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Language Server Protocol implementation for 1C (BSL) - 1C:Enterprise 8 and OneScript languages.
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/*
 * This file is a part of BSL Language Server.
 *
 * Copyright (c) 2018-2024
 * Alexey Sosnoviy , Nikita Fedkin  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.diagnostics;

import com.github._1c_syntax.bsl.languageserver.diagnostics.metadata.DiagnosticMetadata;
import com.github._1c_syntax.bsl.languageserver.diagnostics.metadata.DiagnosticParameter;
import com.github._1c_syntax.bsl.languageserver.diagnostics.metadata.DiagnosticSeverity;
import com.github._1c_syntax.bsl.languageserver.diagnostics.metadata.DiagnosticTag;
import com.github._1c_syntax.bsl.languageserver.diagnostics.metadata.DiagnosticType;
import com.github._1c_syntax.bsl.languageserver.providers.FormatProvider;
import com.github._1c_syntax.bsl.languageserver.utils.Ranges;
import com.github._1c_syntax.bsl.languageserver.utils.Trees;
import com.github._1c_syntax.bsl.languageserver.utils.expressiontree.BinaryOperationNode;
import com.github._1c_syntax.bsl.languageserver.utils.expressiontree.BslExpression;
import com.github._1c_syntax.bsl.languageserver.utils.expressiontree.BslOperator;
import com.github._1c_syntax.bsl.languageserver.utils.expressiontree.ExpressionNodeType;
import com.github._1c_syntax.bsl.languageserver.utils.expressiontree.NodeEqualityComparer;
import com.github._1c_syntax.bsl.languageserver.utils.expressiontree.TransitiveOperationsIgnoringComparer;
import com.github._1c_syntax.bsl.languageserver.utils.expressiontree.UnaryOperationNode;
import com.github._1c_syntax.bsl.parser.BSLParser;
import lombok.RequiredArgsConstructor;
import org.antlr.v4.runtime.Token;
import org.eclipse.lsp4j.FormattingOptions;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;

@DiagnosticMetadata(
  type = DiagnosticType.ERROR,
  severity = DiagnosticSeverity.MAJOR,
  minutesToFix = 5,
  tags = {
    DiagnosticTag.SUSPICIOUS
  }
)
@RequiredArgsConstructor
public class IdenticalExpressionsDiagnostic extends AbstractExpressionTreeDiagnostic {

  private static final int MIN_EXPRESSION_SIZE = 3;
  private static final String POPULAR_DIVISORS_DEFAULT_VALUE = "60, 1024";

  @DiagnosticParameter(
    type = String.class,
    defaultValue = POPULAR_DIVISORS_DEFAULT_VALUE
  )
  private Set popularDivisors = parseCommaSeparatedSet(POPULAR_DIVISORS_DEFAULT_VALUE);
  private final FormatProvider formatProvider;

  private final List binaryOperations = new ArrayList<>();
  private BSLParser.ExpressionContext expressionContext;

  private static Set parseCommaSeparatedSet(String values) {
    if (values.trim().isEmpty()) {
      return Collections.emptySet();
    }

    return Arrays.stream(values.split(","))
      .map(String::trim)
      .collect(Collectors.toSet());

  }

  @Override
  public void configure(Map configuration) {

    String popularDivisorsValue =
      (String) configuration.getOrDefault("popularDivisors", POPULAR_DIVISORS_DEFAULT_VALUE);

    popularDivisors = parseCommaSeparatedSet(popularDivisorsValue);
  }

  @Override
  protected ExpressionVisitorDecision onExpressionEnter(BSLParser.ExpressionContext ctx) {
    expressionContext = ctx;
    return sufficientSize(ctx)? ExpressionVisitorDecision.SKIP : ExpressionVisitorDecision.ACCEPT;
  }

  @Override
  protected void visitTopLevelExpression(BslExpression node) {
    binaryOperations.clear();
    super.visitTopLevelExpression(node);

    var comparer = new TransitiveOperationsIgnoringComparer();
    comparer.logicalOperationsAsTransitive(true);
    binaryOperations
      .stream()
      .filter(x -> checkEquality(comparer, x))
      .forEach(x -> diagnosticStorage.addDiagnostic(expressionContext,
        info.getMessage(x.getRepresentingAst().getText(), getOperandText(x))));
  }

