/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.
 */
package net.hydromatic.optiq.impl;

import net.hydromatic.optiq.*;
import net.hydromatic.optiq.impl.java.JavaTypeFactory;
import net.hydromatic.optiq.jdbc.OptiqConnection;
import net.hydromatic.optiq.jdbc.OptiqPrepare;
import net.hydromatic.optiq.jdbc.OptiqSchema;
import net.hydromatic.optiq.materialize.MaterializationKey;
import net.hydromatic.optiq.materialize.MaterializationService;

import org.eigenbase.rel.RelNode;
import org.eigenbase.relopt.RelOptTable;
import org.eigenbase.reltype.RelDataTypeImpl;
import org.eigenbase.reltype.RelProtoDataType;

import com.google.common.base.Preconditions;

import java.lang.reflect.Type;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.List;

/**
 * Table that is a materialized view.
 *
 * <p>It can exist in two states: materialized and not materialized. Over time,
 * a given materialized view may switch states. How it is expanded depends upon
 * its current state. State is managed by
 * {@link net.hydromatic.optiq.materialize.MaterializationService}.</p>
 */
public class MaterializedViewTable extends ViewTable {

  private final MaterializationKey key;

  /**
   * Internal connection, used to execute queries to materialize views.
   * To be used only by Calcite internals. And sparingly.
   */
  public static final OptiqConnection MATERIALIZATION_CONNECTION;

  static {
    try {
      MATERIALIZATION_CONNECTION = DriverManager.getConnection("jdbc:calcite:")
          .unwrap(OptiqConnection.class);
    } catch (SQLException e) {
      throw new RuntimeException(e);
    }
  }

  public MaterializedViewTable(Type elementType,
      RelProtoDataType relDataType,
      String viewSql,
      List<String> viewSchemaPath,
      MaterializationKey key) {
    super(elementType, relDataType, viewSql, viewSchemaPath);
    this.key = key;
  }

  /** Table macro that returns a materialized view. */
  public static MaterializedViewTableMacro create(final OptiqSchema schema,
      final String viewSql,
      final List<String> viewSchemaPath,
      final String tableName) {
    return new MaterializedViewTableMacro(schema, viewSql, viewSchemaPath,
        tableName);
  }

  @Override
  public RelNode toRel(RelOptTable.ToRelContext context,
      RelOptTable relOptTable) {
    final OptiqSchema.TableEntry tableEntry =
        MaterializationService.instance().checkValid(key);
    if (tableEntry != null) {
      Table materializeTable = tableEntry.getTable();
      if (materializeTable instanceof TranslatableTable) {
        TranslatableTable table = (TranslatableTable) materializeTable;
        return table.toRel(context, relOptTable);
      }
    }
    return super.toRel(context, relOptTable);
  }

  /** Table function that returns the table that materializes a view. */
  public static class MaterializedViewTableMacro
      extends ViewTableMacro {
    private final MaterializationKey key;

    private MaterializedViewTableMacro(OptiqSchema schema, String viewSql,
        List<String> viewSchemaPath, String tableName) {
      super(schema, viewSql, viewSchemaPath);
      this.key = Preconditions.checkNotNull(
          MaterializationService.instance().defineMaterialization(
              schema, null, viewSql, schemaPath, tableName, true));
    }

    @Override
    public TranslatableTable apply(List<Object> arguments) {
      assert arguments.isEmpty();
      OptiqPrepare.ParseResult parsed =
          Schemas.parse(MATERIALIZATION_CONNECTION, schema, schemaPath,
              viewSql);
      final List<String> schemaPath1 =
          schemaPath != null ? schemaPath : schema.path(null);
      final JavaTypeFactory typeFactory =
          MATERIALIZATION_CONNECTION.getTypeFactory();
      return new MaterializedViewTable(typeFactory.getJavaClass(parsed.rowType),
          RelDataTypeImpl.proto(parsed.rowType), viewSql, schemaPath1, key);
    }
  }
}

// End MaterializedViewTable.java