/*
 * Copyright (C) 2012 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.research;

import android.os.SystemClock;
import android.text.TextUtils;
import android.util.JsonWriter;
import android.util.Log;

import com.android.inputmethod.latin.SuggestedWords;
import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
import com.android.inputmethod.latin.define.ProductionFlag;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.regex.Pattern;

/**
 * A group of log statements related to each other.
 *
 * A LogUnit is collection of LogStatements, each of which is generated by at a particular point
 * in the code.  (There is no LogStatement class; the data is stored across the instance variables
 * here.)  A single LogUnit's statements can correspond to all the calls made while in the same
 * composing region, or all the calls between committing the last composing region, and the first
 * character of the next composing region.
 *
 * Individual statements in a log may be marked as potentially private.  If so, then they are only
 * published to a ResearchLog if the ResearchLogger determines that publishing the entire LogUnit
 * will not violate the user's privacy.  Checks for this may include whether other LogUnits have
 * been published recently, or whether the LogUnit contains numbers, etc.
 */
public class LogUnit {
    private static final String TAG = LogUnit.class.getSimpleName();
    private static final boolean DEBUG = false
            && ProductionFlag.USES_DEVELOPMENT_ONLY_DIAGNOSTICS_DEBUG;

    private static final Pattern WHITESPACE_PATTERN = Pattern.compile("\\s+");
    private static final String[] EMPTY_STRING_ARRAY = new String[0];

    private final ArrayList<LogStatement> mLogStatementList;
    private final ArrayList<Object[]> mValuesList;
    // Assume that mTimeList is sorted in increasing order.  Do not insert null values into
    // mTimeList.
    private final ArrayList<Long> mTimeList;
    // Words that this LogUnit generates.  Should be null if the data in the LogUnit does not
    // generate a genuine word (i.e. separators alone do not count as a word).  Should never be
    // empty.  Note that if the user types spaces explicitly, then normally mWords should contain
    // only a single word; it will only contain space-separate multiple words if the user does not
    // enter a space, and the system enters one automatically.
    private String mWords;
    private String[] mWordArray = EMPTY_STRING_ARRAY;
    private boolean mMayContainDigit;
    private boolean mIsPartOfMegaword;
    private boolean mContainsCorrection;

    // mCorrectionType indicates whether the word was corrected at all, and if so, the nature of the
    // correction.
    private int mCorrectionType;
    // LogUnits start in this state.  If a word is entered without being corrected, it will have
    // this CorrectiontType.
    public static final int CORRECTIONTYPE_NO_CORRECTION = 0;
    // The LogUnit was corrected manually by the user in an unspecified way.
    public static final int CORRECTIONTYPE_CORRECTION = 1;
    // The LogUnit was corrected manually by the user to a word not in the list of suggestions of
    // the first word typed here.  (Note: this is a heuristic value, it may be incorrect, for
    // example, if the user repositions the cursor).
    public static final int CORRECTIONTYPE_DIFFERENT_WORD = 2;
    // The LogUnit was corrected manually by the user to a word that was in the list of suggestions
    // of the first word typed here.  (Again, a heuristic).  It is probably a typo correction.
    public static final int CORRECTIONTYPE_TYPO = 3;
    // TODO: Rather than just tracking the current state, keep a historical record of the LogUnit's
    // state and statistics.  This should include how many times it has been corrected, whether
    // other LogUnit edits were done between edits to this LogUnit, etc.  Also track when a LogUnit
    // previously contained a word, but was corrected to empty (because it was deleted, and there is
    // no known replacement).

