/*
 * Copyright 2017 The Error Prone Authors.
 *
 * 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.
 */

package com.google.errorprone.bugpatterns;

import static com.google.common.collect.Streams.stream;
import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.Matchers.allOf;
import static com.google.errorprone.matchers.Matchers.not;
import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
import static com.google.errorprone.util.ASTHelpers.findSuperMethods;
import static com.google.errorprone.util.ASTHelpers.getReceiver;
import static com.google.errorprone.util.ASTHelpers.getSymbol;
import static com.google.errorprone.util.ASTHelpers.getType;
import static com.google.errorprone.util.ASTHelpers.hasAnnotation;
import static com.google.errorprone.util.ASTHelpers.isConsideredFinal;
import static com.google.errorprone.util.ASTHelpers.isSameType;
import static com.sun.source.tree.Tree.Kind.IDENTIFIER;
import static com.sun.source.tree.Tree.Kind.MEMBER_SELECT;
import static com.sun.source.tree.Tree.Kind.METHOD_INVOCATION;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableMap;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.CompilationUnitTreeMatcher;
import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.fixes.SuggestedFixes;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.util.ASTHelpers;
import com.google.errorprone.util.MoreAnnotations;
import com.sun.source.tree.AssignmentTree;
import com.sun.source.tree.CompilationUnitTree;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.IdentifierTree;
import com.sun.source.tree.MemberReferenceTree;
import com.sun.source.tree.MemberSelectTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.MethodTree;
import com.sun.source.tree.VariableTree;
import com.sun.source.util.TreePathScanner;
import com.sun.tools.javac.code.Attribute;
import com.sun.tools.javac.code.Flags;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.MethodSymbol;
import com.sun.tools.javac.code.Symbol.VarSymbol;
import com.sun.tools.javac.code.Type;
import com.sun.tools.javac.code.Types;
import java.util.Map;
import java.util.Optional;
import java.util.stream.Stream;
import javax.lang.model.element.Modifier;

/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
@BugPattern(name = "DoNotCall", summary = "This method should not be called.", severity = ERROR)
public class DoNotCallChecker extends BugChecker
    implements MethodTreeMatcher, CompilationUnitTreeMatcher {
  private static final Matcher<ExpressionTree> THREAD_RUN =
      instanceMethod().onDescendantOf("java.lang.Thread").named("run").withNoParameters();

  private static final Matcher<ExpressionTree> CALL_ON_SUPER =
      (invocation, state) -> {
        if (invocation.getKind() != METHOD_INVOCATION) {
          return false;
        }
        ExpressionTree select = ((MethodInvocationTree) invocation).getMethodSelect();
        if (select.getKind() != MEMBER_SELECT) {
          return false;
        }
        ExpressionTree receiver = ((MemberSelectTree) select).getExpression();
        if (receiver.getKind() != IDENTIFIER) {
          return false;
        }
        return ((IdentifierTree) receiver).getName().contentEquals("super");
      };

