/*
 * Copyright (C) 2008 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.keyboard;

import com.android.inputmethod.latin.R;
import com.android.inputmethod.latin.SubtypeSwitcher;

import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Align;
import android.graphics.PorterDuff;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.Log;

import java.util.List;
import java.util.Locale;

// TODO: We should remove this class
public class LatinKeyboard extends Keyboard {

    private static final boolean DEBUG_PREFERRED_LETTER = false;
    private static final String TAG = "LatinKeyboard";

    public static final int OPACITY_FULLY_OPAQUE = 255;
    private static final int SPACE_LED_LENGTH_PERCENT = 80;

    private final Drawable mSpaceAutoCorrectionIndicator;
    private final Drawable mButtonArrowLeftIcon;
    private final Drawable mButtonArrowRightIcon;
    private final int mSpacebarTextColor;
    private final int mSpacebarTextShadowColor;
    private float mSpacebarTextFadeFactor = 0.0f;
    private final int[] mSpaceKeyIndexArray;
    private int mSpaceDragStartX;
    private int mSpaceDragLastDiff;
    private final Context mContext;
    private boolean mCurrentlyInSpace;
    private SlidingLocaleDrawable mSlidingLocaleIcon;
    private int[] mPrefLetterFrequencies;
    private int mPrefLetter;
    private int mPrefLetterX;
    private int mPrefLetterY;
    private int mPrefDistance;

    private static final float SPACEBAR_DRAG_THRESHOLD = 0.8f;
    private static final float OVERLAP_PERCENTAGE_LOW_PROB = 0.70f;
    private static final float OVERLAP_PERCENTAGE_HIGH_PROB = 0.85f;
    // Minimum width of space key preview (proportional to keyboard width)
    private static final float SPACEBAR_POPUP_MIN_RATIO = 0.4f;
    // Height in space key the language name will be drawn. (proportional to space key height)
    public static final float SPACEBAR_LANGUAGE_BASELINE = 0.6f;
    // If the full language name needs to be smaller than this value to be drawn on space key,
    // its short language name will be used instead.
    private static final float MINIMUM_SCALE_OF_LANGUAGE_NAME = 0.8f;

    private static int sSpacebarVerticalCorrection;

    private static final String SMALL_TEXT_SIZE_OF_LANGUAGE_ON_SPACEBAR = "small";
    private static final String MEDIUM_TEXT_SIZE_OF_LANGUAGE_ON_SPACEBAR = "medium";

    public LatinKeyboard(Context context, KeyboardId id) {
        super(context, id.getXmlId(), id);
        final Resources res = context.getResources();
        mContext = context;
        mSpacebarTextColor = res.getColor(R.color.latinkeyboard_bar_language_text);
        if (id.mColorScheme == KeyboardView.COLOR_SCHEME_BLACK) {
            mSpacebarTextShadowColor = res.getColor(
                    R.color.latinkeyboard_bar_language_shadow_black);
        } else { // default color scheme is KeyboardView.COLOR_SCHEME_WHITE
            mSpacebarTextShadowColor = res.getColor(
                    R.color.latinkeyboard_bar_language_shadow_white);
        }
        mSpaceAutoCorrectionIndicator = res.getDrawable(R.drawable.sym_keyboard_space_led);
        mButtonArrowLeftIcon = res.getDrawable(R.drawable.sym_keyboard_language_arrows_left);
        mButtonArrowRightIcon = res.getDrawable(R.drawable.sym_keyboard_language_arrows_right);
        sSpacebarVerticalCorrection = res.getDimensionPixelOffset(
                R.dimen.spacebar_vertical_correction);
        // The index of space key is available only after Keyboard constructor has finished.
        mSpaceKeyIndexArray = new int[] { indexOf(CODE_SPACE) };
    }

    public void setSpacebarTextFadeFactor(float fadeFactor, LatinKeyboardView view) {
        mSpacebarTextFadeFactor = fadeFactor;
        updateSpacebarForLocale(false);
        if (view != null)
            view.invalidateKey(mSpaceKey);
    }

    private static int getSpacebarTextColor(int color, float fadeFactor) {
        final int newColor = Color.argb((int)(Color.alpha(color) * fadeFactor),
                Color.red(color), Color.green(color), Color.blue(color));
        return newColor;
    }

