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package aQute.lib.json;

import static java.lang.invoke.MethodHandles.publicLookup;

import java.io.IOException;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.invoke.MethodType;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Type;
import java.util.Map;
import java.util.function.Supplier;

import aQute.bnd.exceptions.Exceptions;

public abstract class Handler {
	static final Lookup PUBLIC_LOOKUP = MethodHandles.publicLookup();

	public abstract void encode(Encoder app, Object object, Map visited) throws IOException, Exception;

	public Object decodeObject(Decoder isr) throws Exception {
		throw new UnsupportedOperationException("Cannot be mapped to object " + this);
	}

	public Object decodeArray(Decoder isr) throws Exception {
		throw new UnsupportedOperationException("Cannot be mapped to array " + this);
	}

	public Object decode(Decoder dec, String s) throws Exception {
		throw new UnsupportedOperationException("Cannot be mapped to string " + this);
	}

	public Object decode(Decoder dec, Number s) throws Exception {
		throw new UnsupportedOperationException("Cannot be mapped to number " + this);
	}

	public Object decode(Decoder dec, boolean s) {
		throw new UnsupportedOperationException("Cannot be mapped to boolean " + this);
	}

	public Object decode(Decoder dec) {
		return null;
	}

	private static final MethodType defaultConstructor = MethodType.methodType(void.class);

	static  Supplier newInstanceFunction(Class rawClass) {
		return new Supplier() {
			volatile MethodHandle constructor = null;

			@Override
			public T get() {
				try {
					if (constructor == null)
						constructor = PUBLIC_LOOKUP.findConstructor(rawClass, defaultConstructor);
					return (T) constructor.invoke();
				} catch (Throwable e) {
					throw Exceptions.duck(e);
				}
			}
		};
	}

	static void setField(Field f, Object targetObject, Object value) throws Exception {
		try {
			publicLookup().unreflectSetter(f)
				.invoke(targetObject, value);
		} catch (Error | Exception e) {
			throw e;
		} catch (Throwable e) {
			throw new InvocationTargetException(e);
		}
	}

	static  T getField(Field f, Object targetObject) throws Exception {
		try {
			return (T) publicLookup().unreflectGetter(f)
				.invoke(targetObject);
		} catch (Error | Exception e) {
			throw e;
		} catch (Throwable e) {
			throw new InvocationTargetException(e);
		}
	}

}