        if (mWordComposer.isComposingWord()) {
            mConnection.beginBatchEdit();
            // If we had a composition in progress, we need to commit the word so that the
            // suggestionsSpan will be added. This will allow resuming on the same suggestions
            // after rotation is finished.
            commitTyped(settingsValues, LastComposedWord.NOT_A_SEPARATOR);
            mConnection.endBatchEdit();
        }
    }

    /**
     * Clean up the input logic after input is finished.
     */
    public void finishInput() {
        if (mWordComposer.isComposingWord()) {
            mConnection.finishComposingText();
            StatsUtils.onWordCommitUserTyped(
                    mWordComposer.getTypedWord(), mWordComposer.isBatchMode());
        }
        resetComposingState(true /* alsoResetLastComposedWord */);
        mInputLogicHandler.reset();
    }

    // Normally this class just gets out of scope after the process ends, but in unit tests, we
    // create several instances of LatinIME in the same process, which results in several
    // instances of InputLogic. This cleans up the associated handler so that tests don't leak
    // handlers.
    public void recycle() {
        final InputLogicHandler inputLogicHandler = mInputLogicHandler;
        mInputLogicHandler = InputLogicHandler.NULL_HANDLER;
        inputLogicHandler.destroy();
        mDictionaryFacilitator.closeDictionaries();
    }

    /**
     * React to a string input.
     *
     * This is triggered by keys that input many characters at once, like the ".com" key or
     * some additional keys for example.
     *
     * @param settingsValues the current values of the settings.
     * @param event the input event containing the data.
     * @return the complete transaction object
     */
    public InputTransaction onTextInput(final SettingsValues settingsValues, final Event event,
            final int keyboardShiftMode,
            // TODO: remove this argument
            final LatinIME.UIHandler handler) {
        final String rawText = event.getTextToCommit().toString();
        final InputTransaction inputTransaction = new InputTransaction(settingsValues, event,
                SystemClock.uptimeMillis(), mSpaceState,
                getActualCapsMode(settingsValues, keyboardShiftMode));
        mConnection.beginBatchEdit();
        if (mWordComposer.isComposingWord()) {
            commitCurrentAutoCorrection(settingsValues, rawText, handler);
        } else {
            resetComposingState(true /* alsoResetLastComposedWord */);
        }
        handler.postUpdateSuggestionStrip(SuggestedWords.INPUT_STYLE_TYPING);
        final String text = performSpecificTldProcessingOnTextInput(rawText);
        if (SpaceState.PHANTOM == mSpaceState) {
            insertAutomaticSpaceIfOptionsAndTextAllow(settingsValues);
        }
        mConnection.commitText(text, 1);
        StatsUtils.onWordCommitUserTyped(mEnteredText, mWordComposer.isBatchMode());
        mConnection.endBatchEdit();
        // Space state must be updated before calling updateShiftState
        mSpaceState = SpaceState.NONE;
        mEnteredText = text;
        inputTransaction.setDidAffectContents();
        inputTransaction.requireShiftUpdate(InputTransaction.SHIFT_UPDATE_NOW);
        return inputTransaction;
    }

    /**
     * A suggestion was picked from the suggestion strip.
     * @param settingsValues the current values of the settings.
     * @param suggestionInfo the suggestion info.
     * @param keyboardShiftState the shift state of the keyboard, as returned by
     *     {@link com.android.inputmethod.keyboard.KeyboardSwitcher#getKeyboardShiftMode()}
     * @return the complete transaction object
     */
    // Called from {@link SuggestionStripView} through the {@link SuggestionStripView#Listener}
    // interface
    public InputTransaction onPickSuggestionManually(final SettingsValues settingsValues,
            final SuggestedWordInfo suggestionInfo, final int keyboardShiftState,
            // TODO: remove these arguments
            final int currentKeyboardScriptId, final LatinIME.UIHandler handler) {
        final SuggestedWords suggestedWords = mSuggestedWords;
        final String suggestion = suggestionInfo.mWord;
        // If this is a punctuation picked from the suggestion strip, pass it to onCodeInput
        if (suggestion.length() == 1 && suggestedWords.isPunctuationSuggestions()) {
            // We still want to log a suggestion click.
            StatsUtils.onPickSuggestionManually(
                    mSuggestedWords, suggestionInfo, mDictionaryFacilitator);
            // Word separators are suggested before the user inputs something.
            // Rely on onCodeInput to do the complicated swapping/stripping logic consistently.
            final Event event = Event.createPunctuationSuggestionPickedEvent(suggestionInfo);
            return onCodeInput(settingsValues, event, keyboardShiftState,
                    currentKeyboardScriptId, handler);
        }

        final Event event = Event.createSuggestionPickedEvent(suggestionInfo);
        final InputTransaction inputTransaction = new InputTransaction(settingsValues,
                event, SystemClock.uptimeMillis(), mSpaceState, keyboardShiftState);
        // Manual pick affects the contents of the editor, so we take note of this. It's important
        // for the sequence of language switching.
        inputTransaction.setDidAffectContents();
        mConnection.beginBatchEdit();
        if (SpaceState.PHANTOM == mSpaceState && suggestion.length() > 0
                // In the batch input mode, a manually picked suggested word should just replace
                // the current batch input text and there is no need for a phantom space.
                && !mWordComposer.isBatchMode()) {
            final int firstChar = Character.codePointAt(suggestion, 0);
            if (!settingsValues.isWordSeparator(firstChar)
                    || settingsValues.isUsuallyPrecededBySpace(firstChar)) {
                insertAutomaticSpaceIfOptionsAndTextAllow(settingsValues);
            }
        }

