[AFP-91] 🥅 Create custom exceptions & advices (@asegers)

src/main/java/com/afp/ordermanagement/exception/BadAccessTokenException.java

+package com.afp.ordermanagement.exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ResponseStatus(value = HttpStatus.UNAUTHORIZED)
+public class BadAccessTokenException extends RuntimeException {
+        public BadAccessTokenException() {
+            super("Invalid access token");
+        }
+}

src/main/java/com/afp/ordermanagement/exception/ControllerExceptionAdvice.java

+package com.afp.ordermanagement.exception;
+
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.support.WebExchangeBindException;
+import org.springframework.web.server.ServerWebExchange;
+
+@ControllerAdvice
+@RequiredArgsConstructor
+public class ControllerExceptionAdvice {
+    @ExceptionHandler(BadAccessTokenException.class)
+    public ResponseEntity<ErrorResponse> handleBadAccessTokenException(RuntimeException exc, ServerWebExchange exchange) {
+        final HttpStatus status = HttpStatus.UNAUTHORIZED;
+        final ServerHttpRequest request = exchange.getRequest();
+        return new ResponseEntity<>(new ErrorResponse(
+                status.value(),
+                request.getPath().value(),
+                status.getReasonPhrase(),
+                exc.getMessage()
+        ), status);
+    }
+
+    @ExceptionHandler(ResourceNotFoundException.class)
+    public ResponseEntity<ErrorResponse> handleEntityNotFoundException(RuntimeException exc, ServerWebExchange exchange) {
+        final HttpStatus status = HttpStatus.NOT_FOUND;
+        final ServerHttpRequest request = exchange.getRequest();
+        return new ResponseEntity<>(new ErrorResponse(
+                status.value(),
+                request.getPath().value(),
+                status.getReasonPhrase(),
+                exc.getMessage()
+        ), status);
+    }
+
+    @ExceptionHandler(RuntimeException.class)
+    public ResponseEntity<ErrorResponse> handleRuntimeException(RuntimeException exc, ServerWebExchange exchange) {
+        final HttpStatus status = HttpStatus.INTERNAL_SERVER_ERROR;
+        final ServerHttpRequest request = exchange.getRequest();
+        return new ResponseEntity<>(new ErrorResponse(
+                status.value(),
+                request.getPath().value(),
+                status.getReasonPhrase(),
+                exc.getMessage()
+        ), status);
+    }
+
+    @ExceptionHandler(WebExchangeBindException.class)
+    public ResponseEntity<ErrorResponse> webExchangeBindException(WebExchangeBindException exc, ServerWebExchange exchange) {
+        final HttpStatus status = exc.getStatus();
+        final ServerHttpRequest request = exchange.getRequest();
+
+        if (InvalidEntityResponse.isEntityValid(exc.getTarget())) {
+            return new ResponseEntity<>(new ErrorResponse(
+                    status.value(),
+                    request.getPath().value(),
+                    status.getReasonPhrase(),
+                    exc.getMessage()
+            ), status);
+        }
+
+        return new ResponseEntity<>(new InvalidEntityResponse(
+                status.value(),
+                request.getPath().value(),
+                status.getReasonPhrase(),
+                "Validation failed",
+                exc.getTarget()
+        ), status);
+    }
+}
+

src/main/java/com/afp/ordermanagement/exception/ErrorResponse.java

+package com.afp.ordermanagement.exception;
+
+import lombok.Data;
+import lombok.RequiredArgsConstructor;
+import java.time.Instant;
+
+@Data
+@RequiredArgsConstructor
+public class ErrorResponse {
+    public final Integer status;
+    public final String path, error, message;
+    public String timestamp = Instant.now().toString();
+}

src/main/java/com/afp/ordermanagement/exception/InvalidEntityResponse.java

+package com.afp.ordermanagement.exception;
+
+import javax.validation.ConstraintViolation;
+import javax.validation.Validation;
+import javax.validation.Validator;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class InvalidEntityResponse extends ErrorResponse {
+    public List<Map<String, String>> fieldErrors;
+    public InvalidEntityResponse(Integer status, String path, String type, String message, Object entity) {
+        super(status, path, type, message);
+        this.fieldErrors = InvalidEntityResponse.parseViolations(entity);
+    }
+
+    public static boolean isEntityValid(Object entity) {
+        return validator.validate(entity).isEmpty();
+    }
+
+    static private final Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
+    static private  List<Map<String, String>> parseViolations(Object entity) {
+        List<Map<String, String>> fieldErrors = new ArrayList<>();
+        for (ConstraintViolation<Object> cv : validator.validate(entity)) {
+            Map<String, String> errorMap = new HashMap<String, String>() {{
+                put("field", cv.getPropertyPath().toString());
+                put("message", cv.getMessage());
+            }};
+            fieldErrors.add(errorMap);
+        }
+        return fieldErrors;
+    }
+}

src/main/java/com/afp/ordermanagement/exception/ResourceNotFoundException.java

+package com.afp.ordermanagement.exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ResponseStatus(value = HttpStatus.NOT_FOUND)
+public class ResourceNotFoundException extends RuntimeException {
+    public ResourceNotFoundException() {
+        super("Resource not found");
+    }
+
+    public ResourceNotFoundException(String message) {
+        super(message);
+    }
+}