# Link Nest - Adapter Layer

Provides framework-agnostic data navigation between managed apps (AMAR) and pawprint.

## Status: Initial Implementation ✅

**Working:**
- ✅ FastAPI service with adapter pattern
- ✅ BaseAdapter interface for pluggable frameworks
- ✅ DjangoAdapter with AMAR database queries
- ✅ Docker build and container starts
- ✅ `/health` endpoint (adapter loads successfully)
- ✅ `/api/queries` endpoint (lists available queries)

**Pending:**
- ⏳ Database connection (needs DB_HOST env var fix)
- ⏳ Complete all entity queries (Pet, Vet, ServiceRequest, etc.)
- ⏳ Ward integration (consume JSON and render graph)

## Architecture

```
Managed App (AMAR) ←─── link_nest ───→ Pawprint (Ward)
      ↓                     ↓                  ↓
   Database         Adapter Layer      Graph Renderer
                    (SQL → JSON)        (JSON → SVG)
```

**JSON Contract:**
```json
{
  "nodes": [
    {"id": "User_123", "type": "User", "label": "john", "data": {...}}
  ],
  "edges": [
    {"from": "User_123", "to": "PetOwner_456", "label": "has profile"}
  ],
  "summary": {
    "title": "User #123",
    "credentials": "john | Password: Amar2025!",
    "fields": {"Email": "john@example.com"}
  }
}
```

## Endpoints

- `GET /health` - Health check with adapter status
- `GET /api/queries` - List available predefined queries
- `GET /api/navigate?query=user_with_pets` - Query mode
- `GET /api/navigate?entity=User&id=123` - Entity navigation mode

## Available Queries

1. `user_with_pets` - User with Pet ownership
2. `user_with_requests` - User with ServiceRequests

## Usage

```bash
# Start (from core_nest/ctrl)
./start.sh link_nest -d --build

# Test
curl http://localhost:8100/health
curl http://localhost:8100/api/queries
curl "http://localhost:8100/api/navigate?query=user_with_pets"

# Logs
docker logs core_nest_link_nest
```

## Environment Variables

From `core_nest/.env`:
- `NEST_NAME` - Container naming
- `NETWORK_NAME` - Docker network
- `DB_HOST` - Database host (needs fix: should point to db container)
- `DB_PORT` - Database port
- `DB_NAME` - Database name
- `DB_USER` - Database user
- `DB_PASSWORD` - Database password
- `ADAPTER_TYPE` - Adapter to use (default: django)

## Next Steps

1. **Fix DB connection** - Set correct DB_HOST in core_nest/.env
2. **Complete queries** - Add remaining entity types
3. **Ward integration** - Create ward consumer for JSON
4. **Add graphviz rendering** - Move from data_browse reference
5. **Test end-to-end** - Query → JSON → SVG → Display

## Files

```
link_nest/
├── README.md              # This file
├── main.py                # FastAPI app with endpoints
├── requirements.txt       # Python dependencies
├── Dockerfile             # Container build
├── docker-compose.yml     # Service definition
└── adapters/
    ├── __init__.py        # BaseAdapter interface
    └── django.py          # DjangoAdapter implementation
```

## Design Goals

✅ **Framework-agnostic** - Works with Django, Rails, Express, etc.
✅ **Decoupled** - Managed app owns data, link_nest translates
✅ **Pluggable** - Adapters for different frameworks
✅ **Authenticated** - Ready for remote deployment
✅ **Incremental** - Build and test each piece

## Reference

Previous approach (databrowse direct DB) saved in:
- Branch: `ref/databrowse-direct-db` (ward repo)
- Problem: Tight coupling, won't work remote
- Solution: This adapter pattern