/*
 * Copyright (C) 2008-2009 Google Inc.
 * Copyright (C) 2009 Spiros Papadimitriou <spapadim@cs.cmu.edu>
 * Copyright (C) 2011 AnySoftKeyboard.
 *
 * 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.anysoftkeyboard.dictionaries;

import java.io.FileDescriptor;
import java.util.Arrays;

import com.anysoftkeyboard.WordComposer;
import com.menny.android.anysoftkeyboard.AnyApplication;

import android.content.res.AssetFileDescriptor;
import android.os.AsyncTask;
import android.util.Log;

/**
 * Implements a static, compacted, binary dictionary of standard words.
 */
class BinaryDictionary extends Dictionary {
    private static final String TAG = "ASK_BinaryDictionary";

    public static final int MAX_WORD_LENGTH = 20;
    private static final int MAX_ALTERNATIVES = 16;
    private static final int MAX_WORDS = 16;
    private final AssetFileDescriptor mAfd;

    private static final int TYPED_LETTER_MULTIPLIER = 2;
    private static final boolean ENABLE_MISSED_CHARACTERS = true;

    private int mNativeDict;
    private int[] mInputCodes = new int[MAX_WORD_LENGTH * MAX_ALTERNATIVES];
    private char[] mOutputChars = new char[MAX_WORD_LENGTH * MAX_WORDS];
    private int[] mFrequencies = new int[MAX_WORDS];


    static {
        try {
            System.loadLibrary("anysoftkey_jni");
        } 
        catch (UnsatisfiedLinkError ule) {
        	Log.e(TAG, "******** Could not load native library nativeim ********");
            Log.e(TAG, "******** Could not load native library nativeim ********", ule);
            Log.e(TAG, "******** Could not load native library nativeim ********");
        }
        catch (Throwable t) {
        	Log.e(TAG, "******** Failed to load native dictionary library ********");
            Log.e(TAG, "******** Failed to load native dictionary library *******", t);
            Log.e(TAG, "******** Failed to load native dictionary library ********");
        }
    }

    /**
     * Create a dictionary from a raw resource file
     * @param context application context for reading resources
     * @param resId the resource containing the raw binary dictionary
     */
    public BinaryDictionary(String dictionaryName, AssetFileDescriptor afd) {
    	super(dictionaryName);
    	mAfd = afd;
    }

    @Override
    public void loadDictionary()
    {
    	if (mAfd != null) {
    		new LoadDictionaryTask().execute();
            
        }
    }

    private class LoadDictionaryTask extends AsyncTask<Void, Void, Void> {
        @Override
        protected Void doInBackground(Void... v) {
        	loadDictionary(mAfd);
			return null;
        }
    }
    
    private native int openNative(FileDescriptor fd, long offset, long length,
            int typedLetterMultiplier, int fullWordMultiplier);
    private native void closeNative(int dict);
    private native boolean isValidWordNative(int nativeData, char[] word, int wordLength);
    private native int getSuggestionsNative(int dict, int[] inputCodes, int codesSize,
            char[] outputChars, int[] frequencies,
            int maxWordLength, int maxWords, int maxAlternatives, int skipPos);

    private final void loadDictionary(AssetFileDescriptor afd) {
        long startTime = System.currentTimeMillis();
        mNativeDict = openNative(afd.getFileDescriptor(),
                afd.getStartOffset(), afd.getLength(),
                TYPED_LETTER_MULTIPLIER, FULL_WORD_FREQ_MULTIPLIER);
        Log.i(TAG, "Loaded dictionary in " + (System.currentTimeMillis() - startTime) + "msec");
    }

    @Override
    public void getWords(final WordComposer codes, final WordCallback callback) {
        final int codesSize = codes.size();
        // Wont deal with really long words.
        if (codesSize > MAX_WORD_LENGTH - 1) return;

        Arrays.fill(mInputCodes, -1);
        for (int i = 0; i < codesSize; i++) {
            int[] alternatives = codes.getCodesAt(i);
            System.arraycopy(alternatives, 0, mInputCodes, i * MAX_ALTERNATIVES,
                    Math.min(alternatives.length, MAX_ALTERNATIVES));
        }
        Arrays.fill(mOutputChars, (char) 0);
        Arrays.fill(mFrequencies, 0);

        int count = getSuggestionsNative(mNativeDict, mInputCodes, codesSize,
                mOutputChars, mFrequencies,
                MAX_WORD_LENGTH, MAX_WORDS, MAX_ALTERNATIVES, -1);

        // If there aren't sufficient suggestions, search for words by allowing wild cards at
        // the different character positions. This feature is not ready for prime-time as we need
        // to figure out the best ranking for such words compared to proximity corrections and
        // completions.
        if (ENABLE_MISSED_CHARACTERS && count < 5) {
            for (int skip = 0; skip < codesSize; skip++) {
                int tempCount = getSuggestionsNative(mNativeDict, mInputCodes, codesSize,
                        mOutputChars, mFrequencies,
                        MAX_WORD_LENGTH, MAX_WORDS, MAX_ALTERNATIVES, skip);
                count = Math.max(count, tempCount);
                if (tempCount > 0) break;
            }
        }

        for (int j = 0; j < count; j++) {
            if (mFrequencies[j] < 1) break;
            final int start = j * MAX_WORD_LENGTH;
            
            int position = start;
            while ((mOutputChars.length > position) && (mOutputChars[position] != 0)) {
                position++;
            }
            final int len = (position - start);
            if (len > 0) {
                callback.addWord(mOutputChars, start, len, mFrequencies[j]);
            }
        }
    }


    @Override
    public boolean isValidWord(CharSequence word) {
        if (word == null) return false;
        char[] chars = word.toString().toCharArray();
        return isValidWordNative(mNativeDict, chars, chars.length);
    }

    public synchronized void close() {
        if (mNativeDict != 0) {
        	if (AnyApplication.DEBUG)
        	{
        		Log.w(TAG, "Native Binary Dictionary has been closed!");
        		Thread.dumpStack();
        	}
            closeNative(mNativeDict);
            mNativeDict = 0;
        }
    }

    @Override
    protected void finalize() throws Throwable {
        close();
        super.finalize();
    }
}