  // If your method cannot be annotated with @DoNotCall (e.g., it's a JDK or thirdparty method),
  // then add it to this Map with an explanation.
  private static final ImmutableMap<Matcher<ExpressionTree>, String> THIRD_PARTY_METHODS =
      ImmutableMap.<Matcher<ExpressionTree>, String>builder()
          .put(
              staticMethod()
                  .onClass("org.junit.Assert")
                  .named("assertEquals")
                  .withParameters("double", "double"),
              "This method always throws java.lang.AssertionError. Use assertEquals("
                  + "expected, actual, delta) to compare floating-point numbers")
          .put(
              staticMethod()
                  .onClass("org.junit.Assert")
                  .named("assertEquals")
                  .withParameters("java.lang.String", "double", "double"),
              "This method always throws java.lang.AssertionError. Use assertEquals("
                  + "String, expected, actual, delta) to compare floating-point numbers")
          .put(
              instanceMethod()
                  .onExactClass("java.lang.Thread")
                  .named("stop")
                  .withParameters("java.lang.Throwable"),
              "Thread.stop(Throwable) always throws an UnsupportedOperationException")
          .put(
              instanceMethod()
                  .onExactClass("java.sql.Date")
                  .namedAnyOf(
                      "getHours",
                      "getMinutes",
                      "getSeconds",
                      "setHours",
                      "setMinutes",
                      "setSeconds"),
              "The hour/minute/second getters and setters on java.sql.Date are guaranteed to throw"
                  + " IllegalArgumentException because java.sql.Date does not have a time"
                  + " component.")
          .put(
              instanceMethod().onExactClass("java.sql.Date").named("toInstant"),
              "sqlDate.toInstant() is not supported. Did you mean to call toLocalDate() instead?")
          .put(
              instanceMethod()
                  .onExactClass("java.sql.Time")
                  .namedAnyOf(
                      "getYear", "getMonth", "getDay", "getDate", "setYear", "setMonth", "setDate"),
              "The year/month/day getters and setters on java.sql.Time are guaranteed to throw"
                  + " IllegalArgumentException because java.sql.Time does not have a date"
                  + " component.")
          .put(
              instanceMethod().onExactClass("java.sql.Time").named("toInstant"),
              "sqlTime.toInstant() is not supported. Did you mean to call toLocalTime() instead?")
          .put(
              instanceMethod()
                  .onDescendantOf("java.util.SortedMap")
                  .namedAnyOf("putFirst", "putLast"),
              "Sorted collections do not support insertions with explicit positioning")
          .put(
              instanceMethod()
                  .onDescendantOf("java.util.SortedSet")
                  .namedAnyOf("addFirst", "addLast"),
              "Sorted collections do not support insertions with explicit positioning")
          .put(
              instanceMethod()
                  .onExactClass("java.util.concurrent.ThreadLocalRandom")
                  .named("setSeed"),
              "ThreadLocalRandom does not support setting a seed.")
          .put(
              instanceMethod()
                  .onExactClass("java.util.concurrent.locks.ReentrantReadWriteLock.ReadLock")
                  .named("newCondition"),
              "ReadLocks do not support conditions.")
          .put(
              instanceMethod().onExactClass("java.lang.StackTraceElement").named("getClass"),
              "Calling getClass on StackTraceElement returns the Class object for"
                  + " StackTraceElement, you probably meant to retrieve the class containing the"
                  + " execution point represented by this stack trace element using getClassName")
          .put(
              instanceMethod().onExactClass("java.lang.StackWalker").named("getClass"),
              "Calling getClass on StackWalker returns the Class object for StackWalker, you"
                  + " probably meant to retrieve the class containing the execution point"
                  + " represented by this StackWalker using getCallerClass")
          .put(
              instanceMethod().onExactClass("java.lang.StackWalker$StackFrame").named("getClass"),
              "Calling getClass on StackFrame returns the Class object for StackFrame, you probably"
                  + " meant to retrieve the class containing the execution point represented by"
                  + " this StackFrame using getClassName")
          .put(
              instanceMethod().onExactClass("java.lang.reflect.Constructor").named("getClass"),
              "Calling getClass on Constructor returns the Class object for Constructor, you"
                  + " probably meant to retrieve the class containing the constructor represented"
                  + " by this Constructor using getDeclaringClass")
          .put(
              instanceMethod().onExactClass("java.lang.reflect.Field").named("getClass"),
              "Calling getClass on Field returns the Class object for Field, you probably meant to"
                  + " retrieve the class containing the field represented by this Field using"
                  + " getDeclaringClass")
          .put(
              instanceMethod().onExactClass("java.lang.reflect.Method").named("getClass"),
              "Calling getClass on Method returns the Class object for Method, you probably meant"
                  + " to retrieve the class containing the method represented by this Method using"
                  + " getDeclaringClass")
          .put(
              instanceMethod()
                  .onExactClass("java.lang.reflect.ParameterizedType")
                  .named("getClass"),
              "Calling getClass on ParameterizedType returns the Class object for"
                  + " ParameterizedType, you probably meant to retrieve the class containing the"
                  + " method represented by this ParameterizedType using getRawType")
          .put(
              instanceMethod().onExactClass("java.beans.BeanDescriptor").named("getClass"),
              "Calling getClass on BeanDescriptor returns the Class object for BeanDescriptor, you"
                  + " probably meant to retrieve the class described by this BeanDescriptor using"
                  + " getBeanClass")
          .put(
              /*
               * LockInfo has a publicly visible subclass, MonitorInfo. It seems unlikely that
               * anyone is using getClass() in an attempt to distinguish the two. (If anyone is,
               * then it would make more sense to use instanceof, anyway.)
               */
              instanceMethod().onDescendantOf("java.lang.management.LockInfo").named("getClass"),
              "Calling getClass on LockInfo returns the Class object for LockInfo, you probably"
                  + " meant to retrieve the class of the object that is being locked using"
                  + " getClassName")
          /*
           * These methods are part of Guava, but we have to list them in this "thirdparty" section:
           * We can't annotate them with @DoNotCall because we can't override getClass.
           */
          .put(
              instanceMethod()
                  .onExactClass("com.google.common.reflect.ClassPath$ClassInfo")
                  .named("getClass"),
              "Calling getClass on ClassInfo returns the Class object for ClassInfo, you probably"
                  + " meant to retrieve the class described by this ClassInfo using getName or"
                  + " load")
          /*
           * Users of TypeToken have to create a subclass. The static type of their instance is
           * probably often still "TypeToken," but that may change as we see more usage of `var`. So
           * let's check subclasses, too. If anyone defines an overload of getClass on such a
           * subclass, this check will give that person a bad time in one additional way.
           */
          .put(
              instanceMethod()
                  .onDescendantOf("com.google.common.reflect.TypeToken")
                  .named("getClass"),
              "Calling getClass on TypeToken returns the Class object for TypeToken, you probably"
                  + " meant to retrieve the class described by this TypeToken using getRawType")
          .put(
              /*
               * A call to super.run() from a direct subclass of Thread is a no-op. That could be
               * worth telling the user about, but it's not as big a deal as "You meant to call
               * start()," so we ignore it here.
               *
               * (And if someone defines a MyThread class with a run() method that does something,
               * then a call to super.run() from a subclass of *MyThread* would *not* be a no-op,
               * and we wouldn't want to flag it. Still, *usually* it's likely to be useful to
               * report a warning even on subclasses of Thread, such as anonymous classes.)
               */
              allOf(THREAD_RUN, not(CALL_ON_SUPER)),
              "Calling run on Thread runs work on this thread, rather than the given thread, you"
                  + " probably meant to call start")
          .buildOrThrow();

