/*
 * SPDX-License-Identifier: Apache-2.0
 *
 * The OpenSearch Contributors require contributions made to
 * this file be licensed under the Apache-2.0 license or a
 * compatible open source license.
 */

/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/*
 * Modifications Copyright OpenSearch Contributors. See
 * GitHub history for details.
 */

package org.opensearch.index.analysis;

import org.opensearch.core.common.io.stream.StreamInput;
import org.opensearch.core.common.io.stream.StreamOutput;
import org.opensearch.core.common.io.stream.Writeable;
import org.opensearch.common.settings.Settings;
import org.opensearch.core.xcontent.ToXContentFragment;
import org.opensearch.core.xcontent.XContentBuilder;
import org.opensearch.core.xcontent.XContentParseException;
import org.opensearch.core.xcontent.XContentParser;

import java.io.IOException;
import java.util.Map;
import java.util.Objects;

/**
 * Provides the name and settings for an analyzer
 *
 * @opensearch.internal
 */
public class NameOrDefinition implements Writeable, ToXContentFragment {
    // exactly one of these two members is not null
    public final String name;
    public final Settings definition;

    public NameOrDefinition(String name) {
        this.name = Objects.requireNonNull(name);
        this.definition = null;
    }

    public NameOrDefinition(Map<String, ?> definition) {
        this.name = null;
        Objects.requireNonNull(definition);
        try {
            this.definition = Settings.builder().loadFromMap(definition).build();
        } catch (Exception e) {
            throw new IllegalArgumentException("Failed to parse [" + definition + "]", e);
        }
    }

    public NameOrDefinition(StreamInput in) throws IOException {
        name = in.readOptionalString();
        if (in.readBoolean()) {
            definition = Settings.readSettingsFromStream(in);
        } else {
            definition = null;
        }
    }

    @Override
    public void writeTo(StreamOutput out) throws IOException {
        out.writeOptionalString(name);
        boolean isNotNullDefinition = this.definition != null;
        out.writeBoolean(isNotNullDefinition);
        if (isNotNullDefinition) {
            Settings.writeSettingsToStream(definition, out);
        }
    }

    public static NameOrDefinition fromXContent(XContentParser parser) throws IOException {
        if (parser.currentToken() == XContentParser.Token.VALUE_STRING) {
            return new NameOrDefinition(parser.text());
        }
        if (parser.currentToken() == XContentParser.Token.START_OBJECT) {
            return new NameOrDefinition(parser.map());
        }
        throw new XContentParseException(
            parser.getTokenLocation(),
            "Expected [VALUE_STRING] or [START_OBJECT], got " + parser.currentToken()
        );
    }

    @Override
    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
        if (definition == null) {
            builder.value(name);
        } else {
            builder.startObject();
            definition.toXContent(builder, params);
            builder.endObject();
        }
        return builder;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        NameOrDefinition that = (NameOrDefinition) o;
        return Objects.equals(name, that.name) && Objects.equals(definition, that.definition);
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, definition);
    }
}