/*
 * 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.os.SystemClock;
import android.view.inputmethod.EditorInfo;

import com.android.inputmethod.event.EventInterpreter;
import com.android.inputmethod.keyboard.Keyboard;
import com.android.inputmethod.keyboard.KeyboardSwitcher;
import com.android.inputmethod.latin.Constants;
import com.android.inputmethod.latin.LastComposedWord;
import com.android.inputmethod.latin.LatinIME;
import com.android.inputmethod.latin.LatinImeLogger;
import com.android.inputmethod.latin.RichInputConnection;
import com.android.inputmethod.latin.SubtypeSwitcher;
import com.android.inputmethod.latin.Suggest;
import com.android.inputmethod.latin.SuggestedWords;
import com.android.inputmethod.latin.WordComposer;
import com.android.inputmethod.latin.define.ProductionFlag;
import com.android.inputmethod.latin.utils.CollectionUtils;
import com.android.inputmethod.latin.utils.InputTypeUtils;
import com.android.inputmethod.latin.utils.RecapitalizeStatus;
import com.android.inputmethod.research.ResearchLogger;

import java.util.TreeSet;

/**
 * This class manages the input logic.
 */
public final class InputLogic {
    // TODO : Remove this member when we can.
    private final LatinIME mLatinIME;

    // 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.
    public int mSpaceState;
    // Never null
    public SuggestedWords mSuggestedWords = SuggestedWords.EMPTY;
    public Suggest mSuggest;
    // The event interpreter should never be null.
    public EventInterpreter mEventInterpreter;

    public LastComposedWord mLastComposedWord = LastComposedWord.NOT_A_COMPOSED_WORD;
    public final WordComposer mWordComposer;
    public final RichInputConnection mConnection;
    public final RecapitalizeStatus mRecapitalizeStatus = new RecapitalizeStatus();

    // Keep track of the last selection range to decide if we need to show word alternatives
    public static final int NOT_A_CURSOR_POSITION = -1;
    public int mLastSelectionStart = NOT_A_CURSOR_POSITION;
    public int mLastSelectionEnd = NOT_A_CURSOR_POSITION;

    public int mDeleteCount;
    public long mLastKeyTime;
    public final TreeSet<Long> mCurrentlyPressedHardwareKeys = CollectionUtils.newTreeSet();

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

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

    public InputLogic(final LatinIME latinIME) {
        mLatinIME = latinIME;
        mWordComposer = new WordComposer();
        mEventInterpreter = new EventInterpreter(latinIME);
        mConnection = new RichInputConnection(latinIME);
    }

    public void startInput(final boolean restarting) {
        
    }

    public void onCodeInput(final int primaryCode, final int x, final int y,
            // TODO: remove these three arguments
            final LatinIME.UIHandler handler, final KeyboardSwitcher keyboardSwitcher,
            final SubtypeSwitcher subtypeSwitcher) {
        if (ProductionFlag.USES_DEVELOPMENT_ONLY_DIAGNOSTICS) {
            ResearchLogger.latinIME_onCodeInput(primaryCode, x, y);
        }
        final long when = SystemClock.uptimeMillis();
        if (primaryCode != Constants.CODE_DELETE
                || when > mLastKeyTime + Constants.LONG_PRESS_MILLISECONDS) {
            mDeleteCount = 0;
        }
        mLastKeyTime = when;
        mConnection.beginBatchEdit();
        final KeyboardSwitcher switcher = keyboardSwitcher;
        // The space state depends only on the last character pressed and its own previous
        // state. Here, we revert the space state to neutral if the key is actually modifying
        // the input contents (any non-shift key), which is what we should do for
        // all inputs that do not result in a special state. Each character handling is then
        // free to override the state as they see fit.
        final int spaceState = mSpaceState;
        if (!mWordComposer.isComposingWord()) {
            mIsAutoCorrectionIndicatorOn = false;
        }

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

        boolean didAutoCorrect = false;
        switch (primaryCode) {
        case Constants.CODE_DELETE:
            mSpaceState = SpaceState.NONE;
            handleBackspace(spaceState);
            LatinImeLogger.logOnDelete(x, y);
            break;
        case Constants.CODE_SHIFT:
            // Note: Calling back to the keyboard on Shift key is handled in
            // {@link #onPressKey(int,int,boolean)} and {@link #onReleaseKey(int,boolean)}.
            final Keyboard currentKeyboard = switcher.getKeyboard();
            if (null != currentKeyboard && currentKeyboard.mId.isAlphabetKeyboard()) {
                // TODO: Instead of checking for alphabetic keyboard here, separate keycodes for
                // alphabetic shift and shift while in symbol layout.
                handleRecapitalize();
            }
            break;
        case Constants.CODE_CAPSLOCK:
            // Note: Changing keyboard to shift lock state is handled in
            // {@link KeyboardSwitcher#onCodeInput(int)}.
            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:
            subtypeSwitcher.switchToShortcutIME(mLatinIME);
            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#onCodeInput(int,int)}.
            break;
        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.
                didAutoCorrect = handleNonSpecialCharacter(Constants.CODE_ENTER, x, y, spaceState);
            }
            break;
        case Constants.CODE_SHIFT_ENTER:
            didAutoCorrect = handleNonSpecialCharacter(Constants.CODE_ENTER, x, y, spaceState);
            break;
        default:
            didAutoCorrect = handleNonSpecialCharacter(primaryCode, x, y, spaceState);
            break;
        }
        switcher.onCodeInput(primaryCode);
        // Reset after any single keystroke, except shift, capslock, and symbol-shift
        if (!didAutoCorrect && primaryCode != Constants.CODE_SHIFT
                && primaryCode != Constants.CODE_CAPSLOCK
                && primaryCode != Constants.CODE_SWITCH_ALPHA_SYMBOL)
            mLastComposedWord.deactivate();
        if (Constants.CODE_DELETE != primaryCode) {
            mEnteredText = null;
        }
        mConnection.endBatchEdit();
    }

    /**
     * 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 code the code point associated with the key.
     * @param x the x-coordinate of the key press, or Contants.NOT_A_COORDINATE if not applicable.
     * @param y the y-coordinate of the key press, or Contants.NOT_A_COORDINATE if not applicable.
     * @param spaceState the space state at start of the batch input.
     * @return whether this caused an auto-correction to happen.
     */
    private boolean handleNonSpecialCharacter(final int code, final int x, final int y,
            final int spaceState) {
        return mLatinIME.handleNonSpecialCharacter(code, x, y, spaceState);
    }

    /**
     * Handle a press on the backspace key.
     * @param spaceState The space state at start of this batch edit.
     */
    private void handleBackspace(final int spaceState) {
        mLatinIME.handleBackspace(spaceState);
    }

    /**
     * Handle a press on the language switch key (the "globe key")
     */
    private void handleLanguageSwitchKey() {
        mLatinIME.handleLanguageSwitchKey();
    }

    /**
     * Processes a recapitalize event.
     */
    private void handleRecapitalize() {
        mLatinIME.handleRecapitalize();
    }

    /**
     * @return the editor info for the current editor
     */
    private EditorInfo getCurrentInputEditorInfo() {
        return mLatinIME.getCurrentInputEditorInfo();
    }

    /**
     * @param actionId the action to perform
     */
    private void performEditorAction(final int actionId) {
        mConnection.performEditorAction(actionId);
    }

    /**
     * Handle a press on the settings key.
     */
    private void onSettingsKeyPressed() {
        mLatinIME.onSettingsKeyPressed();
    }
}