/*******************************************************************************
 * Copyright (c) 2015 Jeff Martin.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Lesser General Public
 * License v3.0 which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/lgpl.html
 * <p>
 * Contributors:
 * Jeff Martin - initial API and implementation
 ******************************************************************************/
package cuchaz.enigma.bytecode;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import cuchaz.enigma.mapping.ClassEntry;
import cuchaz.enigma.mapping.ClassNameReplacer;
import cuchaz.enigma.mapping.Translator;
import javassist.CtClass;
import javassist.bytecode.*;
import javassist.bytecode.SignatureAttribute.*;

public class ClassRenamer {

    private enum SignatureType {
        Class {
            @Override
            public String rename(String signature, ReplacerClassMap map) {
                return renameClassSignature(signature, map);
            }
        },
        Field {
            @Override
            public String rename(String signature, ReplacerClassMap map) {
                return renameFieldSignature(signature, map);
            }
        },
        Method {
            @Override
            public String rename(String signature, ReplacerClassMap map) {
                return renameMethodSignature(signature, map);
            }
        };

        public abstract String rename(String signature, ReplacerClassMap map);
    }

    private static class ReplacerClassMap extends HashMap<String, String> {

        private ClassNameReplacer m_replacer;

        public ReplacerClassMap(ClassNameReplacer replacer) {
            m_replacer = replacer;
        }

        @Override
        public String get(Object obj) {
            if (obj instanceof String) {
                return get((String) obj);
            }
            return null;
        }

        public String get(String className) {
            return m_replacer.replace(className);
        }
    }

    public static void renameClasses(CtClass c, final Translator translator) {
        renameClasses(c, className -> {
            ClassEntry entry = translator.translateEntry(new ClassEntry(className));
            if (entry != null) {
                return entry.getName();
            }
            return null;
        });
    }

    public static void moveAllClassesOutOfDefaultPackage(CtClass c, final String newPackageName) {
        renameClasses(c, className -> {
            ClassEntry entry = new ClassEntry(className);
            if (entry.isInDefaultPackage()) {
                return newPackageName + "/" + entry.getName();
            }
            return null;
        });
    }

    @SuppressWarnings("unchecked")
    public static void renameClasses(CtClass c, ClassNameReplacer replacer) {

        // sadly, we can't use CtClass.renameClass() because SignatureAttribute.renameClass() is extremely buggy =(

        ReplacerClassMap map = new ReplacerClassMap(replacer);
        ClassFile classFile = c.getClassFile();

        // rename the constant pool (covers ClassInfo, MethodTypeInfo, and NameAndTypeInfo)
        ConstPool constPool = c.getClassFile().getConstPool();
        constPool.renameClass(map);

        // rename class attributes
        renameAttributes(classFile.getAttributes(), map, SignatureType.Class);

        // rename methods
        for (MethodInfo methodInfo : (List<MethodInfo>) classFile.getMethods()) {
            methodInfo.setDescriptor(Descriptor.rename(methodInfo.getDescriptor(), map));
            renameAttributes(methodInfo.getAttributes(), map, SignatureType.Method);
        }

        // rename fields
        for (FieldInfo fieldInfo : (List<FieldInfo>) classFile.getFields()) {
            fieldInfo.setDescriptor(Descriptor.rename(fieldInfo.getDescriptor(), map));
            renameAttributes(fieldInfo.getAttributes(), map, SignatureType.Field);
        }

        // rename the class name itself last
        // NOTE: don't use the map here, because setName() calls the buggy SignatureAttribute.renameClass()
        // we only want to replace exactly this class name
        String newName = renameClassName(c.getName(), map);
        if (newName != null) {
            c.setName(newName);
        }

        // replace simple names in the InnerClasses attribute too
        InnerClassesAttribute attr = (InnerClassesAttribute) c.getClassFile().getAttribute(InnerClassesAttribute.tag);
        if (attr != null) {
            for (int i = 0; i < attr.tableLength(); i++) {

