Component Refactoring

Complexity Analysis

# Analyze component complexity
pnpm analyze-component <path> --json

# Key metrics to check:
# - complexity: normalized score 0-100 (target < 50)
# - maxComplexity: highest single function complexity
# - lineCount: total lines (target < 300)

Complexity Score Interpretation

Core Refactoring Patterns

Pattern 1: Extract Custom Hooks

When: Component has complex state management, multiple useState/useEffect, or business logic mixed with UI.

Dify Convention: Place hooks in a hooks/ subdirectory or alongside the component as use-<feature>.ts.

// ❌ Before: Complex state logic in component
const Configuration: FC = () => {
  const [modelConfig, setModelConfig] = useState<ModelConfig>(...)
  const [datasetConfigs, setDatasetConfigs] = useState<DatasetConfigs>(...)
  const [completionParams, setCompletionParams] = useState<FormValue>({})
  
  // 50+ lines of state management logic...
  
  return <div>...</div>
}

// ✅ After: Extract to custom hook
// hooks/use-model-config.ts
export const useModelConfig = (appId: string) => {
  const [modelConfig, setModelConfig] = useState<ModelConfig>(...)
  const [completionParams, setCompletionParams] = useState<FormValue>({})
  
  // Related state management logic here
  
  return { modelConfig, setModelConfig, completionParams, setCompletionParams }
}

// Component becomes cleaner
const Configuration: FC = () => {
  const { modelConfig, setModelConfig } = useModelConfig(appId)
  return <div>...</div>
}

Dify Examples:

• web/app/components/app/configuration/hooks/use-advanced-prompt-config.ts
• web/app/components/app/configuration/debug/hooks.tsx
• web/app/components/workflow/hooks/use-workflow.ts

Pattern 2: Extract Sub-Components

When: Single component has multiple UI sections, conditional rendering blocks, or repeated patterns.

Dify Convention: Place sub-components in subdirectories or as separate files in the same directory.

// ❌ Before: Monolithic JSX with multiple sections
const AppInfo = () => {
  return (
    <div>
      {/* 100 lines of header UI */}
      {/* 100 lines of operations UI */}
      {/* 100 lines of modals */}
    </div>
  )
}

// ✅ After: Split into focused components
// app-info/
//   ├── index.tsx           (orchestration only)
//   ├── app-header.tsx      (header UI)
//   ├── app-operations.tsx  (operations UI)
//   └── app-modals.tsx      (modal management)

const AppInfo = () => {
  const { showModal, setShowModal } = useAppInfoModals()
  
  return (
    <div>
      <AppHeader appDetail={appDetail} />
      <AppOperations onAction={handleAction} />
      <AppModals show={showModal} onClose={() => setShowModal(null)} />
    </div>
  )
}

Dify Examples:

• web/app/components/app/configuration/ directory structure
• web/app/components/workflow/nodes/ per-node organization

Pattern 3: Simplify Conditional Logic

When: Deep nesting (> 3 levels), complex ternaries, or multiple if/else chains.

// ❌ Before: Deeply nested conditionals
const Template = useMemo(() => {
  if (appDetail?.mode === AppModeEnum.CHAT) {
    switch (locale) {
      case LanguagesSupported[1]:
        return <TemplateChatZh />
      case LanguagesSupported[7]:
        return <TemplateChatJa />
      default:
        return <TemplateChatEn />
    }
  }
  if (appDetail?.mode === AppModeEnum.ADVANCED_CHAT) {
    // Another 15 lines...
  }
  // More conditions...
}, [appDetail, locale])

// ✅ After: Use lookup tables + early returns
const TEMPLATE_MAP = {
  [AppModeEnum.CHAT]: {
    [LanguagesSupported[1]]: TemplateChatZh,
    [LanguagesSupported[7]]: TemplateChatJa,
    default: TemplateChatEn,
  },
  [AppModeEnum.ADVANCED_CHAT]: {
    [LanguagesSupported[1]]: TemplateAdvancedChatZh,
    // ...
  },
}

const Template = useMemo(() => {
  const modeTemplates = TEMPLATE_MAP[appDetail?.mode]
  if (!modeTemplates) return null
  
  const TemplateComponent = modeTemplates[locale] || modeTemplates.default
  return <TemplateComponent appDetail={appDetail} />
}, [appDetail, locale])

Pattern 4: Extract API/Data Logic

When: Component directly handles API calls, data transformation, or complex async operations.

Dify Convention:

• This skill is for component decomposition, not query/mutation design.
• When refactoring data fetching, follow web/AGENTS.md.
• Use frontend-query-mutation for contracts, query shape, data-fetching wrappers, query/mutation call-site patterns, conditional queries, invalidation, and mutation error handling.
• Do not introduce deprecated useInvalid / useReset.
• Do not add thin passthrough useQuery wrappers during refactoring; only extract a custom hook when it truly orchestrates multiple queries/mutations or shared derived state.

Dify Examples:

• web/service/use-workflow.ts
• web/service/use-common.ts
• web/service/knowledge/use-dataset.ts
• web/service/knowledge/use-document.ts

Pattern 5: Extract Modal/Dialog Management

When: Component manages multiple modals with complex open/close states.

Dify Convention: Modals should be extracted with their state management.