  static final String DO_NOT_CALL = "com.google.errorprone.annotations.DoNotCall";

  @Override
  public Description matchMethod(MethodTree tree, VisitorState state) {
    MethodSymbol symbol = getSymbol(tree);
    if (hasAnnotation(tree, DO_NOT_CALL, state)) {
      if (symbol.getModifiers().contains(Modifier.PRIVATE)) {
        return buildDescription(tree)
            .setMessage("A private method that should not be called should simply be removed.")
            .build();
      }
      if (symbol.getModifiers().contains(Modifier.ABSTRACT)) {
        return NO_MATCH;
      }
      if (!ASTHelpers.methodCanBeOverridden(symbol)) {
        return NO_MATCH;
      }
      return buildDescription(tree)
          .setMessage("Methods annotated with @DoNotCall should be final or static.")
          .addFix(
              SuggestedFixes.addModifiers(tree, state, Modifier.FINAL)
                  .orElse(SuggestedFix.emptyFix()))
          .build();
    }
    return findSuperMethods(symbol, state.getTypes()).stream()
        .filter(s -> hasAnnotation(s, DO_NOT_CALL, state))
        .findAny()
        .map(
            s -> {
              String message =
                  String.format(
                      "Method overrides %s in %s which is annotated @DoNotCall,"
                          + " it should also be annotated.",
                      s.getSimpleName(), s.owner.getSimpleName());
              return buildDescription(tree)
                  .setMessage(message)
                  .addFix(
                      SuggestedFix.builder()
                          .addImport(DO_NOT_CALL)
                          .prefixWith(tree, "@DoNotCall ")
                          .build())
                  .build();
            })
        .orElse(NO_MATCH);
  }

  @Override
  public Description matchCompilationUnit(CompilationUnitTree tree, VisitorState state) {
    ImmutableListMultimap<VarSymbol, Type> assignedTypes = getAssignedTypes(state);

    new SuppressibleTreePathScanner<Void, Void>(state) {
      @Override
      public Void visitMethodInvocation(MethodInvocationTree tree, Void unused) {
        handleTree(tree, getSymbol(tree));
        return super.visitMethodInvocation(tree, null);
      }

