/*
 * Copyright (C) 2016 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.compatibility.common.util;

import static org.junit.Assert.assertTrue;

import android.app.WallpaperManager;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.Color;
import android.util.Log;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.lang.reflect.Method;
import java.util.Random;

public class BitmapUtils {
    private static final String TAG = "BitmapUtils";

    private BitmapUtils() {}

    private static Boolean compareBasicBitmapsInfo(Bitmap bmp1, Bitmap bmp2) {
        if (bmp1 == bmp2) {
            return Boolean.TRUE;
        }

        if (bmp1 == null) {
            Log.d(TAG, "compareBitmaps() failed because bmp1 is null");
            return Boolean.FALSE;
        }

        if (bmp2 == null) {
            Log.d(TAG, "compareBitmaps() failed because bmp2 is null");
            return Boolean.FALSE;
        }

        if ((bmp1.getWidth() != bmp2.getWidth()) || (bmp1.getHeight() != bmp2.getHeight())) {
            Log.d(TAG, "compareBitmaps() failed because sizes don't match "
                    + "bmp1=(" + bmp1.getWidth() + "x" + bmp1.getHeight() + "), "
                    + "bmp2=(" + bmp2.getWidth() + "x" + bmp2.getHeight() + ")");
            return Boolean.FALSE;
        }

        if (bmp1.getConfig() != bmp2.getConfig()) {
            Log.d(TAG, "compareBitmaps() failed because configs don't match "
                    + "bmp1=(" + bmp1.getConfig() + "), "
                    + "bmp2=(" + bmp2.getConfig() + ")");
            return Boolean.FALSE;
        }

        return null;
    }

    /**
     * Compares two bitmaps by pixels.
     */
    public static boolean compareBitmaps(Bitmap bmp1, Bitmap bmp2) {
        final Boolean basicComparison = compareBasicBitmapsInfo(bmp1, bmp2);
        if (basicComparison != null) return basicComparison.booleanValue();

        for (int i = 0; i < bmp1.getWidth(); i++) {
            for (int j = 0; j < bmp1.getHeight(); j++) {
                if (bmp1.getPixel(i, j) != bmp2.getPixel(i, j)) {
                    Log.d(TAG, "compareBitmaps(): pixels (" + i + ", " + j + ") don't match");
                    return false;
                }
            }
        }
        return true;
    }

    /**
     *  Compares two bitmaps by pixels, with a buffer for mistmatches.
     *
     *  <p>For example, if {@code minimumPrecision} is 0.99, at least 99% of the pixels should
     *  match.
     */
    public static boolean compareBitmaps(Bitmap bmp1, Bitmap bmp2, double minimumPrecision) {
        final Boolean basicComparison = compareBasicBitmapsInfo(bmp1, bmp2);
        if (basicComparison != null) return basicComparison.booleanValue();

        final int width = bmp1.getWidth();
        final int height = bmp1.getHeight();

        final long numberPixels = width * height;
        long numberMismatches = 0;

        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                if (bmp1.getPixel(i, j) != bmp2.getPixel(i, j)) {
                    numberMismatches++;
                    if (numberMismatches <= 10) {
                        // Let's not spam logcat...
                        Log.w(TAG, "compareBitmaps(): pixels (" + i + ", " + j + ") don't match");
                    }
                }
            }
        }
        final double actualPrecision = ((double) numberPixels - numberMismatches) / (numberPixels);
        Log.v(TAG, "compareBitmaps(): numberPixels=" + numberPixels
                + ", numberMismatches=" + numberMismatches
                + ", minimumPrecision=" + minimumPrecision
                + ", actualPrecision=" + actualPrecision);
        return actualPrecision >= minimumPrecision;
    }

    public static Bitmap generateRandomBitmap(int width, int height) {
        final Bitmap bmp = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        final Random generator = new Random();
        for (int x = 0; x < width; x++) {
            for (int y = 0; y < height; y++) {
                bmp.setPixel(x, y, generator.nextInt(Integer.MAX_VALUE));
            }
        }
        return bmp;
    }

    public static Bitmap generateWhiteBitmap(int width, int height) {
        final Bitmap bmp = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        bmp.eraseColor(Color.WHITE);
        return bmp;
    }

    public static Bitmap getWallpaperBitmap(Context context) throws Exception {
        WallpaperManager wallpaperManager = WallpaperManager.getInstance(context);
        Class<?> noparams[] = {};
        Class<?> wmClass = wallpaperManager.getClass();
        Method methodGetBitmap = wmClass.getDeclaredMethod("getBitmap", noparams);
        return (Bitmap) methodGetBitmap.invoke(wallpaperManager, null);
    }