    /**
     * @return a key which should be invalidated.
     */
    public Key onAutoCorrectionStateChanged(boolean isAutoCorrection) {
        updateSpacebarForLocale(isAutoCorrection);
        return mSpaceKey;
    }

    private void updateSpacebarForLocale(boolean isAutoCorrection) {
        final Resources res = mContext.getResources();
        // If application locales are explicitly selected.
        if (SubtypeSwitcher.getInstance().needsToDisplayLanguage()) {
            mSpaceKey.setIcon(new BitmapDrawable(res,
                    drawSpacebar(OPACITY_FULLY_OPAQUE, isAutoCorrection)));
        } else {
            // sym_keyboard_space_led can be shared with Black and White symbol themes.
            if (isAutoCorrection) {
                mSpaceKey.setIcon(new BitmapDrawable(res,
                        drawSpacebar(OPACITY_FULLY_OPAQUE, isAutoCorrection)));
            } else {
                mSpaceKey.setIcon(mSpaceIcon);
            }
        }
    }

    // Compute width of text with specified text size using paint.
    private static int getTextWidth(Paint paint, String text, float textSize, Rect bounds) {
        paint.setTextSize(textSize);
        paint.getTextBounds(text, 0, text.length(), bounds);
        return bounds.width();
    }

    // Layout local language name and left and right arrow on spacebar.
    private static String layoutSpacebar(Paint paint, Locale locale, Drawable lArrow,
            Drawable rArrow, int width, int height, float origTextSize,
            boolean allowVariableTextSize) {
        final float arrowWidth = lArrow.getIntrinsicWidth();
        final float arrowHeight = lArrow.getIntrinsicHeight();
        final float maxTextWidth = width - (arrowWidth + arrowWidth);
        final Rect bounds = new Rect();

        // Estimate appropriate language name text size to fit in maxTextWidth.
        String language = SubtypeSwitcher.getFullDisplayName(locale, true);
        int textWidth = getTextWidth(paint, language, origTextSize, bounds);
        // Assuming text width and text size are proportional to each other.
        float textSize = origTextSize * Math.min(maxTextWidth / textWidth, 1.0f);

        final boolean useShortName;
        if (allowVariableTextSize) {
            textWidth = getTextWidth(paint, language, textSize, bounds);
            // If text size goes too small or text does not fit, use short name
            useShortName = textSize / origTextSize < MINIMUM_SCALE_OF_LANGUAGE_NAME
                    || textWidth > maxTextWidth;
        } else {
            useShortName = textWidth > maxTextWidth;
            textSize = origTextSize;
        }
        if (useShortName) {
            language = SubtypeSwitcher.getShortDisplayLanguage(locale);
            textWidth = getTextWidth(paint, language, origTextSize, bounds);
            textSize = origTextSize * Math.min(maxTextWidth / textWidth, 1.0f);
        }
        paint.setTextSize(textSize);

        // Place left and right arrow just before and after language text.
        final float baseline = height * SPACEBAR_LANGUAGE_BASELINE;
        final int top = (int)(baseline - arrowHeight);
        final float remains = (width - textWidth) / 2;
        lArrow.setBounds((int)(remains - arrowWidth), top, (int)remains, (int)baseline);
        rArrow.setBounds((int)(remains + textWidth), top, (int)(remains + textWidth + arrowWidth),
                (int)baseline);

        return language;
    }

    private Bitmap drawSpacebar(int opacity, boolean isAutoCorrection) {
        final int width = mSpaceKey.mWidth;
        final int height = mSpaceIcon != null ? mSpaceIcon.getIntrinsicHeight() : mSpaceKey.mHeight;
        final Bitmap buffer = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        final Canvas canvas = new Canvas(buffer);
        final Resources res = mContext.getResources();
        canvas.drawColor(res.getColor(R.color.latinkeyboard_transparent), PorterDuff.Mode.CLEAR);

        SubtypeSwitcher subtypeSwitcher = SubtypeSwitcher.getInstance();
        // If application locales are explicitly selected.
        if (subtypeSwitcher.needsToDisplayLanguage()) {
            final Paint paint = new Paint();
            paint.setAlpha(opacity);
            paint.setAntiAlias(true);
            paint.setTextAlign(Align.CENTER);

            final String textSizeOfLanguageOnSpacebar = res.getString(
                    R.string.config_text_size_of_language_on_spacebar,
                    SMALL_TEXT_SIZE_OF_LANGUAGE_ON_SPACEBAR);
            final int textStyle;
            final int defaultTextSize;
            if (MEDIUM_TEXT_SIZE_OF_LANGUAGE_ON_SPACEBAR.equals(textSizeOfLanguageOnSpacebar)) {
                textStyle = android.R.style.TextAppearance_Medium;
                defaultTextSize = 18;
            } else {
                textStyle = android.R.style.TextAppearance_Small;
                defaultTextSize = 14;
            }

            final boolean allowVariableTextSize = true;
            final String language = layoutSpacebar(paint, subtypeSwitcher.getInputLocale(),
                    mButtonArrowLeftIcon, mButtonArrowRightIcon, width, height,
                    getTextSizeFromTheme(textStyle, defaultTextSize),
                    allowVariableTextSize);

