thrillwiki_django_no_react/docs/ride-ranking-implementation.md

# Ride Ranking System - Complete Implementation Documentation

## Table of Contents
1. [Overview](#overview)
2. [Backend Implementation](#backend-implementation)
3. [Frontend Implementation](#frontend-implementation)
4. [API Reference](#api-reference)
5. [Usage Examples](#usage-examples)
6. [Deployment & Maintenance](#deployment--maintenance)

## Overview

The ThrillWiki Ride Ranking System implements the Internet Roller Coaster Poll (IRCP) algorithm to provide fair, data-driven rankings of theme park rides based on user ratings. This document covers the complete implementation across both backend (Django) and frontend (Vue.js/TypeScript) components.

### Key Features
- **Pairwise Comparison Algorithm**: Compares every ride against every other ride based on mutual riders
- **Web Interface**: Browse rankings with filtering and detailed views
- **REST API**: Comprehensive API for programmatic access
- **Historical Tracking**: Track ranking changes over time
- **Statistical Analysis**: Head-to-head comparisons and win/loss records

## Backend Implementation

### Database Models

#### Location: `apps/rides/models/rankings.py`

```python
# Core ranking models
- RideRanking: Current ranking data for each ride
- RidePairComparison: Cached pairwise comparison results
- RankingSnapshot: Historical ranking data
```

#### Key Fields

**RideRanking Model**:
- `rank` (Integer): Overall ranking position
- `wins` (Integer): Number of head-to-head wins
- `losses` (Integer): Number of head-to-head losses
- `ties` (Integer): Number of tied comparisons
- `winning_percentage` (Decimal): Win percentage (ties count as 0.5)
- `mutual_riders_count` (Integer): Total users who rated this ride
- `average_rating` (Decimal): Average user rating
- `last_calculated` (DateTime): Timestamp of last calculation

### Service Layer

#### Location: `apps/rides/services/ranking_service.py`

The `RideRankingService` class implements the core ranking algorithm:

```python
class RideRankingService:
    def update_all_rankings(category=None):
        """Main entry point for ranking calculation"""
        
    def _calculate_pairwise_comparison(ride_a, ride_b):
        """Compare two rides based on mutual riders"""
        
    def _calculate_rankings_from_comparisons():
        """Convert comparisons to rankings"""
        
    def _apply_tiebreakers():
        """Resolve ties using head-to-head comparisons"""
```

### Django Views

#### Location: `apps/rides/views.py`

**Web Views**:
```python
class RideRankingsView(ListView):
    """Main rankings list page with filtering"""
    template_name = 'rides/rankings.html'
    paginate_by = 50
    
class RideRankingDetailView(DetailView):
    """Detailed ranking view for a specific ride"""
    template_name = 'rides/ranking_detail.html'
```

**HTMX Endpoints**:
- `ranking_history_chart`: Returns chart data for ranking history
- `ranking_comparisons`: Returns head-to-head comparison data

### URL Configuration

#### Location: `apps/rides/urls.py`

```python
urlpatterns = [
    path('rankings/', RideRankingsView.as_view(), name='ride-rankings'),
    path('rankings/<slug:ride_slug>/', RideRankingDetailView.as_view(), name='ride-ranking-detail'),
    path('rankings/<slug:ride_slug>/history-chart/', ranking_history_chart, name='ranking-history-chart'),
    path('rankings/<slug:ride_slug>/comparisons/', ranking_comparisons, name='ranking-comparisons'),
]
```

### API Implementation

#### Serializers
**Location**: `apps/api/v1/serializers_rankings.py`

```python
class RideRankingSerializer(serializers.ModelSerializer):
    """Basic ranking data serialization"""
    
class RideRankingDetailSerializer(serializers.ModelSerializer):
    """Detailed ranking with relationships"""
    
class RankingSnapshotSerializer(serializers.ModelSerializer):
    """Historical ranking data"""
    
class RankingStatsSerializer(serializers.Serializer):
    """System-wide statistics"""
```

