/*
 * 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 org.apache.calcite.adapter.spark;

import org.apache.calcite.adapter.enumerable.EnumerableRules;
import org.apache.calcite.config.CalciteSystemProperty;
import org.apache.calcite.jdbc.CalcitePrepare;
import org.apache.calcite.linq4j.tree.ClassDeclaration;
import org.apache.calcite.plan.RelOptPlanner;
import org.apache.calcite.plan.RelOptRule;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.runtime.ArrayBindable;
import org.apache.calcite.util.Util;
import org.apache.calcite.util.javac.JaninoCompiler;

import org.apache.spark.api.java.JavaSparkContext;

import java.io.File;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.Calendar;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * Implementation of
 * {@link org.apache.calcite.jdbc.CalcitePrepare.SparkHandler}. Gives the core
 * Calcite engine access to rules that only exist in the Spark module.
 */
public class SparkHandlerImpl implements CalcitePrepare.SparkHandler {
  private final HttpServer classServer;
  private final AtomicInteger classId;
  private final JavaSparkContext sparkContext =
      new JavaSparkContext("local[1]", "calcite");

  /** Thread-safe holder. */
  private static class Holder {
    private static final SparkHandlerImpl INSTANCE = new SparkHandlerImpl();
  }

  private static final File CLASS_DIR = new File("build/sparkServer/classes");

  /** Creates a SparkHandlerImpl. */
  private SparkHandlerImpl() {
    if (!CLASS_DIR.isDirectory() && !CLASS_DIR.mkdirs()) {
      System.err.println("Unable to create temporary folder " + CLASS_DIR);
    }
    classServer = new HttpServer(CLASS_DIR);

    // Start the classServer and store its URI in a spark system property
    // (which will be passed to executors so that they can connect to it)
    classServer.start();
    System.setProperty("spark.repl.class.uri", classServer.uri());

    // Generate a starting point for class names that is unlikely to clash with
    // previous classes. A better solution would be to clear the class directory
    // on startup.
    final Calendar calendar = Util.calendar();
    classId = new AtomicInteger(
        calendar.get(Calendar.HOUR_OF_DAY) * 10000
        + calendar.get(Calendar.MINUTE) * 100
        + calendar.get(Calendar.SECOND));
  }

  /** Creates a SparkHandlerImpl, initializing on first call. Calcite-core calls
   * this via reflection. */
  @SuppressWarnings("UnusedDeclaration")
  public static CalcitePrepare.SparkHandler instance() {
    return Holder.INSTANCE;
  }

  public RelNode flattenTypes(RelOptPlanner planner, RelNode rootRel,
      boolean restructure) {
    RelNode root2 =
        planner.changeTraits(rootRel,
            rootRel.getTraitSet().plus(SparkRel.CONVENTION).simplify());
    return planner.changeTraits(root2, rootRel.getTraitSet().simplify());
  }

  public void registerRules(RuleSetBuilder builder) {
    for (RelOptRule rule : SparkRules.rules()) {
      builder.addRule(rule);
    }
    builder.removeRule(EnumerableRules.ENUMERABLE_VALUES_RULE);
  }

  public Object sparkContext() {
    return sparkContext;
  }

  public boolean enabled() {
    return true;
  }

  public ArrayBindable compile(ClassDeclaration expr, String s) {
    final String className = "CalciteProgram" + classId.getAndIncrement();
    final String classFileName = className + ".java";
    String source = "public class " + className + "\n"
        + "    implements " + ArrayBindable.class.getName()
        + ", " + Serializable.class.getName()
        + " {\n"
        + s + "\n"
        + "}\n";

    if (CalciteSystemProperty.DEBUG.value()) {
      Util.debugCode(System.out, source);
    }

    JaninoCompiler compiler = new JaninoCompiler();
    compiler.getArgs().setDestdir(CLASS_DIR.getAbsolutePath());
    compiler.getArgs().setSource(source, classFileName);
    compiler.getArgs().setFullClassName(className);
    compiler.compile();
    try {
      @SuppressWarnings("unchecked")
      final Class<ArrayBindable> clazz =
          (Class<ArrayBindable>) compiler.getClassLoader().loadClass(className);
      final Constructor<ArrayBindable> constructor = clazz.getConstructor();
      return constructor.newInstance();
    } catch (ClassNotFoundException | InstantiationException
        | IllegalAccessException | NoSuchMethodException
        | InvocationTargetException e) {
      throw new RuntimeException(e);
    }
  }
}