/*
 * Copyright (C) 2017 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 allen.town.podcast.util;

import static androidx.core.graphics.ColorUtils.RGBToXYZ;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.Handler;

import androidx.annotation.ColorInt;
import androidx.annotation.FloatRange;
import androidx.annotation.NonNull;
import androidx.palette.graphics.Palette;

import java.util.List;

import code.name.monkey.appthemehelper.util.ATHUtil;
import code.name.monkey.appthemehelper.util.ColorUtil;
import allen.town.podcast.R;

/** A class the processes media notifications and extracts the right text and background colors. */
public class MediaNotificationProcessor {

  /** The fraction below which we select the vibrant instead of the light/dark vibrant color */
  private static final float POPULATION_FRACTION_FOR_MORE_VIBRANT = 1.0f;

  /**
   * Minimum saturation that a muted color must have if there exists if deciding between two colors
   */
  private static final float MIN_SATURATION_WHEN_DECIDING = 0.19f;

  /** Minimum fraction that any color must have to be picked up as a text color */
  private static final double MINIMUM_IMAGE_FRACTION = 0.002;

  /**
   * The population fraction to select the dominant color as the text color over a the colored ones.
   */
  private static final float POPULATION_FRACTION_FOR_DOMINANT = 0.01f;

  /** The population fraction to select a white or black color as the background over a color. */
  private static final float POPULATION_FRACTION_FOR_WHITE_OR_BLACK = 2.5f;

  private static final float BLACK_MAX_LIGHTNESS = 0.08f;
  private static final float WHITE_MIN_LIGHTNESS = 0.90f;
  private static final int RESIZE_BITMAP_AREA = 150 * 150;
  private static final ThreadLocal<double[]> TEMP_ARRAY = new ThreadLocal<>();
  /**
   * The lightness difference that has to be added to the primary text color to obtain the secondary
   * text color when the background is light.
   */
  private static final int LIGHTNESS_TEXT_DIFFERENCE_LIGHT = 20;
  /**
   * The lightness difference that has to be added to the primary text color to obtain the secondary
   * text color when the background is dark. A bit less then the above value, since it looks better
   * on dark backgrounds.
   */
  private static final int LIGHTNESS_TEXT_DIFFERENCE_DARK = -10;

  private float[] mFilteredBackgroundHsl = null;
  private final Palette.Filter mBlackWhiteFilter =
          (rgb, hsl) -> !isWhiteOrBlack(hsl);
  private int backgroundColor;
  private int secondaryTextColor;
  private int primaryTextColor;
  private int actionBarColor;
  private Drawable drawable;
  private final Context context;

  public MediaNotificationProcessor(Context context, Drawable drawable) {
    this.context = context;
    this.drawable = drawable;
    getMediaPalette();
  }

  public MediaNotificationProcessor(Context context, Bitmap bitmap) {
    this.context = context;
    this.drawable = new BitmapDrawable(context.getResources(), bitmap);
    getMediaPalette();
  }

  public MediaNotificationProcessor(Context context) {
    this.context = context;
  }

  private static boolean isColorLight(int backgroundColor) {
    return calculateLuminance(backgroundColor) > 0.5f;
  }

  /**
   * Returns the luminance of a color as a float between {@code 0.0} and {@code 1.0}.
   *
   * <p>Defined as the Y component in the XYZ representation of {@code color}.
   */
  @FloatRange(from = 0.0, to = 1.0)
  private static double calculateLuminance(@ColorInt int color) {
    final double[] result = getTempDouble3Array();
    colorToXYZ(color, result);
    // Luminance is the Y component
    return result[1] / 100;
  }

  private static double[] getTempDouble3Array() {
    double[] result = TEMP_ARRAY.get();
    if (result == null) {
      result = new double[3];
      TEMP_ARRAY.set(result);
    }
    return result;
  }

  private static void colorToXYZ(@ColorInt int color, @NonNull double[] outXyz) {
    RGBToXYZ(Color.red(color), Color.green(color), Color.blue(color), outXyz);
  }

  public void getPaletteAsync(
      final OnPaletteLoadedListener onPaletteLoadedListener, Drawable drawable) {
    this.drawable = drawable;
    final Handler handler = new Handler();
    new Thread(
            () -> {
              getMediaPalette();
              handler.post(
                      () -> onPaletteLoadedListener.onPaletteLoaded(MediaNotificationProcessor.this));
            })
        .start();
  }

  public void getPaletteAsync(OnPaletteLoadedListener onPaletteLoadedListener, Bitmap bitmap) {
    this.drawable = new BitmapDrawable(context.getResources(), bitmap);
    getPaletteAsync(onPaletteLoadedListener, this.drawable);
  }