#### ViewSets
**Location**: `apps/api/v1/viewsets_rankings.py`

```python
class RideRankingViewSet(viewsets.ReadOnlyModelViewSet):
    """
    REST API endpoint for ride rankings
    Supports filtering, ordering, and custom actions
    """
    
    @action(detail=True, methods=['get'])
    def history(self, request, pk=None):
        """Get historical ranking data"""
        
    @action(detail=True, methods=['get'])
    def comparisons(self, request, pk=None):
        """Get head-to-head comparisons"""
        
    @action(detail=False, methods=['get'])
    def statistics(self, request):
        """Get system-wide statistics"""

class TriggerRankingCalculationView(APIView):
    """Admin endpoint to trigger manual calculation"""
```

#### API URLs
**Location**: `apps/api/v1/urls.py`

```python
router.register(r'rankings', RideRankingViewSet, basename='ranking')

urlpatterns = [
    path('', include(router.urls)),
    path('rankings/calculate/', TriggerRankingCalculationView.as_view()),
]
```

### Management Commands

#### Location: `apps/rides/management/commands/update_ride_rankings.py`

```bash
# Update all rankings
python manage.py update_ride_rankings

# Update specific category
python manage.py update_ride_rankings --category RC
```

### Admin Interface

#### Location: `apps/rides/admin.py`

```python
@admin.register(RideRanking)
class RideRankingAdmin(admin.ModelAdmin):
    list_display = ['rank', 'ride', 'winning_percentage', 'wins', 'losses']
    list_filter = ['ride__category', 'last_calculated']
    search_fields = ['ride__name']
    ordering = ['rank']
```

## Frontend Implementation

### TypeScript Type Definitions

#### Location: `frontend/src/types/index.ts`

```typescript
// Core ranking types
export interface RideRanking {
  id: number
  rank: number
  ride: {
    id: number
    name: string
    slug: string
    park: {
      id: number
      name: string
      slug: string
    }
    category: 'RC' | 'DR' | 'FR' | 'WR' | 'TR' | 'OT'
  }
  wins: number
  losses: number
  ties: number
  winning_percentage: number
  mutual_riders_count: number
  comparison_count: number
  average_rating: number
  last_calculated: string
  rank_change?: number
  previous_rank?: number | null
}

export interface RideRankingDetail extends RideRanking {
  ride: {
    // Extended ride information
    description?: string
    manufacturer?: { id: number; name: string }
    opening_date?: string
    status: string
  }
  calculation_version?: string
  head_to_head_comparisons?: HeadToHeadComparison[]
  ranking_history?: RankingSnapshot[]
}

export interface HeadToHeadComparison {
  opponent: {
    id: number
    name: string
    slug: string
    park: string
  }
  wins: number
  losses: number
  ties: number
  result: 'win' | 'loss' | 'tie'
  mutual_riders: number
}

export interface RankingSnapshot {
  date: string
  rank: number
  winning_percentage: number
}

export interface RankingStatistics {
  total_ranked_rides: number
  total_comparisons: number
  last_calculation_time: string
  calculation_duration: number
  top_rated_ride?: RideInfo
  most_compared_ride?: RideInfo
  biggest_rank_change?: RankChangeInfo
}
```

### API Service Class

#### Location: `frontend/src/services/api.ts`

```typescript
export class RankingsApi {
  // Core API methods
  async getRankings(params?: RankingParams): Promise<ApiResponse<RideRanking>>
  async getRankingDetail(rideSlug: string): Promise<RideRankingDetail>
  async getRankingHistory(rideSlug: string): Promise<RankingSnapshot[]>
  async getHeadToHeadComparisons(rideSlug: string): Promise<HeadToHeadComparison[]>
  async getRankingStatistics(): Promise<RankingStatistics>
  async calculateRankings(category?: string): Promise<CalculationResult>
  
  // Convenience methods
  async getTopRankings(limit: number, category?: string): Promise<RideRanking[]>
  async getParkRankings(parkSlug: string, params?: Params): Promise<ApiResponse<RideRanking>>
  async searchRankings(query: string): Promise<RideRanking[]>
  async getRankChange(rideSlug: string): Promise<RankChangeInfo>
}
```

