content: /*
   * This file is a part of BSL Language Server.
   *
   * Copyright (c) 2018-2025
   * Alexey Sosnoviy <labotamy@gmail.com>, Nikita Fedkin <nixel2007@gmail.com> and contributors
   *
   * SPDX-License-Identifier: LGPL-3.0-or-later
   *
   * BSL Language Server is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 3.0 of the License, or (at your option) any later version.
   *
   * BSL Language Server is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with BSL Language Server.
   */
  package com.github._1c_syntax.bsl.languageserver.cfg;
  
  import lombok.Getter;
  import lombok.RequiredArgsConstructor;
  
  import java.util.Set;
  
  @RequiredArgsConstructor
  public class ControlFlowGraphWalker {
    private final ControlFlowGraph graph;
  
    @Getter
    private CfgVertex currentNode;
  
    public void start() {
      currentNode = graph.getEntryPoint();
    }
  
    public Set<CfgEdge> availableRoutes() {
      return graph.outgoingEdgesOf(currentNode);
    }
  
    public CfgEdge walkNext() {
      var edges = availableRoutes();
      var edgeOrNot = edges.stream()
        .filter(x -> x.getType() == CfgEdgeType.DIRECT)
        .reduce((CfgEdge a, CfgEdge b) -> {
          throw new IllegalStateException("Multiple DIRECT outgoing edges in " + currentNode);
        });
  
      if (edgeOrNot.isPresent()) {
        currentNode = graph.getEdgeTarget(edgeOrNot.get());
        return edgeOrNot.get();
      }
  
      throw new IllegalStateException("DIRECT edge is not found for node " + currentNode);
    }
  
    public CfgEdge walkNext(CfgEdgeType edgeType) {
      var edgeOrNot = availableRoutes().stream()
        .filter(x -> x.getType() == edgeType)
        .findAny();
  
      if (edgeOrNot.isPresent()) {
        currentNode = graph.getEdgeTarget(edgeOrNot.get());
        return edgeOrNot.get();
      }
  
      throw new IllegalStateException("Edge is not found for node " + currentNode);
    }
  
    public void walkTo(CfgVertex target) {
      currentNode = target;
    }
  
    public boolean isOnBranch() {
      return currentNode instanceof BranchingVertex;
    }
  }
  