/*

 * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.internal.vm.compiler.libgraal;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.DataInputStream;

import java.io.DataOutputStream;

import java.io.IOException;

import java.util.LinkedHashMap;

import java.util.Map;

/**

 * Facilities for encoding/decoding a set of options to/from a byte array.

 */

public final class OptionsEncoder {

    private OptionsEncoder() {

    }

    /**

     * Determines if {@code value} is supported by {@link #encode(Map)}.

     */

    public static boolean isValueSupported(Object value) {

        if (value == null) {

            return false;

        }

        Class<?> valueClass = value.getClass();

        return valueClass == Boolean.class ||

                        valueClass == Byte.class ||

                        valueClass == Short.class ||

                        valueClass == Character.class ||

                        valueClass == Integer.class ||

                        valueClass == Long.class ||

                        valueClass == Float.class ||

                        valueClass == Double.class ||

                        valueClass == String.class ||

                        value.getClass().isEnum();

    }

    /**

     * Encodes {@code options} into a byte array.

     *

     * @throws IllegalArgumentException if any value in {@code options} is not

     *             {@linkplain #isValueSupported(Object) supported}

     */

    public static byte[] encode(final Map<String, Object> options) {

        try (ByteArrayOutputStream baout = new ByteArrayOutputStream()) {

            try (DataOutputStream out = new DataOutputStream(baout)) {

                out.writeInt(options.size());

                for (Map.Entry<String, Object> e : options.entrySet()) {

                    final String key = e.getKey();

                    out.writeUTF(key);

                    final Object value = e.getValue();

                    final Class<?> valueClz = value.getClass();

                    if (valueClz == Boolean.class) {

                        out.writeByte('Z');

                        out.writeBoolean((Boolean) value);

                    } else if (valueClz == Byte.class) {

                        out.writeByte('B');

                        out.writeByte((Byte) value);

                    } else if (valueClz == Short.class) {

                        out.writeByte('S');

                        out.writeShort((Short) value);

                    } else if (valueClz == Character.class) {

                        out.writeByte('C');

                        out.writeChar((Character) value);

                    } else if (valueClz == Integer.class) {

                        out.writeByte('I');

                        out.writeInt((Integer) value);

                    } else if (valueClz == Long.class) {

                        out.writeByte('J');

                        out.writeLong((Long) value);

                    } else if (valueClz == Float.class) {

                        out.writeByte('F');

                        out.writeFloat((Float) value);

                    } else if (valueClz == Double.class) {

                        out.writeByte('D');

                        out.writeDouble((Double) value);

                    } else if (valueClz == String.class) {

                        out.writeByte('U');

                        out.writeUTF((String) value);

                    } else if (valueClz.isEnum()) {

                        out.writeByte('U');

                        out.writeUTF(((Enum<?>) value).name());

                    } else {

                        throw new IllegalArgumentException(String.format("Key: %s, Value: %s, Value type: %s", key, value, valueClz));

                    }

                }

            }

            return baout.toByteArray();

        } catch (IOException ioe) {

            throw new IllegalArgumentException(ioe);

        }

    }

    /**

     * Decodes {@code input} into a name/value map.

     *

     * @throws IllegalArgumentException if {@code input} cannot be decoded

     */

    public static Map<String, Object> decode(byte[] input) {

        Map<String, Object> res = new LinkedHashMap<>();

        try (DataInputStream in = new DataInputStream(new ByteArrayInputStream(input))) {

            final int size = in.readInt();

            for (int i = 0; i < size; i++) {

                final String key = in.readUTF();

                final Object value;

                final byte type = in.readByte();

                switch (type) {

                    case 'Z':

                        value = in.readBoolean();

                        break;

                    case 'B':

                        value = in.readByte();

                        break;

                    case 'S':

                        value = in.readShort();

                        break;

                    case 'C':

                        value = in.readChar();

                        break;

                    case 'I':

                        value = in.readInt();

                        break;

                    case 'J':

                        value = in.readLong();

                        break;

                    case 'F':

                        value = in.readFloat();

                        break;

                    case 'D':

                        value = in.readDouble();

                        break;

                    case 'U':

                        value = in.readUTF();

                        break;

                    default:

                        throw new IllegalArgumentException("Unsupported value type: " + Integer.toHexString(type));

                }

                res.put(key, value);

            }

            if (in.available() != 0) {

                throw new IllegalArgumentException(in.available() + " undecoded bytes");

            }

        } catch (IOException ioe) {

            throw new IllegalArgumentException(ioe);

        }

        return res;

    }

}