no-copy/src/main/java/ru/soune/no_copy/controller/ApiController.java

package ru.soune.no_copy.controller;

import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.BeanPropertyBindingResult;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.annotation.*;
import ru.soune.no_copy.dto.BaseRequest;
import ru.soune.no_copy.dto.MessageCode;
import ru.soune.no_copy.dto.RegRequest;
import ru.soune.no_copy.exception.UserAlreadyExistsException;
import ru.soune.no_copy.handler.RegRequestValidator;
import ru.soune.no_copy.repository.UserRepository;
import ru.soune.no_copy.service.AuthService;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

@Slf4j
@RestController
@RequestMapping("/api")
@RequiredArgsConstructor
public class ApiController {

    private final ObjectMapper objectMapper;

    private final UserRepository userRepository;

    private final RegRequestValidator regRequestValidator;

    @Autowired
    private AuthService authService;

    @PostMapping("/v{version}/data")
    public ResponseEntity<?> handlePostRequest(@RequestBody BaseRequest request, @PathVariable("version") int version) {
        Integer msgId = request.getMsgId();
        Map<String, Object> response;

        switch (msgId) {
            case 20002:
                RegRequest regRequest = objectMapper.convertValue(request.getMessageBody(), RegRequest.class);

                if (userRepository.existsByEmail(regRequest.getEmail())) {
                    throw new UserAlreadyExistsException("User already exists with email: " + regRequest.getEmail(),
                            msgId, MessageCode.REG_EMAIL_EXISTS.getCode(), MessageCode.REG_EMAIL_EXISTS.getDescription());
                }

                BindingResult bindingResult = new BeanPropertyBindingResult(regRequest, "regRequest");

                regRequestValidator.validate(regRequest, bindingResult);

                if (bindingResult.hasErrors()) {
                    return createValidationErrorResponse(bindingResult, msgId);
                } else {
                    authService.register(regRequest);
                    response = fillResponseInfo(msgId, MessageCode.SUCCESS.getCode(),
                            MessageCode.SUCCESS.getDescription());
                }
                break;
            case 20001:
            default:
                return ResponseEntity.ok().body(fillResponseInfo(msgId, MessageCode.MSG_ID_NOT_FOUND.getCode(),
                        MessageCode.MSG_ID_NOT_FOUND.getDescription()));
        }

        return ResponseEntity.ok().body(response);
    }

    private ResponseEntity<Map<String, Object>> createValidationErrorResponse(
            BindingResult bindingResult, Integer msgId) {

        Map<String, Object> response = fillResponseInfo(msgId, MessageCode.INVALID_FIELD.getCode(),
                MessageCode.INVALID_FIELD.getDescription());

        List<Map<String, String>> fieldErrors = bindingResult.getFieldErrors()
                .stream()
                .map(this::createErrorDetail)
                .collect(Collectors.toList());

        response.put("field_errors", fieldErrors);

        return ResponseEntity.badRequest().body(response);
    }

    private Map<String, String> createErrorDetail(FieldError fieldError) {
        Map<String, String> errorDetail = new HashMap<>();
        errorDetail.put("field", fieldError.getField());
        errorDetail.put("code", fieldError.getCode() != null ? fieldError.getCode() : "VALIDATION_ERROR");
        errorDetail.put("message", fieldError.getDefaultMessage());

        if (fieldError.getRejectedValue() != null &&
                !fieldError.getField().toLowerCase().contains("password")) {
            errorDetail.put("rejected_value", fieldError.getRejectedValue().toString());
        }

        return errorDetail;
    }

    private Map<String, Object> fillResponseInfo(Integer msgId, Integer messageCode, String messageDesc) {
        Map<String, Object> response = new HashMap<>();
        response.put("msg_id", msgId);
        response.put("message_code", messageCode);
        response.put("message_desc", messageDesc);

        return response;
    }
}