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/*
 * Copyright © 2021-present Arcade Data Ltd ([email protected])
 *
 * 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.
 *
 * SPDX-FileCopyrightText: 2021-present Arcade Data Ltd ([email protected])
 * SPDX-License-Identifier: Apache-2.0
 */
package com.arcadedb.query.sql.executor;

import com.arcadedb.database.Document;
import com.arcadedb.database.Identifiable;
import com.arcadedb.query.sql.parser.PInteger;
import com.arcadedb.query.sql.parser.TraverseProjectionItem;
import com.arcadedb.query.sql.parser.WhereClause;

import java.util.*;

/**
 * Created by luigidellaquila on 26/10/16.
 */
public class DepthFirstTraverseStep extends AbstractTraverseStep {

  public DepthFirstTraverseStep(final List projections, final WhereClause whileClause, final PInteger maxDepth,
      final CommandContext context, final boolean profilingEnabled) {
    super(projections, whileClause, maxDepth, context, profilingEnabled);
  }

  @Override
  protected void fetchNextEntryPoints(final CommandContext context, final int nRecords) {
    final ResultSet nextN = getPrev().syncPull(context, nRecords);
    while (nextN.hasNext()) {
      final Result item = toTraverseResult(nextN.next());
      if (item == null)
        continue;

      ((ResultInternal) item).setMetadata("$depth", 0);

      final List stack = new ArrayList();
      item.getIdentity().ifPresent(x -> stack.add(x));
      ((ResultInternal) item).setMetadata("$stack", stack);

      final List path = new ArrayList<>();
      if (item.getIdentity().isPresent()) {
        path.add(item.getIdentity().get());
      } else if (item.getProperty("@rid") != null) {
        path.add(item.getProperty("@rid"));
      }
      ((ResultInternal) item).setMetadata("$path", path);

      if (item.isElement() && !traversed.contains(item.getElement().get().getIdentity())) {
        tryAddEntryPointAtTheEnd(item, context);
        traversed.add(item.getElement().get().getIdentity());
      } else if (item.getProperty("@rid") != null && item.getProperty("@rid") instanceof Identifiable) {
        tryAddEntryPointAtTheEnd(item, context);
        traversed.add(((Identifiable) item.getProperty("@rid")).getIdentity());
      }
    }
  }

  private Result toTraverseResult(final Result item) {
    TraverseResult res = null;
    if (item instanceof TraverseResult)
      res = (TraverseResult) item;
    else if (item.isElement() && item.getElement().get().getIdentity() != null) {
      res = new TraverseResult(item.getElement().get());
      res.depth = 0;
    } else if (item.getPropertyNames().size() == 1) {
      final Object val = item.getProperty(item.getPropertyNames().iterator().next());
      if (val instanceof Identifiable) {
        res = new TraverseResult((Document) ((Identifiable) val).getRecord());
        res.depth = 0;
        res.setMetadata("$depth", 0);
      }
    } else {
      res = new TraverseResult();
      for (final String key : item.getPropertyNames())
        res.setProperty(key, item.getProperty(key));

      for (final String md : item.getMetadataKeys())
        res.setMetadata(md, item.getMetadata(md));
    }

    return res;
  }

  @Override
  protected void fetchNextResults(final CommandContext context, final int nRecords) {
    if (!this.entryPoints.isEmpty()) {
      final TraverseResult item = (TraverseResult) this.entryPoints.remove(0);
      this.results.add(item);
      for (final TraverseProjectionItem proj : projections) {
        final Object nextStep = proj.execute(item, context);
        final Integer depth = item.depth != null ? item.depth : (Integer) item.getMetadata("$depth");
        if (this.maxDepth == null || this.maxDepth.getValue().intValue() > depth)
          addNextEntryPoints(nextStep, depth + 1, (List) item.getMetadata("$path"), (List) item.getMetadata("$stack"), context);
      }
    }
  }

  private void addNextEntryPoints(final Object nextStep, final int depth, final List path, final List stack,
      final CommandContext context) {
    if (nextStep instanceof Identifiable)
      addNextEntryPoint(((Identifiable) nextStep), depth, path, stack, context);
    else if (nextStep instanceof Iterable)
      addNextEntryPoints(((Iterable) nextStep).iterator(), depth, path, stack, context);
    else if (nextStep instanceof Map)
      addNextEntryPoints(((Map) nextStep).values().iterator(), depth, path, stack, context);
    else if (nextStep instanceof Result)
      addNextEntryPoint(((Result) nextStep), depth, path, stack, context);
  }

