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

package ftbsc.lll.processor;

import com.squareup.javapoet.*;
import ftbsc.lll.IInjector;
import ftbsc.lll.exceptions.AmbiguousDefinitionException;
import ftbsc.lll.exceptions.InvalidResourceException;
import ftbsc.lll.processor.annotations.Find;
import ftbsc.lll.processor.annotations.Injector;
import ftbsc.lll.processor.annotations.Patch;
import ftbsc.lll.processor.annotations.Target;
import ftbsc.lll.processor.tools.obfuscation.ObfuscationMapper;
import ftbsc.lll.proxies.FieldProxy;
import ftbsc.lll.proxies.MethodProxy;

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.*;
import java.net.URI;
import java.net.URISyntaxException;
import java.nio.charset.StandardCharsets;
import java.util.*;
import java.util.stream.Collectors;

import static ftbsc.lll.processor.tools.ASTUtils.*;
import static ftbsc.lll.processor.tools.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")
@SupportedSourceVersion(SourceVersion.RELEASE_8)
@SupportedOptions("mappingsFile")
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> generatedInjectors = new HashSet<>();

   /**
    * The {@link ObfuscationMapper} used to convert classes and variables
    * to their obfuscated equivalent. Will be null when no mapper is in use.
    */
   private ObfuscationMapper mapper;

   /**
    * Initializes the processor with the processing environment by
    * setting the {@code processingEnv} field to the value of the
    * {@code processingEnv} argument.
    * @param processingEnv environment to access facilities the tool framework
    * provides to the processor
    * @throws IllegalStateException if this method is called more than once.
    * @since 0.3.0
    */
   @Override
   public synchronized void init(ProcessingEnvironment processingEnv) {
      super.init(processingEnv);
      String location = processingEnv.getOptions().get("mappingsFile");
      if(location == null)
         mapper = null;
      else {
         InputStream targetStream;
         try {
            URI target = new URI(location);
            targetStream = target.toURL().openStream();
         } catch(URISyntaxException | IOException e) {
            //may be a local file path
            File f = new File(location);
            if(!f.exists())
               throw new InvalidResourceException(location);
            try {
               targetStream = new FileInputStream(f);
            } catch(FileNotFoundException ex) {
               throw new InvalidResourceException(location);
            }
         }
         //assuming its tsrg file
         //todo: replace crappy homebaked parser with actual library
         this.mapper = new ObfuscationMapper(new BufferedReader(new InputStreamReader(targetStream,
            StandardCharsets.UTF_8)).lines());
      }
   }

   /**
    * 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())) {
            Set<TypeElement> validInjectors =
               roundEnv.getElementsAnnotatedWith(annotation)
                  .stream()
                  .map(e -> (TypeElement) e)
                  .filter(this::isValidInjector)
                  .collect(Collectors.toSet());
            if(!validInjectors.isEmpty()) {
               validInjectors.forEach(this::generateInjectors);
               if (!this.generatedInjectors.isEmpty()) {
                  generateServiceProvider();
                  return true;
               }
            }
         }
      }
      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 a ClassNode and MethodNode from ObjectWeb's ASM library.
    * @param elem the element to check.
    * @return whether it can be converted into a valid {@link IInjector}.
    */
   private boolean isValidInjector(TypeElement elem) {
      TypeMirror classNodeType = processingEnv.getElementUtils().getTypeElement("org.objectweb.asm.tree.ClassNode").asType();
      TypeMirror methodNodeType = processingEnv.getElementUtils().getTypeElement("org.objectweb.asm.tree.MethodNode").asType();
      if (elem.getEnclosedElements().stream().anyMatch(e -> e.getAnnotation(Target.class) != null)
         && elem.getEnclosedElements().stream().anyMatch(e -> {
         List<? extends TypeMirror> params = ((ExecutableType) e.asType()).getParameterTypes();
         return e.getAnnotation(Injector.class) != null
            && e.getAnnotation(Target.class) == null
            && params.size() == 2
            && processingEnv.getTypeUtils().isSameType(params.get(0), classNodeType)
            && processingEnv.getTypeUtils().isSameType(params.get(1), methodNodeType);
      })) return true;
      else {
         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 generateInjectors(TypeElement cl) {
      //find class information
      Patch patchAnn = cl.getAnnotation(Patch.class);
      String targetClassFQN =
         findClassName(
            getClassFullyQualifiedName(
               patchAnn,
               Patch::value,
               getInnerName(patchAnn, Patch::innerClass, Patch::anonymousClassCounter)
            ), this.mapper
         ).replace('/', '.');

