/*

 * 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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.jfr.internal;

import static jdk.jfr.internal.MetadataDescriptor.ATTRIBUTE_CONSTANT_POOL;

import static jdk.jfr.internal.MetadataDescriptor.ATTRIBUTE_DEFAULT_VALUE;

import static jdk.jfr.internal.MetadataDescriptor.ATTRIBUTE_DIMENSION;

import static jdk.jfr.internal.MetadataDescriptor.ATTRIBUTE_GMT_OFFSET;

import static jdk.jfr.internal.MetadataDescriptor.ATTRIBUTE_ID;

import static jdk.jfr.internal.MetadataDescriptor.ATTRIBUTE_LOCALE;

import static jdk.jfr.internal.MetadataDescriptor.ATTRIBUTE_NAME;

import static jdk.jfr.internal.MetadataDescriptor.ATTRIBUTE_SIMPLE_TYPE;

import static jdk.jfr.internal.MetadataDescriptor.ATTRIBUTE_SUPER_TYPE;

import static jdk.jfr.internal.MetadataDescriptor.ATTRIBUTE_TYPE_ID;

import static jdk.jfr.internal.MetadataDescriptor.ELEMENT_ANNOTATION;

import static jdk.jfr.internal.MetadataDescriptor.ELEMENT_FIELD;

import static jdk.jfr.internal.MetadataDescriptor.ELEMENT_SETTING;

import static jdk.jfr.internal.MetadataDescriptor.ELEMENT_TYPE;

import java.io.DataOutput;

import java.io.IOException;

import java.util.HashMap;

import java.util.HashSet;

import java.util.LinkedHashMap;

import java.util.List;

import java.util.Set;

import jdk.jfr.AnnotationElement;

import jdk.jfr.SettingDescriptor;

import jdk.jfr.ValueDescriptor;

import jdk.jfr.internal.MetadataDescriptor.Attribute;

import jdk.jfr.internal.MetadataDescriptor.Element;

/**

 * Class responsible for converting a list of types into a format that can be

 * parsed by a client.

 *

 */

final class MetadataWriter {

    private final Element metadata = new Element("metadata");

    private final Element root = new Element("root");

    public MetadataWriter(MetadataDescriptor descriptor) {

        descriptor.getTypes().forEach(type -> makeTypeElement(metadata, type));

        root.add(metadata);

        Element region = new Element("region");

        region.addAttribute(ATTRIBUTE_LOCALE, descriptor.locale);

        region.addAttribute(ATTRIBUTE_GMT_OFFSET, descriptor.gmtOffset);

        root.add(region);

    }

    public void writeBinary(DataOutput output) throws IOException {

        Set<String> stringPool = new HashSet<>(1000);

        // Possible improvement, sort string by how often they occur.

        // and assign low number to the most frequently used.

        buildStringPool(root, stringPool);

        HashMap<String, Integer> lookup = new LinkedHashMap<>(stringPool.size());

        int index = 0;

        int poolSize = stringPool.size();

        writeInt(output, poolSize);

        for (String s : stringPool) {

            lookup.put(s, index);

            writeString(output, s);

            index++;

        }

        write(output, root, lookup);

    }

    private void writeString(DataOutput out, String s) throws IOException {

        if (s == null ) {

            return;

        }

        int length = s.length();

        writeInt(out, length);

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

                writeInt(out, s.charAt(i));

            }

    }

    private void writeInt(DataOutput out, int v) throws IOException {

        long s = v & 0xffffffffL;

        if (s < 1 << 7) {

            out.write((byte) (s));

            return;

        }

        out.write((byte) (s | 0x80)); // first byte written

        s >>= 7;

        if (s < 1 << 7) {

            out.write((byte) (s));

            return;

        }

        out.write((byte) (s | 0x80)); // second byte written

        s >>= 7;

        if (s < 1 << 7) {

            out.write((byte) (s));

            return;

        }

        out.write((byte) (s | 0x80)); // third byte written

        s >>= 7;

        if (s < 1 << 7) {

            out.write((byte) (s));

            return;

        }

        s >>= 7;

        out.write((byte) (s));// fourth byte written

    }

    private void buildStringPool(Element element, Set<String> pool) {

        pool.add(element.name);

        for (Attribute a : element.attributes) {

            pool.add(a.name);

            pool.add(a.value);

        }

        for (Element child : element.elements) {

            buildStringPool(child, pool);

        }

    }

    private void write(DataOutput output,Element element, HashMap<String, Integer> lookup) throws IOException {

        writeInt(output, lookup.get(element.name));

        writeInt(output, element.attributes.size());

        for (Attribute a : element.attributes) {

            writeInt(output, lookup.get(a.name));

            writeInt(output, lookup.get(a.value));

        }

        writeInt(output, element.elements.size());

        for (Element child : element.elements) {

            write(output, child, lookup);

        }

    }

    private void makeTypeElement(Element root, Type type) {

        Element element = root.newChild(ELEMENT_TYPE);

        element.addAttribute(ATTRIBUTE_NAME, type.getName());

        String superType = type.getSuperType();

        if (superType != null) {

            element.addAttribute(ATTRIBUTE_SUPER_TYPE, superType);

        }

        if (type.isSimpleType()) {

            element.addAttribute(ATTRIBUTE_SIMPLE_TYPE, true);

        }

        element.addAttribute(ATTRIBUTE_ID, type.getId());

        if (type instanceof PlatformEventType) {

            for (SettingDescriptor v : ((PlatformEventType)type).getSettings()) {

                makeSettingElement(element, v);

            }

        }

        for (ValueDescriptor v : type.getFields()) {

            makeFieldElement(element, v);

        }

        for (AnnotationElement a : type.getAnnotationElements()) {

            makeAnnotation(element, a);

        }

    }

    private void makeSettingElement(Element typeElement, SettingDescriptor s) {

        Element element = typeElement.newChild(ELEMENT_SETTING);

        element.addAttribute(ATTRIBUTE_NAME, s.getName());

        element.addAttribute(ATTRIBUTE_TYPE_ID, s.getTypeId());

        element.addAttribute(ATTRIBUTE_DEFAULT_VALUE, s.getDefaultValue());

        for (AnnotationElement a : s.getAnnotationElements()) {

            makeAnnotation(element, a);

        }

    }

    private void makeFieldElement(Element typeElement, ValueDescriptor v) {

        Element element = typeElement.newChild(ELEMENT_FIELD);

        element.addAttribute(ATTRIBUTE_NAME, v.getName());

        element.addAttribute(ATTRIBUTE_TYPE_ID, v.getTypeId());

        if (v.isArray()) {

            element.addAttribute(ATTRIBUTE_DIMENSION, 1);

        }

        if (PrivateAccess.getInstance().isConstantPool(v)) {

            element.addAttribute(ATTRIBUTE_CONSTANT_POOL, true);

        }

        for (AnnotationElement a : v.getAnnotationElements()) {

            makeAnnotation(element, a);

        }

    }

    private void makeAnnotation(Element entity, AnnotationElement annotation) {

        Element element = entity.newChild(ELEMENT_ANNOTATION);

        element.addAttribute(ATTRIBUTE_TYPE_ID, annotation.getTypeId());

        List<Object> values = annotation.getValues();

        int index = 0;

        for (ValueDescriptor v : annotation.getValueDescriptors()) {

            Object value = values.get(index++);

            if (v.isArray()) {

                element.addArrayAttribute(element, v.getName(), value);

            } else {

                element.addAttribute(v.getName(), value);

            }

        }

    }

}