        // TODO: We should not need the following branch. We should be able to take the same
        // code path as for other kinds, use commitChosenWord, and do everything normally. We will
        // however need to reset the suggestion strip right away, because we know we can't take
        // the risk of calling commitCompletion twice because we don't know how the app will react.
        if (suggestionInfo.isKindOf(SuggestedWordInfo.KIND_APP_DEFINED)) {
            mSuggestedWords = SuggestedWords.getEmptyInstance();
            mSuggestionStripViewAccessor.setNeutralSuggestionStrip();
            inputTransaction.requireShiftUpdate(InputTransaction.SHIFT_UPDATE_NOW);
            resetComposingState(true /* alsoResetLastComposedWord */);
            mConnection.commitCompletion(suggestionInfo.mApplicationSpecifiedCompletionInfo);
            mConnection.endBatchEdit();
            return inputTransaction;
        }

        commitChosenWord(settingsValues, suggestion, LastComposedWord.COMMIT_TYPE_MANUAL_PICK,
                LastComposedWord.NOT_A_SEPARATOR);
        mConnection.endBatchEdit();
        // Don't allow cancellation of manual pick
        mLastComposedWord.deactivate();
        // Space state must be updated before calling updateShiftState
        mSpaceState = SpaceState.PHANTOM;
        inputTransaction.requireShiftUpdate(InputTransaction.SHIFT_UPDATE_NOW);

        // If we're not showing the "Touch again to save", then update the suggestion strip.
        // That's going to be predictions (or punctuation suggestions), so INPUT_STYLE_NONE.
        handler.postUpdateSuggestionStrip(SuggestedWords.INPUT_STYLE_NONE);

        StatsUtils.onPickSuggestionManually(
                mSuggestedWords, suggestionInfo, mDictionaryFacilitator);
        StatsUtils.onWordCommitSuggestionPickedManually(
                suggestionInfo.mWord, mWordComposer.isBatchMode());
        return inputTransaction;
    }

    /**
     * Consider an update to the cursor position. Evaluate whether this update has happened as
     * part of normal typing or whether it was an explicit cursor move by the user. In any case,
     * do the necessary adjustments.
     * @param oldSelStart old selection start
     * @param oldSelEnd old selection end
     * @param newSelStart new selection start
     * @param newSelEnd new selection end
     * @param settingsValues the current values of the settings.
     * @return whether the cursor has moved as a result of user interaction.
     */
    public boolean onUpdateSelection(final int oldSelStart, final int oldSelEnd,
            final int newSelStart, final int newSelEnd, final SettingsValues settingsValues) {
        if (mConnection.isBelatedExpectedUpdate(oldSelStart, newSelStart, oldSelEnd, newSelEnd)) {
            return false;
        }
        // TODO: the following is probably better done in resetEntireInputState().
        // it should only happen when the cursor moved, and the very purpose of the
        // test below is to narrow down whether this happened or not. Likewise with
        // the call to updateShiftState.
        // We set this to NONE because after a cursor move, we don't want the space
        // state-related special processing to kick in.
        mSpaceState = SpaceState.NONE;

        final boolean selectionChangedOrSafeToReset =
                oldSelStart != newSelStart || oldSelEnd != newSelEnd // selection changed
                || !mWordComposer.isComposingWord(); // safe to reset
        final boolean hasOrHadSelection = (oldSelStart != oldSelEnd || newSelStart != newSelEnd);
        final int moveAmount = newSelStart - oldSelStart;
        // As an added small gift from the framework, it happens upon rotation when there
        // is a selection that we get a wrong cursor position delivered to startInput() that
        // does not get reflected in the oldSel{Start,End} parameters to the next call to
        // onUpdateSelection. In this case, we may have set a composition, and when we're here
        // we realize we shouldn't have. In theory, in this case, selectionChangedOrSafeToReset
        // should be true, but that is if the framework had taken that wrong cursor position
        // into account, which means we have to reset the entire composing state whenever there
        // is or was a selection regardless of whether it changed or not.
        if (hasOrHadSelection || !settingsValues.needsToLookupSuggestions()
                || (selectionChangedOrSafeToReset
                        && !mWordComposer.moveCursorByAndReturnIfInsideComposingWord(moveAmount))) {
            // If we are composing a word and moving the cursor, we would want to set a
            // suggestion span for recorrection to work correctly. Unfortunately, that
            // would involve the keyboard committing some new text, which would move the
            // cursor back to where it was. Latin IME could then fix the position of the cursor
            // again, but the asynchronous nature of the calls results in this wreaking havoc
            // with selection on double tap and the like.
            // Another option would be to send suggestions each time we set the composing
            // text, but that is probably too expensive to do, so we decided to leave things
            // as is.
            // Also, we're posting a resume suggestions message, and this will update the
            // suggestions strip in a few milliseconds, so if we cleared the suggestion strip here
            // we'd have the suggestion strip noticeably janky. To avoid that, we don't clear
            // it here, which means we'll keep outdated suggestions for a split second but the
            // visual result is better.
            resetEntireInputState(newSelStart, newSelEnd, false /* clearSuggestionStrip */);
        } else {
            // resetEntireInputState calls resetCachesUponCursorMove, but forcing the
            // composition to end. But in all cases where we don't reset the entire input
            // state, we still want to tell the rich input connection about the new cursor
            // position so that it can update its caches.
            mConnection.resetCachesUponCursorMoveAndReturnSuccess(
                    newSelStart, newSelEnd, false /* shouldFinishComposition */);
        }