  /** Processes a drawable and calculates the appropriate colors that should be used. */
  private void getMediaPalette() {
    Bitmap bitmap;
    if (drawable != null) {
      // We're transforming the builder, let's make sure all baked in RemoteViews are
      // rebuilt!

      int width = drawable.getIntrinsicWidth();
      int height = drawable.getIntrinsicHeight();
      int area = width * height;
      if (area > RESIZE_BITMAP_AREA) {
        double factor = Math.sqrt((float) RESIZE_BITMAP_AREA / area);
        width = (int) (factor * width);
        height = (int) (factor * height);
      }
      bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
      Canvas canvas = new Canvas(bitmap);
      drawable.setBounds(0, 0, width, height);
      drawable.draw(canvas);

      // for the background we only take the left side of the image to ensure
      // a smooth transition
      Palette.Builder paletteBuilder =
              Palette.from(bitmap)
                      .setRegion(0, 0, bitmap.getWidth() / 2, bitmap.getHeight())
                      .clearFilters() // we want all colors, red / white / black ones too!
                      .resizeBitmapArea(RESIZE_BITMAP_AREA);
      Palette palette;
      backgroundColor = findBackgroundColorAndFilter(drawable);
      // we want most of the full region again, slightly shifted to the right
      float textColorStartWidthFraction = 0.4f;
      paletteBuilder.setRegion(
              (int) (bitmap.getWidth() * textColorStartWidthFraction),
              0,
              bitmap.getWidth(),
              bitmap.getHeight());
      if (mFilteredBackgroundHsl != null) {
        paletteBuilder.addFilter(
                (rgb, hsl) -> {
                  // at least 10 degrees hue difference
                  float diff = Math.abs(hsl[0] - mFilteredBackgroundHsl[0]);
                  return diff > 10 && diff < 350;
                });
      }
      paletteBuilder.addFilter(mBlackWhiteFilter);
      palette = paletteBuilder.generate();
      int foregroundColor = selectForegroundColor(backgroundColor, palette);
      ensureColors(backgroundColor, foregroundColor);
    }
  }

  private int selectForegroundColor(int backgroundColor, Palette palette) {
    if (isColorLight(backgroundColor)) {
      return selectForegroundColorForSwatches(
          palette.getDarkVibrantSwatch(),
          palette.getVibrantSwatch(),
          palette.getDarkMutedSwatch(),
          palette.getMutedSwatch(),
          palette.getDominantSwatch(),
          Color.BLACK);
    } else {
      return selectForegroundColorForSwatches(
          palette.getLightVibrantSwatch(),
          palette.getVibrantSwatch(),
          palette.getLightMutedSwatch(),
          palette.getMutedSwatch(),
          palette.getDominantSwatch(),
          Color.WHITE);
    }
  }

  public boolean isLight() {
    return isColorLight(backgroundColor);
  }

  private int selectForegroundColorForSwatches(
      Palette.Swatch moreVibrant,
      Palette.Swatch vibrant,
      Palette.Swatch moreMutedSwatch,
      Palette.Swatch mutedSwatch,
      Palette.Swatch dominantSwatch,
      int fallbackColor) {
    Palette.Swatch coloredCandidate = selectVibrantCandidate(moreVibrant, vibrant);
    if (coloredCandidate == null) {
      coloredCandidate = selectMutedCandidate(mutedSwatch, moreMutedSwatch);
    }
    if (coloredCandidate != null) {
      if (dominantSwatch == coloredCandidate) {
        return coloredCandidate.getRgb();
      } else if ((float) coloredCandidate.getPopulation() / dominantSwatch.getPopulation()
              < POPULATION_FRACTION_FOR_DOMINANT
          && dominantSwatch.getHsl()[1] > MIN_SATURATION_WHEN_DECIDING) {
        return dominantSwatch.getRgb();
      } else {
        return coloredCandidate.getRgb();
      }
    } else if (hasEnoughPopulation(dominantSwatch)) {
      return dominantSwatch.getRgb();
    } else {
      return fallbackColor;
    }
  }

