path: root/src/main/java/ftbsc/lll/processor/tools/ASTUtils.java

package ftbsc.lll.processor.tools;

import com.squareup.javapoet.*;
import ftbsc.lll.exceptions.AmbiguousDefinitionException;
import ftbsc.lll.exceptions.MappingNotFoundException;
import ftbsc.lll.exceptions.TargetNotFoundException;
import ftbsc.lll.processor.annotations.FindField;
import ftbsc.lll.processor.annotations.FindMethod;
import ftbsc.lll.processor.annotations.Patch;
import ftbsc.lll.processor.annotations.Target;
import ftbsc.lll.processor.tools.obfuscation.ObfuscationMapper;

import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.*;
import javax.lang.model.type.MirroredTypeException;
import javax.lang.model.type.MirroredTypesException;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.util.Elements;
import java.lang.annotation.Annotation;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.function.Function;
import java.util.stream.Collectors;

import static ftbsc.lll.processor.tools.JavaPoetUtils.descriptorFromExecutableElement;
import static ftbsc.lll.processor.tools.JavaPoetUtils.methodDescriptorFromParams;

/**
 * Collection of AST-related static utils that didn't really fit into the main class.
 */
public class ASTUtils {
   /**
    * Finds, among the methods of a class cl, the one annotated with ann, and tries to build
    * a {@link ExecutableElement} from it.
    * @param cl the {@link ExecutableElement} for the class containing the desired method
    * @param ann the {@link Class} corresponding to the desired annotation
    * @return a {@link List} of {@link MethodSpec}s annotated with the given annotation
    * @since 0.2.0
    */
   public static List<ExecutableElement> findAnnotatedMethods(TypeElement cl, Class<? extends Annotation> ann) {
      return cl.getEnclosedElements()
         .stream()
         .filter(e -> e.getAnnotationsByType(ann).length != 0)
         .map(e -> (ExecutableElement) e)
         .collect(Collectors.toList());
   }

   /**
    * Maps a {@link javax.lang.model.element.Modifier} to its reflective
    * {@link java.lang.reflect.Modifier} equivalent.
    * @param m the {@link Modifier} to map
    * @return an integer representing the modifier
    * @see java.lang.reflect.Modifier
    * @since 0.2.0
    */
   public static int mapModifier(Modifier m) {
      switch(m) {
         case PUBLIC:
            return java.lang.reflect.Modifier.PUBLIC;
         case PROTECTED:
            return java.lang.reflect.Modifier.PROTECTED;
         case PRIVATE:
            return java.lang.reflect.Modifier.PRIVATE;
         case ABSTRACT:
            return java.lang.reflect.Modifier.ABSTRACT;
         case STATIC:
            return java.lang.reflect.Modifier.STATIC;
         case FINAL:
            return java.lang.reflect.Modifier.FINAL;
         case TRANSIENT:
            return java.lang.reflect.Modifier.TRANSIENT;
         case VOLATILE:
            return java.lang.reflect.Modifier.VOLATILE;
         case SYNCHRONIZED:
            return java.lang.reflect.Modifier.SYNCHRONIZED;
         case NATIVE:
            return java.lang.reflect.Modifier.NATIVE;
         case STRICTFP:
            return java.lang.reflect.Modifier.STRICT;
         default:
            return 0;
      }
   }

   /**
    * Safely extracts a {@link Class} from an annotation and gets its fully qualified name.
    * @param ann the annotation containing the class
    * @param fun the annotation function returning the class
    * @return the fully qualified name of the given class
    * @since 0.3.0
    */
   public static <T extends Annotation> String getClassFullyQualifiedName(T ann, Function<T, Class<?>> fun) {
      try {
         return fun.apply(ann).getCanonicalName();
      } catch(MirroredTypeException e) {
         return e.getTypeMirror().toString();
      }
   }

   /**
    * Safely extracts a {@link Class} array from an annotation.
    * @param ann the annotation containing the class
    * @param fun the annotation function returning the class
    * @param elementUtils the element utils corresponding to the {@link ProcessingEnvironment}
    * @return a list of {@link TypeMirror}s representing the classes
    * @since 0.3.0
    */
   public static <T extends Annotation> List<TypeMirror> classArrayFromAnnotation(T ann, Function<T, Class<?>[]> fun, Elements elementUtils) {
      List<TypeMirror> params = new ArrayList<>();
      try {
         params.addAll(Arrays.stream(fun.apply(ann))
            .map(Class::getCanonicalName)
            .map(fqn -> elementUtils.getTypeElement(fqn).asType())
            .collect(Collectors.toList()));
      } catch(MirroredTypesException e) {
         params.addAll(e.getTypeMirrors());
      }
      return params;
   }


   /**
    * Finds the class name and maps it to the correct format.
    * @param name the fully qualified name of the class to convert
    * @param mapper the {@link ObfuscationMapper} to use, may be null
    * @return the fully qualified class name
    * @since 0.3.0
    */
   public static String findClassName(String name, ObfuscationMapper mapper) {
      try {
         return mapper == null ? name : mapper.obfuscateClass(name).replace('/', '.');
      } catch(MappingNotFoundException e) {
         return name;
      }
   }

   /**
    * Finds the class name and maps it to the correct format.
    * @param patchAnn  the {@link Patch} annotation containing target class info
    * @param finderAnn an annotation containing metadata about the target, may be null
    * @param parentFun the function to get the parent from the finderAnn
    * @return the fully qualified class name
    * @since 0.3.0
    */
   private static <T extends Annotation> String findClassName(Patch patchAnn, T finderAnn, Function<T, Class<?>> parentFun) {
      String fullyQualifiedName;
      if(finderAnn != null) {
         fullyQualifiedName = getClassFullyQualifiedName(finderAnn, parentFun);
         if(!fullyQualifiedName.equals("java.lang.Object"))
            return findClassName(fullyQualifiedName, null);
      }
      fullyQualifiedName = getClassFullyQualifiedName(patchAnn, Patch::value);
      return findClassName(fullyQualifiedName, null);
   }

