package com.esotericsoftware.reflectasm;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;

import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

import static org.objectweb.asm.Opcodes.*;

public abstract class MethodAccess {
	private String[] methodNames;
	private Class[][] parameterTypes;

	abstract public Object invoke (Object object, int methodIndex, Object... args);

	/** Invokes the first method with the specified name. */
	public Object invoke (Object object, String methodName, Object... args) {
		return invoke(object, getIndex(methodName), args);
	}

	/** Returns the index of the first method with the specified name. */
	public int getIndex (String methodName) {
		for (int i = 0, n = methodNames.length; i < n; i++)
			if (methodNames[i].equals(methodName)) return i;
		throw new IllegalArgumentException("Unable to find public method: " + methodName);
	}

	public int getIndex (String methodName, Class... paramTypes) {
		for (int i = 0, n = methodNames.length; i < n; i++)
			if (methodNames[i].equals(methodName) && Arrays.equals(paramTypes, parameterTypes[i])) return i;
		throw new IllegalArgumentException("Unable to find public method: " + methodName + " " + Arrays.toString(parameterTypes));
	}

	public String[] getMethodNames () {
		return methodNames;
	}

	public Class[][] getParameterTypes () {
		return parameterTypes;
	}

	static public MethodAccess get (Class type) {
		AccessClassLoader loader = AccessClassLoader.get(type);

		ArrayList<Method> methods = new ArrayList();
		Class nextClass = type;
		while (nextClass != Object.class) {
			Method[] declaredMethods = nextClass.getDeclaredMethods();
			for (int i = 0, n = declaredMethods.length; i < n; i++) {
				Method method = declaredMethods[i];
				int modifiers = method.getModifiers();
				if (Modifier.isStatic(modifiers)) continue;
				if (Modifier.isPrivate(modifiers)) continue;
				methods.add(method);
			}
			nextClass = nextClass.getSuperclass();
		}

		Class[][] parameterTypes = new Class[methods.size()][];
		String[] methodNames = new String[methods.size()];
		for (int i = 0, n = methodNames.length; i < n; i++) {
			Method method = methods.get(i);
			methodNames[i] = method.getName();
			parameterTypes[i] = method.getParameterTypes();
		}

		String className = type.getName();
		String accessClassName = className + "MethodAccess";
		if (accessClassName.startsWith("java.")) accessClassName = "reflectasm." + accessClassName;
		Class accessClass = null;
		try {
			accessClass = loader.loadClass(accessClassName);
		} catch (ClassNotFoundException ignored) {
		}
		if (accessClass == null) {
			String accessClassNameInternal = accessClassName.replace('.', '/');
			String classNameInternal = className.replace('.', '/');

			ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
			MethodVisitor mv;
			cw.visit(V1_1, ACC_PUBLIC + ACC_SUPER, accessClassNameInternal, null, "com/esotericsoftware/reflectasm/MethodAccess",
				null);
			{
				mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
				mv.visitCode();
				mv.visitVarInsn(ALOAD, 0);
				mv.visitMethodInsn(INVOKESPECIAL, "com/esotericsoftware/reflectasm/MethodAccess", "<init>", "()V");
				mv.visitInsn(RETURN);
				mv.visitMaxs(0, 0);
				mv.visitEnd();
			}
			{
				mv = cw.visitMethod(ACC_PUBLIC + ACC_VARARGS, "invoke", "(Ljava/lang/Object;I[Ljava/lang/Object;)Ljava/lang/Object;",
					null, null);
				mv.visitCode();

				if (!methods.isEmpty()) {
					mv.visitVarInsn(ALOAD, 1);
					mv.visitTypeInsn(CHECKCAST, classNameInternal);
					mv.visitVarInsn(ASTORE, 4);

					mv.visitVarInsn(ILOAD, 2);
					Label[] labels = new Label[methods.size()];
					for (int i = 0, n = labels.length; i < n; i++)
						labels[i] = new Label();
					Label defaultLabel = new Label();
					mv.visitTableSwitchInsn(0, labels.length - 1, defaultLabel, labels);

					StringBuilder buffer = new StringBuilder(128);
					for (int i = 0, n = labels.length; i < n; i++) {
						mv.visitLabel(labels[i]);
						if (i == 0)
							mv.visitFrame(Opcodes.F_APPEND, 1, new Object[] {classNameInternal}, 0, null);
						else
							mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
						mv.visitVarInsn(ALOAD, 4);

						buffer.setLength(0);
						buffer.append('(');