    private SuggestedWords mSuggestedWords;

    public LogUnit() {
        mLogStatementList = new ArrayList<LogStatement>();
        mValuesList = new ArrayList<Object[]>();
        mTimeList = new ArrayList<Long>();
        mIsPartOfMegaword = false;
        mCorrectionType = CORRECTIONTYPE_NO_CORRECTION;
        mSuggestedWords = null;
    }

    private LogUnit(final ArrayList<LogStatement> logStatementList,
            final ArrayList<Object[]> valuesList,
            final ArrayList<Long> timeList,
            final boolean isPartOfMegaword) {
        mLogStatementList = logStatementList;
        mValuesList = valuesList;
        mTimeList = timeList;
        mIsPartOfMegaword = isPartOfMegaword;
        mCorrectionType = CORRECTIONTYPE_NO_CORRECTION;
        mSuggestedWords = null;
    }

    private static final Object[] NULL_VALUES = new Object[0];
    /**
     * Adds a new log statement.  The time parameter in successive calls to this method must be
     * monotonically increasing, or splitByTime() will not work.
     */
    public void addLogStatement(final LogStatement logStatement, final long time,
            Object... values) {
        if (values == null) {
            values = NULL_VALUES;
        }
        mLogStatementList.add(logStatement);
        mValuesList.add(values);
        mTimeList.add(time);
    }

    /**
     * Publish the contents of this LogUnit to {@code researchLog}.
     *
     * For each publishable {@code LogStatement}, invoke {@link LogStatement#outputToLocked}.
     *
     * @param researchLog where to publish the contents of this {@code LogUnit}
     * @param canIncludePrivateData whether the private data in this {@code LogUnit} should be
     * included
     *
     * @throws IOException if publication to the log file is not possible
     */
    public synchronized void publishTo(final ResearchLog researchLog,
            final boolean canIncludePrivateData) throws IOException {
        // Write out any logStatement that passes the privacy filter.
        final int size = mLogStatementList.size();
        if (size != 0) {
            // Note that jsonWriter is only set to a non-null value if the logUnit start text is
            // output and at least one logStatement is output.
            JsonWriter jsonWriter = null;
            for (int i = 0; i < size; i++) {
                final LogStatement logStatement = mLogStatementList.get(i);
                if (!canIncludePrivateData && logStatement.isPotentiallyPrivate()) {
                    continue;
                }
                if (mIsPartOfMegaword && logStatement.isPotentiallyRevealing()) {
                    continue;
                }
                // Only retrieve the jsonWriter if we need to.  If we don't get this far, then
                // researchLog.getInitializedJsonWriterLocked() will not ever be called, and the
                // file will not have been opened for writing.
                if (jsonWriter == null) {
                    jsonWriter = researchLog.getInitializedJsonWriterLocked();
                    outputLogUnitStart(jsonWriter, canIncludePrivateData);
                }
                logStatement.outputToLocked(jsonWriter, mTimeList.get(i), mValuesList.get(i));
            }
            if (jsonWriter != null) {
                // We must have called logUnitStart earlier, so emit a logUnitStop.
                outputLogUnitStop(jsonWriter);
            }
        }
    }

    private static final String WORD_KEY = "_wo";
    private static final String CORRECTION_TYPE_KEY = "_corType";
    private static final String LOG_UNIT_BEGIN_KEY = "logUnitStart";
    private static final String LOG_UNIT_END_KEY = "logUnitEnd";

    final LogStatement LOGSTATEMENT_LOG_UNIT_BEGIN_WITH_PRIVATE_DATA =
            new LogStatement(LOG_UNIT_BEGIN_KEY, false /* isPotentiallyPrivate */,
                    false /* isPotentiallyRevealing */, WORD_KEY, CORRECTION_TYPE_KEY);
    final LogStatement LOGSTATEMENT_LOG_UNIT_BEGIN_WITHOUT_PRIVATE_DATA =
            new LogStatement(LOG_UNIT_BEGIN_KEY, false /* isPotentiallyPrivate */,
                    false /* isPotentiallyRevealing */);
    private void outputLogUnitStart(final JsonWriter jsonWriter,
            final boolean canIncludePrivateData) {
        final LogStatement logStatement;
        if (canIncludePrivateData) {
            LOGSTATEMENT_LOG_UNIT_BEGIN_WITH_PRIVATE_DATA.outputToLocked(jsonWriter,
                    SystemClock.uptimeMillis(), getWordsAsString(), getCorrectionType());
        } else {
            LOGSTATEMENT_LOG_UNIT_BEGIN_WITHOUT_PRIVATE_DATA.outputToLocked(jsonWriter,
                    SystemClock.uptimeMillis());
        }
    }