      @Override
      public Void visitMemberReference(MemberReferenceTree tree, Void unused) {
        handleTree(tree, getSymbol(tree));
        return super.visitMemberReference(tree, null);
      }

      private void handleTree(ExpressionTree tree, MethodSymbol symbol) {
        for (Map.Entry<Matcher<ExpressionTree>, String> matcher : THIRD_PARTY_METHODS.entrySet()) {
          if (matcher.getKey().matches(tree, state)) {
            state.reportMatch(buildDescription(tree).setMessage(matcher.getValue()).build());
            return;
          }
        }
        checkTree(tree, symbol, state);
      }

      private void checkTree(ExpressionTree tree, MethodSymbol sym, VisitorState state) {
        mustNotCall(tree, sym, state).ifPresent(symbol -> handleDoNotCall(tree, symbol, state));
      }

      private void handleDoNotCall(ExpressionTree tree, Symbol symbol, VisitorState state) {
        String doNotCall = getDoNotCallValue(symbol);
        StringBuilder message =
            new StringBuilder(symbol.owner.toString())
                .append('.')
                .append(symbol.toString())
                .append(" should not be called");
        if (doNotCall.isEmpty()) {
          message.append(", see its documentation for details.");
        } else {
          message.append(": ").append(doNotCall);
        }
        state.reportMatch(buildDescription(tree).setMessage(message.toString()).build());
      }

      private Optional<Symbol> mustNotCall(
          ExpressionTree tree, MethodSymbol sym, VisitorState state) {
        if (hasAnnotation(sym, DO_NOT_CALL, state)) {
          return Optional.of(sym);
        }
        ExpressionTree receiver = getReceiver(tree);
        Symbol receiverSymbol = getSymbol(receiver);
        if (!(receiverSymbol instanceof VarSymbol)) {
          return Optional.empty();
        }
        ImmutableList<Type> assigned = assignedTypes.get((VarSymbol) receiverSymbol);
        if (!assigned.stream().allMatch(t -> isSameType(t, assigned.get(0), state))) {
          return Optional.empty();
        }
        Types types = state.getTypes();
        return assigned.stream()
            .flatMap(
                typeSeen ->
                    types.closure(typeSeen).stream()
                        .flatMap(
                            t ->
                                t.tsym.members() == null
                                    ? Stream.empty()
                                    : stream(t.tsym.members().getSymbolsByName(sym.name)))
                        .filter(
                            symbol ->
                                !sym.isStatic()
                                    && (sym.flags() & Flags.SYNTHETIC) == 0
                                    && hasAnnotation(symbol, DO_NOT_CALL, state)
                                    && symbol.overrides(
                                        sym,
                                        types.erasure(typeSeen).tsym,
                                        types,
                                        /* checkResult= */ true)))
            .findFirst();
      }
    }.scan(state.getPath(), null);
    return NO_MATCH;
  }

  private ImmutableListMultimap<VarSymbol, Type> getAssignedTypes(VisitorState state) {
    ImmutableListMultimap.Builder<VarSymbol, Type> assignedTypes = ImmutableListMultimap.builder();
    new TreePathScanner<Void, Void>() {
      @Override
      public Void visitVariable(VariableTree node, Void unused) {
        VarSymbol symbol = getSymbol(node);
        if (node.getInitializer() != null && isConsideredFinal(symbol)) {
          Type type = getType(node.getInitializer());
          if (type != null) {
            assignedTypes.put(symbol, type);
          }
        }
        return super.visitVariable(node, null);
      }

      @Override
      public Void visitAssignment(AssignmentTree node, Void unused) {
        Symbol assignee = getSymbol(node.getVariable());
        if (assignee instanceof VarSymbol && isConsideredFinal(assignee)) {
          Type type = getType(node.getExpression());
          if (type != null) {
            assignedTypes.put((VarSymbol) assignee, type);
          }
        }
        return super.visitAssignment(node, null);
      }
    }.scan(state.getPath(), null);
    return assignedTypes.build();
  }

  private static String getDoNotCallValue(Symbol symbol) {
    for (Attribute.Compound a : symbol.getRawAttributes()) {
      if (!a.type.tsym.getQualifiedName().contentEquals(DO_NOT_CALL)) {
        continue;
      }
      return MoreAnnotations.getAnnotationValue(a, "value")
          .flatMap(MoreAnnotations::asStringValue)
          .orElse("");
    }
    throw new IllegalStateException();
  }
}
