package com.imyeyu.spring.annotation;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.imyeyu.java.TimiJava;
import com.imyeyu.java.bean.timi.TimiCode;
import com.imyeyu.java.bean.timi.TimiException;
import jakarta.servlet.http.HttpServletRequest;
import org.springframework.core.MethodParameter;
import org.springframework.lang.NonNull;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;

/**
 * {@link RequestBodyValue} 参数解析器。
 *
 * @author 夜雨
 * @version 2026-04-08 11:00
 */
@Component
public class RequestBodyValueArgumentResolver implements HandlerMethodArgumentResolver {

	private static final String REQUEST_BODY_JSON_NODE_ATTR = RequestBodyValueArgumentResolver.class.getName() + ".REQUEST_BODY_JSON_NODE";

	private final ObjectMapper objectMapper;

	/**
	 * 创建 {@link RequestBodyValue} 参数解析器。
	 *
	 * @param objectMapper Jackson 对象映射器
	 */
	public RequestBodyValueArgumentResolver(ObjectMapper objectMapper) {
		this.objectMapper = objectMapper;
	}

	@Override
	public boolean supportsParameter(@NonNull MethodParameter parameter) {
		return parameter.hasParameterAnnotation(RequestBodyValue.class);
	}

	@Override
	public Object resolveArgument(@NonNull MethodParameter parameter, ModelAndViewContainer mavContainer, @NonNull NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
		RequestBodyValue bodyValue = parameter.getParameterAnnotation(RequestBodyValue.class);
		if (bodyValue == null) {
			return null;
		}
		HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class);
		TimiException.required(request, "not found request");
		assert request != null;

		JsonNode requestBody;
		{
			Object cached = request.getAttribute(REQUEST_BODY_JSON_NODE_ATTR);
			if (cached instanceof JsonNode jsonNode) {
				return jsonNode;
			}
			byte[] bodyBytes = request.getInputStream().readAllBytes();
			TimiException.requiredTrue(1 < bodyBytes.length, "empty request body");
			requestBody = objectMapper.readTree(bodyBytes);
			TimiException.requiredTrue(requestBody != null && requestBody.isObject(), "not object request body");
			request.setAttribute(REQUEST_BODY_JSON_NODE_ATTR, requestBody);
		}
		String fieldName = bodyValue.value();
		{
			if (TimiJava.isEmpty(fieldName)) {
				fieldName = parameter.getParameterName();
			}
			TimiException.required(fieldName, "not found @RequestBodyValue parameter name");
		}
		JsonNode fieldNode = requestBody.get(fieldName);
		if (fieldNode == null || fieldNode.isMissingNode() || fieldNode.isNull()) {
			if (!bodyValue.required()) {
				return null;
			}
			throw new TimiException(TimiCode.ARG_MISS, "not found json field: %s".formatted(fieldName));
		}
		return objectMapper.treeToValue(fieldNode, parameter.getParameterType());
	}
}