      //find package information
      Element packageElement = cl.getEnclosingElement();
      while (packageElement.getKind() != ElementKind.PACKAGE)
         packageElement = packageElement.getEnclosingElement();
      String packageName = packageElement.toString();

      //find injector(s) and target(s)
      List<ExecutableElement> injectors = findAnnotatedMethods(cl, Injector.class);

      List<ExecutableElement> targets = findAnnotatedMethods(cl, Target.class);

      //declare it once for efficiency
      List<String> targetNames =
         targets.stream()
            .map(ExecutableElement::getSimpleName)
            .map(Object::toString)
            .collect(Collectors.toList());

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

      for(ExecutableElement inj : injectors) {
         Injector[] minjAnn = inj.getAnnotationsByType(Injector.class);
         int iterationNumber = 1;
         for(Injector injectorAnn : minjAnn) { //java is dumb
            List<ExecutableElement> injectionCandidates = targets;

            if(!injectorAnn.targetName().equals("") && targetNames.contains(injectorAnn.targetName())) {
               //case 1: it has a name, try to match it
               injectionCandidates =
                  injectionCandidates
                     .stream()
                     .filter(i -> i.getSimpleName().contentEquals(injectorAnn.targetName()))
                     .collect(Collectors.toList());
            } else if(targets.size() == 1) {
               //case 2: there is only one target
               injectionCandidates = new ArrayList<>();
               injectionCandidates.add(targets.get(0));
            } else {
               //case 3: try to match by injectTargetName
               String inferredName = inj.getSimpleName()
                  .toString()
                  .replaceFirst("inject", "");
               injectionCandidates =
                  injectionCandidates
                     .stream()
                     .filter(t -> t.getSimpleName().toString().equalsIgnoreCase(inferredName))
                     .collect(Collectors.toList());
            }

            ExecutableElement injectionTarget = null;

            if(injectionCandidates.size() == 1)
               injectionTarget = injectionCandidates.get(0);

            else {
               List<TypeMirror> params = classArrayFromAnnotation(injectorAnn, Injector::params, processingEnv.getElementUtils());

               if(params.size() != 0) {
                  StringBuilder descr = new StringBuilder("(");
                  for(TypeMirror p : params)
                     descr.append(descriptorFromType(TypeName.get(p)));
                  descr.append(")");
                  injectionCandidates =
                     injectionCandidates
                        .stream()
                        .filter(t -> //we care about arguments but not really about return type
                           descr.toString()
                              .split("\\)")[0]
                              .equalsIgnoreCase(descriptorFromExecutableElement(t).split("\\)")[0])
                        ).collect(Collectors.toList());
               }

               if(injectionCandidates.size() == 1)
                  injectionTarget = injectionCandidates.get(0);
            }

            //if we haven't found it yet, it's an ambiguity
            if(injectionTarget == null)
               throw new AmbiguousDefinitionException(String.format("Unclear target for injector %s::%s!", cl.getSimpleName(), inj.getSimpleName()));
            else toGenerate.put(
                  String.format("%sInjector%d", cl.getSimpleName(), iterationNumber),
                  new InjectorInfo(inj, injectionTarget)
               );
            iterationNumber++;
         }
      }

      //iterate over the map and generate the classes
      for(String injName : toGenerate.keySet()) {
         String targetMethodDescriptor = descriptorFromExecutableElement(toGenerate.get(injName).target);
         String targetMethodName = findMemberName(targetClassFQN, toGenerate.get(injName).target.getSimpleName().toString(), targetMethodDescriptor, this.mapper);

         MethodSpec stubOverride = MethodSpec.overriding(toGenerate.get(injName).targetStub)
            .addStatement("throw new $T($S)", RuntimeException.class, "This is a stub and should not have been called")
            .build();

         MethodSpec inject = MethodSpec.methodBuilder("inject")
            .addModifiers(Modifier.PUBLIC)
            .returns(void.class)
            .addAnnotation(Override.class)
            .addParameter(ParameterSpec.builder(
               TypeName.get(processingEnv
                  .getElementUtils()
                  .getTypeElement("org.objectweb.asm.tree.ClassNode").asType()), "clazz").build())
            .addParameter(ParameterSpec.builder(
               TypeName.get(processingEnv
                  .getElementUtils()
                  .getTypeElement("org.objectweb.asm.tree.MethodNode").asType()), "main").build())
            .addStatement(String.format("super.%s(clazz, main)", toGenerate.get(injName).injector.getSimpleName()), TypeName.get(cl.asType()))
            .build();

