# Architecture Patterns

**Domain:** Weekly Scheduler with Calendar Integration
**Researched:** Sat Jan 24 2026

## Recommended Architecture

A weekly scheduler with calendar integration typically follows a component-based architecture with clear separation between UI presentation, data management, and external integrations.

The core architecture consists of:

1. **Presentation Layer** - Responsible for rendering the weekly schedule grid
2. **Data Management Layer** - Handles task storage, retrieval, and organization 
3. **Calendar Integration Layer** - Manages connections to external calendar services
4. **Business Logic Layer** - Manages scheduling rules and workflows

### Component Boundaries

| Component | Responsibility | Communicates With |
|-----------|---------------|-------------------|
| Weekly View Component | Renders the weekly schedule grid with days and time slots | Task Data Store, Navigation Controls |
| Task List Component | Displays tasks for a specific week/day | Data Store, Task Creation Form |
| Task Creation Form | Handles creating/editing tasks with validation | Data Store, Validation Layer |
| Navigation Controls | Manage week navigation (previous/next week) | Data Store, Week Calculator |
| Data Store | Centralized storage and management of tasks and schedule data | Persistence Layer, UI Components |
| Persistence Layer | Handles local storage or database operations | Data Store, External Sync |
| Calendar Sync Service | Manages integration with external calendars (Google, Apple) | Calendar APIs, Data Store |
| Week Calculation Service | Handles date calculations and week boundary logic | Navigation Components, Data Store |
| Validation Layer | Validates task data before saving | Form Components, Data Store |

### Data Flow

1. **User Interaction**: User interacts with UI (clicking days, creating tasks)
2. **Component Updates**: UI components update state or dispatch actions
3. **Data Processing**: Business logic processes task creation/update/deletion
4. **Storage Operation**: Data Store coordinates with persistence layer
5. **External Sync**: Calendar sync service handles external calendar integration
6. **UI Refresh**: Changes propagate back to UI through state updates

## Patterns to Follow

### Pattern 1: Component-Based Architecture
**What:** Break the application into reusable, self-contained components
**When:** For maintainability and scalability of UI elements
**Example:**
```jsx
// WeeklyView Component
function WeeklyView({ tasks, onTaskSelect, onTaskCreate }) {
  return (
    <div className="weekly-view">
      <WeekNavigation />
      <DayColumns tasks={tasks} />
    </div>
  );
}
```

### Pattern 2: State Management with Context API or Similar
**What:** Centralized state management for task data and UI state
**When:** When multiple components need access to the same data
**Example:**
```javascript
const TaskContext = createContext();

function TaskProvider({ children }) {
  const [tasks, setTasks] = useState([]);
  
  return (
    <TaskContext.Provider value={{ tasks, setTasks }}>
      {children}
    </TaskContext.Provider>
  );
}
```

### Pattern 3: Observer Pattern for Calendar Sync
**What:** Event-driven architecture for keeping data synchronized
**When:** For external calendar integration and real-time updates
**Example:**
```javascript
class CalendarSyncService {
  constructor() {
    this.observers = [];
  }
  
  subscribe(observer) {
    this.observers.push(observer);
  }
  
  notifyObservers(change) {
    this.observers.forEach(obs => obs.update(change));
  }
}
```

## Anti-Patterns to Avoid

### Anti-Pattern 1: Monolithic Component Structure
**What:** Having one massive component that handles everything
**Why bad:** Makes code hard to maintain, debug, and test
**Instead:** Break into smaller, focused components

### Anti-Pattern 2: Direct DOM Manipulation
**What:** Interacting directly with DOM elements instead of using state management
**Why bad:** Breaks React's declarative model, leads to unpredictable UI states
**Instead:** Use React state and props for all UI changes

### Anti-Pattern 3: Inconsistent Data Flow
**What:** Mixing different state management patterns throughout the app
**Why bad:** Makes code hard to reason about and maintain
**Instead:** Choose one consistent pattern (Context API, Redux, or Jotai)

## Scalability Considerations

| Concern | At 100 users | At 10K users | At 1M users |
|---------|--------------|--------------|-------------|
| UI Rendering | Standard rendering | Virtualized lists for performance | Server-side rendering + caching |
| Data Storage | Client-side storage (localStorage) | Backend database with indexing | Distributed database with sharding |
| Calendar Sync | Client-side polling | Background sync jobs | Asynchronous processing queues |
| Concurrent Access | Single user context | Multi-user isolation | Database transactions with locking |

## Sources

- React-based calendar application architecture patterns
- Modern web application design principles
- Calendar integration best practices (Google Calendar API, Apple Calendar API)