    final LogStatement LOGSTATEMENT_LOG_UNIT_END =
            new LogStatement(LOG_UNIT_END_KEY, false /* isPotentiallyPrivate */,
                    false /* isPotentiallyRevealing */);
    private void outputLogUnitStop(final JsonWriter jsonWriter) {
        LOGSTATEMENT_LOG_UNIT_END.outputToLocked(jsonWriter, SystemClock.uptimeMillis());
    }

    /**
     * Mark the current logUnit as containing data to generate {@code newWords}.
     *
     * If {@code setWord()} was previously called for this LogUnit, then the method will try to
     * determine what kind of correction it is, and update its internal state of the correctionType
     * accordingly.
     *
     * @param newWords The words this LogUnit generates.  Caller should not pass null or the empty
     * string.
     */
    public void setWords(final String newWords) {
        if (hasOneOrMoreWords()) {
            // The word was already set once, and it is now being changed.  See if the new word
            // is close to the old word.  If so, then the change is probably a typo correction.
            // If not, the user may have decided to enter a different word, so flag it.
            if (mSuggestedWords != null) {
                if (isInSuggestedWords(newWords, mSuggestedWords)) {
                    mCorrectionType = CORRECTIONTYPE_TYPO;
                } else {
                    mCorrectionType = CORRECTIONTYPE_DIFFERENT_WORD;
                }
            } else {
                // No suggested words, so it's not clear whether it's a typo or different word.
                // Mark it as a generic correction.
                mCorrectionType = CORRECTIONTYPE_CORRECTION;
            }
        } else {
            mCorrectionType = CORRECTIONTYPE_NO_CORRECTION;
        }
        mWords = newWords;

        // Update mWordArray
        mWordArray = (TextUtils.isEmpty(mWords)) ? EMPTY_STRING_ARRAY
                : WHITESPACE_PATTERN.split(mWords);
        if (mWordArray.length > 0 && TextUtils.isEmpty(mWordArray[0])) {
            // Empty string at beginning of array.  Must have been whitespace at the start of the
            // word.  Remove the empty string.
            mWordArray = Arrays.copyOfRange(mWordArray, 1, mWordArray.length);
        }
    }

    public String getWordsAsString() {
        return mWords;
    }

    /**
     * Retuns the words generated by the data in this LogUnit.
     *
     * The first word may be an empty string, if the data in the LogUnit started by generating
     * whitespace.
     *
     * @return the array of words. an empty list of there are no words associated with this LogUnit.
     */
    public String[] getWordsAsStringArray() {
        return mWordArray;
    }

    public boolean hasOneOrMoreWords() {
        return mWordArray.length >= 1;
    }

    public int getNumWords() {
        return mWordArray.length;
    }

    // TODO: Refactor to eliminate getter/setters
    public void setMayContainDigit() {
        mMayContainDigit = true;
    }

    // TODO: Refactor to eliminate getter/setters
    public boolean mayContainDigit() {
        return mMayContainDigit;
    }

    // TODO: Refactor to eliminate getter/setters
    public void setContainsCorrection() {
        mContainsCorrection = true;
    }

    // TODO: Refactor to eliminate getter/setters
    public boolean containsCorrection() {
        return mContainsCorrection;
    }

    // TODO: Refactor to eliminate getter/setters
    public void setCorrectionType(final int correctionType) {
        mCorrectionType = correctionType;
    }