### Integration with Main API

```typescript
// Singleton instance with all API services
export const api = new ThrillWikiApi()

// Direct access to rankings API
export const rankingsApi = api.rankings
```

## API Reference

### REST Endpoints

#### Get Rankings List
```http
GET /api/v1/rankings/
```

**Query Parameters**:
- `page` (integer): Page number
- `page_size` (integer): Results per page (default: 20)
- `category` (string): Filter by category (RC, DR, FR, WR, TR, OT)
- `min_riders` (integer): Minimum mutual riders
- `park` (string): Filter by park slug
- `ordering` (string): Sort order (rank, -rank, winning_percentage, -winning_percentage)

**Response**:
```json
{
  "count": 523,
  "next": "http://api.example.com/api/v1/rankings/?page=2",
  "previous": null,
  "results": [
    {
      "id": 1,
      "rank": 1,
      "ride": {
        "id": 123,
        "name": "Steel Vengeance",
        "slug": "steel-vengeance",
        "park": {
          "id": 45,
          "name": "Cedar Point",
          "slug": "cedar-point"
        },
        "category": "RC"
      },
      "wins": 487,
      "losses": 23,
      "ties": 13,
      "winning_percentage": 0.9405,
      "mutual_riders_count": 1543,
      "comparison_count": 523,
      "average_rating": 9.4,
      "last_calculated": "2024-01-15T02:00:00Z"
    }
  ]
}
```

#### Get Ranking Details
```http
GET /api/v1/rankings/{ride-slug}/
```

**Response**: Extended ranking data with full ride details, comparisons, and history

#### Get Ranking History
```http
GET /api/v1/rankings/{ride-slug}/history/
```

**Response**: Array of ranking snapshots (last 90 days)

#### Get Head-to-Head Comparisons
```http
GET /api/v1/rankings/{ride-slug}/comparisons/
```

**Response**: Array of comparison results with all other rides

#### Get Statistics
```http
GET /api/v1/rankings/statistics/
```

**Response**: System-wide ranking statistics

#### Trigger Calculation (Admin)
```http
POST /api/v1/rankings/calculate/
```

**Request Body**:
```json
{
  "category": "RC"  // Optional
}
```

**Response**:
```json
{
  "status": "success",
  "rides_ranked": 523,
  "comparisons_made": 136503,
  "duration": 45.23,
  "timestamp": "2024-01-15T02:00:45Z"
}
```

## Usage Examples

### Frontend (Vue.js/TypeScript)

#### Display Top Rankings
```typescript
import { rankingsApi } from '@/services/api'

export default {
  async mounted() {
    try {
      // Get top 10 rankings
      const topRides = await rankingsApi.getTopRankings(10)
      this.rankings = topRides
      
      // Get roller coasters only
      const response = await rankingsApi.getRankings({
        category: 'RC',
        page_size: 20,
        ordering: 'rank'
      })
      this.rollerCoasters = response.results
    } catch (error) {
      console.error('Failed to load rankings:', error)
    }
  }
}
```

#### Display Ranking Details
```typescript
// In a Vue component
async loadRankingDetails(rideSlug: string) {
  const [details, history, comparisons] = await Promise.all([
    rankingsApi.getRankingDetail(rideSlug),
    rankingsApi.getRankingHistory(rideSlug),
    rankingsApi.getHeadToHeadComparisons(rideSlug)
  ])
  
  this.rankingDetails = details
  this.chartData = this.prepareChartData(history)
  this.comparisons = comparisons
}
```

#### Search Rankings
```typescript
async searchRides(query: string) {
  const results = await rankingsApi.searchRankings(query)
  this.searchResults = results
}
```