						Method method = methods.get(i);
						Class[] paramTypes = method.getParameterTypes();
						for (int paramIndex = 0; paramIndex < paramTypes.length; paramIndex++) {
							mv.visitVarInsn(ALOAD, 3);
							mv.visitIntInsn(BIPUSH, paramIndex);
							mv.visitInsn(AALOAD);
							Type paramType = Type.getType(paramTypes[paramIndex]);
							switch (paramType.getSort()) {
							case Type.BOOLEAN:
								mv.visitTypeInsn(CHECKCAST, "java/lang/Boolean");
								mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Boolean", "booleanValue", "()Z");
								break;
							case Type.BYTE:
								mv.visitTypeInsn(CHECKCAST, "java/lang/Byte");
								mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Byte", "byteValue", "()B");
								break;
							case Type.CHAR:
								mv.visitTypeInsn(CHECKCAST, "java/lang/Character");
								mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Character", "charValue", "()C");
								break;
							case Type.SHORT:
								mv.visitTypeInsn(CHECKCAST, "java/lang/Short");
								mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Short", "shortValue", "()S");
								break;
							case Type.INT:
								mv.visitTypeInsn(CHECKCAST, "java/lang/Integer");
								mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Integer", "intValue", "()I");
								break;
							case Type.FLOAT:
								mv.visitTypeInsn(CHECKCAST, "java/lang/Float");
								mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Float", "floatValue", "()F");
								break;
							case Type.LONG:
								mv.visitTypeInsn(CHECKCAST, "java/lang/Long");
								mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Long", "longValue", "()J");
								break;
							case Type.DOUBLE:
								mv.visitTypeInsn(CHECKCAST, "java/lang/Double");
								mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Double", "doubleValue", "()D");
								break;
							case Type.ARRAY:
								mv.visitTypeInsn(CHECKCAST, paramType.getDescriptor());
								break;
							case Type.OBJECT:
								mv.visitTypeInsn(CHECKCAST, paramType.getInternalName());
								break;
							}
							buffer.append(paramType.getDescriptor());
						}

						buffer.append(')');
						buffer.append(Type.getDescriptor(method.getReturnType()));
						mv.visitMethodInsn(INVOKEVIRTUAL, classNameInternal, method.getName(), buffer.toString());

						switch (Type.getType(method.getReturnType()).getSort()) {
						case Type.VOID:
							mv.visitInsn(ACONST_NULL);
							break;
						case Type.BOOLEAN:
							mv.visitMethodInsn(INVOKESTATIC, "java/lang/Boolean", "valueOf", "(Z)Ljava/lang/Boolean;");
							break;
						case Type.BYTE:
							mv.visitMethodInsn(INVOKESTATIC, "java/lang/Byte", "valueOf", "(B)Ljava/lang/Byte;");
							break;
						case Type.CHAR:
							mv.visitMethodInsn(INVOKESTATIC, "java/lang/Character", "valueOf", "(C)Ljava/lang/Character;");
							break;
						case Type.SHORT:
							mv.visitMethodInsn(INVOKESTATIC, "java/lang/Short", "valueOf", "(S)Ljava/lang/Short;");
							break;
						case Type.INT:
							mv.visitMethodInsn(INVOKESTATIC, "java/lang/Integer", "valueOf", "(I)Ljava/lang/Integer;");
							break;
						case Type.FLOAT:
							mv.visitMethodInsn(INVOKESTATIC, "java/lang/Float", "valueOf", "(F)Ljava/lang/Float;");
							break;
						case Type.LONG:
							mv.visitMethodInsn(INVOKESTATIC, "java/lang/Long", "valueOf", "(J)Ljava/lang/Long;");
							break;
						case Type.DOUBLE:
							mv.visitMethodInsn(INVOKESTATIC, "java/lang/Double", "valueOf", "(D)Ljava/lang/Double;");
							break;
						}

						mv.visitInsn(ARETURN);
					}

					mv.visitLabel(defaultLabel);
					mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
				}
				mv.visitTypeInsn(NEW, "java/lang/IllegalArgumentException");
				mv.visitInsn(DUP);
				mv.visitTypeInsn(NEW, "java/lang/StringBuilder");
				mv.visitInsn(DUP);
				mv.visitLdcInsn("Method not found: ");
				mv.visitMethodInsn(INVOKESPECIAL, "java/lang/StringBuilder", "<init>", "(Ljava/lang/String;)V");
				mv.visitVarInsn(ILOAD, 2);
				mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(I)Ljava/lang/StringBuilder;");
				mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "toString", "()Ljava/lang/String;");
				mv.visitMethodInsn(INVOKESPECIAL, "java/lang/IllegalArgumentException", "<init>", "(Ljava/lang/String;)V");
				mv.visitInsn(ATHROW);
				mv.visitMaxs(0, 0);
				mv.visitEnd();
			}
			cw.visitEnd();
			byte[] data = cw.toByteArray();
			accessClass = loader.defineClass(accessClassName, data);
		}
		try {
			MethodAccess access = (MethodAccess)accessClass.newInstance();
			access.methodNames = methodNames;
			access.parameterTypes = parameterTypes;
			return access;
		} catch (Exception ex) {
			throw new RuntimeException("Error constructing method access class: " + accessClassName, ex);
		}
	}
}