    // TODO: Refactor to eliminate getter/setters
    public int getCorrectionType() {
        return mCorrectionType;
    }

    public boolean isEmpty() {
        return mLogStatementList.isEmpty();
    }

    /**
     * Split this logUnit, with all events before maxTime staying in the current logUnit, and all
     * events after maxTime going into a new LogUnit that is returned.
     */
    public LogUnit splitByTime(final long maxTime) {
        // Assume that mTimeList is in sorted order.
        final int length = mTimeList.size();
        // TODO: find time by binary search, e.g. using Collections#binarySearch()
        for (int index = 0; index < length; index++) {
            if (mTimeList.get(index) > maxTime) {
                final List<LogStatement> laterLogStatements =
                        mLogStatementList.subList(index, length);
                final List<Object[]> laterValues = mValuesList.subList(index, length);
                final List<Long> laterTimes = mTimeList.subList(index, length);

                // Create the LogUnit containing the later logStatements and associated data.
                final LogUnit newLogUnit = new LogUnit(
                        new ArrayList<LogStatement>(laterLogStatements),
                        new ArrayList<Object[]>(laterValues),
                        new ArrayList<Long>(laterTimes),
                        true /* isPartOfMegaword */);
                newLogUnit.mWords = null;
                newLogUnit.mMayContainDigit = mMayContainDigit;
                newLogUnit.mContainsCorrection = mContainsCorrection;

                // Purge the logStatements and associated data from this LogUnit.
                laterLogStatements.clear();
                laterValues.clear();
                laterTimes.clear();
                mIsPartOfMegaword = true;

                return newLogUnit;
            }
        }
        return new LogUnit();
    }

    public void append(final LogUnit logUnit) {
        mLogStatementList.addAll(logUnit.mLogStatementList);
        mValuesList.addAll(logUnit.mValuesList);
        mTimeList.addAll(logUnit.mTimeList);
        mWords = null;
        if (logUnit.mWords != null) {
            setWords(logUnit.mWords);
        }
        mMayContainDigit = mMayContainDigit || logUnit.mMayContainDigit;
        mContainsCorrection = mContainsCorrection || logUnit.mContainsCorrection;
        mIsPartOfMegaword = false;
    }

    public SuggestedWords getSuggestions() {
        return mSuggestedWords;
    }

    /**
     * Initialize the suggestions.
     *
     * Once set to a non-null value, the suggestions may not be changed again.  This is to keep
     * track of the list of words that are close to the user's initial effort to type the word.
     * Only words that are close to the initial effort are considered typo corrections.
     */
    public void initializeSuggestions(final SuggestedWords suggestedWords) {
        if (mSuggestedWords == null) {
            mSuggestedWords = suggestedWords;
        }
    }

    private static boolean isInSuggestedWords(final String queryWord,
            final SuggestedWords suggestedWords) {
        if (TextUtils.isEmpty(queryWord)) {
            return false;
        }
        final int size = suggestedWords.size();
        for (int i = 0; i < size; i++) {
            final SuggestedWordInfo wordInfo = suggestedWords.getInfo(i);
            if (queryWord.equals(wordInfo.mWord)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Remove data associated with selecting the Research button.
     *
     * A LogUnit will capture all user interactions with the IME, including the "meta-interactions"
     * of using the Research button to control the logging (e.g. by starting and stopping recording
     * of a test case).  Because meta-interactions should not be part of the normal log, calling
     * this method will set a field in the LogStatements of the motion events to indiciate that
     * they should be disregarded.
     *
     * This implementation assumes that the data recorded by the meta-interaction takes the
     * form of all events following the first MotionEvent.ACTION_DOWN before the first long-press
     * before the last onCodeEvent containing a code matching {@code LogStatement.VALUE_RESEARCH}.
     *
     * @returns true if data was removed
     */
    public boolean removeResearchButtonInvocation() {
        // This method is designed to be idempotent.

