Reduce AssignOperatorToMerchant complexity in MerchantDomainService

[Copilot]

MerchantDomainService.AssignOperatorToMerchant exceeded the configured cyclomatic complexity threshold, making the method harder to scan and maintain. This change narrows the public method to orchestration and moves operator-specific branching into focused private helpers.

• Refactor

  • Extracted operator lookup / estate membership validation into GetOperatorAssignmentDetails(...)
  • Extracted operator rule checks into ValidateOperatorAssignment(...)
  • Kept the main method focused on aggregate retrieval, high-level validation, state transition, and persistence

• Behavior preserved

  • Retains the original validation order:
    1. load estate + merchant
    2. validate estate + merchant state
    3. verify operator is configured for the estate
    4. load operator aggregate
    5. enforce required merchant/terminal numbers
    6. assign operator and save

• Readability cleanup

  • Replaced inline branching with named helper methods
  • Clarified helper return contract by using a named tuple field and non-null fallback for the operator name on failure paths

Example of the new flow:

(Result validationResult, String operatorName) =
    await this.GetOperatorAssignmentDetails(command, estateAggregate, cancellationToken);

if (validationResult.IsFailed)
    return validationResult;

Result stateResult = merchantAggregate.AssignOperator(
    command.RequestDto.OperatorId,
    operatorName,
    command.RequestDto.MerchantNumber,
    command.RequestDto.TerminalNumber);

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• f.feedz.io
  • Triggering command: /usr/bin/dotnet dotnet test /home/REDACTED/work/TransactionProcessor/TransactionProcessor/TransactionProcessor.BusinessLogic.Tests/TransactionProcessor.BusinessLogic.Tests.csproj -p:RestoreIgnoreFailedSources=true --filter AssignOperatorToMerchant (dns block)
  • Triggering command: /opt/hostedtoolcache/CodeQL/2.24.2/x64/codeql/csharp/tools/linux64/Semmle.Autobuild.CSharp /opt/hostedtoolcache/CodeQL/2.24.2/x64/codeql/csharp/tools/linux64/Semmle.Autobuild.CSharp (dns block)
  • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /home/REDACTED/work/TransactionProcessor/TransactionProcessor/TransactionProcessor.sln --packages /tmp/codeql-scratch-7ae8d40573b4aa77/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/tmp/codeql-scratch-7ae8d40573b4aa77/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/tmp/codeql-scratch-7ae8d40573b4aa77/dbs/csharp/working/emptyFakeDotnetRoot /p:AllowMissingPrunePackageData=true (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Complexity] Method MerchantDomainService::AssignOperatorToMerchant has a cyclomatic complexity of 14 (limit is 8)</issue_title>
<issue_description>

Codacy ID: b51a0a395bd17a4feafb03f5c0ff3138

File: TransactionProcessor.BusinessLogic/Services/MerchantDomainService.cs
Line: 108
Rule: Complexity (Warning)
Commit: b53b61ccb0be078d0067c6404180c069a16f839b

Message: Method MerchantDomainService::AssignOperatorToMerchant has a cyclomatic complexity of 14 (limit is 8)

**Code Snippet:**
```csharp
        public async Task<Result> AssignOperatorToMerchant(MerchantCommands.AssignOperatorToMerchantCommand command, 
```

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Complexity] Method MerchantDomainService::AssignOperatorToMerchant has a cyclomatic complexity of 14 (limit is 8) #1523

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[StuartFerguson]

@copilot my integration tests failed can you explain why ?

[Copilot]

@copilot my integration tests failed can you explain why ?

The failure doesn’t look related to AssignOperatorToMerchant in 2d7a9a8. Build + unit tests passed; the only failing step was the integration test job. In run 23052318131, the failure happened during scenario setup at Given I have created the following estates, where TransactionProcessorClient.GetEstates(...) returned IsSuccess = False after 181.5s. That means the test never got as far as the operator-assignment steps. The same log also shows transient SQL Server pre-login handshake errors during container startup, so this looks more like an environment/read-model startup issue in the integration test stack than a regression from this refactor.