         TypeSpec injectorClass = TypeSpec.classBuilder(injName)
            .addModifiers(Modifier.PUBLIC)
            .superclass(cl.asType())
            .addSuperinterface(ClassName.get(IInjector.class))
            .addMethod(buildStringReturnMethod("name", cl.getSimpleName().toString()))
            .addMethod(buildStringReturnMethod("reason", patchAnn.reason()))
            .addMethod(buildStringReturnMethod("targetClass", targetClassFQN))
            .addMethod(buildStringReturnMethod("methodName", targetMethodName))
            .addMethod(buildStringReturnMethod("methodDesc", targetMethodDescriptor))
            .addMethods(generateRequestedProxies(cl, this.mapper))
            .addMethod(stubOverride)
            .addMethod(inject)
            .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.generatedInjectors.add(injectorClassName);
      }
   }

   /**
    * Finds any method annotated with {@link Find} within the given class, generates
    * the {@link MethodSpec} necessary for building it.
    * @param cl the class to search
    * @return a {@link List} of method specs
    * @since 0.2.0
    */
   private List<MethodSpec> generateRequestedProxies(TypeElement cl, ObfuscationMapper mapper) {
      List<MethodSpec> generated = new ArrayList<>();
      findAnnotatedMethods(cl, Find.class)
         .stream()
         .filter(m -> !m.getModifiers().contains(Modifier.STATIC)) //skip static stuff as we can't override it
         .filter(m -> !m.getModifiers().contains(Modifier.FINAL)) //in case someone is trying to be funny
         .forEach(m -> {
            boolean isMethod = isMethodProxyStub(m);
            Element target = findMemberFromStub(m, processingEnv);

            MethodSpec.Builder b = MethodSpec.overriding(m);

            String targetParentFQN = findClassName(((TypeElement) target.getEnclosingElement()).getQualifiedName().toString(), mapper);
            String methodDescriptor = isMethod ? descriptorFromExecutableElement((ExecutableElement) target) : null;

            b.addStatement("$T bd = $T.builder($S)",
               isMethod ? MethodProxy.Builder.class : FieldProxy.Builder.class,
               isMethod ? MethodProxy.class : FieldProxy.class,
               findMemberName(targetParentFQN, target.getSimpleName().toString(), methodDescriptor, mapper)
            );

            b.addStatement("bd.setParent($S)", targetParentFQN);

            for(Modifier mod : target.getModifiers())
               b.addStatement("bd.addModifier($L)", mapModifier(mod));

            if(isMethod) {
               ExecutableElement targetMethod = (ExecutableElement) target;
               for(VariableElement p : targetMethod.getParameters())
                  addTypeToProxyGenerator(b, "bd", "addParameter", p.asType());
               addTypeToProxyGenerator(b, "bd", "setReturnType", targetMethod.getReturnType());
            } else addTypeToProxyGenerator(b, "bd", "setType", target.asType());

            b.addStatement("return bd.build()");

            generated.add(b.build());
         });
      return generated;
   }

   /**
    * 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.generatedInjectors.forEach(out::println);
         out.close();
      } catch(IOException e) {
         throw new RuntimeException(e);
      }
   }

   /**
    * Container for information about a class that is to be generated.
    * Only used internally.
    */
   private class InjectorInfo {
      /**
       * The {@link ExecutableElement} corresponding to the injector method.
       */
      public final ExecutableElement injector;

      /**
       * The {@link ExecutableElement} corresponding to the target method stub.
       */
      public final ExecutableElement targetStub;

      /**
       * The {@link ExecutableElement} corresponding to the target method.
       */
      private final ExecutableElement target;

      /**
       * Public constructor.
       * @param injector the injector {@link ExecutableElement}
       * @param targetStub the target {@link ExecutableElement}
       */
      public InjectorInfo(ExecutableElement injector, ExecutableElement targetStub) {
         this.injector = injector;
         this.targetStub = targetStub;
         this.target = (ExecutableElement) findMemberFromStub(targetStub, processingEnv);
      }
   }
}