    public static ByteArrayInputStream bitmapToInputStream(Bitmap bmp) {
        final ByteArrayOutputStream bos = new ByteArrayOutputStream();
        bmp.compress(CompressFormat.PNG, 0 /*ignored for PNG*/, bos);
        byte[] bitmapData = bos.toByteArray();
        return new ByteArrayInputStream(bitmapData);
    }

    private static void logIfBitmapSolidColor(String fileName, Bitmap bitmap) {
        int firstColor = bitmap.getPixel(0, 0);
        for (int x = 0; x < bitmap.getWidth(); x++) {
            for (int y = 0; y < bitmap.getHeight(); y++) {
                if (bitmap.getPixel(x, y) != firstColor) {
                    return;
                }
            }
        }

        Log.w(TAG, String.format("%s entire bitmap color is %x", fileName, firstColor));
    }

    public static void saveBitmap(Bitmap bitmap, String directoryName, String fileName) {
        new File(directoryName).mkdirs(); // create dirs if needed

        Log.d(TAG, "Saving file: " + fileName + " in directory: " + directoryName);

        if (bitmap == null) {
            Log.d(TAG, "File not saved, bitmap was null");
            return;
        }

        logIfBitmapSolidColor(fileName, bitmap);

        File file = new File(directoryName, fileName);
        try (FileOutputStream fileStream = new FileOutputStream(file)) {
            bitmap.compress(Bitmap.CompressFormat.PNG, 0 /* ignored for PNG */, fileStream);
            fileStream.flush();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    // Compare expected to actual to see if their diff is less than mseMargin.
    // lessThanMargin is to indicate whether we expect the diff to be
    // "less than" or "no less than".
    public static boolean compareBitmapsMse(Bitmap expected, Bitmap actual,
            int mseMargin, boolean lessThanMargin, boolean isPremultiplied) {
        final Boolean basicComparison = compareBasicBitmapsInfo(expected, actual);
        if (basicComparison != null) return basicComparison.booleanValue();

        double mse = 0;
        int width = expected.getWidth();
        int height = expected.getHeight();

        // Bitmap.getPixels() returns colors with non-premultiplied ARGB values.
        int[] expColors = new int [width * height];
        expected.getPixels(expColors, 0, width, 0, 0, width, height);

        int[] actualColors = new int [width * height];
        actual.getPixels(actualColors, 0, width, 0, 0, width, height);

        for (int row = 0; row < height; ++row) {
            for (int col = 0; col < width; ++col) {
                int idx = row * width + col;
                mse += distance(expColors[idx], actualColors[idx], isPremultiplied);
            }
        }
        mse /= width * height;

        Log.i(TAG, "MSE: " + mse);
        if (lessThanMargin) {
            if (mse > mseMargin) {
                Log.d(TAG, "MSE too large for normal case: " + mse);
                return false;
            }
            return true;
        } else {
            if (mse <= mseMargin) {
                Log.d(TAG, "MSE too small for abnormal case: " + mse);
                return false;
            }
            return true;
        }
    }

    // Same as above, but asserts compareBitmapsMse's return value.
    public static void assertBitmapsMse(Bitmap expected, Bitmap actual,
            int mseMargin, boolean lessThanMargin, boolean isPremultiplied) {
        assertTrue(compareBitmapsMse(expected, actual, mseMargin, lessThanMargin, isPremultiplied));
    }

    private static int multiplyAlpha(int color, int alpha) {
        return (color * alpha + 127) / 255;
    }

    // For the Bitmap with Alpha, multiply the Alpha values to get the effective
    // RGB colors and then compute the color-distance.
    private static double distance(int expect, int actual, boolean isPremultiplied) {
        if (isPremultiplied) {
            final int a1 = Color.alpha(actual);
            final int a2 = Color.alpha(expect);
            final int r = multiplyAlpha(Color.red(actual), a1) -
                    multiplyAlpha(Color.red(expect), a2);
            final int g = multiplyAlpha(Color.green(actual), a1) -
                    multiplyAlpha(Color.green(expect), a2);
            final int b = multiplyAlpha(Color.blue(actual), a1) -
                    multiplyAlpha(Color.blue(expect), a2);
            return r * r + g * g + b * b;
        } else {
            int r = Color.red(actual) - Color.red(expect);
            int g = Color.green(actual) - Color.green(expect);
            int b = Color.blue(actual) - Color.blue(expect);
            return r * r + g * g + b * b;
        }
    }
}