  private Palette.Swatch selectMutedCandidate(Palette.Swatch first, Palette.Swatch second) {
    boolean firstValid = hasEnoughPopulation(first);
    boolean secondValid = hasEnoughPopulation(second);
    if (firstValid && secondValid) {
      float firstSaturation = first.getHsl()[1];
      float secondSaturation = second.getHsl()[1];
      float populationFraction = first.getPopulation() / (float) second.getPopulation();
      if (firstSaturation * populationFraction > secondSaturation) {
        return first;
      } else {
        return second;
      }
    } else if (firstValid) {
      return first;
    } else if (secondValid) {
      return second;
    }
    return null;
  }

  private Palette.Swatch selectVibrantCandidate(Palette.Swatch first, Palette.Swatch second) {
    boolean firstValid = hasEnoughPopulation(first);
    boolean secondValid = hasEnoughPopulation(second);
    if (firstValid && secondValid) {
      int firstPopulation = first.getPopulation();
      int secondPopulation = second.getPopulation();
      if (firstPopulation / (float) secondPopulation < POPULATION_FRACTION_FOR_MORE_VIBRANT) {
        return second;
      } else {
        return first;
      }
    } else if (firstValid) {
      return first;
    } else if (secondValid) {
      return second;
    }
    return null;
  }

  private boolean hasEnoughPopulation(Palette.Swatch swatch) {
    // We want a fraction that is at least 1% of the image
    return swatch != null
        && (swatch.getPopulation() / (float) RESIZE_BITMAP_AREA > MINIMUM_IMAGE_FRACTION);
  }

  public int findBackgroundColorAndFilter(Drawable drawable) {
    int width = drawable.getIntrinsicWidth();
    int height = drawable.getIntrinsicHeight();
    int area = width * height;

    double factor = Math.sqrt((float) RESIZE_BITMAP_AREA / area);
    width = (int) (factor * width);
    height = (int) (factor * height);

    Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0, 0, width, height);
    drawable.draw(canvas);

    // for the background we only take the left side of the image to ensure
    // a smooth transition
    Palette.Builder paletteBuilder =
        Palette.from(bitmap)
            .setRegion(0, 0, bitmap.getWidth() / 2, bitmap.getHeight())
            .clearFilters() // we want all colors, red / white / black ones too!
            .resizeBitmapArea(RESIZE_BITMAP_AREA);
    Palette palette = paletteBuilder.generate();
    // by default we use the dominant palette
    Palette.Swatch dominantSwatch = palette.getDominantSwatch();
    if (dominantSwatch == null) {
      // We're not filtering on white or black
      mFilteredBackgroundHsl = null;
      return Color.WHITE;
    }

    if (!isWhiteOrBlack(dominantSwatch.getHsl())) {
      mFilteredBackgroundHsl = dominantSwatch.getHsl();
      return dominantSwatch.getRgb();
    }
    // Oh well, we selected black or white. Lets look at the second color!
    List<Palette.Swatch> swatches = palette.getSwatches();
    float highestNonWhitePopulation = -1;
    Palette.Swatch second = null;
    for (Palette.Swatch swatch : swatches) {
      if (swatch != dominantSwatch
          && swatch.getPopulation() > highestNonWhitePopulation
          && !isWhiteOrBlack(swatch.getHsl())) {
        second = swatch;
        highestNonWhitePopulation = swatch.getPopulation();
      }
    }
    if (second == null) {
      // We're not filtering on white or black
      mFilteredBackgroundHsl = null;
      return dominantSwatch.getRgb();
    }
    if (dominantSwatch.getPopulation() / highestNonWhitePopulation
        > POPULATION_FRACTION_FOR_WHITE_OR_BLACK) {
      // The dominant swatch is very dominant, lets take it!
      // We're not filtering on white or black
      mFilteredBackgroundHsl = null;
      return dominantSwatch.getRgb();
    } else {
      mFilteredBackgroundHsl = second.getHsl();
      return second.getRgb();
    }
  }

  private boolean isWhiteOrBlack(float[] hsl) {
    return isBlack(hsl) || isWhite(hsl);
  }

  /** @return true if the color represents a color which is close to black. */
  private boolean isBlack(float[] hslColor) {
    return hslColor[2] <= BLACK_MAX_LIGHTNESS;
  }

