package expo.modules.lineargradient;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.graphics.Shader;
import android.util.TypedValue;
import android.view.View;
import expo.modules.core.interfaces.DoNotStrip;

public class LinearGradientView extends View {
  private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG);
  private Path mPathForBorderRadius;
  private RectF mTempRectForBorderRadius;

  private float[] mLocations;
  private float[] mStartPos = {0.5F, 0};
  private float[] mEndPos = {0.5F, 1};
  private int[] mColors;
  private int[] mSize = {0, 0};
  private float[] mBorderRadii = {0, 0, 0, 0, 0, 0, 0, 0};

  // Keeps this primary constructor from Proguard/R8 for ViewDefinitionBuilder
  @DoNotStrip
  public LinearGradientView(Context context) {
    super(context);
  }

  public void setStartPosition(final float x, final float y) {
    mStartPos = new float[]{x, y};
    drawGradient();
  }

  public void setEndPosition(final float x, final float y) {
    mEndPos = new float[]{x, y};
    drawGradient();
  }

  public void setColors(final int[] colors) {
    mColors = colors;
    drawGradient();
  }

  public void setLocations(final float[] locations) {
    mLocations = locations;
    drawGradient();
  }

  public void setBorderRadii(final float[] borderRadii) {
    for (int i = 0; i < borderRadii.length; i++) {
      borderRadii[i] = toPixelFromDIP(borderRadii[i]);
    }
    mBorderRadii = borderRadii;
    updatePath();
    drawGradient();
  }

  public void setDither(final boolean dither){
    mPaint.setDither(dither);
    drawGradient();
  }

  // Copied from RN PixelUtil
  // We might want to expose display metrics on @unimodules/core somewhere to avoid
  // having code similar to this littered throughout modules
  private float toPixelFromDIP(float value) {
    return TypedValue.applyDimension(
      TypedValue.COMPLEX_UNIT_DIP,
      value,
      getContext().getResources().getDisplayMetrics()
    );
  }

  @Override
  protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    mSize = new int[]{w, h};
    updatePath();
    drawGradient();
  }

  private void drawGradient() {
    // guard against crashes happening while multiple properties are updated
    if (mColors == null || (mLocations != null && mColors.length != mLocations.length))
      return;
    LinearGradient mShader = new LinearGradient(
      mStartPos[0] * mSize[0],
      mStartPos[1] * mSize[1],
      mEndPos[0] * mSize[0],
      mEndPos[1] * mSize[1],
      mColors,
      mLocations,
      Shader.TileMode.CLAMP);
    mPaint.setShader(mShader);
    invalidate();
  }

  private void updatePath() {
    if (mPathForBorderRadius == null) {
      mPathForBorderRadius = new Path();
      mTempRectForBorderRadius = new RectF();
    }
    mPathForBorderRadius.reset();
    mTempRectForBorderRadius.set(0f, 0f, (float) mSize[0], (float) mSize[1]);
    mPathForBorderRadius.addRoundRect(
      mTempRectForBorderRadius,
      mBorderRadii,
      Path.Direction.CW);
  }

  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    if (mPathForBorderRadius == null) {
      canvas.drawPaint(mPaint);
    } else {
      canvas.drawPath(mPathForBorderRadius, mPaint);
    }
  }
}