/*
 * Licensed to Crate under one or more contributor license agreements.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.  Crate 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.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial
 * agreement.
 */

package io.crate.operation.collect.sources;

import com.google.common.collect.Iterables;
import com.google.common.collect.Ordering;
import io.crate.analyze.OrderBy;
import io.crate.analyze.symbol.Reference;
import io.crate.analyze.symbol.Symbol;
import io.crate.analyze.symbol.Symbols;
import io.crate.core.collections.Row;
import io.crate.metadata.Functions;
import io.crate.metadata.ReferenceInfo;
import io.crate.metadata.table.TableInfo;
import io.crate.metadata.tablefunctions.TableFunctionImplementation;
import io.crate.operation.BaseImplementationSymbolVisitor;
import io.crate.operation.Input;
import io.crate.operation.InputRow;
import io.crate.operation.collect.CrateCollector;
import io.crate.operation.collect.InputCollectExpression;
import io.crate.operation.collect.JobCollectContext;
import io.crate.operation.collect.RowsCollector;
import io.crate.operation.projectors.RowReceiver;
import io.crate.operation.projectors.sorting.OrderingByPosition;
import io.crate.planner.node.dql.CollectPhase;
import io.crate.planner.node.dql.TableFunctionCollectPhase;
import org.elasticsearch.cluster.ClusterService;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.inject.Singleton;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

@Singleton
public class TableFunctionCollectSource implements CollectSource {

    private final ClusterService clusterService;
    private final Functions functions;
    private final TableFunctionImplementationVisitor implementationVisitor;

    @Inject
    public TableFunctionCollectSource(ClusterService clusterService, Functions functions) {
        this.clusterService = clusterService;
        this.functions = functions;
        implementationVisitor = new TableFunctionImplementationVisitor(functions);
    }

    @Override
    public Collection<CrateCollector> getCollectors(CollectPhase collectPhase,
                                                    RowReceiver downstream,
                                                    JobCollectContext jobCollectContext) {
        TableFunctionCollectPhase phase = (TableFunctionCollectPhase) collectPhase;
        TableFunctionImplementation tableFunctionSafe = functions.getTableFunctionSafe(phase.functionName());
        TableInfo tableInfo = tableFunctionSafe.createTableInfo(clusterService, Symbols.extractTypes(phase.arguments()));
        //noinspection unchecked  Only literals can be passed to table functions. Anything else is invalid SQL
        List<Input<?>> inputs = (List<Input<?>>) (List) phase.arguments();

        final Context context = new Context(new ArrayList<>(tableInfo.columns()));
        List<Input<?>> topLevelInputs = new ArrayList<>(phase.toCollect().size());
        for (Symbol symbol : phase.toCollect()) {
            topLevelInputs.add(implementationVisitor.process(symbol, context));
        }
        Iterable<Row> rows = Iterables.transform(
                tableFunctionSafe.execute(inputs),
                InputRow.toInputRowFunction(topLevelInputs, context.collectExpressions));
        OrderBy orderBy = phase.orderBy();
        if (orderBy != null) {
            rows = SystemCollectSource.sortRows(Iterables.transform(rows, Row.MATERIALIZE), phase);
        }
        RowsCollector rowsCollector = new RowsCollector(downstream, rows);
        return Collections.<CrateCollector>singletonList(rowsCollector);
    }

    private static class Context {
        final List<ReferenceInfo> columns;
        final List<InputCollectExpression> collectExpressions = new ArrayList<>();

        public Context(List<ReferenceInfo> columns) {
            this.columns = columns;
        }
    }

    private static final class TableFunctionImplementationVisitor extends BaseImplementationSymbolVisitor<Context> {

        public TableFunctionImplementationVisitor(Functions functions) {
            super(functions);
        }

        @Override
        public Input<?> visitReference(Reference symbol, Context context) {
            int position = context.columns.indexOf(symbol.info());
            InputCollectExpression collectExpression = new InputCollectExpression(position);
            context.collectExpressions.add(collectExpression);
            return collectExpression;
        }
    }
}