  /** @return true if the color represents a color which is close to white. */
  private boolean isWhite(float[] hslColor) {
    return hslColor[2] >= WHITE_MIN_LIGHTNESS;
  }

  private void ensureColors(int backgroundColor, int mForegroundColor) {
    {
      double backLum = NotificationColorUtil.calculateLuminance(backgroundColor);
      double textLum = NotificationColorUtil.calculateLuminance(mForegroundColor);
      double contrast = NotificationColorUtil.calculateContrast(mForegroundColor, backgroundColor);
      // We only respect the given colors if worst case Black or White still has
      // contrast
      boolean backgroundLight =
          backLum > textLum
                  && NotificationColorUtil.satisfiesTextContrast(backgroundColor, Color.BLACK)
              || backLum <= textLum
                  && !NotificationColorUtil.satisfiesTextContrast(backgroundColor, Color.WHITE);
      if (contrast < 4.5f) {
        if (backgroundLight) {
          secondaryTextColor =
              NotificationColorUtil.findContrastColor(
                  mForegroundColor, backgroundColor, true /* findFG */, 4.5f);
          primaryTextColor =
              NotificationColorUtil.changeColorLightness(
                  secondaryTextColor, -LIGHTNESS_TEXT_DIFFERENCE_LIGHT);
        } else {
          secondaryTextColor =
              NotificationColorUtil.findContrastColorAgainstDark(
                  mForegroundColor, backgroundColor, true /* findFG */, 4.5f);
          primaryTextColor =
              NotificationColorUtil.changeColorLightness(
                  secondaryTextColor, -LIGHTNESS_TEXT_DIFFERENCE_DARK);
        }
      } else {
        primaryTextColor = mForegroundColor;
        secondaryTextColor =
            NotificationColorUtil.changeColorLightness(
                primaryTextColor,
                backgroundLight ? LIGHTNESS_TEXT_DIFFERENCE_LIGHT : LIGHTNESS_TEXT_DIFFERENCE_DARK);
        if (NotificationColorUtil.calculateContrast(secondaryTextColor, backgroundColor) < 4.5f) {
          // oh well the secondary is not good enough
          if (backgroundLight) {
            secondaryTextColor =
                NotificationColorUtil.findContrastColor(
                    secondaryTextColor, backgroundColor, true /* findFG */, 4.5f);
          } else {
            secondaryTextColor =
                NotificationColorUtil.findContrastColorAgainstDark(
                    secondaryTextColor, backgroundColor, true /* findFG */, 4.5f);
          }
          primaryTextColor =
              NotificationColorUtil.changeColorLightness(
                  secondaryTextColor,
                  backgroundLight
                      ? -LIGHTNESS_TEXT_DIFFERENCE_LIGHT
                      : -LIGHTNESS_TEXT_DIFFERENCE_DARK);
        }
      }
    }
    actionBarColor = NotificationColorUtil.resolveActionBarColor(context, backgroundColor);
  }

  public int getPrimaryTextColor() {
    return primaryTextColor;
  }

  public int getSecondaryTextColor() {
    return secondaryTextColor;
  }

  public int getActionBarColor() {
    return actionBarColor;
  }

  public int getBackgroundColor() {
    return backgroundColor;
  }

  boolean isWhiteColor(int color) {
    return calculateLuminance(color) > 0.6f;
  }

  public int getMightyColor() {
    boolean isDarkBg =
        ColorUtil.INSTANCE.isColorLight(
            ATHUtil.INSTANCE.resolveColor(context, R.attr.colorSurface));
    if (isDarkBg) {
      if (isColorLight(backgroundColor)) {
        return primaryTextColor;
      } else {
        return backgroundColor;
      }
    } else {
      if (isColorLight(backgroundColor)) {
        return backgroundColor;
      } else {
        return primaryTextColor;
      }
    }
  }

  public interface OnPaletteLoadedListener {
    void onPaletteLoaded(MediaNotificationProcessor mediaNotificationProcessor);
  }

  public static MediaNotificationProcessor errorColor(Context context) {
    MediaNotificationProcessor errorColors = new MediaNotificationProcessor(context);
    errorColors.backgroundColor = -15724528;
    errorColors.primaryTextColor = -6974059;
    errorColors.secondaryTextColor = -8684677;
    errorColors.actionBarColor = -6974059;
    return errorColors;
  }
}