        // The cursor has been moved : we now accept to perform recapitalization
        mRecapitalizeStatus.enable();
        // We moved the cursor. If we are touching a word, we need to resume suggestion.
        mLatinIME.mHandler.postResumeSuggestions(true /* shouldDelay */);
        // Stop the last recapitalization, if started.
        mRecapitalizeStatus.stop();
        return true;
    }

    /**
     * React to a code input. It may be a code point to insert, or a symbolic value that influences
     * the keyboard behavior.
     *
     * Typically, this is called whenever a key is pressed on the software keyboard. This is not
     * the entry point for gesture input; see the onBatchInput* family of functions for this.
     *
     * @param settingsValues the current settings values.
     * @param event the event to handle.
     * @param keyboardShiftMode the current shift mode of the keyboard, as returned by
     *     {@link com.android.inputmethod.keyboard.KeyboardSwitcher#getKeyboardShiftMode()}
     * @return the complete transaction object
     */
    public InputTransaction onCodeInput(final SettingsValues settingsValues,
            @Nonnull final Event event, final int keyboardShiftMode,
            // TODO: remove these arguments
            final int currentKeyboardScriptId, final LatinIME.UIHandler handler) {
        final Event processedEvent = mWordComposer.processEvent(event);
        final InputTransaction inputTransaction = new InputTransaction(settingsValues,
                processedEvent, SystemClock.uptimeMillis(), mSpaceState,
                getActualCapsMode(settingsValues, keyboardShiftMode));
        if (processedEvent.mKeyCode != Constants.CODE_DELETE
                || inputTransaction.mTimestamp > mLastKeyTime + Constants.LONG_PRESS_MILLISECONDS) {
            mDeleteCount = 0;
        }
        mLastKeyTime = inputTransaction.mTimestamp;
        mConnection.beginBatchEdit();
        if (!mWordComposer.isComposingWord()) {
            // TODO: is this useful? It doesn't look like it should be done here, but rather after
            // a word is committed.
            mIsAutoCorrectionIndicatorOn = false;
        }

        // TODO: Consolidate the double-space period timer, mLastKeyTime, and the space state.
        if (processedEvent.mCodePoint != Constants.CODE_SPACE) {
            cancelDoubleSpacePeriodCountdown();
        }

        Event currentEvent = processedEvent;
        while (null != currentEvent) {
            if (currentEvent.isConsumed()) {
                handleConsumedEvent(currentEvent, inputTransaction);
            } else if (currentEvent.isFunctionalKeyEvent()) {
                handleFunctionalEvent(currentEvent, inputTransaction, currentKeyboardScriptId,
                        handler);
            } else {
                handleNonFunctionalEvent(currentEvent, inputTransaction, handler);
            }
            currentEvent = currentEvent.mNextEvent;
        }
        if (!inputTransaction.didAutoCorrect() && processedEvent.mKeyCode != Constants.CODE_SHIFT
                && processedEvent.mKeyCode != Constants.CODE_CAPSLOCK
                && processedEvent.mKeyCode != Constants.CODE_SWITCH_ALPHA_SYMBOL)
            mLastComposedWord.deactivate();
        if (Constants.CODE_DELETE != processedEvent.mKeyCode) {
            mEnteredText = null;
        }
        mConnection.endBatchEdit();
        return inputTransaction;
    }

