package eu.bitfield.recipes.api;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.MessageSourceResolvable;
import org.springframework.core.MethodParameter;
import org.springframework.http.ProblemDetail;
import org.springframework.util.MultiValueMap;
import org.springframework.validation.FieldError;
import org.springframework.validation.ObjectError;
import org.springframework.validation.method.ParameterValidationResult;
import org.springframework.web.ErrorResponse;
import org.springframework.web.ErrorResponseException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.support.WebExchangeBindException;
import org.springframework.web.method.annotation.HandlerMethodValidationException;
import org.springframework.web.server.ServerWebInputException;

import java.lang.reflect.Executable;
import java.lang.reflect.Parameter;
import java.util.List;

import static eu.bitfield.recipes.util.CollectionUtils.*;
import static org.springframework.http.HttpStatus.*;

public interface ErrorResponseHandling {
    Logger log = LoggerFactory.getLogger(ErrorResponseHandling.class);

    private static void addMethodParameter(ProblemDetail problemDetail, MethodParameter methodParam) {
        Executable executable = methodParam.getExecutable();
        Parameter param = methodParam.getParameter();
        String method = executable.toGenericString();
        String argument = param.getType().getCanonicalName() + " " + param.getName();
        problemDetail.setProperty("method", method);
        problemDetail.setProperty("argument", argument);
    }

    @ExceptionHandler
    default ErrorResponse handleError(HandlerMethodValidationException e) {
        log.debug("""
                  Handling {}:
                    method: {}
                    errors: {}""",
                  e.getClass().getName(), e.getMethod(), e.getAllErrors(), e);

        ProblemDetail problemDetail = ProblemDetail.forStatusAndDetail(BAD_REQUEST, e.getReason());

        String method = e.getMethod().toGenericString();
        problemDetail.setProperty("method", method);

        MultiValueMap<String, String> errors = multiValueMap();
        for (ParameterValidationResult result : e.getParameterValidationResults()) {
            Parameter param = result.getMethodParameter().getParameter();
            String errorKey = param.getName();
            List<String> errorValues = result.getResolvableErrors()
                .stream()
                .map(MessageSourceResolvable::getDefaultMessage)
                .toList();
            errors.addAll(errorKey, errorValues);
        }
        problemDetail.setProperty("errors", errors);

        return ErrorResponse.builder(e, problemDetail).build();
    }

    @ExceptionHandler
    default ErrorResponse handleError(WebExchangeBindException e) {
        List<ObjectError> objectErrors = e.getAllErrors();
        log.debug("""
                  Handling {}:
                    methodParameter: {}
                    errors: {}""",
                  e.getClass().getName(), e.getMethodParameter(), e.getAllErrors(), e);

        ProblemDetail problemDetail = ProblemDetail.forStatusAndDetail(BAD_REQUEST, e.getReason());

        MethodParameter methodParam = e.getMethodParameter();
        if (methodParam != null) addMethodParameter(problemDetail, methodParam);

        MultiValueMap<String, String> errors = multiValueMap();
        for (ObjectError objectError : objectErrors) {
            String errorKey = objectError.getObjectName();
            if (objectError instanceof FieldError fieldError) {
                errorKey += "." + fieldError.getField();
            }
            errors.add(errorKey, objectError.getDefaultMessage());
        }
        problemDetail.setProperty("errors", errors);

        return ErrorResponse.builder(e, problemDetail).build();
    }

    @ExceptionHandler
    default ErrorResponse handleError(ServerWebInputException e) {
        log.debug("""
                  Handling {}:
                    methodParameter: {}""",
                  e.getClass().getName(), e.getMethodParameter(), e);

        ProblemDetail problemDetail = ProblemDetail.forStatusAndDetail(BAD_REQUEST, e.getReason());

        MethodParameter methodParam = e.getMethodParameter();
        if (methodParam != null) addMethodParameter(problemDetail, methodParam);

        return ErrorResponse.builder(e, problemDetail).build();
    }

    @ExceptionHandler
    default ErrorResponse handleError(ErrorResponseException e) {
        log.debug("Handling {}", e.getClass().getName(), e);
        return e;
    }
}