path: root/src/main/java/ftbsc/lll/processor/LilleroProcessor.java

package ftbsc.lll.processor;

import com.squareup.javapoet.ClassName;
import com.squareup.javapoet.JavaFile;
import com.squareup.javapoet.MethodSpec;
import com.squareup.javapoet.TypeSpec;
import ftbsc.lll.IInjector;
import ftbsc.lll.exceptions.AmbiguousDefinitionException;
import ftbsc.lll.exceptions.OrphanElementException;
import ftbsc.lll.processor.annotations.*;
import ftbsc.lll.processor.containers.ClassContainer;
import ftbsc.lll.processor.containers.InjectorInfo;
import ftbsc.lll.processor.containers.MethodContainer;
import ftbsc.lll.proxies.ProxyType;
import ftbsc.lll.proxies.impl.TypeProxy;

import javax.annotation.processing.*;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.*;
import javax.lang.model.type.ExecutableType;
import javax.lang.model.type.TypeMirror;
import javax.tools.Diagnostic;
import javax.tools.FileObject;
import javax.tools.JavaFileObject;
import javax.tools.StandardLocation;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
import java.util.stream.Collectors;

import static ftbsc.lll.processor.utils.ASTUtils.*;
import static ftbsc.lll.processor.utils.JavaPoetUtils.*;

/**
 * The actual annotation processor behind the magic.
 * It (implicitly) implements the {@link Processor} interface by extending {@link AbstractProcessor}.
 */
@SupportedAnnotationTypes({"ftbsc.lll.processor.annotations.Patch", "ftbsc.lll.processor.annotations.BareInjector"})
@SupportedSourceVersion(SourceVersion.RELEASE_8)
public class LilleroProcessor extends AbstractProcessor {
   /**
    * A {@link Set} of {@link String}s that will contain the fully qualified names
    * of the generated injector files.
    */
   private final Set<String> injectors = new HashSet<>();

   /**
    * An object representing the various options passed to the processor.
    */
   private ProcessorOptions options = null;

   /**
    * Method overriding default implementation to manually pass supported options.
    * @return a {@link Set} of options supported by this processor.
    */
   @Override
   public Set<String> getSupportedOptions() {
      return ProcessorOptions.SUPPORTED;
   }

   /**
    * Returns the {@link ProcessorOptions} for this instance, creating the object if
    * it hasn't been already.
    * @return the {@link ProcessorOptions} for this instance
    */
   public ProcessorOptions getProcessorOptions() {
      if(this.options == null) this.options = new ProcessorOptions(this.processingEnv);
      return this.options;
   }

   /**
    * Where the actual processing happens.
    * It filters through whatever annotated class it's fed, and checks whether it contains
    * the required information. It then generates injectors and a service provider for every
    * remaining class.
    * @see LilleroProcessor#isValidInjector(TypeElement)
    * @param annotations the annotation types requested to be processed
    * @param roundEnv environment for information about the current and prior round
    * @return whether or not the set of annotation types are claimed by this processor
    */
   @Override
   public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
      for(TypeElement annotation : annotations) {
         if(annotation.getQualifiedName().contentEquals(Patch.class.getName())) {
            roundEnv.getElementsAnnotatedWith(annotation)
               .stream()
               .map(e -> (TypeElement) e)
               .filter(this::isValidInjector)
               .forEach(this::generateClasses);
         } else if(annotation.getQualifiedName().contentEquals(BareInjector.class.getName())) {
            TypeMirror injectorType = this.processingEnv.getElementUtils().getTypeElement("ftbsc.lll.IInjector").asType();
            for(Element e : roundEnv.getElementsAnnotatedWith(annotation)) {
               if(this.processingEnv.getTypeUtils().isAssignable(e.asType(), injectorType))
                  this.injectors.add(((TypeElement) e).getQualifiedName().toString());
               else this.processingEnv.getMessager().printMessage(Diagnostic.Kind.WARNING, String.format(
                  "Class %s annotated with @RegisterBareInjector is not an instance of IInjector, skipping...",
                  ((TypeElement) e).getQualifiedName().toString()
               ));
            }
         }
      }
      if (!this.getProcessorOptions().noServiceProvider && !this.injectors.isEmpty()) {
         generateServiceProvider();
         return true;
      } else return false;
   }