    public void onStartBatchInput(final SettingsValues settingsValues,
            // TODO: remove these arguments
            final KeyboardSwitcher keyboardSwitcher, final LatinIME.UIHandler handler) {
        mInputLogicHandler.onStartBatchInput();
        handler.showGesturePreviewAndSuggestionStrip(
                SuggestedWords.getEmptyInstance(), false /* dismissGestureFloatingPreviewText */);
        handler.cancelUpdateSuggestionStrip();
        ++mAutoCommitSequenceNumber;
        mConnection.beginBatchEdit();
        if (mWordComposer.isComposingWord()) {
            if (mWordComposer.isCursorFrontOrMiddleOfComposingWord()) {
                // If we are in the middle of a recorrection, we need to commit the recorrection
                // first so that we can insert the batch input at the current cursor position.
                resetEntireInputState(mConnection.getExpectedSelectionStart(),
                        mConnection.getExpectedSelectionEnd(), true /* clearSuggestionStrip */);
            } else if (mWordComposer.isSingleLetter()) {
                // We auto-correct the previous (typed, not gestured) string iff it's one character
                // long. The reason for this is, even in the middle of gesture typing, you'll still
                // tap one-letter words and you want them auto-corrected (typically, "i" in English
                // should become "I"). However for any longer word, we assume that the reason for
                // tapping probably is that the word you intend to type is not in the dictionary,
                // so we do not attempt to correct, on the assumption that if that was a dictionary
                // word, the user would probably have gestured instead.
                commitCurrentAutoCorrection(settingsValues, LastComposedWord.NOT_A_SEPARATOR,
                        handler);
            } else {
                commitTyped(settingsValues, LastComposedWord.NOT_A_SEPARATOR);
            }
        }
        final int codePointBeforeCursor = mConnection.getCodePointBeforeCursor();
        if (Character.isLetterOrDigit(codePointBeforeCursor)
                || settingsValues.isUsuallyFollowedBySpace(codePointBeforeCursor)) {
            final boolean autoShiftHasBeenOverriden = keyboardSwitcher.getKeyboardShiftMode() !=
                    getCurrentAutoCapsState(settingsValues);
            mSpaceState = SpaceState.PHANTOM;
            if (!autoShiftHasBeenOverriden) {
                // When we change the space state, we need to update the shift state of the
                // keyboard unless it has been overridden manually. This is happening for example
                // after typing some letters and a period, then gesturing; the keyboard is not in
                // caps mode yet, but since a gesture is starting, it should go in caps mode,
                // unless the user explictly said it should not.
                keyboardSwitcher.requestUpdatingShiftState(getCurrentAutoCapsState(settingsValues),
                        getCurrentRecapitalizeState());
            }
        }
        mConnection.endBatchEdit();
        mWordComposer.setCapitalizedModeAtStartComposingTime(
                getActualCapsMode(settingsValues, keyboardSwitcher.getKeyboardShiftMode()));
    }

    /* The sequence number member is only used in onUpdateBatchInput. It is increased each time
     * auto-commit happens. The reason we need this is, when auto-commit happens we trim the
     * input pointers that are held in a singleton, and to know how much to trim we rely on the
     * results of the suggestion process that is held in mSuggestedWords.
     * However, the suggestion process is asynchronous, and sometimes we may enter the
     * onUpdateBatchInput method twice without having recomputed suggestions yet, or having
     * received new suggestions generated from not-yet-trimmed input pointers. In this case, the
     * mIndexOfTouchPointOfSecondWords member will be out of date, and we must not use it lest we
     * remove an unrelated number of pointers (possibly even more than are left in the input
     * pointers, leading to a crash).
     * To avoid that, we increase the sequence number each time we auto-commit and trim the
     * input pointers, and we do not use any suggested words that have been generated with an
     * earlier sequence number.
     */
    private int mAutoCommitSequenceNumber = 1;
    public void onUpdateBatchInput(final SettingsValues settingsValues,
            final InputPointers batchPointers,
            // TODO: remove these arguments
            final KeyboardSwitcher keyboardSwitcher) {
        mInputLogicHandler.onUpdateBatchInput(batchPointers, mAutoCommitSequenceNumber);
    }

    public void onEndBatchInput(final InputPointers batchPointers) {
        mInputLogicHandler.updateTailBatchInput(batchPointers, mAutoCommitSequenceNumber);
        ++mAutoCommitSequenceNumber;
    }

    // TODO: remove this argument
    public void onCancelBatchInput(final LatinIME.UIHandler handler) {
        mInputLogicHandler.onCancelBatchInput();
        handler.showGesturePreviewAndSuggestionStrip(
                SuggestedWords.getEmptyInstance(), true /* dismissGestureFloatingPreviewText */);
    }

    // TODO: on the long term, this method should become private, but it will be difficult.
    // Especially, how do we deal with InputMethodService.onDisplayCompletions?
    public void setSuggestedWords(final SuggestedWords suggestedWords) {
        if (!suggestedWords.isEmpty()) {
            final SuggestedWordInfo suggestedWordInfo;
            if (suggestedWords.mWillAutoCorrect) {
                suggestedWordInfo = suggestedWords.getInfo(SuggestedWords.INDEX_OF_AUTO_CORRECTION);
            } else {
                // We can't use suggestedWords.getWord(SuggestedWords.INDEX_OF_TYPED_WORD)
                // because it may differ from mWordComposer.mTypedWord.
                suggestedWordInfo = suggestedWords.mTypedWordInfo;
            }
            mWordComposer.setAutoCorrection(suggestedWordInfo);
        }
        mSuggestedWords = suggestedWords;
        final boolean newAutoCorrectionIndicator = suggestedWords.mWillAutoCorrect;

