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/*
 * SonarQube Python Plugin
 * Copyright (C) 2011-2024 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the Sonar Source-Available License Version 1, as published by SonarSource SA.
 *
 * This program 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 Sonar Source-Available License for more details.
 *
 * You should have received a copy of the Sonar Source-Available License
 * along with this program; if not, see https://sonarsource.com/license/ssal/
 */
package org.sonar.python.cfg;

import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import org.sonar.plugins.python.api.cfg.CfgBlock;
import org.sonar.plugins.python.api.tree.Token;
import org.sonar.plugins.python.api.tree.Tree;

public abstract class PythonCfgBlock implements CfgBlock {

  private final LinkedList elements = new LinkedList<>();
  private final Set predecessors = new LinkedHashSet<>();

  @Override
  public Set predecessors() {
    return predecessors;
  }

  @Override
  public List elements() {
    return elements;
  }

  public void addElement(Tree tree) {
    elements.addFirst(tree);
  }

  public boolean isEmptyBlock() {
    return elements.isEmpty() && successors().size() == 1;
  }

  PythonCfgBlock firstNonEmptySuccessor() {
    PythonCfgBlock block = this;
    Set skippedBlocks = new HashSet<>();
    while (block.isEmptyBlock()) {
      PythonCfgBlock next = (PythonCfgBlock) block.successors().iterator().next();
      if (skippedBlocks.add(next)) {
        block = next;
      } else {
        return block;
      }
    }
    return block;
  }

  /**
   * Replace successors based on a replacement map.
   * This method is used when we remove empty blocks:
   * we have to replace empty successors in the remaining blocks by non-empty successors.
   */
  abstract void replaceSuccessors(Map replacements);

  @Override
  public String toString() {
    return toStringDisplayPosition() + elements.stream().map(elem -> elem.getKind().toString()).collect(Collectors.joining(";"));
  }

  protected String toStringDisplayPosition() {
    if (elements.isEmpty()) {
      return "empty";
    }
    Token token = elements.get(0).firstToken();
    return token.line() + ":" + token.column() + ":";
  }

  void addPredecessor(PythonCfgBlock block) {
    predecessors.add(block);
  }
}