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/*
 * SonarQube Java
 * Copyright (C) 2012-2024 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.java.checks;

import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Deque;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import org.sonar.check.Rule;
import org.sonar.java.checks.helpers.ExpressionsHelper;
import org.sonar.plugins.java.api.IssuableSubscriptionVisitor;
import org.sonar.plugins.java.api.semantic.Symbol;
import org.sonar.plugins.java.api.semantic.Type;
import org.sonar.plugins.java.api.tree.BaseTreeVisitor;
import org.sonar.plugins.java.api.tree.ClassTree;
import org.sonar.plugins.java.api.tree.ExpressionTree;
import org.sonar.plugins.java.api.tree.LambdaExpressionTree;
import org.sonar.plugins.java.api.tree.MethodInvocationTree;
import org.sonar.plugins.java.api.tree.MethodTree;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.plugins.java.api.tree.TypeTree;
import org.sonar.plugins.java.api.tree.VariableTree;
import org.sonarsource.analyzer.commons.collections.MapBuilder;

@Rule(key = "S1149")
public class SynchronizedClassUsageCheck extends IssuableSubscriptionVisitor {

  private static final Map REPLACEMENTS = MapBuilder.newMap()
    .put("java.util.Vector", "\"ArrayList\" or \"LinkedList\"")
    .put("java.util.Hashtable", "\"HashMap\"")
    .put("java.lang.StringBuffer", "\"StringBuilder\"")
    .put("java.util.Stack", "\"Deque\"")
    .build();

  private final Deque> exclusions = new ArrayDeque<>();

  private final Set visited = new HashSet<>();

  @Override
  public List nodesToVisit() {
    // We register on compilation units to clear the visited set when scanning a new file
    return Arrays.asList(Tree.Kind.CLASS, Tree.Kind.COMPILATION_UNIT, Tree.Kind.ENUM, Tree.Kind.INTERFACE, Tree.Kind.ANNOTATION_TYPE);
  }

  @Override
  public void visitNode(Tree tree) {
    if (tree.is(Tree.Kind.COMPILATION_UNIT)) {
      // We clear the visited set when entering every file
      visited.clear();
      return;
    }
    ExclusionsVisitor exclusionsVisitor = new ExclusionsVisitor();
    tree.accept(exclusionsVisitor);
    Set currentClassExclusions = exclusionsVisitor.exclusions;
    if (!exclusions.isEmpty()) {
      currentClassExclusions.addAll(exclusions.peek());
    }
    exclusions.push(currentClassExclusions);
    tree.accept(new DeprecatedTypeVisitor());
  }

  @Override
  public void leaveNode(Tree tree) {
    if (tree.is(Tree.Kind.COMPILATION_UNIT)) {
      return;
    }
    exclusions.pop();
  }

  private static class ExclusionsVisitor extends BaseTreeVisitor {
    Set exclusions = new HashSet<>();

    @Override
    public void visitMethodInvocation(MethodInvocationTree tree) {
      if (tree.methodSymbol().isMethodSymbol() && tree.methodSymbol().declaration() == null) {
        String fqn = tree.methodSymbol().owner().type().fullyQualifiedName();
        if (isMethodFromJavaPackage(fqn)) {
          Symbol.MethodSymbol methodSymbol = tree.methodSymbol();
          List types = new ArrayList<>(methodSymbol.parameterTypes());
          Symbol.TypeSymbol returnType = methodSymbol.returnType();
          if (returnType != null) {
            types.add(returnType.type());
          }
          types.forEach(t -> exclusions.addAll(REPLACEMENTS.keySet().stream().filter(t::isSubtypeOf).collect(Collectors.toSet())));
        }
      }
      super.visitMethodInvocation(tree);
    }

    private static boolean isMethodFromJavaPackage(String fqn) {
      return fqn.startsWith("java") && !REPLACEMENTS.containsKey(fqn);
    }
  }

  private class DeprecatedTypeVisitor extends BaseTreeVisitor {

    private Deque> overridingMethodTypes = new ArrayDeque<>();

    @Override
    public void visitClass(ClassTree tree) {
      TypeTree superClass = tree.superClass();
      if (superClass != null) {
        reportIssueOnDeprecatedType(ExpressionsHelper.reportOnClassTree(tree), superClass.symbolType());
      }

      scan(tree.members());
    }

    @Override
    public void visitMethod(MethodTree tree) {
      TypeTree returnTypeTree = tree.returnType();
      boolean isConstructor = tree.is(Tree.Kind.CONSTRUCTOR);
      if (isOverriding(tree) && !isConstructor) {
        overridingMethodTypes.push(collectOverridingMethodExclusions(tree, returnTypeTree));
      } else {
        overridingMethodTypes.push(Collections.emptySet());
        if (!isConstructor) {
          reportIssueOnDeprecatedType(returnTypeTree, returnTypeTree.symbolType());
        }
        scan(tree.parameters());
      }
      scan(tree.block());
      overridingMethodTypes.pop();
    }

    private Set collectOverridingMethodExclusions(MethodTree methodTree, TypeTree returnType) {
      var methodTypes = new HashSet();
      methodTypes.add(returnType.symbolType().fullyQualifiedName());
      methodTree.parameters().stream()
        .map(param -> param.type().symbolType().fullyQualifiedName())
        .forEach(methodTypes::add);
      return methodTypes;
    }

    private boolean isOverriding(MethodTree tree) {
      // In case it can not be determined (isOverriding returns null), return false to avoid FP.
      return Boolean.TRUE.equals(tree.isOverriding());
    }

    @Override
    public void visitVariable(VariableTree tree) {
      ExpressionTree initializer = tree.initializer();
      if (!reportIssueOnDeprecatedType(tree.type(), tree.symbol().type()) && initializer != null && !initializer.is(Tree.Kind.METHOD_INVOCATION)) {
        reportIssueOnDeprecatedType(initializer, initializer.symbolType());
      }
    }

    @Override
    public void visitLambdaExpression(LambdaExpressionTree lambdaExpressionTree) {
      // Skip parameter types
      scan(lambdaExpressionTree.body());
    }

    private boolean reportIssueOnDeprecatedType(Tree tree, Type type) {
      if (visited.contains(tree) || isAllowedByOverridingSignature(type)) {
        return false;
      }
      visited.add(tree);
      if (isDeprecatedType(type)) {
        reportIssue(tree, "Replace the synchronized class \"" + type.name() + "\" by an unsynchronized one such as " + REPLACEMENTS.get(type.fullyQualifiedName()) + ".");
        return true;
      }
      return false;
    }

    private boolean isAllowedByOverridingSignature(Type type) {
      return !overridingMethodTypes.isEmpty() && overridingMethodTypes.peek().contains(type.fullyQualifiedName());
    }

    private boolean isDeprecatedType(Type symbolType) {
      if (symbolType.isClass()) {
        for (String deprecatedType : REPLACEMENTS.keySet()) {
          if (symbolType.is(deprecatedType)) {
            return !exclusions.peek().contains(deprecatedType);
          }
        }
      }
      return false;
    }

  }
}