        // Put a blue underline to a word in TextView which will be auto-corrected.
        if (mIsAutoCorrectionIndicatorOn != newAutoCorrectionIndicator
                && mWordComposer.isComposingWord()) {
            mIsAutoCorrectionIndicatorOn = newAutoCorrectionIndicator;
            final CharSequence textWithUnderline =
                    getTextWithUnderline(mWordComposer.getTypedWord());
            // TODO: when called from an updateSuggestionStrip() call that results from a posted
            // message, this is called outside any batch edit. Potentially, this may result in some
            // janky flickering of the screen, although the display speed makes it unlikely in
            // the practice.
            setComposingTextInternal(textWithUnderline, 1);
        }
    }

    /**
     * Handle a consumed event.
     *
     * Consumed events represent events that have already been consumed, typically by the
     * combining chain.
     *
     * @param event The event to handle.
     * @param inputTransaction The transaction in progress.
     */
    private void handleConsumedEvent(final Event event, final InputTransaction inputTransaction) {
        // A consumed event may have text to commit and an update to the composing state, so
        // we evaluate both. With some combiners, it's possible than an event contains both
        // and we enter both of the following if clauses.
        final CharSequence textToCommit = event.getTextToCommit();
        if (!TextUtils.isEmpty(textToCommit)) {
            mConnection.commitText(textToCommit, 1);
            inputTransaction.setDidAffectContents();
        }
        if (mWordComposer.isComposingWord()) {
            setComposingTextInternal(mWordComposer.getTypedWord(), 1);
            inputTransaction.setDidAffectContents();
            inputTransaction.setRequiresUpdateSuggestions();
        }
    }

    /**
     * Handle a functional key event.
     *
     * A functional event is a special key, like delete, shift, emoji, or the settings key.
     * Non-special keys are those that generate a single code point.
     * This includes all letters, digits, punctuation, separators, emoji. It excludes keys that
     * manage keyboard-related stuff like shift, language switch, settings, layout switch, or
     * any key that results in multiple code points like the ".com" key.
     *
     * @param event The event to handle.
     * @param inputTransaction The transaction in progress.
     */
    private void handleFunctionalEvent(final Event event, final InputTransaction inputTransaction,
            // TODO: remove these arguments
            final int currentKeyboardScriptId, final LatinIME.UIHandler handler) {
        switch (event.mKeyCode) {
            case Constants.CODE_DELETE:
                handleBackspaceEvent(event, inputTransaction, currentKeyboardScriptId);
                // Backspace is a functional key, but it affects the contents of the editor.
                inputTransaction.setDidAffectContents();
                break;
            case Constants.CODE_SHIFT:
                performRecapitalization(inputTransaction.mSettingsValues);
                inputTransaction.requireShiftUpdate(InputTransaction.SHIFT_UPDATE_NOW);
                if (mSuggestedWords.isPrediction()) {
                    inputTransaction.setRequiresUpdateSuggestions();
                }
                break;
            case Constants.CODE_CAPSLOCK:
                // Note: Changing keyboard to shift lock state is handled in
                // {@link KeyboardSwitcher#onEvent(Event)}.
                break;
            case Constants.CODE_SYMBOL_SHIFT:
                // Note: Calling back to the keyboard on the symbol Shift key is handled in
                // {@link #onPressKey(int,int,boolean)} and {@link #onReleaseKey(int,boolean)}.
                break;
            case Constants.CODE_SWITCH_ALPHA_SYMBOL:
                // Note: Calling back to the keyboard on symbol key is handled in
                // {@link #onPressKey(int,int,boolean)} and {@link #onReleaseKey(int,boolean)}.
                break;
            case Constants.CODE_SETTINGS:
                onSettingsKeyPressed();
                break;
            case Constants.CODE_SHORTCUT:
                // We need to switch to the shortcut IME. This is handled by LatinIME since the
                // input logic has no business with IME switching.
                break;
            case Constants.CODE_ACTION_NEXT:
                performEditorAction(EditorInfo.IME_ACTION_NEXT);
                break;
            case Constants.CODE_ACTION_PREVIOUS:
                performEditorAction(EditorInfo.IME_ACTION_PREVIOUS);
                break;
            case Constants.CODE_LANGUAGE_SWITCH:
                handleLanguageSwitchKey();
                break;
            case Constants.CODE_EMOJI:
                // Note: Switching emoji keyboard is being handled in
                // {@link KeyboardState#onEvent(Event,int)}.
                break;
            case Constants.CODE_ALPHA_FROM_EMOJI:
                // Note: Switching back from Emoji keyboard to the main keyboard is being
                // handled in {@link KeyboardState#onEvent(Event,int)}.
                break;
            case Constants.CODE_SHIFT_ENTER:
                // TODO: remove this object
                final Event tmpEvent = Event.createSoftwareKeypressEvent(Constants.CODE_ENTER,
                        event.mKeyCode, event.mX, event.mY, event.isKeyRepeat());
                handleNonSpecialCharacterEvent(tmpEvent, inputTransaction, handler);
                // Shift + Enter is treated as a functional key but it results in adding a new
                // line, so that does affect the contents of the editor.
                inputTransaction.setDidAffectContents();
                break;
            default:
                throw new RuntimeException("Unknown key code : " + event.mKeyCode);
        }
    }