  private void addNextEntryPoints(final Iterator nextStep, final int depth, final List path, final List stack,
      final CommandContext context) {
    while (nextStep.hasNext())
      addNextEntryPoints(nextStep.next(), depth, path, stack, context);
  }

  private void addNextEntryPoint(final Identifiable nextStep, final int depth, final List path, final List stack,
      final CommandContext context) {
    if (this.traversed.contains(nextStep.getIdentity()))
      return;

    final TraverseResult res = new TraverseResult((Document) nextStep);
    res.depth = depth;
    res.setMetadata("$depth", depth);

    final List newPath = new ArrayList<>(path);
    newPath.add(res.getIdentity().get());
    res.setMetadata("$path", newPath);

    final List newStack = new ArrayList();
    newStack.add(res.getIdentity().get());
    newStack.addAll(stack);
    //    for (int i = 0; i < newPath.size(); i++) {
    //      newStack.offerLast(newPath.get(i));
    //    }
    res.setMetadata("$stack", newStack);

    tryAddEntryPoint(res, context);
  }

  private void addNextEntryPoint(final Result nextStep, final int depth, final List path, final List stack,
      final CommandContext context) {
    if (!nextStep.isElement())
      return;

    if (this.traversed.contains(nextStep.getElement().get().getIdentity()))
      return;

    if (nextStep instanceof TraverseResult) {
      ((TraverseResult) nextStep).depth = depth;
      ((TraverseResult) nextStep).setMetadata("$depth", depth);
      final List newPath = new ArrayList<>(path);
      nextStep.getIdentity().ifPresent(x -> newPath.add(x.getIdentity()));
      ((TraverseResult) nextStep).setMetadata("$path", newPath);

      final List reverseStack = new ArrayList(newPath);
      Collections.reverse(reverseStack);
      final List newStack = new ArrayList(reverseStack);
      ((TraverseResult) nextStep).setMetadata("$stack", newStack);

      tryAddEntryPoint(nextStep, context);
    } else {
      final TraverseResult res = new TraverseResult(nextStep.getElement().get());
      res.depth = depth;
      res.setMetadata("$depth", depth);
      final List newPath = new ArrayList<>(path);
      nextStep.getIdentity().ifPresent(x -> newPath.add(x.getIdentity()));
      res.setMetadata("$path", newPath);

      final List reverseStack = new ArrayList(newPath);
      Collections.reverse(reverseStack);
      final List newStack = new ArrayList(reverseStack);
      res.setMetadata("$stack", newStack);
      tryAddEntryPoint(res, context);
    }
  }

  private void tryAddEntryPoint(final Result res, final CommandContext context) {
    if (whileClause == null || whileClause.matchesFilters(res, context)) {
      this.entryPoints.add(0, res);
    }

    if (res.isElement())
      traversed.add(res.getElement().get().getIdentity());
    else if (res.getProperty("@rid") != null && res.getProperty("@rid") instanceof Identifiable)
      traversed.add(((Identifiable) res.getProperty("@rid")).getIdentity());
  }

  private void tryAddEntryPointAtTheEnd(final Result res, final CommandContext context) {
    if (whileClause == null || whileClause.matchesFilters(res, context))
      this.entryPoints.add(res);

    if (res.isElement())
      traversed.add(res.getElement().get().getIdentity());
    else if (res.getProperty("@rid") != null && res.getProperty("@rid") instanceof Identifiable)
      traversed.add(((Identifiable) res.getProperty("@rid")).getIdentity());
  }

  @Override
  public String prettyPrint(final int depth, final int indent) {
    final String spaces = ExecutionStepInternal.getIndent(depth, indent);
    final StringBuilder result = new StringBuilder();
    result.append(spaces);
    result.append("+ DEPTH-FIRST TRAVERSE \n");
    result.append(spaces);
    result.append("  ").append(projections.toString());
    if (whileClause != null) {
      result.append("\n");
      result.append(spaces);
      result.append("WHILE ").append(whileClause);
    }
    return result.toString();
  }
}