   /**
    * Finds the member name and maps it to the correct format.
    * @param parentFQN the already mapped FQN of the parent class
    * @param memberName the name of the member
    * @param mapper the {@link ObfuscationMapper} to use, may be null
    * @return the internal class name
    * @since 0.3.0
    */
   public static String findMemberName(String parentFQN, String memberName, String methodDescriptor, ObfuscationMapper mapper) {
      try {
         return mapper == null ? memberName : mapper.obfuscateMember(parentFQN, memberName, methodDescriptor);
      } catch(MappingNotFoundException e) {
         return memberName;
      }
   }

   /**
    * Finds a method given name, container and descriptor.
    * @param parentFQN the fully qualified name of the parent class of the method
    * @param name the name to search for
    * @param descr the descriptor to search for
    * @param strict whether the search should be strict (see {@link Target#strict()} for more info)
    * @param env the {@link ProcessingEnvironment} to perform the operation in
    * @return the desired method, if it exists
    * @throws AmbiguousDefinitionException if it finds more than one candidate
    * @throws TargetNotFoundException if it finds no valid candidate
    * @since 0.3.0
    */
   private static ExecutableElement findMethod(String parentFQN, String name, String descr, boolean strict, ProcessingEnvironment env) {
      TypeElement parent = env.getElementUtils().getTypeElement(parentFQN);
      if(parent == null)
         throw new AmbiguousDefinitionException(String.format("Could not find parent class %s!", parentFQN));

      //try to find by name
      List<ExecutableElement> candidates = parent.getEnclosedElements()
         .stream()
         .filter(e -> e instanceof ExecutableElement)
         .map(e -> (ExecutableElement) e)
         .filter(e -> e.getSimpleName().contentEquals(name))
         .collect(Collectors.toList());
      if(candidates.size() == 0)
         throw new TargetNotFoundException(String.format("%s %s", name, descr));
      if(candidates.size() == 1 && !strict)
         return candidates.get(0);
      if(descr == null) {
         throw new AmbiguousDefinitionException(
            String.format("Found %d methods named %s in class %s!", candidates.size(), name, parentFQN)
         );
      } else {
         candidates = candidates.stream()
            .filter(strict
               ? c -> descr.equals(descriptorFromExecutableElement(c))
               : c -> descr.split("\\)")[0].equalsIgnoreCase(descriptorFromExecutableElement(c).split("\\)")[0])
            ).collect(Collectors.toList());
         if(candidates.size() == 0)
            throw new TargetNotFoundException(String.format("%s %s", name, descr));
         if(candidates.size() > 1)
            throw new AmbiguousDefinitionException(
               String.format("Found %d methods named %s in class %s!", candidates.size(), name, parentFQN)
            );
         return candidates.get(0);
      }
   }

   /**
    * Finds the real class member (field or method) corresponding to a stub annotated with
    * {@link Target} or {@link FindMethod} or {@link FindField}.
    * @param stub the {@link ExecutableElement} for the stub
    * @param env the {@link ProcessingEnvironment} to perform the operation in
    * @return the {@link Element} corresponding to the method or field
    * @throws AmbiguousDefinitionException if it finds more than one candidate
    * @throws TargetNotFoundException if it finds no valid candidate
    * @since 0.3.0
    */
   public static Element findMemberFromStub(ExecutableElement stub, ProcessingEnvironment env) {
      //the parent always has a @Patch annotation
      Patch patchAnn = stub.getEnclosingElement().getAnnotation(Patch.class);
      //there should ever only be one of these
      Target targetAnn = stub.getAnnotation(Target.class); //if this is null strict mode is always disabled
      FindMethod findMethodAnn = stub.getAnnotation(FindMethod.class); //this may be null, it means no fallback info
      FindField findFieldAnn = stub.getAnnotation(FindField.class);
      String parentFQN, memberName;
      if(findFieldAnn == null) { //methods
         parentFQN = findClassName(patchAnn, findMethodAnn, FindMethod::parent);
         String methodDescriptor =
            findMethodAnn != null
               ? methodDescriptorFromParams(findMethodAnn, FindMethod::params, env.getElementUtils())
               : descriptorFromExecutableElement(stub);
         memberName =
            findMethodAnn != null && !findMethodAnn.name().equals("")
               ? findMethodAnn.name()
               : stub.getSimpleName().toString();
         return findMethod(
            parentFQN,
            memberName,
            methodDescriptor,
            targetAnn != null && targetAnn.strict(),
            env
         );
      } else { //fields
         parentFQN = findClassName(patchAnn, findFieldAnn, FindField::parent);
         memberName = findFieldAnn.name().equals("")
            ? stub.getSimpleName().toString()
            : findFieldAnn.name();
         TypeElement parent = env.getElementUtils().getTypeElement(parentFQN);
         List<VariableElement> candidates =
            parent.getEnclosedElements()
               .stream()
               .filter(f -> f instanceof VariableElement)
               .filter(f -> f.getSimpleName().contentEquals(memberName))
               .map(f -> (VariableElement) f)
               .collect(Collectors.toList());
         if(candidates.size() == 0)
            throw new TargetNotFoundException(stub.getSimpleName().toString());
         else return candidates.get(0); //there can only ever be one
      }
   }
}