  @Override
  protected void visitBinaryOperation(BinaryOperationNode node) {
    var operator = node.getOperator();

    // разыменования отбросим, хотя comparer их и не зачтет, но для производительности
    // лучше выкинем их сразу
    if (operator == BslOperator.DEREFERENCE || operator == BslOperator.INDEX_ACCESS) {
      return;
    }

    // одинаковые умножения и сложения - не считаем, см. тесты
    if (operator != BslOperator.ADD && operator != BslOperator.MULTIPLY) {
      binaryOperations.add(node);
    }

    super.visitBinaryOperation(node);
  }

  private boolean checkEquality(NodeEqualityComparer comparer, BinaryOperationNode node) {

    var justEqual = comparer.areEqual(node.getLeft(), node.getRight());
    if (justEqual) {
      // отбрасывает популярные деления на время и байты
      return !isPopularQuantification(node);
    }

    if (isComplementary(node)) {
      // left не должен встречаться ни в одной из подветок right
      var searchableLeft = node.getLeft();
      BinaryOperationNode complementaryNode = node.getRight().cast();
      while (true) {
        var equal = comparer.areEqual(searchableLeft, complementaryNode.getLeft()) ||
          comparer.areEqual(searchableLeft, complementaryNode.getRight());

        if (equal) {
          return true;
        }

        if (isComplementary(complementaryNode)) {
          complementaryNode = complementaryNode.getRight().cast();
        } else {
          break;
        }
      }
    }

    return false;
  }

  private boolean isPopularQuantification(BinaryOperationNode node) {
    if (popularDivisors.isEmpty()) {
      return false; // выключено игнорирование популярных делителей
    }

    if (node.getOperator() == BslOperator.DIVIDE
      && node.getLeft().getNodeType() == ExpressionNodeType.LITERAL) {

      // проверяем только левое, т.к. принципиальное равенство L и R проверено выше по стеку
      // left заведомо равен right
      var leftAst = (BSLParser.ConstValueContext) node.getLeft().getRepresentingAst();
      var number = leftAst.numeric();
      if (number != null) {
        var text = number.getText();
        return popularDivisors.contains(text);
      }

    }

    return false;
  }

  private String getOperandText(BinaryOperationNode node) {

    assert node.getRepresentingAst() != null;

    var pairedOperand = node.getLeft();
    List tokens = new ArrayList<>();

    fillTokens(pairedOperand, tokens);

    // todo: очень плохое место для этого метода
    return formatProvider.getNewText(
      tokens, documentContext.getScriptVariantLocale(), Ranges.create(), 0, new FormattingOptions()).trim();

  }

  private static List collectTokensForUnaryOperation(UnaryOperationNode unary, List tokens) {
    tokens.addAll(Trees.getTokens(unary.getRepresentingAst()));
    fillTokens(unary.getOperand(), tokens);
    return tokens;
  }

  private static List collectTokensForBinaryOperation(BinaryOperationNode binary, List tokens) {

    fillTokens(binary.getLeft(), tokens);
    tokens.addAll(Trees.getTokens(binary.getRepresentingAst()));
    fillTokens(binary.getRight(), tokens);

    return tokens;
  }

  private static void fillTokens(BslExpression node, List collection) {
    if (node instanceof BinaryOperationNode) {
      collectTokensForBinaryOperation(node.cast(), collection);
    } else if (node instanceof UnaryOperationNode) {
      collectTokensForUnaryOperation(node.cast(), collection);
    } else {
      collection.addAll(Trees.getTokens(node.getRepresentingAst()));
    }
  }

  private static boolean isComplementary(BinaryOperationNode binary) {
    var operator = binary.getOperator();
    if ((operator == BslOperator.OR || operator == BslOperator.AND)
      && binary.getRight() instanceof BinaryOperationNode) {
      return ((BinaryOperationNode) binary.getRight()).getOperator() == operator;
    }

    return false;
  }

  private static boolean sufficientSize(BSLParser.ExpressionContext ctx) {
    return ctx.children.size() < MIN_EXPRESSION_SIZE;
  }
}