Communication: Prevent multiple group chats with same users

[asliayk]

Checklist

General

• I tested all changes and their related features with all corresponding user types on a test server.
• Language: I followed the guidelines for inclusive, diversity-sensitive, and appreciative language.
• I chose a title conforming to the naming conventions for pull requests.

Server

• Important: I implemented the changes with a very good performance and prevented too many (unnecessary) and too complex database calls.
• I strictly followed the principle of data economy for all database calls.
• I strictly followed the server coding and design guidelines.
• I documented the Java code using JavaDoc style.

Motivation and Context

Currently, it is possible to create multiple group chats with the same set of participants, leading to redundancy and confusion. (Closes #9985)

Description

Validation was added to ensure group chats are unique based on their participants. Existing chats with the same users are now reused instead of creating duplicates, aligning with one-to-one chat behavior.

Steps for Testing

Prerequisites:

• 1 User
• 1 Course with Communication enabled

1. Log in to Artemis.
2. Navigate to the Communication section of a course.
3. Click the "Create Group Chat" button, which appears after clicking the plus button.
4. Create a group chat with a random set of users.
5. Attempt to create another group chat with the exact same set of users.
6. Observe that it navigates to the pre-existing group chat instead of creating a duplicate.

Testserver States

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Review Progress

Code Review

• Code Review 1
• Code Review 2

Manual Tests

• Test 1
• Test 2

Test Coverage

Server

Class/File	Line Coverage	Confirmation (assert/expect)
GroupChatService.java	87%	✅

Summary by CodeRabbit

• New Features

  • Enhanced group chat functionality to prevent duplicate chats
  • Added ability to retrieve group chats with exact participants

• Tests

  • Added integration test to verify group chat creation behavior

• Bug Fixes

  • Improved group chat creation logic to handle existing chats more efficiently

[coderabbitai]

Warning

There were issues while running some tools. Please review the errors and either fix the tool’s configuration or disable the tool if it’s a critical failure.

🔧 pmd (7.8.0)

src/main/java/de/tum/cit/aet/artemis/communication/repository/conversation/GroupChatRepository.java

The following rules are missing or misspelled in your ruleset file category/vm/bestpractices.xml: BooleanInstantiation, DontImportJavaLang, DuplicateImports, EmptyFinallyBlock, EmptyIfStmt, EmptyInitializer, EmptyStatementBlock, EmptyStatementNotInLoop, EmptySwitchStatements, EmptySynchronizedBlock, EmptyTryBlock, EmptyWhileStmt, ExcessiveClassLength, ExcessiveMethodLength, ImportFromSamePackage, MissingBreakInSwitch, SimplifyBooleanAssertion. Please check your ruleset configuration.

src/main/java/de/tum/cit/aet/artemis/communication/service/conversation/GroupChatService.java

The following rules are missing or misspelled in your ruleset file category/vm/bestpractices.xml: BooleanInstantiation, DontImportJavaLang, DuplicateImports, EmptyFinallyBlock, EmptyIfStmt, EmptyInitializer, EmptyStatementBlock, EmptyStatementNotInLoop, EmptySwitchStatements, EmptySynchronizedBlock, EmptyTryBlock, EmptyWhileStmt, ExcessiveClassLength, ExcessiveMethodLength, ImportFromSamePackage, MissingBreakInSwitch, SimplifyBooleanAssertion. Please check your ruleset configuration.

src/test/java/de/tum/cit/aet/artemis/communication/GroupChatIntegrationTest.java

The following rules are missing or misspelled in your ruleset file category/vm/bestpractices.xml: BooleanInstantiation, DontImportJavaLang, DuplicateImports, EmptyFinallyBlock, EmptyIfStmt, EmptyInitializer, EmptyStatementBlock, EmptyStatementNotInLoop, EmptySwitchStatements, EmptySynchronizedBlock, EmptyTryBlock, EmptyWhileStmt, ExcessiveClassLength, ExcessiveMethodLength, ImportFromSamePackage, MissingBreakInSwitch, SimplifyBooleanAssertion. Please check your ruleset configuration.

Walkthrough

This pull request addresses the issue of duplicate group chat creation by introducing a new method in the GroupChatRepository to find group chats with exact participants. The GroupChatService has been updated to check for existing group chats before creating a new one. A corresponding integration test has been added to verify the new behavior, ensuring that when a group chat is created with the same participants, the existing chat is returned instead of creating a duplicate.

Changes

File	Change Summary
.../GroupChatRepository.java	Added findGroupChatWithExactParticipants() method to query group chats with specific participants
.../GroupChatService.java	Modified startGroupChat() to check for existing group chats and handle creator reassignment
.../GroupChatIntegrationTest.java	Added test method to verify existing group chat retrieval

Assessment against linked issues

Objective	Addressed	Explanation
Prevent duplicate group chats	✅
Return existing group chat when same users are used	✅

Possibly related PRs

• Development: Fix duplicate server calls for messages when selecting a conversation #9611: Involves conversation messages component, related to communication functionality

Suggested labels

small, bugfix, component:Communication

Suggested reviewers

• sachmii
• HawKhiem
• cremertim
• krusche
• eceeeren

Finishing Touches

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (2)

src/main/java/de/tum/cit/aet/artemis/communication/repository/conversation/GroupChatRepository.java (1)

61-74: Consider optimizing the query performance.