                // get the inner class full name (which has already been translated)
                ClassEntry classEntry = new ClassEntry(Descriptor.toJvmName(attr.innerClass(i)));

                if (attr.innerNameIndex(i) != 0) {
                    // update the inner name
                    attr.setInnerNameIndex(i, constPool.addUtf8Info(classEntry.getInnermostClassName()));
                }

				/* DEBUG
                System.out.println(String.format("\tDEOBF: %s-> ATTR: %s,%s,%s", classEntry, attr.outerClass(i), attr.innerClass(i), attr.innerName(i)));
				*/
            }
        }
    }

    @SuppressWarnings("unchecked")
    private static void renameAttributes(List<AttributeInfo> attributes, ReplacerClassMap map, SignatureType type) {
        try {

            // make the rename class method accessible
            Method renameClassMethod = AttributeInfo.class.getDeclaredMethod("renameClass", Map.class);
            renameClassMethod.setAccessible(true);

            for (AttributeInfo attribute : attributes) {
                if (attribute instanceof SignatureAttribute) {
                    // this has to be handled specially because SignatureAttribute.renameClass() is buggy as hell
                    SignatureAttribute signatureAttribute = (SignatureAttribute) attribute;
                    String newSignature = type.rename(signatureAttribute.getSignature(), map);
                    if (newSignature != null) {
                        signatureAttribute.setSignature(newSignature);
                    }
                } else if (attribute instanceof CodeAttribute) {
                    // code attributes have signature attributes too (indirectly)
                    CodeAttribute codeAttribute = (CodeAttribute) attribute;
                    renameAttributes(codeAttribute.getAttributes(), map, type);
                } else if (attribute instanceof LocalVariableTypeAttribute) {
                    // lvt attributes have signature attributes too
                    LocalVariableTypeAttribute localVariableAttribute = (LocalVariableTypeAttribute) attribute;
                    renameLocalVariableTypeAttribute(localVariableAttribute, map);
                } else {
                    renameClassMethod.invoke(attribute, map);
                }
            }

        } catch (NoSuchMethodException | IllegalAccessException | IllegalArgumentException | InvocationTargetException ex) {
            throw new Error("Unable to call javassist methods by reflection!", ex);
        }
    }

    private static void renameLocalVariableTypeAttribute(LocalVariableTypeAttribute attribute, ReplacerClassMap map) {

        // adapted from LocalVariableAttribute.renameClass()
        ConstPool cp = attribute.getConstPool();
        int n = attribute.tableLength();
        byte[] info = attribute.get();
        for (int i = 0; i < n; ++i) {
            int pos = i * 10 + 2;
            int index = ByteArray.readU16bit(info, pos + 6);
            if (index != 0) {
                String signature = cp.getUtf8Info(index);
                String newSignature = renameLocalVariableSignature(signature, map);
                if (newSignature != null) {
                    ByteArray.write16bit(cp.addUtf8Info(newSignature), info, pos + 6);
                }
            }
        }
    }

    private static String renameLocalVariableSignature(String signature, ReplacerClassMap map) {

        // for some reason, signatures with . in them don't count as field signatures
        // looks like anonymous classes delimit with . in stead of $
        // convert the . to $, but keep track of how many we replace
        // we need to put them back after we translate
        int start = signature.lastIndexOf('$') + 1;
        int numConverted = 0;
        StringBuilder buf = new StringBuilder(signature);
        for (int i = buf.length() - 1; i >= start; i--) {
            char c = buf.charAt(i);
            if (c == '.') {
                buf.setCharAt(i, '$');
                numConverted++;
            }
        }
        signature = buf.toString();

        // translate
        String newSignature = renameFieldSignature(signature, map);
        if (newSignature != null) {

