package com.codebyte.api.common.error;

import jakarta.validation.ConstraintViolationException;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatusCode;
import org.springframework.http.ProblemDetail;
import org.springframework.http.ResponseEntity;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;

/**
 * Renders all errors as RFC 7807 {@link ProblemDetail} responses carrying a stable {@code code}
 * property (see {@link ErrorCode}). Nothing here leaks stack traces or internal messages to
 * clients.
 */
@RestControllerAdvice
public class GlobalExceptionHandler extends ResponseEntityExceptionHandler {

    private static final Logger log = LoggerFactory.getLogger(GlobalExceptionHandler.class);

    @ExceptionHandler(ApiException.class)
    ProblemDetail handleApiException(ApiException ex) {
        return problem(ex.getErrorCode(), ex.getMessage());
    }

    @ExceptionHandler(ConstraintViolationException.class)
    ProblemDetail handleConstraintViolation(ConstraintViolationException ex) {
        ProblemDetail problem =
                problem(ErrorCode.CONSTRAINT_VIOLATION, "Request constraints violated");
        List<String> violations =
                ex.getConstraintViolations().stream()
                        .map(v -> v.getPropertyPath() + ": " + v.getMessage())
                        .sorted()
                        .toList();
        problem.setProperty("errors", violations);
        return problem;
    }

    @ExceptionHandler(Exception.class)
    ProblemDetail handleUnexpected(Exception ex) {
        // Log the real cause server-side; return an opaque 500 to the client.
        log.error("Unhandled exception", ex);
        return problem(ErrorCode.INTERNAL_ERROR, "An unexpected error occurred");
    }

    @Override
    protected ResponseEntity<Object> handleMethodArgumentNotValid(
            MethodArgumentNotValidException ex,
            HttpHeaders headers,
            HttpStatusCode status,
            WebRequest request) {
        ProblemDetail problem = problem(ErrorCode.VALIDATION_FAILED, "Request validation failed");
        List<String> errors =
                ex.getBindingResult().getFieldErrors().stream()
                        .map(fe -> fe.getField() + ": " + fe.getDefaultMessage())
                        .sorted()
                        .toList();
        problem.setProperty("errors", errors);
        return ResponseEntity.status(ErrorCode.VALIDATION_FAILED.getStatus()).body(problem);
    }

    @Override
    protected ResponseEntity<Object> handleHttpMessageNotReadable(
            HttpMessageNotReadableException ex,
            HttpHeaders headers,
            HttpStatusCode status,
            WebRequest request) {
        ProblemDetail problem = problem(ErrorCode.MALFORMED_REQUEST, "Request body is malformed");
        return ResponseEntity.status(ErrorCode.MALFORMED_REQUEST.getStatus()).body(problem);
    }

    private static ProblemDetail problem(ErrorCode code, String detail) {
        ProblemDetail problem = ProblemDetail.forStatusAndDetail(code.getStatus(), detail);
        problem.setTitle(code.getTitle());
        problem.setProperty("code", code.name());
        return problem;
    }
}