The current implementation uses two subqueries which might impact performance for large datasets. Consider this alternative approach using a HAVING clause:

    @Query("""
            SELECT gc
            FROM GroupChat gc
            JOIN gc.conversationParticipants cp
            WHERE gc.course.id = :courseId
            GROUP BY gc
            HAVING COUNT(CASE WHEN cp.user.id IN :participantIds THEN 1 END) = :participantCount
            AND COUNT(cp) = :participantCount
            """)

This version:

• Reduces the number of subqueries
• Maintains the same logic but with potentially better performance
• Uses a single GROUP BY with conditional counting

src/test/java/de/tum/cit/aet/artemis/communication/GroupChatIntegrationTest.java (1)

326-342: Enhance test coverage with additional scenarios.

While the test verifies basic functionality, consider adding these scenarios:

1. Creator reassignment when chat has no messages
2. Different participant order (e.g., student3, student2 vs student2, student3)
3. Edge cases:
   • Maximum participant limit
   • Participants from different courses

Example test for different participant order:

@Test
@WithMockUser(username = TEST_PREFIX + "student1", roles = "USER")
void shouldReturnSameGroupChatWithDifferentParticipantOrder() throws Exception {
    var chat1 = request.postWithResponseBody("/api/courses/" + exampleCourseId + "/group-chats", 
        List.of(testPrefix + "student2", testPrefix + "student3"), GroupChatDTO.class,
        HttpStatus.CREATED);

    var chat2 = request.postWithResponseBody("/api/courses/" + exampleCourseId + "/group-chats", 
        List.of(testPrefix + "student3", testPrefix + "student2"), GroupChatDTO.class,
        HttpStatus.CREATED);

    assertThat(chat1.getId()).isEqualTo(chat2.getId());
}

📜 Review details

Configuration used: .coderabbit.yaml
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between e0cda16 and d7e8724.

📒 Files selected for processing (3)

• src/main/java/de/tum/cit/aet/artemis/communication/repository/conversation/GroupChatRepository.java (2 hunks)
• src/main/java/de/tum/cit/aet/artemis/communication/service/conversation/GroupChatService.java (1 hunks)
• src/test/java/de/tum/cit/aet/artemis/communication/GroupChatIntegrationTest.java (1 hunks)

🧰 Additional context used

📓 Path-based instructions (3)

src/test/java/de/tum/cit/aet/artemis/communication/GroupChatIntegrationTest.java (1)

Pattern src/test/java/**/*.java: test_naming: descriptive; test_size: small_specific; fixed_data: true; junit5_features: true; assert_use: assertThat; assert_specificity: true; archunit_use: enforce_package_rules; db_query_count_tests: track_performance; util_service_factory_pattern: true; avoid_db_access: true; mock_strategy: static_mocks; context_restart_minimize: true

src/main/java/de/tum/cit/aet/artemis/communication/repository/conversation/GroupChatRepository.java (1)

Pattern src/main/java/**/*.java: naming:CamelCase; principles:{single_responsibility,small_methods,no_duplication}; db:{perf_queries,datetime_not_timestamp}; rest:{stateless,singleton,delegate_logic,http_only,minimal_dtos}; dtos:{java_records,no_entities,min_data,single_resp}; di:constructor_injection; kiss:simple_code; file_handling:os_indep_paths; practices:{least_access,avoid_transactions,code_reuse,static_member_ref,prefer_primitives}; sql:{param_annotation,uppercase,avoid_subqueries};java:avoid_star_imports

src/main/java/de/tum/cit/aet/artemis/communication/service/conversation/GroupChatService.java (1)

Pattern src/main/java/**/*.java: naming:CamelCase; principles:{single_responsibility,small_methods,no_duplication}; db:{perf_queries,datetime_not_timestamp}; rest:{stateless,singleton,delegate_logic,http_only,minimal_dtos}; dtos:{java_records,no_entities,min_data,single_resp}; di:constructor_injection; kiss:simple_code; file_handling:os_indep_paths; practices:{least_access,avoid_transactions,code_reuse,static_member_ref,prefer_primitives}; sql:{param_annotation,uppercase,avoid_subqueries};java:avoid_star_imports

⏰ Context from checks skipped due to timeout of 90000ms (1)

• GitHub Check: Codacy Static Code Analysis

🔇 Additional comments (1)

src/main/java/de/tum/cit/aet/artemis/communication/service/conversation/GroupChatService.java (1)

59-62: Validate creator reassignment logic.

The current implementation allows creator reassignment when the chat has no messages. Consider adding additional validation:

1. Check if the new creator is a course instructor
2. Verify the new creator's permissions

[ItsaaaMeMario]

Tested on TS2, everything works as described. It navigates to the alreaddy existing group chat and does not create a duplicate group.

[vinceclifford]

Tested on TS2, works as expected

[PaRangger]

Tested on TS5. Works as described.

[Feras797]

Tested on TS2, everything works as described. When creating a group chat twice with the same members, it automatically uses the already existing group chat.

[sachmii]

Tested on TS2, works as expected. Cannot create two group chats with the same users.

[SindiBuklaji]

Tested on TS4 and it works as described,

[Cathy0123456789]

Tested on TS4. Works as expected