package com.ankurm.jackson3.part4custom;

import tools.jackson.core.JsonParser;
import tools.jackson.databind.DeserializationContext;
import tools.jackson.databind.JsonNode;
import tools.jackson.databind.deser.std.StdDeserializer;

import java.math.BigDecimal;

/**
 * Post: Custom Serialisers and Mix-ins — https://ankurm.com/jackson-custom-serializer-mixin/
 * Section: "Writing a Custom Deserialiser"
 *
 * Jackson 3 differences from the post's code:
 *   1. jsonParser.getCodec().readTree(jsonParser) is gone. Use ctxt.readTree(parser).
 *   2. No `throws IOException` — JacksonException is unchecked.
 *   3. path() rather than get(), so a missing field yields a MissingNode instead of
 *      a NullPointerException. The post's version NPEs on {"currency":"USD"}.
 *   4. A bare decimalValue() on a MissingNode THROWS in Jackson 3 (it returned
 *      BigDecimal.ZERO in Jackson 2). Use the defaulting overload.
 */
public class E02MoneyValueDeserializer extends StdDeserializer<Money> {

    public E02MoneyValueDeserializer() {
        super(Money.class);
    }

    @Override
    public Money deserialize(JsonParser jsonParser, DeserializationContext ctxt) {
        JsonNode rootNode = ctxt.readTree(jsonParser);
        BigDecimal amount = rootNode.path("amount").decimalValue(BigDecimal.ZERO);
        String currency   = rootNode.path("currency").asString("GBP");  // default when absent
        return new Money(amount, currency);
    }
}