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package com.fasterxml.jackson.databind.ser;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.impl.PropertySerializerMap;
import se.fortnox.reactivewizard.json.LambdaSerializerModifier;

import java.lang.invoke.CallSite;
import java.lang.invoke.LambdaMetafactory;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Modifier;
import java.util.function.Function;

/**
 * A version of @{@link BeanPropertyWriter} that uses lambdas to access getters with better performance.
 *
 * Unfortunately there was some copy and paste needed, which means that we are quite dependent on the version of jackson here.
 */
public class LambdaWriter extends BeanPropertyWriter {
    private Function lambda;

    public LambdaWriter(BeanPropertyWriter writer) {
        super(writer);
        resolveLambda();
    }

    private void resolveLambda() {
        if (_accessorMethod != null) {
            if (!Modifier.isPublic(_accessorMethod.getModifiers()) || !Modifier.isPublic(_accessorMethod.getDeclaringClass().getModifiers())) {
                return;
            }
            final MethodHandles.Lookup lookup = MethodHandles.lookup();
            try {
                MethodHandle methodHandle = lookup.unreflect(_accessorMethod);
                CallSite callSite = LambdaMetafactory.metafactory(
                        lookup,
                        "apply",
                        MethodType.methodType(Function.class),
                        MethodType.methodType(Object.class, Object.class),
                        methodHandle,
                        methodHandle.type()
                );
                lambda = (Function) callSite.getTarget().invoke();
            } catch (Throwable t) {
                throw new RuntimeException(t);
            }

        }
    }

    Object readResolve() {
        super.readResolve();
        resolveLambda();
        return this;
    }


    @Override
    @SuppressWarnings("checkstyle:LocalVariableName")
    public void serializeAsField(Object bean, JsonGenerator gen, SerializerProvider prov) throws Exception {
        Object value;
        if (this.lambda != null) {
            value = this.lambda.apply(bean);
        } else if (this._accessorMethod == null) {
            value = this._field.get(bean);
        } else {
            value = this._accessorMethod.invoke(bean, (Object[]) null);
        }

        ////////////////////////////////
        // BEGIN COPY & PASTE Jackson 2.9.9.3

        // Null handling is bit different, check that first
        if (value == null) {
            if (_nullSerializer != null) {
                gen.writeFieldName(_name);
                _nullSerializer.serialize(null, gen, prov);
            }
            return;
        }
        // then find serializer to use
        JsonSerializer