import java.io.*;

public class SimpleImageInfo {
    private final int _width;
    private final int _height;
    private final String type;

    private SimpleImageInfo(final int width, final int height, final String type) {
        _width = width;
        _height = height;
        this.type = type;
    }

    @Override
    public String toString() {
        return "SimpleImageInfo{" + "_width=" + _width + ", _height=" + _height + ", type='" + type + '\'' + '}';
    }

    @Override
    public boolean equals(final Object o) {
        if (this == o) return true;
        if (!(o instanceof SimpleImageInfo)) return false;

        final SimpleImageInfo that = (SimpleImageInfo) o;

        if (_width != that._width) return false;
        if (_height != that._height) return false;
        return type != null ? type.equals(that.type) : that.type == null;

    }

    @Override
    public int hashCode() {
        int result = _width;
        result = 31 * result + _height;
        result = 31 * result + (type != null ? type.hashCode() : 0);
        return result;
    }

    public int getWidth() {
        return _width;
    }

    public int getHeight() {
        return _height;
    }

    public String getType() {
        return type;
    }

    private interface StreamSupplier {
        int read() throws IOException;

        long skip(long skip) throws IOException;
    }

    public static SimpleImageInfo getInfo(File file, File target) throws IOException {
        final InputStream is = new FileInputStream(file);
        try {
            return getInfo(is, target);
        } finally {
            is.close();
        }
    }

    public static SimpleImageInfo getInfo(InputStream inputStream, File target) throws IOException {
        final OutputStream outputStream = new FileOutputStream(target);
        try {
            return getInfo(inputStream, outputStream);
        } finally {
            outputStream.close();
        }
    }

    public static SimpleImageInfo getInfo(byte[] bytes, OutputStream outputStream) throws IOException {
        final InputStream is = new ByteArrayInputStream(bytes);
        try {
            return getInfo(is, outputStream);
        } finally {
            is.close();
        }
    }

    public static SimpleImageInfo getInfo(final InputStream is, final OutputStream outputStream) throws IOException {
        final SimpleImageInfo info = getInfo(new StreamSupplier() {
            @Override
            public int read() throws IOException {
                final int read = is.read();
                outputStream.write(read);
                return read;
            }

            @Override
            public long skip(final long n) throws IOException {

                if (n <= 0) {
                    return 0;
                }

                long remaining = n;
                final int size = (int) Math.min(2048, remaining);
                final byte[] skipBuffer = new byte[size];
                while (remaining > 0) {
                    final int length = (int) Math.min(size, remaining);
                    final int nr = is.read(skipBuffer, 0, length);

                    if (nr < 0) {
                        break;
                    }
                    outputStream.write(skipBuffer, 0, nr);
                    remaining -= nr;
                }

                return n - remaining;
            }
        });

        final byte[] buffer = new byte[2048];
        int n;
        while (-1 != (n = is.read(buffer))) {
            outputStream.write(buffer, 0, n);
        }
        return info;
    }

    public static SimpleImageInfo getInfo(File file) throws IOException {
        final InputStream is = new FileInputStream(file);
        try {
            return getInfo(is);
        } finally {
            is.close();
        }
    }

    public static SimpleImageInfo getInfo(byte[] bytes) throws IOException {
        final InputStream is = new ByteArrayInputStream(bytes);
        try {
            return getInfo(is);
        } finally {
            is.close();
        }
    }


    /**
     * Based on SimplaImageInfo class from  Jaimon Mathew <http://www.jaimon.co.uk>
     * http://blog.jaimon.co.uk/simpleimageinfo/SimpleImageInfo.java.html
     */
    public static SimpleImageInfo getInfo(final InputStream is) throws IOException {
        return getInfo(new StreamSupplier() {
            @Override
            public int read() throws IOException {
                return is.read();
            }

