/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

package org.elasticsearch.cluster.metadata;

import org.elasticsearch.TransportVersion;
import org.elasticsearch.cluster.Diff;
import org.elasticsearch.cluster.DiffableUtils;
import org.elasticsearch.cluster.NamedDiff;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.xcontent.ChunkedToXContentHelper;
import org.elasticsearch.xcontent.ConstructingObjectParser;
import org.elasticsearch.xcontent.ParseField;
import org.elasticsearch.xcontent.ToXContent;
import org.elasticsearch.xcontent.XContentParser;

import java.io.IOException;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Objects;

/**
 * {@link ComponentTemplateMetadata} is a custom {@link Metadata} implementation for storing a map
 * of component templates and their names.
 */
public class ComponentTemplateMetadata implements Metadata.Custom {
    public static final String TYPE = "component_template";
    private static final ParseField COMPONENT_TEMPLATE = new ParseField("component_template");
    @SuppressWarnings("unchecked")
    private static final ConstructingObjectParser<ComponentTemplateMetadata, Void> PARSER = new ConstructingObjectParser<>(
        TYPE,
        false,
        a -> new ComponentTemplateMetadata((Map<String, ComponentTemplate>) a[0])
    );

    static {
        PARSER.declareObject(ConstructingObjectParser.constructorArg(), (p, c) -> {
            Map<String, ComponentTemplate> templates = new HashMap<>();
            while (p.nextToken() != XContentParser.Token.END_OBJECT) {
                String name = p.currentName();
                templates.put(name, ComponentTemplate.parse(p));
            }
            return templates;
        }, COMPONENT_TEMPLATE);
    }
    private final Map<String, ComponentTemplate> componentTemplates;

    public ComponentTemplateMetadata(Map<String, ComponentTemplate> componentTemplates) {
        this.componentTemplates = componentTemplates;
    }

    public ComponentTemplateMetadata(StreamInput in) throws IOException {
        this.componentTemplates = in.readMap(ComponentTemplate::new);
    }

    public Map<String, ComponentTemplate> componentTemplates() {
        return this.componentTemplates;
    }

    @Override
    public Diff<Metadata.Custom> diff(Metadata.Custom before) {
        return new ComponentTemplateMetadataDiff((ComponentTemplateMetadata) before, this);
    }

    public static NamedDiff<Metadata.Custom> readDiffFrom(StreamInput in) throws IOException {
        return new ComponentTemplateMetadataDiff(in);
    }

    @Override
    public EnumSet<Metadata.XContentContext> context() {
        return Metadata.ALL_CONTEXTS;
    }

    @Override
    public String getWriteableName() {
        return TYPE;
    }

    @Override
    public TransportVersion getMinimalSupportedVersion() {
        return TransportVersion.V_7_7_0;
    }

    @Override
    public void writeTo(StreamOutput out) throws IOException {
        out.writeMap(this.componentTemplates, StreamOutput::writeString, (stream, val) -> val.writeTo(stream));
    }

    public static ComponentTemplateMetadata fromXContent(XContentParser parser) throws IOException {
        return PARSER.parse(parser, null);
    }

    @Override
    public Iterator<? extends ToXContent> toXContentChunked(ToXContent.Params ignored) {
        return ChunkedToXContentHelper.xContentValuesMap(COMPONENT_TEMPLATE.getPreferredName(), componentTemplates);
    }

    @Override
    public int hashCode() {
        return Objects.hash(this.componentTemplates);
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (obj.getClass() != getClass()) {
            return false;
        }
        ComponentTemplateMetadata other = (ComponentTemplateMetadata) obj;
        return Objects.equals(this.componentTemplates, other.componentTemplates);
    }

    @Override
    public String toString() {
        return Strings.toString(this);
    }

    static class ComponentTemplateMetadataDiff implements NamedDiff<Metadata.Custom> {

        final Diff<Map<String, ComponentTemplate>> componentTemplateDiff;

        ComponentTemplateMetadataDiff(ComponentTemplateMetadata before, ComponentTemplateMetadata after) {
            this.componentTemplateDiff = DiffableUtils.diff(
                before.componentTemplates,
                after.componentTemplates,
                DiffableUtils.getStringKeySerializer()
            );
        }

        ComponentTemplateMetadataDiff(StreamInput in) throws IOException {
            this.componentTemplateDiff = DiffableUtils.readJdkMapDiff(
                in,
                DiffableUtils.getStringKeySerializer(),
                ComponentTemplate::new,
                ComponentTemplate::readComponentTemplateDiffFrom
            );
        }

        @Override
        public Metadata.Custom apply(Metadata.Custom part) {
            return new ComponentTemplateMetadata(componentTemplateDiff.apply(((ComponentTemplateMetadata) part).componentTemplates));
        }

        @Override
        public void writeTo(StreamOutput out) throws IOException {
            componentTemplateDiff.writeTo(out);
        }

        @Override
        public String getWriteableName() {
            return TYPE;
        }

        @Override
        public TransportVersion getMinimalSupportedVersion() {
            return TransportVersion.V_7_7_0;
        }
    }
}
