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

package ftbsc.lll.processor.tools;

import ftbsc.lll.exceptions.AmbiguousDefinitionException;
import ftbsc.lll.exceptions.MappingNotFoundException;
import ftbsc.lll.exceptions.NotAProxyException;
import ftbsc.lll.exceptions.TargetNotFoundException;
import ftbsc.lll.processor.annotations.Find;
import ftbsc.lll.processor.annotations.Patch;
import ftbsc.lll.processor.annotations.Target;
import ftbsc.lll.processor.tools.containers.ClassContainer;
import ftbsc.lll.processor.tools.obfuscation.ObfuscationMapper;
import ftbsc.lll.proxies.ProxyType;

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.Collection;
import java.util.List;
import java.util.function.Function;
import java.util.stream.Collectors;

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

/**
 * 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
    * an {@link Element} from it.
    * @param parent the parent {@link Element} to the desired element
    * @param ann the {@link Class} corresponding to the desired annotation
    * @param <T> the type of {@link Element} to use
    * @return a {@link List} of {@link Element}s annotated with the given annotation
    * @since 0.2.0
    */
   @SuppressWarnings("unchecked")
   public static <T extends Element>  List<T> findAnnotatedElement(Element parent, Class<? extends Annotation> ann) {
      return parent.getEnclosedElements()
         .stream()
         .filter(e -> e.getAnnotationsByType(ann).length != 0)
         .map(e -> (T) 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;
      }
   }

   /**
    * Takes in a {@link Collection} of AST {@link Modifier}s and
    * returns them mapped to their reflective integer equivalent.
    * @param modifiers the {@link Modifier}s
    * @return an integer value representing them
    * @since 0.5.0
    */
   public static int mapModifiers(Collection<Modifier> modifiers) {
      int i = 0;
      for(Modifier m : modifiers)
         i |= mapModifier(m);
      return i;
   }

   /**
    * Safely extracts a {@link Class} from an annotation and gets its fully qualified name.
    * @param ann the annotation containing the class
    * @param parentFunction the annotation function returning the class
    * @param name a string containing the FQN, the inner class name or nothing
    * @param <T> the type of the annotation carrying the information
    * @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<?>> parentFunction, String name) {
      if(name.contains("."))
         return name;
      String fqn;
      try {
         fqn = parentFunction.apply(ann).getCanonicalName();
      } catch(MirroredTypeException e) {
         fqn = e.getTypeMirror().toString();
      }
      if(!name.equals(""))
         fqn = String.format("%s$%s", fqn, name);
      return fqn;
   }

   /**
    * 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 fallback  the (unobfuscated) FQN to fall back on
    * @param finderAnn an annotation containing metadata about the target, may be null
    * @return the fully qualified class name
    * @since 0.5.0
    */
   public static String findClassNameFromAnnotations(String fallback, Find finderAnn) {
      if(finderAnn != null) {
         String fullyQualifiedName =
            getClassFullyQualifiedName(
               finderAnn,
               Find::value,
               finderAnn.className()
            );
         if(!fullyQualifiedName.equals("java.lang.Object"))
            return findClassName(fullyQualifiedName, null);
      }
      return findClassName(fallback, null);
   }

   /**
    * 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
    * @return the fully qualified class name
    * @since 0.3.0
    */
   public static String findClassNameFromAnnotations(Patch patchAnn, Find finderAnn) {
      return findClassNameFromAnnotations(
         getClassFullyQualifiedName(
            patchAnn,
            Patch::value,
            patchAnn.className()
         ), finderAnn);
   }

   /**
    * 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 methodDescriptor the descriptor of the method, may be null if it's not a method
    * @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 member given the name, the container class and (if it's a method) the descriptor.
    * @param parentFQN the fully qualified name of the parent class
    * @param name the name to search for
    * @param descr the descriptor to search for, or null if it's not a method
    * @param strict whether the search should be strict (see {@link Target#strict()} for more info),
    *               only applies to method searches
    * @param field whether the member being searched is a field
    * @param env the {@link ProcessingEnvironment} to perform the operation in
    * @return the desired member, if it exists
    * @throws AmbiguousDefinitionException if it finds more than one candidate
    * @throws TargetNotFoundException if it finds no valid candidate
    * @since 0.3.0
    */
   public static Element findMember(String parentFQN, String name, String descr, boolean strict, boolean field, ProcessingEnvironment env) {
      TypeElement parent = env.getElementUtils().getTypeElement(parentFQN);
      if(parent == null)
         throw new AmbiguousDefinitionException(String.format("Could not find parent class %s for member %s!", parentFQN, descr == null ? name : name + descr));
      //try to find by name
      List<Element> candidates = parent.getEnclosedElements()
         .stream()
         .filter(e -> (field && e instanceof VariableElement) || e instanceof ExecutableElement)
         .filter(e -> e.getSimpleName().contentEquals(name))
         .collect(Collectors.toList());