    /**
     * Handle an event that is not a functional event.
     *
     * These events are generally events that cause input, but in some cases they may do other
     * things like trigger an editor action.
     *
     * @param event The event to handle.
     * @param inputTransaction The transaction in progress.
     */
    private void handleNonFunctionalEvent(final Event event,
            final InputTransaction inputTransaction,
            // TODO: remove this argument
            final LatinIME.UIHandler handler) {
        inputTransaction.setDidAffectContents();
        switch (event.mCodePoint) {
            case Constants.CODE_ENTER:
                final EditorInfo editorInfo = getCurrentInputEditorInfo();
                final int imeOptionsActionId =
                        InputTypeUtils.getImeOptionsActionIdFromEditorInfo(editorInfo);
                if (InputTypeUtils.IME_ACTION_CUSTOM_LABEL == imeOptionsActionId) {
                    // Either we have an actionLabel and we should performEditorAction with
                    // actionId regardless of its value.
                    performEditorAction(editorInfo.actionId);
                } else if (EditorInfo.IME_ACTION_NONE != imeOptionsActionId) {
                    // We didn't have an actionLabel, but we had another action to execute.
                    // EditorInfo.IME_ACTION_NONE explicitly means no action. In contrast,
                    // EditorInfo.IME_ACTION_UNSPECIFIED is the default value for an action, so it
                    // means there should be an action and the app didn't bother to set a specific
                    // code for it - presumably it only handles one. It does not have to be treated
                    // in any specific way: anything that is not IME_ACTION_NONE should be sent to
                    // performEditorAction.
                    performEditorAction(imeOptionsActionId);
                } else {
                    // No action label, and the action from imeOptions is NONE: this is a regular
                    // enter key that should input a carriage return.
                    handleNonSpecialCharacterEvent(event, inputTransaction, handler);
                }
                break;
            default:
                handleNonSpecialCharacterEvent(event, inputTransaction, handler);
                break;
        }
    }

    /**
     * Handle inputting a code point to the editor.
     *
     * Non-special keys are those that generate a single code point.
     * This includes all letters, digits, punctuation, separators, emoji. It excludes keys that
     * manage keyboard-related stuff like shift, language switch, settings, layout switch, or
     * any key that results in multiple code points like the ".com" key.
     *
     * @param event The event to handle.
     * @param inputTransaction The transaction in progress.
     */
    private void handleNonSpecialCharacterEvent(final Event event,
            final InputTransaction inputTransaction,
            // TODO: remove this argument
            final LatinIME.UIHandler handler) {
        final int codePoint = event.mCodePoint;
        mSpaceState = SpaceState.NONE;
        if (inputTransaction.mSettingsValues.isWordSeparator(codePoint)
                || Character.getType(codePoint) == Character.OTHER_SYMBOL) {
            handleSeparatorEvent(event, inputTransaction, handler);
        } else {
            if (SpaceState.PHANTOM == inputTransaction.mSpaceState) {
                if (mWordComposer.isCursorFrontOrMiddleOfComposingWord()) {
                    // If we are in the middle of a recorrection, we need to commit the recorrection
                    // first so that we can insert the character at the current cursor position.
                    resetEntireInputState(mConnection.getExpectedSelectionStart(),
                            mConnection.getExpectedSelectionEnd(), true /* clearSuggestionStrip */);
                } else {
                    commitTyped(inputTransaction.mSettingsValues, LastComposedWord.NOT_A_SEPARATOR);
                }
            }
            handleNonSeparatorEvent(event, inputTransaction.mSettingsValues, inputTransaction);
        }
    }

    /**
     * Handle a non-separator.
     * @param event The event to handle.
     * @param settingsValues The current settings values.
     * @param inputTransaction The transaction in progress.
     */
    private void handleNonSeparatorEvent(final Event event, final SettingsValues settingsValues,
            final InputTransaction inputTransaction) {
        final int codePoint = event.mCodePoint;
        // TODO: refactor this method to stop flipping isComposingWord around all the time, and
        // make it shorter (possibly cut into several pieces). Also factor
        // handleNonSpecialCharacterEvent which has the same name as other handle* methods but is
        // not the same.
        boolean isComposingWord = mWordComposer.isComposingWord();

        // TODO: remove isWordConnector() and use isUsuallyFollowedBySpace() instead.
        // See onStartBatchInput() to see how to do it.
        if (SpaceState.PHANTOM == inputTransaction.mSpaceState
                && !settingsValues.isWordConnector(codePoint)) {
            if (isComposingWord) {
                // Sanity check
                throw new RuntimeException("Should not be composing here");
            }
            insertAutomaticSpaceIfOptionsAndTextAllow(settingsValues);
        }

