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package org.mozc.android.inputmethod.japanese.view;

import com.google.common.base.Optional;

import android.graphics.Canvas;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Shader;
import android.graphics.Shader.TileMode;

/**
 * Drawable to render a rectangle key's background.
 *
 */
public class RectKeyDrawable extends BaseBackgroundDrawable {

  private final int topColor;
  private final int bottomColor;

  private final int highlightColor;
  private final int lightShadeColor;
  private final int darkShadeColor;
  private final int shadowColor;

  private int left;
  private int top;
  private int right;
  private int bottom;

  /** Cached Paint instance to reuse for performance reason. */
  private final Paint paint = new Paint();
  private Optional<Shader> shader = Optional.absent();

  public RectKeyDrawable(
      int leftPadding, int topPadding, int rightPadding, int bottomPadding,
      int topColor, int bottomColor,
      int highlightColor, int lightShadeColor, int darkShadeColor,
      int shadowColor) {
    super(leftPadding, topPadding, rightPadding, bottomPadding);
    this.topColor = topColor;
    this.bottomColor = bottomColor;

    this.highlightColor = highlightColor;
    this.lightShadeColor = lightShadeColor;
    this.darkShadeColor = darkShadeColor;
    this.shadowColor = shadowColor;
  }

  @Override
  public void draw(Canvas canvas) {
    if (isCanvasRectEmpty()) {
      return;
    }

    // Local variable cache for better performance.
    Paint paint = this.paint;
    int left = this.left;
    int top = this.top;
    int right = this.right;
    int bottom = this.bottom;

    // Render shadow first.
    if ((shadowColor & 0xFF000000) != 0) {
      Rect bound = getBounds();
      paint.reset();
      paint.setAntiAlias(true);
      paint.setColor(shadowColor);
      canvas.drawRect(left + 1, top + 1,
                      Math.min(right + 1, bound.right),
                      Math.min(bottom + 1, bound.bottom),
                      paint);
    }

    // Render base region.
    if (shader.isPresent()) {
      paint.reset();
      paint.setAntiAlias(true);
      paint.setShader(shader.get());
      canvas.drawRect(left, top, right, bottom, paint);
    }

    // Render highlight and shade.
    if (((highlightColor | lightShadeColor | darkShadeColor) & 0xFF000000) != 0) {
      paint.reset();
      paint.setAntiAlias(true);

      paint.setColor(highlightColor);
      canvas.drawRect(left, top, right, top + 1, paint);
      paint.setColor(lightShadeColor);
      canvas.drawRect(left, top, left + 1, bottom, paint);
      canvas.drawRect(right - 1, top, right, bottom, paint);
      paint.setColor(darkShadeColor);
      canvas.drawRect(left, bottom - 1, right, bottom, paint);
    }
  }

  @Override
  protected void onBoundsChange(Rect rect) {
    super.onBoundsChange(rect);

    Rect canvasRect = getCanvasRect();
    left = canvasRect.left;
    top = canvasRect.top;
    right = canvasRect.right;
    bottom = canvasRect.bottom;
    shader = Optional.<Shader>of(
        new LinearGradient(0, top, 0, bottom, topColor, bottomColor, TileMode.CLAMP));
  }
}