      if(candidates.size() == 0)
         throw new TargetNotFoundException(field ? "field" : "method", name, parentFQN);
      if(candidates.size() == 1 && (!strict || field))
         return candidates.get(0);
      if(field || descr == null) {
         throw new AmbiguousDefinitionException(
            String.format("Found %d members named %s in class %s!", candidates.size(), name, parentFQN)
         );
      } else {
         candidates = candidates.stream()
            .map(e -> (ExecutableElement) e)
            .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("method", String.format("%s %s", name, descr), parentFQN);
         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 method corresponding to a stub annotated with {@link Target}.
    * @param stub the {@link ExecutableElement} for the stub
    * @param f the {@link Find} annotation containing fallback data, may be null
    * @param env the {@link ProcessingEnvironment} to perform the operation in
    * @return the {@link ExecutableElement} corresponding to the method
    * @throws AmbiguousDefinitionException if it finds more than one candidate
    * @throws TargetNotFoundException if it finds no valid candidate
    * @since 0.3.0
    */
   public static ExecutableElement findMethodFromStub(ExecutableElement stub, Find f, ProcessingEnvironment env) {
      //the parent always has a @Patch annotation
      Patch patchAnn = stub.getEnclosingElement().getAnnotation(Patch.class);
      //there should ever only be one of these two
      Target targetAnn = stub.getAnnotation(Target.class); //if this is null strict mode is always disabled
      String parentFQN = findClassNameFromAnnotations(patchAnn, f);
      String methodName = stub.getSimpleName().toString();
      String methodDescriptor = descriptorFromExecutableElement(stub);
      return (ExecutableElement) findMember(
         parentFQN,
         methodName,
         methodDescriptor,
         targetAnn != null && targetAnn.strict(),
         false, //only evaluate if target is null
         env
      );
   }

   /**
    * Utility method for finding out what type of proxy a field is.
    * It will fail if the return type is not a known type of proxy.
    * @param v the annotated {@link VariableElement}
    * @return the {@link ProxyType} for the element
    * @throws NotAProxyException if it's neither
    * @since 0.4.0
    */
   public static ProxyType getProxyType(VariableElement v) {
      String returnTypeFQN = v.asType().toString();
      switch(returnTypeFQN) {
         case "ftbsc.lll.proxies.impl.FieldProxy":
            return ProxyType.FIELD;
         case "ftbsc.lll.proxies.impl.MethodProxy":
            return ProxyType.METHOD;
         case "ftbsc.lll.proxies.impl.TypeProxy":
            return ProxyType.TYPE;
         case "ftbsc.lll.proxies.impl.PackageProxy":
            return ProxyType.PACKAGE;
         default:
            throw new NotAProxyException(v.getEnclosingElement().getSimpleName().toString(), v.getSimpleName().toString());
      }
   }

   /**
    * Finds and builds a {@link ClassContainer} based on information contained
    * within a {@link Find} annotation, else returns a fallback.
    * @param fallback the {@link ClassContainer} it falls back on
    * @param f the {@link Find} annotation to get info from
    * @param env the {@link ProcessingEnvironment} to perform the operation in
    * @param mapper the {@link ObfuscationMapper} to use, may be null
    * @return the built {@link ClassContainer} or the fallback if not enough information was present
    * @since 0.5.0
    */
   public static ClassContainer findClassOrFallback(ClassContainer fallback, Find f, ProcessingEnvironment env, ObfuscationMapper mapper) {
      String fqn = getClassFullyQualifiedName(f, Find::value, f.className());
      return fqn.equals("java.lang.Object")
         ? fallback
         : new ClassContainer(fqn, env, mapper);
   }
}