            @Override
            public long skip(final long skip) throws IOException {
                return is.skip(skip);
            }
        });
    }


    private static SimpleImageInfo getInfo(StreamSupplier is) throws IOException {
        final int h1 = is.read();
        final int h2 = is.read();
        if (h1 == 0xFF && h2 == 0xD8) {   //JPG
            return getJPG(is);
        } else if (h1 == 66 && h2 == 77) { // BMP
            return getBMP(is);
        } else {
            final int h3 = is.read();
            if (h1 == 137 && h2 == 80 && h3 == 78) { // PNG
                return getPNG(is);
            } else if (h1 == 'G' && h2 == 'I' && h3 == 'F') { // GIF
                return getGIF(is);
            } else {
                final int c4 = is.read();
                if ((h1 == 'M' && h2 == 'M' && h3 == 0 && c4 == 42) || (h1 == 'I' && h2 == 'I' && h3 == 42 && c4 == 0)) { //TIFF
                    final boolean bigEndian = h1 == 'M';
                    return getTIFF(is, bigEndian);
                } else {
                    throw new IOException("Unsupported Image Type");
                }
            }
        }
    }


    private static SimpleImageInfo getJPG(final StreamSupplier is) throws IOException {
        int currentRead = is.read();
        while (currentRead == 255) {
            final int marker = is.read();
            final int len = readInt(is, 2, true);
            if (marker == 192 || marker == 193 || marker == 194) {
                is.skip(1);
                final int height = readInt(is, 2, true);
                final int width = readInt(is, 2, true);
                return new SimpleImageInfo(width, height, "JPG");
            } else {
                is.skip(len - 2);
                currentRead = is.read();
            }
        }
        throw new IOException("Unsupported Jpg format");
    }

    private static SimpleImageInfo getTIFF(final StreamSupplier is, final boolean bigEndian) throws IOException {
        int height = -1;
        int width = -1;
        final int ifd = readInt(is, 4, bigEndian);
        is.skip(ifd - 8);
        final int entries = readInt(is, 2, bigEndian);
        for (int i = 1; i <= entries; i++) {
            final int tag = readInt(is, 2, bigEndian);
            final int fieldType = readInt(is, 2, bigEndian);
            final long count = readInt(is, 4, bigEndian);
            final int valOffset;
            if ((fieldType == 3 || fieldType == 8)) {
                valOffset = readInt(is, 2, bigEndian);
                is.skip(2);
            } else {
                valOffset = readInt(is, 4, bigEndian);
            }

            if (tag == 256) {
                width = valOffset;
            } else if (tag == 257) {
                height = valOffset;
            }
            if (width != -1 && height != -1) {
                return new SimpleImageInfo(width, height, "TIF");
            }
        }
        throw new IOException("Unsupported Tiff Format");
    }

    private static SimpleImageInfo getBMP(final StreamSupplier is) throws IOException {
        is.skip(16);
        final int width = readInt(is, 2, false);
        is.skip(2);
        final int height = readInt(is, 2, false);
        return new SimpleImageInfo(width, height, "BMP");
    }

    private static SimpleImageInfo getPNG(final StreamSupplier is) throws IOException {
        is.skip(15);
        final int width = readInt(is, 2, true);
        is.skip(2);
        final int height = readInt(is, 2, true);
        return new SimpleImageInfo(width, height, "PNG");
    }

    private static SimpleImageInfo getGIF(final StreamSupplier is) throws IOException {
        is.skip(3);
        final int width = readInt(is, 2, false);
        final int height = readInt(is, 2, false);
        return new SimpleImageInfo(width, height, "GIF");
    }


    private static int readInt(StreamSupplier is, int noOfBytes, boolean bigEndian) throws IOException {
        int result = 0;
        int sv = bigEndian ? ((noOfBytes - 1) * 8) : 0;
        final int cnt = bigEndian ? -8 : 8;
        for (int i = 0; i < noOfBytes; i++) {
            result |= is.read() << sv;
            sv += cnt;
        }
        return result;
    }
}