        // First, find last invocation of "research" key
        final int indexOfLastResearchKey = findLastIndexContainingKeyValue(
                LogStatement.TYPE_POINTER_TRACKER_CALL_LISTENER_ON_CODE_INPUT,
                LogStatement.KEY_CODE, LogStatement.VALUE_RESEARCH);
        if (indexOfLastResearchKey < 0) {
            // Could not find invocation of "research" key.  Leave log as is.
            if (DEBUG) {
                Log.d(TAG, "Could not find research key");
            }
            return false;
        }

        // Look for the long press that started the invocation of the research key code input.
        final int indexOfLastLongPressBeforeResearchKey =
                findLastIndexBefore(LogStatement.TYPE_MAIN_KEYBOARD_VIEW_ON_LONG_PRESS,
                        indexOfLastResearchKey);

        // Look for DOWN event preceding the long press
        final int indexOfLastDownEventBeforeLongPress =
                findLastIndexContainingKeyValueBefore(LogStatement.TYPE_MOTION_EVENT,
                        LogStatement.ACTION, LogStatement.VALUE_DOWN,
                        indexOfLastLongPressBeforeResearchKey);

        // Flag all LatinKeyboardViewProcessMotionEvents from the DOWN event to the research key as
        // logging-related
        final int startingIndex = indexOfLastDownEventBeforeLongPress == -1 ? 0
                : indexOfLastDownEventBeforeLongPress;
        for (int index = startingIndex; index < indexOfLastResearchKey; index++) {
            final LogStatement logStatement = mLogStatementList.get(index);
            final String type = logStatement.getType();
            final Object[] values = mValuesList.get(index);
            if (type.equals(LogStatement.TYPE_MOTION_EVENT)) {
                logStatement.setValue(LogStatement.KEY_IS_LOGGING_RELATED, values, true);
            }
        }
        return true;
    }

    /**
     * Find the index of the last LogStatement before {@code startingIndex} of type {@code type}.
     *
     * @param queryType a String that must be {@code String.equals()} to the LogStatement type
     * @param startingIndex the index to start the backward search from.  Must be less than the
     * length of mLogStatementList, or an IndexOutOfBoundsException is thrown.  Can be negative,
     * in which case -1 is returned.
     *
     * @return The index of the last LogStatement, -1 if none exists.
     */
    private int findLastIndexBefore(final String queryType, final int startingIndex) {
        return findLastIndexContainingKeyValueBefore(queryType, null, null, startingIndex);
    }

    /**
     * Find the index of the last LogStatement before {@code startingIndex} of type {@code type}
     * containing the given key-value pair.
     *
     * @param queryType a String that must be {@code String.equals()} to the LogStatement type
     * @param queryKey a String that must be {@code String.equals()} to a key in the LogStatement
     * @param queryValue an Object that must be {@code String.equals()} to the key's corresponding
     * value
     *
     * @return The index of the last LogStatement, -1 if none exists.
     */
    private int findLastIndexContainingKeyValue(final String queryType, final String queryKey,
            final Object queryValue) {
        return findLastIndexContainingKeyValueBefore(queryType, queryKey, queryValue,
                mLogStatementList.size() - 1);
    }

    /**
     * Find the index of the last LogStatement before {@code startingIndex} of type {@code type}
     * containing the given key-value pair.
     *
     * @param queryType a String that must be {@code String.equals()} to the LogStatement type
     * @param queryKey a String that must be {@code String.equals()} to a key in the LogStatement
     * @param queryValue an Object that must be {@code String.equals()} to the key's corresponding
     * value
     * @param startingIndex the index to start the backward search from.  Must be less than the
     * length of mLogStatementList, or an IndexOutOfBoundsException is thrown.  Can be negative,
     * in which case -1 is returned.
     *
     * @return The index of the last LogStatement, -1 if none exists.
     */
    private int findLastIndexContainingKeyValueBefore(final String queryType, final String queryKey,
            final Object queryValue, final int startingIndex) {
        if (startingIndex < 0) {
            return -1;
        }
        for (int index = startingIndex; index >= 0; index--) {
            final LogStatement logStatement = mLogStatementList.get(index);
            final String type = logStatement.getType();
            if (type.equals(queryType) && (queryKey == null
                    || logStatement.containsKeyValuePair(queryKey, queryValue,
                            mValuesList.get(index)))) {
                return index;
            }
        }
        return -1;
    }
}