            // put the delimiters back
            buf = new StringBuilder(newSignature);
            for (int i = buf.length() - 1; i >= 0 && numConverted > 0; i--) {
                char c = buf.charAt(i);
                if (c == '$') {
                    buf.setCharAt(i, '.');
                    numConverted--;
                }
            }
            assert (numConverted == 0);
            newSignature = buf.toString();

            return newSignature;
        }

        return null;
    }

    private static String renameClassSignature(String signature, ReplacerClassMap map) {
        try {
            ClassSignature type = renameType(SignatureAttribute.toClassSignature(signature), map);
            return type.encode();
        } catch (BadBytecode ex) {
            throw new Error("Can't parse field signature: " + signature);
        }
    }

    private static String renameFieldSignature(String signature, ReplacerClassMap map) {
        try {
            ObjectType type = renameType(SignatureAttribute.toFieldSignature(signature), map);
            if (type != null) {
                return type.encode();
            }
            return null;
        } catch (BadBytecode ex) {
            throw new Error("Can't parse class signature: " + signature);
        }
    }

    private static String renameMethodSignature(String signature, ReplacerClassMap map) {
        try {
            MethodSignature type = renameType(SignatureAttribute.toMethodSignature(signature), map);
            return type.encode();
        } catch (BadBytecode ex) {
            throw new Error("Can't parse method signature: " + signature);
        }
    }

    private static ClassSignature renameType(ClassSignature type, ReplacerClassMap map) {

        TypeParameter[] typeParamTypes = type.getParameters();
        if (typeParamTypes != null) {
            typeParamTypes = Arrays.copyOf(typeParamTypes, typeParamTypes.length);
            for (int i = 0; i < typeParamTypes.length; i++) {
                TypeParameter newParamType = renameType(typeParamTypes[i], map);
                if (newParamType != null) {
                    typeParamTypes[i] = newParamType;
                }
            }
        }

        ClassType superclassType = type.getSuperClass();
        if (superclassType != ClassType.OBJECT) {
            ClassType newSuperclassType = renameType(superclassType, map);
            if (newSuperclassType != null) {
                superclassType = newSuperclassType;
            }
        }

        ClassType[] interfaceTypes = type.getInterfaces();
        if (interfaceTypes != null) {
            interfaceTypes = Arrays.copyOf(interfaceTypes, interfaceTypes.length);
            for (int i = 0; i < interfaceTypes.length; i++) {
                ClassType newInterfaceType = renameType(interfaceTypes[i], map);
                if (newInterfaceType != null) {
                    interfaceTypes[i] = newInterfaceType;
                }
            }
        }

        return new ClassSignature(typeParamTypes, superclassType, interfaceTypes);
    }

    private static MethodSignature renameType(MethodSignature type, ReplacerClassMap map) {

        TypeParameter[] typeParamTypes = type.getTypeParameters();
        if (typeParamTypes != null) {
            typeParamTypes = Arrays.copyOf(typeParamTypes, typeParamTypes.length);
            for (int i = 0; i < typeParamTypes.length; i++) {
                TypeParameter newParamType = renameType(typeParamTypes[i], map);
                if (newParamType != null) {
                    typeParamTypes[i] = newParamType;
                }
            }
        }

        Type[] paramTypes = type.getParameterTypes();
        if (paramTypes != null) {
            paramTypes = Arrays.copyOf(paramTypes, paramTypes.length);
            for (int i = 0; i < paramTypes.length; i++) {
                Type newParamType = renameType(paramTypes[i], map);
                if (newParamType != null) {
                    paramTypes[i] = newParamType;
                }
            }
        }

        Type returnType = type.getReturnType();
        if (returnType != null) {
            Type newReturnType = renameType(returnType, map);
            if (newReturnType != null) {
                returnType = newReturnType;
            }
        }

        ObjectType[] exceptionTypes = type.getExceptionTypes();
        if (exceptionTypes != null) {
            exceptionTypes = Arrays.copyOf(exceptionTypes, exceptionTypes.length);
            for (int i = 0; i < exceptionTypes.length; i++) {
                ObjectType newExceptionType = renameType(exceptionTypes[i], map);
                if (newExceptionType != null) {
                    exceptionTypes[i] = newExceptionType;
                }
            }
        }

        return new MethodSignature(typeParamTypes, paramTypes, returnType, exceptionTypes);
    }

    private static Type renameType(Type type, ReplacerClassMap map) {
        if (type instanceof ObjectType) {
            return renameType((ObjectType) type, map);
        } else if (type instanceof BaseType) {
            return renameType((BaseType) type, map);
        } else {
            throw new Error("Don't know how to rename type " + type.getClass());
        }
    }

