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package com.cedarsoftware.io.reflect;

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.lang.reflect.Type;

import com.cedarsoftware.io.JsonIoException;
import com.cedarsoftware.util.Converter;
import com.cedarsoftware.util.StringUtilities;

/**
 * @author Ken Partlow ([email protected])
 *         

 *         Copyright (c) Cedar Software LLC
 *         


 *         Licensed under the Apache License, Version 2.0 (the "License");
 *         you may not use this file except in compliance with the License.
 *         You may obtain a copy of the License at
 *         


 *         License
 *         


 *         Unless required by applicable law or agreed to in writing, software
 *         distributed under the License is distributed on an "AS IS" BASIS,
 *         WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *         See the License for the specific language governing permissions and
 *         limitations under the License.
 */
public class Injector {

    private final Field field;
    private final String displayName;
    private final String uniqueFieldName;
    private MethodHandle injector;


    public Injector(Field field, MethodHandle handle, String uniqueFieldName, String displayName) {
        this.field = field;
        this.displayName = displayName;
        this.uniqueFieldName = uniqueFieldName;
        this.injector = handle;
    }

    public static Injector create(Field field, String uniqueFieldName) {
        if (!Modifier.isStatic(field.getModifiers()) && !field.isAccessible()) {
            try {
                // it makes Lookup to be changed to trusted during the unreflectField
                field.setAccessible(true);
            } catch (Exception ioe) {
                // If object could not be set accessible let's escape here instead
                // of continuing on with more reflection and possible exceptions being thrown.
                // this will speed things up a bit to short circuit.
                // Anything that shows up in System.out.println() above should either be added to ignored
                // fields if there is no method that can access it or add a nonstandard mapping to the method.
                return null;
            }
        }

        try {
            MethodHandle handle = MethodHandles.lookup().unreflectSetter(field);
            return new Injector(field, handle, uniqueFieldName, field.getName());
        } catch (IllegalAccessException ignore) {
            return null;
        }
    }

    public static Injector create(Field field, String methodName, String uniqueFieldName) {
        // find method that returns void
        try {
            MethodType methodType = MethodType.methodType(Void.class, field.getType());
            MethodHandle handle = MethodHandles.publicLookup().findVirtual(field.getDeclaringClass(), methodName, methodType);
            return new Injector(field, handle, uniqueFieldName, methodName);
        } catch (NoSuchMethodException | IllegalAccessException ex) {
            // ignore
            return null;
        }
    }

    public void inject(Object object, Object value) {
        if (object == null) {
            throw new JsonIoException("Attempting to set field: " + getName() + " on null object.");
        }

        try {
            injector.invoke(object, value);
        } catch (ClassCastException e) {
            String msg = e.getMessage();
            if (StringUtilities.hasContent(msg) && msg.contains("LinkedHashMap")) {
                throw new JsonIoException("Unable to set field: " + getName() + " using " + getDisplayName() + ".", e);
            }
            try {
                injector.invoke(object, Converter.convert(value, field.getType()));
            } catch (Throwable t) {
                throw new JsonIoException("Unable to set field: " + getName() + " using " + getDisplayName() + ". Getting a ClassCastException.", e);
            }
        } catch (Throwable t) {
            if (t instanceof JsonIoException) {
                throw (JsonIoException) t;
            }
            throw new JsonIoException("Unable to set field: " + getName() + " using " + getDisplayName(), t);
        }
    }

    public Class getType() {
        return field.getType();
    }

    public String getName() {
        return field.getName();
    }

    public Type getGenericType() {
        return field.getGenericType();
    }

    public String getDisplayName() {
        return displayName;
    }

    public String getUniqueFieldName() {
        return uniqueFieldName;
    }
}