            // Draw language text with shadow
            // In case there is no space icon, we will place the language text at the center of
            // spacebar.
            final float descent = paint.descent();
            final float textHeight = -paint.ascent() + descent;
            final float baseline = (mSpaceIcon != null) ? height * SPACEBAR_LANGUAGE_BASELINE
                    : height / 2 + textHeight / 2;
            paint.setColor(getSpacebarTextColor(mSpacebarTextShadowColor, mSpacebarTextFadeFactor));
            canvas.drawText(language, width / 2, baseline - descent - 1, paint);
            paint.setColor(getSpacebarTextColor(mSpacebarTextColor, mSpacebarTextFadeFactor));
            canvas.drawText(language, width / 2, baseline - descent, paint);

            // Put arrows that are already layed out on either side of the text
            if (SubtypeSwitcher.getInstance().useSpacebarLanguageSwitcher()
                    && subtypeSwitcher.getEnabledKeyboardLocaleCount() > 1) {
                mButtonArrowLeftIcon.draw(canvas);
                mButtonArrowRightIcon.draw(canvas);
            }
        }

        // Draw the spacebar icon at the bottom
        if (isAutoCorrection) {
            final int iconWidth = width * SPACE_LED_LENGTH_PERCENT / 100;
            final int iconHeight = mSpaceAutoCorrectionIndicator.getIntrinsicHeight();
            int x = (width - iconWidth) / 2;
            int y = height - iconHeight;
            mSpaceAutoCorrectionIndicator.setBounds(x, y, x + iconWidth, y + iconHeight);
            mSpaceAutoCorrectionIndicator.draw(canvas);
        } else if (mSpaceIcon != null) {
            final int iconWidth = mSpaceIcon.getIntrinsicWidth();
            final int iconHeight = mSpaceIcon.getIntrinsicHeight();
            int x = (width - iconWidth) / 2;
            int y = height - iconHeight;
            mSpaceIcon.setBounds(x, y, x + iconWidth, y + iconHeight);
            mSpaceIcon.draw(canvas);
        }
        return buffer;
    }

    private void updateLocaleDrag(int diff) {
        if (mSlidingLocaleIcon == null) {
            final int width = Math.max(mSpaceKey.mWidth,
                    (int)(getMinWidth() * SPACEBAR_POPUP_MIN_RATIO));
            final int height = mSpacePreviewIcon.getIntrinsicHeight();
            mSlidingLocaleIcon =
                    new SlidingLocaleDrawable(mContext, mSpacePreviewIcon, width, height);
            mSlidingLocaleIcon.setBounds(0, 0, width, height);
            mSpaceKey.setPreviewIcon(mSlidingLocaleIcon);
        }
        mSlidingLocaleIcon.setDiff(diff);
        if (Math.abs(diff) == Integer.MAX_VALUE) {
            mSpaceKey.setPreviewIcon(mSpacePreviewIcon);
        } else {
            mSpaceKey.setPreviewIcon(mSlidingLocaleIcon);
        }
        mSpaceKey.getPreviewIcon().invalidateSelf();
    }

    public int getLanguageChangeDirection() {
        if (mSpaceKey == null || SubtypeSwitcher.getInstance().getEnabledKeyboardLocaleCount() <= 1
                || Math.abs(mSpaceDragLastDiff) < mSpaceKey.mWidth * SPACEBAR_DRAG_THRESHOLD) {
            return 0; // No change
        }
        return mSpaceDragLastDiff > 0 ? 1 : -1;
    }

    public void setPreferredLetters(int[] frequencies) {
        mPrefLetterFrequencies = frequencies;
        mPrefLetter = 0;
    }

    public void keyReleased() {
        mCurrentlyInSpace = false;
        mSpaceDragLastDiff = 0;
        mPrefLetter = 0;
        mPrefLetterX = 0;
        mPrefLetterY = 0;
        mPrefDistance = Integer.MAX_VALUE;
        if (mSpaceKey != null) {
            updateLocaleDrag(Integer.MAX_VALUE);
        }
    }