   /**
    * This checks whether a given class contains the requirements to be parsed into a Lillero injector.
    * It must have at least one method annotated with {@link Target}, and one method annotated with {@link Injector}
    * that must take in either a ClassNode and MethodNode (from ObjectWeb's ASM library) or only a MethodNode.
    * @param elem the element to check.
    * @return whether it can be converted into a valid {@link IInjector}.
    */
   private boolean isValidInjector(TypeElement elem) {
      TypeMirror classNodeType = this.processingEnv.getElementUtils().getTypeElement("org.objectweb.asm.tree.ClassNode").asType();
      TypeMirror methodNodeType = this.processingEnv.getElementUtils().getTypeElement("org.objectweb.asm.tree.MethodNode").asType();
      if(elem.getEnclosedElements().stream().anyMatch(e -> e.getAnnotation(Target.class) != null)
         && elem.getEnclosedElements().stream().filter(e -> e instanceof ExecutableElement).anyMatch(e -> {
         List<? extends TypeMirror> params = ((ExecutableType) e.asType()).getParameterTypes();
         return e.getAnnotation(Injector.class) != null
            && e.getAnnotation(Target.class) == null
            && (
               (params.size() == 2
                  && this.processingEnv.getTypeUtils().isSameType(params.get(0), classNodeType)
                  && this.processingEnv.getTypeUtils().isSameType(params.get(1), methodNodeType)
               ) || (params.size() == 1 && this.processingEnv.getTypeUtils().isSameType(params.get(0), methodNodeType))
         );
      })) return true;
      else {
         this.processingEnv.getMessager().printMessage(Diagnostic.Kind.WARNING,
            String.format("Missing valid @Injector method in @Patch class %s, skipping.", elem));
         return false;
      }
   }

   /**
    * Generates the Injector(s) contained in the given class.
    * Basically implements the {@link IInjector} interface for you.
    * @param cl the {@link TypeElement} for the given class
    */
   private void generateClasses(TypeElement cl) {
      //find class information
      Patch patchAnn = cl.getAnnotation(Patch.class);
      ClassContainer targetClass = ClassContainer.from(
         patchAnn, Patch::value, patchAnn.innerName(), this.getProcessorOptions()
      );
      //find package information
      Element packageElement = cl.getEnclosingElement();
      while (packageElement.getKind() != ElementKind.PACKAGE)
         packageElement = packageElement.getEnclosingElement();
      String packageName = packageElement.toString();

      //find annotated elements
      List<ExecutableElement> targets = findAnnotatedElement(cl, Target.class);
      List<ExecutableElement> injectors = findAnnotatedElement(cl, Injector.class);
      List<VariableElement> finders = findAnnotatedElement(cl, Find.class);

      //initialize the constructor builder
      MethodSpec.Builder constructorBuilder = MethodSpec.constructorBuilder();
      constructorBuilder.addModifiers(Modifier.PUBLIC);

      List<VariableElement> methodFinders = new ArrayList<>();

      //take care of TypeProxies and FieldProxies first
      for(VariableElement proxyVar : finders) {
         ProxyType type = getProxyType(proxyVar);
         if(type == ProxyType.METHOD && proxyVar.getAnnotation(Find.class).name().isEmpty()) {
            //methods without a specified name will be handled later
            methodFinders.add(proxyVar);
            continue;
         }
         //case-specific handling
         if(type == ProxyType.TYPE) {
            //find and validate
            ClassContainer clazz = ClassContainer.findOrFallback(
               ClassContainer.from(cl, this.getProcessorOptions()),
               patchAnn,
               proxyVar.getAnnotation(Find.class),
               this.getProcessorOptions()
            );
            //types can be generated with a single instruction
            constructorBuilder.addStatement(
               "super.$L = $T.from($S, 0, $L)",
               proxyVar.getSimpleName().toString(),
               TypeProxy.class,
               clazz.data.nameMapped.replace('/', '.'), //use obf name, at runtime it will be obfuscated
               clazz.elem == null ? 0 : mapModifiers(clazz.elem.getModifiers())
            );
         } else if(type == ProxyType.FIELD)
            appendMemberFinderDefinition(
               proxyVar,
               null,
               null,
               constructorBuilder,
               this.getProcessorOptions()
            );
      }

      //this will contain the classes to generate: the key is the class name
      HashMap<String, InjectorInfo> toGenerate = new HashMap<>();

      //these are needed for orphan checks
      HashSet<ExecutableElement> matchedInjectors = new HashSet<>();
      HashSet<VariableElement> matchedMethodFinders = new HashSet<>();

      int iterationNumber = 1;
      for(ExecutableElement tg : targets) {
         Target[] mtgAnn = tg.getAnnotationsByType(Target.class);
         for(Target targetAnn : mtgAnn) {
            List<ExecutableElement> injectorCandidates = injectors;
            List<VariableElement> finderCandidates = methodFinders;

            //find target by name
            injectorCandidates =
               injectorCandidates
                  .stream()
                  .filter(i -> i.getSimpleName().contentEquals(targetAnn.of()))
                  .collect(Collectors.toList());
            finderCandidates =
               finderCandidates
                  .stream()
                  .filter(i -> i.getSimpleName().contentEquals(targetAnn.of()))
                  .collect(Collectors.toList());

