# ABN Lookup Caching Implementation

## Summary

Successfully implemented caching for ABN lookups in the RateRight app to reduce API calls to the Australian Business Register (ABR).

## Changes Made

### 1. Database Migration
- **File**: `supabase/migrations/20260210000001_create_abn_cache_table.sql`
- Created `abn_cache` table with the following features:
  - Stores ABN number, company name, status, address details, entity type, GST registration status
  - Automatic expiry calculation (30 days for valid ABNs, 7 days for invalid/not found)
  - Cache metadata (lookup count, last lookup time, created/updated timestamps)
  - ABR response data stored as JSON for flexibility
  - Indexes for fast lookups and cleanup operations
  - RLS policies for security (read-only for authenticated users, admin operations via service role)

### 2. Cache Service Library
- **File**: `src/lib/abn-cache.ts`
- Provides functions for:
  - `getCachedABN()`: Retrieve cached ABN data if available and not expired
  - `cacheABNData()`: Store ABN data from ABR response with appropriate expiry
  - `cleanupExpiredABNCache()`: Clean up expired cache entries
  - `getABNCacheStats()`: Get cache statistics for monitoring

### 3. API Route Integration
- **File**: `src/app/api/abn-lookup/route.ts`
- Modified the ABN lookup flow:
  1. Check cache first before calling ABR API
  2. If cache hit: return cached data with `cached: true` flag
  3. If cache miss: call ABR API, cache the result, then return
  4. Different expiry times based on ABN status (30 days for active, 7 days for not found)

### 4. Bug Fix
- **File**: `src/lib/constants.ts`
- Added missing `SEND_MESSAGE_RATE_LIMIT` constant that was causing build errors

## Cache Strategy

### Expiry Logic
- **Valid ABNs (Active status)**: 30 days expiry
- **Invalid/Not found ABNs**: 7 days expiry (shorter to allow retry)

### Cache Hit Statistics
- Tracks lookup count and last lookup time for each cached ABN
- Provides insights into cache effectiveness

### Cleanup
- Built-in function to clean up expired entries
- Can be run periodically via cron job or manual trigger

## Usage

The caching is transparent to the frontend. The API response includes a `cached` flag to indicate if the data came from cache:

```json
{
  "success": true,
  "data": { /* company data */ },
  "cached": true,
  "cachedAt": "2026-02-09T04:50:00Z"
}
```

## Benefits

1. **Reduced API Calls**: Significantly reduces calls to ABR API
2. **Improved Performance**: Faster response times for repeated ABN lookups
3. **Cost Savings**: Less external API usage
4. **Better User Experience**: Faster form validation and company registration
5. **Intelligent Expiry**: Different expiry times based on data validity

## Monitoring

Use the provided functions to monitor cache performance:

```sql
-- Check cache statistics
SELECT * FROM get_abn_cache_stats();

-- Manual cleanup of expired entries
SELECT * FROM cleanup_expired_abn_cache();
```

## Build Status

✅ Build completed successfully
✅ No TypeScript errors
✅ All imports resolved correctly

The implementation is ready for deployment and will start caching ABN lookups immediately upon deployment.