    /**
     * Does the magic of locking the touch gesture into the spacebar when
     * switching input languages.
     */
    @Override
    public boolean isInside(Key key, int pointX, int pointY) {
        int x = pointX;
        int y = pointY;
        final int code = key.mCode;
        if (code == CODE_SPACE) {
            y += LatinKeyboard.sSpacebarVerticalCorrection;
            if (SubtypeSwitcher.getInstance().useSpacebarLanguageSwitcher()
                    && SubtypeSwitcher.getInstance().getEnabledKeyboardLocaleCount() > 1) {
                if (mCurrentlyInSpace) {
                    int diff = x - mSpaceDragStartX;
                    if (Math.abs(diff - mSpaceDragLastDiff) > 0) {
                        updateLocaleDrag(diff);
                    }
                    mSpaceDragLastDiff = diff;
                    return true;
                } else {
                    boolean isOnSpace = key.isOnKey(x, y);
                    if (isOnSpace) {
                        mCurrentlyInSpace = true;
                        mSpaceDragStartX = x;
                        updateLocaleDrag(0);
                    }
                    return isOnSpace;
                }
            }
        } else if (mPrefLetterFrequencies != null) {
            // New coordinate? Reset
            if (mPrefLetterX != x || mPrefLetterY != y) {
                mPrefLetter = 0;
                mPrefDistance = Integer.MAX_VALUE;
            }
            // Handle preferred next letter
            final int[] pref = mPrefLetterFrequencies;
            if (mPrefLetter > 0) {
                if (DEBUG_PREFERRED_LETTER) {
                    if (mPrefLetter == code && !key.isOnKey(x, y)) {
                        Log.d(TAG, "CORRECTED !!!!!!");
                    }
                }
                return mPrefLetter == code;
            } else {
                final boolean isOnKey = key.isOnKey(x, y);
                int[] nearby = getNearestKeys(x, y);
                List<Key> nearbyKeys = getKeys();
                if (isOnKey) {
                    // If it's a preferred letter
                    if (inPrefList(code, pref)) {
                        // Check if its frequency is much lower than a nearby key
                        mPrefLetter = code;
                        mPrefLetterX = x;
                        mPrefLetterY = y;
                        for (int i = 0; i < nearby.length; i++) {
                            Key k = nearbyKeys.get(nearby[i]);
                            if (k != key && inPrefList(k.mCode, pref)) {
                                final int dist = distanceFrom(k, x, y);
                                if (dist < (int) (k.mWidth * OVERLAP_PERCENTAGE_LOW_PROB) &&
                                        (pref[k.mCode] > pref[mPrefLetter] * 3))  {
                                    mPrefLetter = k.mCode;
                                    mPrefDistance = dist;
                                    if (DEBUG_PREFERRED_LETTER) {
                                        Log.d(TAG, "CORRECTED ALTHOUGH PREFERRED !!!!!!");
                                    }
                                    break;
                                }
                            }
                        }

                        return mPrefLetter == code;
                    }
                }

                // Get the surrounding keys and intersect with the preferred list
                // For all in the intersection
                //   if distance from touch point is within a reasonable distance
                //       make this the pref letter
                // If no pref letter
                //   return inside;
                // else return thiskey == prefletter;

                for (int i = 0; i < nearby.length; i++) {
                    Key k = nearbyKeys.get(nearby[i]);
                    if (inPrefList(k.mCode, pref)) {
                        final int dist = distanceFrom(k, x, y);
                        if (dist < (int) (k.mWidth * OVERLAP_PERCENTAGE_HIGH_PROB)
                                && dist < mPrefDistance)  {
                            mPrefLetter = k.mCode;
                            mPrefLetterX = x;
                            mPrefLetterY = y;
                            mPrefDistance = dist;
                        }
                    }
                }
                // Didn't find any
                if (mPrefLetter == 0) {
                    return isOnKey;
                } else {
                    return mPrefLetter == code;
                }
            }
        }

        // Lock into the spacebar
        if (mCurrentlyInSpace) return false;

        return key.isOnKey(x, y);
    }

    private boolean inPrefList(int code, int[] pref) {
        if (code < pref.length && code >= 0) return pref[code] > 0;
        return false;
    }

    private int distanceFrom(Key k, int x, int y) {
        if (y > k.mY && y < k.mY + k.mHeight) {
            return Math.abs(k.mX + k.mWidth / 2 - x);
        } else {
            return Integer.MAX_VALUE;
        }
    }

    @Override
    public int[] getNearestKeys(int x, int y) {
        if (mCurrentlyInSpace) {
            return mSpaceKeyIndexArray;
        } else {
            // Avoid dead pixels at edges of the keyboard
            return super.getNearestKeys(Math.max(0, Math.min(x, getMinWidth() - 1)),
                    Math.max(0, Math.min(y, getHeight() - 1)));
        }
    }

    private int indexOf(int code) {
        List<Key> keys = getKeys();
        int count = keys.size();
        for (int i = 0; i < count; i++) {
            if (keys.get(i).mCode == code) return i;
        }
        return -1;
    }

    private int getTextSizeFromTheme(int style, int defValue) {
        TypedArray array = mContext.getTheme().obtainStyledAttributes(
                style, new int[] { android.R.attr.textSize });
        int textSize = array.getDimensionPixelSize(array.getResourceId(0, 0), defValue);
        return textSize;
    }
}