/*
 * 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", the "GNU Affero General Public License v3.0 only", 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", the "GNU Affero General Public
 * License v3.0 only", or the "Server Side Public License, v 1".
 */

package org.elasticsearch.plugins.internal.rewriter;

import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.QueryRewriteContext;

import java.util.Map;

/**
 * Enables modules and plugins to intercept and rewrite queries during the query rewrite phase on the coordinator node.
 */
public interface QueryRewriteInterceptor {

    /**
     * Intercepts and returns a rewritten query if modifications are required; otherwise,
     * returns the same provided {@link QueryBuilder} instance unchanged.
     *
     * @param context the {@link QueryRewriteContext} providing the context for the rewrite operation
     * @param queryBuilder the original {@link QueryBuilder} to potentially rewrite
     * @return the rewritten {@link QueryBuilder}, or the original instance if no rewrite was needed
     */
    QueryBuilder interceptAndRewrite(QueryRewriteContext context, QueryBuilder queryBuilder);

    /**
     * Name of the query to be intercepted and rewritten.
     */
    String getQueryName();

    static QueryRewriteInterceptor multi(Map<String, QueryRewriteInterceptor> interceptors) {
        return interceptors.isEmpty() ? new NoOpQueryRewriteInterceptor() : new CompositeQueryRewriteInterceptor(interceptors);
    }

    class CompositeQueryRewriteInterceptor implements QueryRewriteInterceptor {
        final String NAME = "composite";
        private final Map<String, QueryRewriteInterceptor> interceptors;

        private CompositeQueryRewriteInterceptor(Map<String, QueryRewriteInterceptor> interceptors) {
            this.interceptors = interceptors;
        }

        @Override
        public String getQueryName() {
            return NAME;
        }

        @Override
        public QueryBuilder interceptAndRewrite(QueryRewriteContext context, QueryBuilder queryBuilder) {
            QueryRewriteInterceptor interceptor = interceptors.get(queryBuilder.getName());
            if (interceptor != null) {
                return interceptor.interceptAndRewrite(context, queryBuilder);
            }
            return queryBuilder;
        }
    }

    class NoOpQueryRewriteInterceptor implements QueryRewriteInterceptor {
        @Override
        public QueryBuilder interceptAndRewrite(QueryRewriteContext context, QueryBuilder queryBuilder) {
            return queryBuilder;
        }

        @Override
        public String getQueryName() {
            return null;
        }
    }
}