/*-
 * ============LICENSE_START=======================================================
 * ONAP - SO
 * ================================================================================
 * Copyright (C) 2017 - 2019 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * Licensed 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.so.client.graphinventory.entities;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import org.onap.so.client.aai.entities.QueryStep;
import org.onap.so.client.graphinventory.GraphInventoryObjectName;
import com.google.common.base.Joiner;


public class DSLQueryBuilder<S, E> implements QueryStep {

    private List<QueryStep> steps = new ArrayList<>();
    private String suffix = "";

    public DSLQueryBuilder() {

    }

    public DSLQueryBuilder(DSLNode node) {
        steps.add(node);
    }

    public DSLQueryBuilder<S, DSLNode> node(DSLNode node) {
        steps.add(node);

        return (DSLQueryBuilder<S, DSLNode>) this;
    }

    public DSLQueryBuilder<S, E> output() {
        if (steps.get(steps.size() - 1) instanceof DSLNode) {
            ((DSLNode) steps.get(steps.size() - 1)).output();
        }
        return this;
    }

    public <E2> DSLQueryBuilder<S, E2> union(final DSLQueryBuilder<?, E2>... union) {

        List<DSLQueryBuilder<?, ?>> unions = Arrays.asList(union);
        steps.add(() -> {
            StringBuilder query = new StringBuilder();

            query.append("> [ ").append(
                    Joiner.on(", ").join(unions.stream().map(item -> item.build()).collect(Collectors.toList())))
                    .append(" ]");
            return query.toString();
        });

        return (DSLQueryBuilder<S, E2>) this;
    }

    public DSLQueryBuilder<S, E> where(DSLQueryBuilder<?, ?> where) {

        steps.add(() -> {
            StringBuilder query = new StringBuilder();
            query.append(where.build()).append(")");
            String result = query.toString();
            if (!result.startsWith(">")) {
                result = "> " + result;
            }
            return "(" + result;
        });
        return this;
    }

    public DSLQueryBuilder<S, E> to(DSLQueryBuilder<?, ?> to) {
        steps.add(() -> {
            StringBuilder query = new StringBuilder();

            query.append("> ").append(to.build());
            return query.toString();
        });
        return this;
    }

    public DSLQueryBuilder<S, E> to(GraphInventoryObjectName name) {
        return to(__.node(name));
    }

    public DSLQueryBuilder<S, E> to(GraphInventoryObjectName name, DSLNodeKey... key) {
        return to(__.node(name, key));
    }

    public DSLQueryBuilder<S, E> limit(int limit) {
        suffix = " LIMIT " + limit;
        return this;
    }

    @Override
    public String build() {
        return compile();
    }

    @Override
    public String toString() {
        return build();
    }

    @Override
    public boolean equals(Object o) {
        if (o != null) {
            if (o instanceof QueryStep) {
                return ((QueryStep) o).build().equals(this.build());
            } else if (o instanceof String) {
                return o.equals(this.build());
            }
        }
        return false;
    }

    @Override
    public int hashCode() {

        return build().hashCode();
    }

    private String compile() {
        return Joiner.on(" ").join(steps.stream().map(item -> item.build()).collect(Collectors.toList())) + suffix;
    }

    protected QueryStep getFirst() {
        return steps.get(0);
    }
}