        if (mWordComposer.isCursorFrontOrMiddleOfComposingWord()) {
            // If we are in the middle of a recorrection, we need to commit the recorrection
            // first so that we can insert the character at the current cursor position.
            resetEntireInputState(mConnection.getExpectedSelectionStart(),
                    mConnection.getExpectedSelectionEnd(), true /* clearSuggestionStrip */);
            isComposingWord = false;
        }
        // We want to find out whether to start composing a new word with this character. If so,
        // we need to reset the composing state and switch isComposingWord. The order of the
        // tests is important for good performance.
        // We only start composing if we're not already composing.
        if (!isComposingWord
        // We only start composing if this is a word code point. Essentially that means it's a
        // a letter or a word connector.
                && settingsValues.isWordCodePoint(codePoint)
        // We never go into composing state if suggestions are not requested.
                && settingsValues.needsToLookupSuggestions() &&
        // In languages with spaces, we only start composing a word when we are not already
        // touching a word. In languages without spaces, the above conditions are sufficient.
                (!mConnection.isCursorTouchingWord(settingsValues.mSpacingAndPunctuations)
                        || !settingsValues.mSpacingAndPunctuations.mCurrentLanguageHasSpaces)) {
            // Reset entirely the composing state anyway, then start composing a new word unless
            // the character is a word connector. The idea here is, word connectors are not
            // separators and they should be treated as normal characters, except in the first
            // position where they should not start composing a word.
            isComposingWord = !settingsValues.mSpacingAndPunctuations.isWordConnector(codePoint);
            // Here we don't need to reset the last composed word. It will be reset
            // when we commit this one, if we ever do; if on the other hand we backspace
            // it entirely and resume suggestions on the previous word, we'd like to still
            // have touch coordinates for it.
            resetComposingState(false /* alsoResetLastComposedWord */);
        }
        if (isComposingWord) {
            mWordComposer.applyProcessedEvent(event);
            // If it's the first letter, make note of auto-caps state
            if (mWordComposer.isSingleLetter()) {
                mWordComposer.setCapitalizedModeAtStartComposingTime(inputTransaction.mShiftState);
            }
            setComposingTextInternal(getTextWithUnderline(mWordComposer.getTypedWord()), 1);
        } else {
            final boolean swapWeakSpace = tryStripSpaceAndReturnWhetherShouldSwapInstead(event,
                    inputTransaction);

            if (swapWeakSpace && trySwapSwapperAndSpace(event, inputTransaction)) {
                mSpaceState = SpaceState.WEAK;
            } else {
                sendKeyCodePoint(settingsValues, codePoint);
            }
        }
        inputTransaction.setRequiresUpdateSuggestions();
    }

    /**
     * Handle input of a separator code point.
     * @param event The event to handle.
     * @param inputTransaction The transaction in progress.
     */
    private void handleSeparatorEvent(final Event event, final InputTransaction inputTransaction,
            // TODO: remove this argument
            final LatinIME.UIHandler handler) {
        final int codePoint = event.mCodePoint;
        final SettingsValues settingsValues = inputTransaction.mSettingsValues;
        final boolean wasComposingWord = mWordComposer.isComposingWord();
        // We avoid sending spaces in languages without spaces if we were composing.
        final boolean shouldAvoidSendingCode = Constants.CODE_SPACE == codePoint
                && !settingsValues.mSpacingAndPunctuations.mCurrentLanguageHasSpaces
                && wasComposingWord;
        if (mWordComposer.isCursorFrontOrMiddleOfComposingWord()) {
            // If we are in the middle of a recorrection, we need to commit the recorrection
            // first so that we can insert the separator at the current cursor position.
            resetEntireInputState(mConnection.getExpectedSelectionStart(),
                    mConnection.getExpectedSelectionEnd(), true /* clearSuggestionStrip */);
        }
        // isComposingWord() may have changed since we stored wasComposing
        if (mWordComposer.isComposingWord()) {
            if (settingsValues.mAutoCorrectionEnabledPerUserSettings) {
                final String separator = shouldAvoidSendingCode ? LastComposedWord.NOT_A_SEPARATOR
                        : StringUtils.newSingleCodePointString(codePoint);
                commitCurrentAutoCorrection(settingsValues, separator, handler);
                inputTransaction.setDidAutoCorrect();
            } else {
                commitTyped(settingsValues,
                        StringUtils.newSingleCodePointString(codePoint));
            }
        }

        final boolean swapWeakSpace = tryStripSpaceAndReturnWhetherShouldSwapInstead(event,
                inputTransaction);

        final boolean isInsideDoubleQuoteOrAfterDigit = Constants.CODE_DOUBLE_QUOTE == codePoint
                && mConnection.isInsideDoubleQuoteOrAfterDigit();

        final boolean needsPrecedingSpace;
        if (SpaceState.PHANTOM != inputTransaction.mSpaceState) {
            needsPrecedingSpace = false;
        } else if (Constants.CODE_DOUBLE_QUOTE == codePoint) {
            // Double quotes behave like they are usually preceded by space iff we are
            // not inside a double quote or after a digit.
            needsPrecedingSpace = !isInsideDoubleQuoteOrAfterDigit;
        } else if (settingsValues.mSpacingAndPunctuations.isClusteringSymbol(codePoint)
                && settingsValues.mSpacingAndPunctuations.isClusteringSymbol(
                        mConnection.getCodePointBeforeCursor())) {
            needsPrecedingSpace = false;
        } else {
            needsPrecedingSpace = settingsValues.isUsuallyPrecededBySpace(codePoint);
        }

