package me.everything.webp;

import android.graphics.Bitmap;

import java.nio.ByteBuffer;

public class WebPDecoder {
    private static WebPDecoder instance = null;

    private WebPDecoder() {
        System.loadLibrary("webp_evme");
    }

    public static WebPDecoder getInstance() {
        if (instance == null) {
            synchronized (WebPDecoder.class) {
                if (instance == null) {
                    instance = new WebPDecoder();
                }
            }
        }

        return instance;
    }

    public Bitmap decodeWebP(byte[] encoded) {
        return decodeWebP(encoded, 0, 0);
    }

    public Bitmap decodeWebP(byte[] encoded, int w, int h) {
        int[] width = new int[]{w};
        int[] height = new int[]{h};

        byte[] decoded = decodeRGBAnative(encoded, encoded.length, width, height);
        if (decoded.length == 0) return null;

        int[] pixels = new int[decoded.length / 4];
        ByteBuffer.wrap(decoded).asIntBuffer().get(pixels);

        return Bitmap.createBitmap(pixels, width[0], height[0], Bitmap.Config.ARGB_8888);
    }

    public static native byte[] decodeRGBAnative(byte[] encoded, long encodedLength, int[] width, int[] height);
}

/**
 * A {@link ImageView} with WebP support </p>
 * Use to load WebP resources to ImageView from View decleration in layout xmls </p>
 * <me.everything.webp.WebPImageView
 *     android:layout_width="wrap_content"
 *     android:layout_height="wrap_content"
 *     webp:webp_src="@drawable/your_webp_image" />
 */
public class WebpImageView extends ImageView {

    /**
     * Native WEBP support with lossless and transparency is officially supported in Android 4.2.1+.
     * Before that it was without transparency. Since we can only safely check for SDK version we
     * and 4.2 and 4.2.x are SDK version 17 will use SDK 18 (Android 4.3 and above).
     */
    public static final boolean NATIVE_WEB_P_SUPPORT = Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2;

    public WebpImageView(Context context) {
        super(context);
        init(context, null);
    }

    public WebpImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context, attrs);
    }

    public WebpImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context, attrs);
    }

    private void init(Context context, AttributeSet attrs) {
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.webp);

        int webpSourceResourceID = a.getResourceId(R.styleable.webp_webp_src, 0);
        a.recycle();

        InputStream inputStream = getResources().openRawResource(webpSourceResourceID);
        byte[] bytes = streamToBytes(inputStream);
        Bitmap bitmap = null;

        // Prefer the BitmapFactory decoder on post JB_MR2 OSs
        if (!NATIVE_WEB_P_SUPPORT) {
            bitmap = WebPDecoder.getInstance().decodeWebP(bytes);
        } else {
            bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
        }
        this.setImageBitmap(bitmap);
    }

    private static byte[] streamToBytes(InputStream is) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        int i = -1;
        try {
            byte[] bytes = new byte[1024];
            while ((i = is.read(bytes)) != -1) {
                baos.write(bytes, 0, i);
                bytes = new byte[1024];
            }
            return baos.toByteArray();
        } catch (Exception e) {
        }
        return null;
    }
}