    private static ObjectType renameType(ObjectType type, ReplacerClassMap map) {
        if (type instanceof ArrayType) {
            return renameType((ArrayType) type, map);
        } else if (type instanceof ClassType) {
            return renameType((ClassType) type, map);
        } else if (type instanceof TypeVariable) {
            return renameType((TypeVariable) type, map);
        } else {
            throw new Error("Don't know how to rename type " + type.getClass());
        }
    }

    private static BaseType renameType(BaseType type, ReplacerClassMap map) {
        // don't have to rename primitives
        return null;
    }

    private static TypeVariable renameType(TypeVariable type, ReplacerClassMap map) {
        // don't have to rename template args
        return null;
    }

    private static ClassType renameType(ClassType type, ReplacerClassMap map) {

        // translate type args
        TypeArgument[] args = type.getTypeArguments();
        if (args != null) {
            args = Arrays.copyOf(args, args.length);
            for (int i = 0; i < args.length; i++) {
                TypeArgument newType = renameType(args[i], map);
                if (newType != null) {
                    args[i] = newType;
                }
            }
        }

        if (type instanceof NestedClassType) {
            NestedClassType nestedType = (NestedClassType) type;

            // translate the name
            String name = getClassName(type);
            String newName = map.get(name);
            if (newName != null) {
                name = new ClassEntry(newName).getInnermostClassName();
            }

            // translate the parent class too
            ClassType parent = renameType(nestedType.getDeclaringClass(), map);
            if (parent == null) {
                parent = nestedType.getDeclaringClass();
            }

            return new NestedClassType(parent, name, args);
        } else {

            // translate the name
            String name = type.getName();
            String newName = renameClassName(name, map);
            if (newName != null) {
                name = newName;
            }

            return new ClassType(name, args);
        }
    }

    private static String getClassName(ClassType type) {
        if (type instanceof NestedClassType) {
            NestedClassType nestedType = (NestedClassType) type;
            return getClassName(nestedType.getDeclaringClass()) + "$" + Descriptor.toJvmName(type.getName().replace('.', '$'));
        } else {
            return Descriptor.toJvmName(type.getName());
        }
    }

    private static String renameClassName(String name, ReplacerClassMap map) {
        String newName = map.get(Descriptor.toJvmName(name));
        if (newName != null) {
            return Descriptor.toJavaName(newName);
        }
        return null;
    }

    private static TypeArgument renameType(TypeArgument type, ReplacerClassMap map) {
        ObjectType subType = type.getType();
        if (subType != null) {
            ObjectType newSubType = renameType(subType, map);
            if (newSubType != null) {
                switch (type.getKind()) {
                    case ' ':
                        return new TypeArgument(newSubType);
                    case '+':
                        return TypeArgument.subclassOf(newSubType);
                    case '-':
                        return TypeArgument.superOf(newSubType);
                    default:
                        throw new Error("Unknown type kind: " + type.getKind());
                }
            }
        }
        return null;
    }

    private static ArrayType renameType(ArrayType type, ReplacerClassMap map) {
        Type newSubType = renameType(type.getComponentType(), map);
        if (newSubType != null) {
            return new ArrayType(type.getDimension(), newSubType);
        }
        return null;
    }

    private static TypeParameter renameType(TypeParameter type, ReplacerClassMap map) {

        ObjectType superclassType = type.getClassBound();
        if (superclassType != null) {
            ObjectType newSuperclassType = renameType(superclassType, map);
            if (newSuperclassType != null) {
                superclassType = newSuperclassType;
            }
        }

        ObjectType[] interfaceTypes = type.getInterfaceBound();
        if (interfaceTypes != null) {
            interfaceTypes = Arrays.copyOf(interfaceTypes, interfaceTypes.length);
            for (int i = 0; i < interfaceTypes.length; i++) {
                ObjectType newInterfaceType = renameType(interfaceTypes[i], map);
                if (newInterfaceType != null) {
                    interfaceTypes[i] = newInterfaceType;
                }
            }
        }

        return new TypeParameter(type.getName(), superclassType, interfaceTypes);
    }
}