        if (needsPrecedingSpace) {
            insertAutomaticSpaceIfOptionsAndTextAllow(settingsValues);
        }

        if (tryPerformDoubleSpacePeriod(event, inputTransaction)) {
            mSpaceState = SpaceState.DOUBLE;
            inputTransaction.setRequiresUpdateSuggestions();
            StatsUtils.onDoubleSpacePeriod();
        } else if (swapWeakSpace && trySwapSwapperAndSpace(event, inputTransaction)) {
            mSpaceState = SpaceState.SWAP_PUNCTUATION;
            mSuggestionStripViewAccessor.setNeutralSuggestionStrip();
        } else if (Constants.CODE_SPACE == codePoint) {
            if (!mSuggestedWords.isPunctuationSuggestions()) {
                mSpaceState = SpaceState.WEAK;
            }

            startDoubleSpacePeriodCountdown(inputTransaction);
            if (wasComposingWord || mSuggestedWords.isEmpty()) {
                inputTransaction.setRequiresUpdateSuggestions();
            }

            if (!shouldAvoidSendingCode) {
                sendKeyCodePoint(settingsValues, codePoint);
            }
        } else {
            if ((SpaceState.PHANTOM == inputTransaction.mSpaceState
                    && settingsValues.isUsuallyFollowedBySpace(codePoint))
                    || (Constants.CODE_DOUBLE_QUOTE == codePoint
                            && isInsideDoubleQuoteOrAfterDigit)) {
                // If we are in phantom space state, and the user presses a separator, we want to
                // stay in phantom space state so that the next keypress has a chance to add the
                // space. For example, if I type "Good dat", pick "day" from the suggestion strip
                // then insert a comma and go on to typing the next word, I want the space to be
                // inserted automatically before the next word, the same way it is when I don't
                // input the comma. A double quote behaves like it's usually followed by space if
                // we're inside a double quote.
                // The case is a little different if the separator is a space stripper. Such a
                // separator does not normally need a space on the right (that's the difference
                // between swappers and strippers), so we should not stay in phantom space state if
                // the separator is a stripper. Hence the additional test above.
                mSpaceState = SpaceState.PHANTOM;
            }

            sendKeyCodePoint(settingsValues, codePoint);

            // Set punctuation right away. onUpdateSelection will fire but tests whether it is
            // already displayed or not, so it's okay.
            mSuggestionStripViewAccessor.setNeutralSuggestionStrip();
        }

        inputTransaction.requireShiftUpdate(InputTransaction.SHIFT_UPDATE_NOW);
    }

    /**
     * Handle a press on the backspace key.
     * @param event The event to handle.
     * @param inputTransaction The transaction in progress.
     */
    private void handleBackspaceEvent(final Event event, final InputTransaction inputTransaction,
            // TODO: remove this argument, put it into settingsValues
            final int currentKeyboardScriptId) {
        mSpaceState = SpaceState.NONE;
        mDeleteCount++;

        // In many cases after backspace, we need to update the shift state. Normally we need
        // to do this right away to avoid the shift state being out of date in case the user types
        // backspace then some other character very fast. However, in the case of backspace key
        // repeat, this can lead to flashiness when the cursor flies over positions where the
        // shift state should be updated, so if this is a key repeat, we update after a small delay.
        // Then again, even in the case of a key repeat, if the cursor is at start of text, it
        // can't go any further back, so we can update right away even if it's a key repeat.
        final int shiftUpdateKind =
                event.isKeyRepeat() && mConnection.getExpectedSelectionStart() > 0
                ? InputTransaction.SHIFT_UPDATE_LATER : InputTransaction.SHIFT_UPDATE_NOW;
        inputTransaction.requireShiftUpdate(shiftUpdateKind);

        if (mWordComposer.isCursorFrontOrMiddleOfComposingWord()) {
            // If we are in the middle of a recorrection, we need to commit the recorrection
            // first so that we can remove the character at the current cursor position.
            resetEntireInputState(mConnection.getExpectedSelectionStart(),
                    mConnection.getExpectedSelectionEnd(), true /* clearSuggestionStrip */);
            // When we exit this if-clause, mWordComposer.isComposingWord() will return false.
        }
        if (mWordComposer.isComposingWord()) {
            if (mWordComposer.isBatchMode()) {
                final String rejectedSuggestion = mWordComposer.getTypedWord();
                mWordComposer.reset();
                mWordComposer.setRejectedBatchModeSuggestion(rejectedSuggestion);
                if (!TextUtils.isEmpty(rejectedSuggestion)) {
                    unlearnWord(rejectedSuggestion, inputTransaction.mSettingsValues,
                            Constants.EVENT_REJECTION);
                }
                StatsUtils.onBackspaceWordDelete(rejectedSuggestion.length());
            } else {
                mWordComposer.applyProcessedEvent(event);
                StatsUtils.onBackspacePressed(1);
            }
            if (mWordComposer.isComposingWord()) {
                setComposingTextInternal(getTextWithUnderline(mWordComposer.getTypedWord()), 1);
            } else {