            //throw exception if user is a moron and defined a finder and an injector with the same name
            if(!finderCandidates.isEmpty() && !injectorCandidates.isEmpty())
               throw new AmbiguousDefinitionException(
                  String.format("Target specified user %s, but name was used by both a finder and injector.", targetAnn.of())
               );
            else if(finderCandidates.isEmpty() && injectorCandidates.isEmpty())
               processingEnv.getMessager().printMessage(Diagnostic.Kind.WARNING,
                  String.format(
                     "Found orphan @Target annotation on method %s.%s pointing at method %s, it will be ignored!",
                     cl.getSimpleName().toString(),
                     tg.getSimpleName().toString(),
                     targetAnn.of()
                  )
               );
            else if(finderCandidates.isEmpty() && injectorCandidates.size() != 1)
               throw new AmbiguousDefinitionException(
                  String.format("Found multiple candidate injectors for target %s::%s!", cl.getSimpleName(), tg.getSimpleName())
               );
            else if(injectorCandidates.isEmpty() && finderCandidates.size() != 1)
               throw new AmbiguousDefinitionException(
                  String.format("Found multiple candidate finders for target %s::%s!", cl.getSimpleName(), tg.getSimpleName())
               );
            else {
               if(injectorCandidates.size() == 1) {
                  //matched an injector!
                  ExecutableElement injector = injectorCandidates.get(0);
                  matchedInjectors.add(injector);
                  toGenerate.put(
                     String.format("%sInjector%d", cl.getSimpleName(), iterationNumber),
                     new InjectorInfo(injector, tg, targetAnn, this.getProcessorOptions())
                  );
                  iterationNumber++; //increment is only used by injectors
               } else {
                  //matched a finder!
                  VariableElement finder = finderCandidates.get(0);
                  matchedMethodFinders.add(finder);
                  appendMemberFinderDefinition(
                     finder,
                     tg,
                     targetAnn,
                     constructorBuilder,
                     this.getProcessorOptions()
                  );
               }
            }
         }
      }

      //find orphans, throw exception if any are found
      for(ExecutableElement e : injectors)
         if(!matchedInjectors.contains(e))
            throw new OrphanElementException(e);
      for(VariableElement e : methodFinders)
         if(!matchedMethodFinders.contains(e))
            throw new OrphanElementException(e);

      //iterate over the map and generate the classes
      for(String injName : toGenerate.keySet()) {
         MethodContainer target = toGenerate.get(injName).target;
         TypeSpec injectorClass = TypeSpec.classBuilder(injName)
            .addModifiers(Modifier.PUBLIC)
            .superclass(cl.asType())
            .addSuperinterface(ClassName.get(IInjector.class))
            .addMethod(constructorBuilder.build())
            .addMethod(buildStringReturnMethod("name", injName))
            .addMethod(buildStringReturnMethod("reason", toGenerate.get(injName).reason))
            .addMethod(buildStringReturnMethod("targetClass", this.getProcessorOptions().obfuscateInjectorMetadata
               ? targetClass.data.nameMapped.replace('/', '.')
               : targetClass.data.name.replace('/', '.')))
            .addMethod(buildStringReturnMethod("methodName", this.getProcessorOptions().obfuscateInjectorMetadata
               ? target.data.nameMapped : target.data.signature.name))
            .addMethod(buildStringReturnMethod("methodDesc", this.getProcessorOptions().obfuscateInjectorMetadata
               ? target.descriptorObf : target.data.signature.name))
            .addMethods(generateDummies(cl))
            .addMethod(generateInjector(toGenerate.get(injName), this.processingEnv))
            .build();

         JavaFile javaFile = JavaFile.builder(packageName, injectorClass).build();
         String injectorClassName = String.format("%s.%s", packageName, injName);

         try {
            JavaFileObject injectorFile = processingEnv.getFiler().createSourceFile(injectorClassName);
            PrintWriter out = new PrintWriter(injectorFile.openWriter());
            javaFile.writeTo(out);
            out.close();
         } catch(IOException e) {
            throw new RuntimeException(e);
         }

         this.injectors.add(injectorClassName);
      }
   }

   /**
    * Generates the Service Provider file for the generated injectors.
    */
   private void generateServiceProvider() {
      try {
         FileObject serviceProvider =
            processingEnv.getFiler().createResource(
               StandardLocation.CLASS_OUTPUT, "", "META-INF/services/ftbsc.lll.IInjector"
            );
         PrintWriter out = new PrintWriter(serviceProvider.openWriter());
         this.injectors.forEach(out::println);
         this.injectors.clear();
         out.close();
      } catch(IOException e) {
         throw new RuntimeException(e);
      }
   }
}