Generate valid filenames for exports

core/src/main/java/nl/tudelft/ewi/auta/core/controller/AssignmentExportController.java

@@ -30,6 +30,7 @@ import java.io.OutputStreamWriter;
 import java.nio.charset.StandardCharsets;
 import java.time.Instant;
 import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Consumer;
@@ -39,6 +40,12 @@ import java.util.function.Consumer;
  */
 @Controller
 public class AssignmentExportController {
+    /**
+     * The datetime formatter for timestamps included in filenames.
+     */
+    private static final DateTimeFormatter FILENAME_TIMESTAMP_FORMATTER =
+            DateTimeFormatter.ofPattern("yyyy-MM-dd--HH-mm-ssxx");
+
     /**
      * The header all CSV files are given.
      *
@@ -384,7 +391,7 @@ public class AssignmentExportController {
         return assignment.getName().replace('"', '-')
                        + "-export"
                        + '-' + kind
-                       + '-' + ZonedDateTime.now()
+                       + '-' + ZonedDateTime.now().format(FILENAME_TIMESTAMP_FORMATTER)
                        + '.' + format;
     }
 }

core/src/test/java/nl/tudelft/ewi/auta/core/controller/AssignmentExportControllerTest.java

@@ -22,6 +22,7 @@ import org.springframework.test.web.servlet.setup.MockMvcBuilders;
 import java.time.Instant;
 import java.util.List;
 import java.util.Optional;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -39,6 +40,10 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 public class AssignmentExportControllerTest {
+    private static final Pattern VALID_FILENAME_ATTRIBUTE_PATTERN = Pattern.compile(
+            "filename=\"[^<>:\"/\\\\|?*]+\""
+    );
+
     private static final String AID = "test assignment ID";
     private static final String ANAME = "test assignment - look ma, no metrics";
 
@@ -257,6 +262,17 @@ public class AssignmentExportControllerTest {
                 .andExpect(jsonPath("$.errors[0].code", equalTo("INVALID_FORMAT")));
     }
 
+    @Test
+    public void testFilenameIsValidWindowsFilename() throws Exception {
+        // Specifically Windows because it is the most strict common platform
+        // (Linux accepts pretty much anything)
+
+        final var res = this.performAsync(get("/api/v1/assignment/" + AID + "/export")).andReturn();
+
+        assertThat(res.getResponse().getHeader("Content-Disposition"))
+                .containsPattern(VALID_FILENAME_ATTRIBUTE_PATTERN);
+    }
+
     @Test
     public void testCsvContents() throws Exception {
         final var csv = this.performAsync(get("/api/v1/assignment/" + AID + "/export?format=csv"))