package com.lemonhc.mplus.framework.util;

import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.util.Log;

public class Exif {
    private static final String TAG = "CameraExif";

    // Returns the degrees in clockwise. Values are 0, 90, 180, or 270.
    public static int getOrientation(byte[] jpeg) {
        if (jpeg == null) {
            return 0;
        }

        int offset = 0;
        int length = 0;

        // ISO/IEC 10918-1:1993(E)
        while (offset + 3 < jpeg.length && (jpeg[offset++] & 0xFF) == 0xFF) {
            int marker = jpeg[offset] & 0xFF;

            // Check if the marker is a padding.
            if (marker == 0xFF) {
                continue;
            }
            offset++;

            // Check if the marker is SOI or TEM.
            if (marker == 0xD8 || marker == 0x01) {
                continue;
            }
            // Check if the marker is EOI or SOS.
            if (marker == 0xD9 || marker == 0xDA) {
                break;
            }

            // Get the length and check if it is reasonable.
            length = pack(jpeg, offset, 2, false);
            if (length < 2 || offset + length > jpeg.length) {
                Log.e(TAG, "Invalid length");
                return 0;
            }

            // Break if the marker is EXIF in APP1.
            if (marker == 0xE1 && length >= 8 &&
                    pack(jpeg, offset + 2, 4, false) == 0x45786966 &&
                    pack(jpeg, offset + 6, 2, false) == 0) {
                offset += 8;
                length -= 8;
                break;
            }

            // Skip other markers.
            offset += length;
            length = 0;
        }

        // JEITA CP-3451 Exif Version 2.2
        if (length > 8) {
            // Identify the byte order.
            int tag = pack(jpeg, offset, 4, false);
            if (tag != 0x49492A00 && tag != 0x4D4D002A) {
                Log.e(TAG, "Invalid byte order");
                return 0;
            }
            boolean littleEndian = (tag == 0x49492A00);

            // Get the offset and check if it is reasonable.
            int count = pack(jpeg, offset + 4, 4, littleEndian) + 2;
            if (count < 10 || count > length) {
                Log.e(TAG, "Invalid offset");
                return 0;
            }
            offset += count;
            length -= count;

            // Get the count and go through all the elements.
            count = pack(jpeg, offset - 2, 2, littleEndian);
            while (count-- > 0 && length >= 12) {
                // Get the tag and check if it is orientation.
                tag = pack(jpeg, offset, 2, littleEndian);
                if (tag == 0x0112) {
                    // We do not really care about type and count, do we?
                    int orientation = pack(jpeg, offset + 8, 2, littleEndian);
                    switch (orientation) {
                        case 1:
                            return 0;
                        case 3:
                            return 180;
                        case 6:
                            return 90;
                        case 8:
                            return 270;
                    }
                    Log.i(TAG, "Unsupported orientation");
                    return 0;
                }
                offset += 12;
                length -= 12;
            }
        }

        Log.i(TAG, "Orientation not found");
        return 0;
    }

    private static int pack(byte[] bytes, int offset, int length,
                            boolean littleEndian) {
        int step = 1;
        if (littleEndian) {
            offset += length - 1;
            step = -1;
        }

        int value = 0;
        while (length-- > 0) {
            value = (value << 8) | (bytes[offset] & 0xFF);
            offset += step;
        }
        return value;
    }

    /**
     * 이미지를 회전시킵니다.
     *
     * @param bitmap 비트맵 이미지
     * @param degrees 회전 각도
     * @return 회전된 이미지
     */
    public static Bitmap rotate(Bitmap bitmap, int degrees)
    {
        if(degrees != 0 && bitmap != null)
        {
            Matrix m = new Matrix();
            m.setRotate(degrees, (float) bitmap.getWidth() / 2,
                    (float) bitmap.getHeight() / 2);

            try
            {
                Bitmap converted = Bitmap.createBitmap(bitmap, 0, 0,
                        bitmap.getWidth(), bitmap.getHeight(), m, true);
                if(bitmap != converted)
                {
                    bitmap.recycle();
                    bitmap = converted;
                }
            }
            catch(OutOfMemoryError ex)
            {
                // 메모리가 부족하여 회전을 시키지 못할 경우 그냥 원본을 반환합니다.
            }
        }
        return bitmap;
    }
}