### Backend (Python/Django)

#### Access Rankings in Views
```python
from apps.rides.models import RideRanking

# Get top 10 rides
top_rides = RideRanking.objects.select_related('ride', 'ride__park').order_by('rank')[:10]

# Get rankings for a specific category
coaster_rankings = RideRanking.objects.filter(
    ride__category='RC'
).order_by('rank')

# Get ranking with change indicator
ranking = RideRanking.objects.get(ride__slug='millennium-force')
if ranking.previous_rank:
    change = ranking.previous_rank - ranking.rank
    direction = 'up' if change > 0 else 'down' if change < 0 else 'same'
```

#### Trigger Ranking Update
```python
from apps.rides.services.ranking_service import RideRankingService

# Update all rankings
service = RideRankingService()
result = service.update_all_rankings()

# Update specific category
result = service.update_all_rankings(category='RC')

print(f"Ranked {result['rides_ranked']} rides")
print(f"Made {result['comparisons_made']} comparisons")
print(f"Duration: {result['duration']:.2f} seconds")
```

### Command Line

```bash
# Update rankings via management command
uv run python manage.py update_ride_rankings

# Update only roller coasters
uv run python manage.py update_ride_rankings --category RC

# Schedule daily updates with cron
0 2 * * * cd /path/to/project && uv run python manage.py update_ride_rankings
```

## Deployment & Maintenance

### Initial Setup

1. **Run Migrations**:
```bash
uv run python manage.py migrate
```

2. **Initial Ranking Calculation**:
```bash
uv run python manage.py update_ride_rankings
```

3. **Verify in Admin**:
- Navigate to `/admin/rides/rideranking/`
- Verify rankings are populated

### Scheduled Updates

Add to crontab for daily updates:
```bash
# Update rankings daily at 2 AM
0 2 * * * cd /path/to/thrillwiki && uv run python manage.py update_ride_rankings

# Optional: Update different categories at different times
0 2 * * * cd /path/to/thrillwiki && uv run python manage.py update_ride_rankings --category RC
0 3 * * * cd /path/to/thrillwiki && uv run python manage.py update_ride_rankings --category DR
```

### Monitoring

1. **Check Logs**:
```bash
tail -f /path/to/logs/ranking_updates.log
```

2. **Monitor Performance**:
- Track calculation duration via API statistics endpoint
- Monitor database query performance
- Check comparison cache hit rates

3. **Data Validation**:
```python
# Check for ranking anomalies
from apps.rides.models import RideRanking

# Verify all ranks are unique
ranks = RideRanking.objects.values_list('rank', flat=True)
assert len(ranks) == len(set(ranks))

# Check winning percentage calculation
for ranking in RideRanking.objects.all():
    expected = (ranking.wins + 0.5 * ranking.ties) / ranking.comparison_count
    assert abs(ranking.winning_percentage - expected) < 0.001
```

### Performance Optimization

1. **Database Indexes**:
```sql
-- Ensure these indexes exist
CREATE INDEX idx_ranking_rank ON rides_rideranking(rank);
CREATE INDEX idx_ranking_ride ON rides_rideranking(ride_id);
CREATE INDEX idx_comparison_rides ON rides_ridepaircomparison(ride_a_id, ride_b_id);
```

2. **Cache Configuration**:
```python
# settings.py
CACHES = {
    'rankings': {
        'BACKEND': 'django.core.cache.backends.redis.RedisCache',
        'LOCATION': 'redis://127.0.0.1:6379/2',
        'TIMEOUT': 3600,  # 1 hour
    }
}
```

3. **Batch Processing**:
- Process comparisons in batches of 1000
- Use bulk_create for database inserts
- Consider parallel processing for large datasets

### Troubleshooting

**Common Issues**:

1. **Rankings not updating**:
   - Check cron job is running
   - Verify database connectivity
   - Check for lock files preventing concurrent runs