// ❌ Before: Multiple modal states in component
const AppInfo = () => {
  const [showEditModal, setShowEditModal] = useState(false)
  const [showDuplicateModal, setShowDuplicateModal] = useState(false)
  const [showConfirmDelete, setShowConfirmDelete] = useState(false)
  const [showSwitchModal, setShowSwitchModal] = useState(false)
  const [showImportDSLModal, setShowImportDSLModal] = useState(false)
  // 5+ more modal states...
}

// ✅ After: Extract to modal management hook
type ModalType = 'edit' | 'duplicate' | 'delete' | 'switch' | 'import' | null

const useAppInfoModals = () => {
  const [activeModal, setActiveModal] = useState<ModalType>(null)
  
  const openModal = useCallback((type: ModalType) => setActiveModal(type), [])
  const closeModal = useCallback(() => setActiveModal(null), [])
  
  return {
    activeModal,
    openModal,
    closeModal,
    isOpen: (type: ModalType) => activeModal === type,
  }
}

Pattern 6: Extract Form Logic

When: Complex form validation, submission handling, or field transformation.

Dify Convention: Use @tanstack/react-form patterns from web/app/components/base/form/.

// ✅ Use existing form infrastructure
import { useAppForm } from '@/app/components/base/form'

const ConfigForm = () => {
  const form = useAppForm({
    defaultValues: { name: '', description: '' },
    onSubmit: handleSubmit,
  })
  
  return <form.Provider>...</form.Provider>
}

Dify-Specific Refactoring Guidelines

1. Context Provider Extraction

When: Component provides complex context values with multiple states.

// ❌ Before: Large context value object
const value = {
  appId, isAPIKeySet, isTrailFinished, mode, modelModeType,
  promptMode, isAdvancedMode, isAgent, isOpenAI, isFunctionCall,
  // 50+ more properties...
}
return <ConfigContext.Provider value={value}>...</ConfigContext.Provider>

// ✅ After: Split into domain-specific contexts
<ModelConfigProvider value={modelConfigValue}>
  <DatasetConfigProvider value={datasetConfigValue}>
    <UIConfigProvider value={uiConfigValue}>
      {children}
    </UIConfigProvider>
  </DatasetConfigProvider>
</ModelConfigProvider>

Dify Reference: web/context/ directory structure

2. Workflow Node Components

When: Refactoring workflow node components (web/app/components/workflow/nodes/).

Conventions:

• Keep node logic in use-interactions.ts
• Extract panel UI to separate files
• Use _base components for common patterns

nodes/<node-type>/
  ├── index.tsx              # Node registration
  ├── node.tsx               # Node visual component
  ├── panel.tsx              # Configuration panel
  ├── use-interactions.ts    # Node-specific hooks
  └── types.ts               # Type definitions

3. Configuration Components

When: Refactoring app configuration components.

Conventions:

• Separate config sections into subdirectories
• Use existing patterns from web/app/components/app/configuration/
• Keep feature toggles in dedicated components

4. Tool/Plugin Components

When: Refactoring tool-related components (web/app/components/tools/).

Conventions:

• Follow existing modal patterns
• Use service hooks from web/service/use-tools.ts
• Keep provider-specific logic isolated

Refactoring Workflow

Step 1: Generate Refactoring Prompt

pnpm refactor-component <path>

This command will:

• Analyze component complexity and features
• Identify specific refactoring actions needed
• Generate a prompt for AI assistant (auto-copied to clipboard on macOS)
• Provide detailed requirements based on detected patterns

Step 2: Analyze Details

pnpm analyze-component <path> --json

Identify:

• Total complexity score
• Max function complexity
• Line count
• Features detected (state, effects, API, etc.)

Step 3: Plan

Create a refactoring plan based on detected features:

Step 4: Execute Incrementally

1. Extract one piece at a time
2. Run lint, type-check, and tests after each extraction
3. Verify functionality before next step

For each extraction:
  ┌────────────────────────────────────────┐
  │ 1. Extract code                        │
  │ 2. Run: pnpm lint:fix                  │
  │ 3. Run: pnpm type-check:tsgo           │
  │ 4. Run: pnpm test                      │
  │ 5. Test functionality manually         │
  │ 6. PASS? → Next extraction             │
  │    FAIL? → Fix before continuing       │
  └────────────────────────────────────────┘

Step 5: Verify

After refactoring:

# Re-run refactor command to verify improvements
pnpm refactor-component <path>

# If complexity < 25 and lines < 200, you'll see:
# ✅ COMPONENT IS WELL-STRUCTURED

# For detailed metrics:
pnpm analyze-component <path> --json

# Target metrics:
# - complexity < 50
# - lineCount < 300
# - maxComplexity < 30

Common Mistakes to Avoid

❌ Over-Engineering

// ❌ Too many tiny hooks
const useButtonText = () => useState('Click')
const useButtonDisabled = () => useState(false)
const useButtonLoading = () => useState(false)

// ✅ Cohesive hook with related state
const useButtonState = () => {
  const [text, setText] = useState('Click')
  const [disabled, setDisabled] = useState(false)
  const [loading, setLoading] = useState(false)
  return { text, setText, disabled, setDisabled, loading, setLoading }
}

❌ Breaking Existing Patterns

• Follow existing directory structures
• Maintain naming conventions
• Preserve export patterns for compatibility

❌ Premature Abstraction

• Only extract when there's clear complexity benefit
• Don't create abstractions for single-use code
• Keep refactored code in the same domain area

References

Dify Codebase Examples

• Hook extraction: web/app/components/app/configuration/hooks/
• Component splitting: web/app/components/app/configuration/
• Service hooks: web/service/use-*.ts
• Workflow patterns: web/app/components/workflow/hooks/
• Form patterns: web/app/components/base/form/

Related Skills

• frontend-testing - For testing refactored components
• web/docs/test.md - Testing specification