[duplicate-code] 🔍 Duplicate Code Pattern: Optional Gateway Config Pointer Dereferencing

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Part of duplicate code analysis: #1006

Summary

High-impact duplication in internal/config/config_stdin.go where optional pointer field assignment is repeated 3 times in a single function. This repetitive pattern reduces code clarity and makes future config field additions error-prone.

Duplication Details

Pattern: Repeated Pointer Nil-Check and Dereference

• Severity: HIGH
• Occurrences: 3 instances in one function (15 lines total)
• Locations:
  • internal/config/config_stdin.go lines 145-156 (convertStdinConfig function)

Code Sample (lines 145-156):

// Apply optional port override
if stdinCfg.Gateway.Port != nil {
    cfg.Gateway.Port = *stdinCfg.Gateway.Port
}

// Apply optional timeout overrides
if stdinCfg.Gateway.StartupTimeout != nil {
    cfg.Gateway.StartupTimeout = *stdinCfg.Gateway.StartupTimeout
}
if stdinCfg.Gateway.ToolTimeout != nil {
    cfg.Gateway.ToolTimeout = *stdinCfg.Gateway.ToolTimeout
}

Each field requires:

1. Nil check on optional pointer
2. Dereferencing and assignment to target config
3. Identical error-prone structure

Impact Analysis

• Maintainability: HIGH - Adding new optional fields requires copy-pasting this pattern
• Bug Risk: MEDIUM - Easy to forget nil check or dereference incorrectly
• Code Clarity: MEDIUM - Repetitive pattern obscures the actual configuration logic
• Future Risk: As more optional fields are added, this pattern will proliferate

Refactoring Recommendations

1. Extract Generic Optional Field Helper

Recommended implementation:

// Add to internal/config/config_stdin.go or internal/config/helpers.go

// applyOptionalInt applies a non-nil optional integer value to a destination.
// If source is nil, destination remains unchanged.
func applyOptionalInt(source *int, destination *int) {
    if source != nil {
        *destination = *source
    }
}

// For string fields, if needed:
func applyOptionalString(source *string, destination *string) {
    if source != nil {
        *destination = *source
    }
}

// Generic version using type parameters (Go 1.18+):
func applyOptional[T any](source *T, destination *T) {
    if source != nil {
        *destination = *source
    }
}

Refactored usage in convertStdinConfig (lines 145-156):

// Apply optional overrides using helper
applyOptionalInt(stdinCfg.Gateway.Port, &cfg.Gateway.Port)
applyOptionalInt(stdinCfg.Gateway.StartupTimeout, &cfg.Gateway.StartupTimeout)
applyOptionalInt(stdinCfg.Gateway.ToolTimeout, &cfg.Gateway.ToolTimeout)

• Estimated effort: 1-2 hours (create helper, refactor callers, test)
• Benefits:
  • Reduces 15 lines to 3 lines (80% reduction)
  • Single point of change for optional field logic
  • Type-safe with generics
  • Self-documenting code
  • Easy to extend for new optional fields

2. Alternative: Use Struct Helper Method

// Method on StdinGatewayConfig
func (s *StdinGatewayConfig) applyOverrides(cfg *GatewayConfig) {
    if s.Port != nil {
        cfg.Port = *s.Port
    }
    if s.StartupTimeout != nil {
        cfg.StartupTimeout = *s.StartupTimeout
    }
    if s.ToolTimeout != nil {
        cfg.ToolTimeout = *s.ToolTimeout
    }
}

// Usage
stdinCfg.Gateway.applyOverrides(cfg.Gateway)

This encapsulates the logic but is less generic than option #1.

Implementation Checklist

• Review approach with team (generic helper vs struct method)
• Implement chosen helper function
• Refactor convertStdinConfig to use helper
• Verify all config parsing tests pass
• Test with JSON stdin config containing optional fields
• Test with JSON stdin config with all fields nil
• Document helper function usage
• Consider applying pattern to other optional fields in codebase

Parent Issue

See parent analysis report: #1006
Related to #1006

Generated by Duplicate Code Detector

• expires on Feb 24, 2026, 3:01 AM UTC