2. **Incorrect rankings**:
   - Clear comparison cache and recalculate
   - Verify rating data integrity
   - Check for duplicate user ratings

3. **Performance issues**:
   - Analyze slow queries with Django Debug Toolbar
   - Consider increasing database resources
   - Implement incremental updates for large datasets

### API Rate Limiting

Configure in `settings.py`:
```python
REST_FRAMEWORK = {
    'DEFAULT_THROTTLE_CLASSES': [
        'rest_framework.throttling.AnonRateThrottle',
        'rest_framework.throttling.UserRateThrottle'
    ],
    'DEFAULT_THROTTLE_RATES': {
        'anon': '100/hour',
        'user': '1000/hour'
    }
}
```

## Architecture Decisions

### Why Pairwise Comparison?
- **Fairness**: Only compares rides among users who've experienced both
- **Reduces Bias**: Popular rides aren't advantaged over less-ridden ones
- **Head-to-Head Logic**: Direct comparisons matter for tie-breaking
- **Robust to Outliers**: One extreme rating doesn't skew results

### Caching Strategy
- **Comparison Cache**: Store pairwise results to avoid recalculation
- **Snapshot History**: Keep 365 days of historical data
- **API Response Cache**: Cache ranking lists for 1 hour

### Scalability Considerations
- **O(n²) Complexity**: Scales quadratically with number of rides
- **Batch Processing**: Process in chunks to manage memory
- **Incremental Updates**: Future enhancement for real-time updates

## Testing

### Unit Tests
```python
# apps/rides/tests/test_ranking_service.py
class RankingServiceTestCase(TestCase):
    def test_pairwise_comparison(self):
        """Test comparison logic between two rides"""
        
    def test_ranking_calculation(self):
        """Test overall ranking calculation"""
        
    def test_tiebreaker_logic(self):
        """Test head-to-head tiebreaker"""
```

### Integration Tests
```python
# apps/api/tests/test_ranking_api.py
class RankingAPITestCase(APITestCase):
    def test_get_rankings_list(self):
        """Test ranking list endpoint"""
        
    def test_filtering_and_ordering(self):
        """Test query parameters"""
        
    def test_calculation_trigger(self):
        """Test admin calculation endpoint"""
```

### Frontend Tests
```typescript
// frontend/tests/api/rankings.test.ts
describe('Rankings API', () => {
  it('should fetch top rankings', async () => {
    const rankings = await rankingsApi.getTopRankings(10)
    expect(rankings).toHaveLength(10)
    expect(rankings[0].rank).toBe(1)
  })
  
  it('should filter by category', async () => {
    const response = await rankingsApi.getRankings({ category: 'RC' })
    expect(response.results.every(r => r.ride.category === 'RC')).toBe(true)
  })
})
```

## Future Enhancements

### Planned Features
1. **Real-time Updates**: Update rankings immediately after new reviews
2. **Regional Rankings**: Rankings by geographic region
3. **Time-Period Rankings**: Best new rides, best classic rides
4. **User Preferences**: Personalized rankings based on user history
5. **Confidence Intervals**: Statistical confidence for rankings
6. **Mobile App API**: Optimized endpoints for mobile applications

### Potential Optimizations
1. **Incremental Updates**: Only recalculate affected comparisons
2. **Parallel Processing**: Distribute calculation across workers
3. **Machine Learning**: Predict rankings for new rides
4. **GraphQL API**: More flexible data fetching
5. **WebSocket Updates**: Real-time ranking changes

## Support & Documentation

### Additional Resources
- [Original IRCP Algorithm](https://ushsho.com/ridesurvey.py)
- [Django REST Framework Documentation](https://www.django-rest-framework.org/)
- [Vue.js Documentation](https://vuejs.org/)
- [TypeScript Documentation](https://www.typescriptlang.org/)

### Contact
For questions or issues related to the ranking system:
- Create an issue in the project repository
- Contact the development team
- Check the troubleshooting section above

---

*Last Updated: January 2025*
*Version: 1.0*