# Module: DataAccess/Repositories/TileRepository

## Purpose
Dapper-based repository for the `tiles` table. Handles CRUD operations and spatial queries for satellite tile records.

## Public Interface

### ITileRepository (interface)
- `GetByIdAsync(Guid id) → Task<TileEntity?>`
- `GetByTileCoordinatesAsync(int tileZoom, int tileX, int tileY) → Task<TileEntity?>`: finds tile by slippy map coordinates, returns latest version
- `FindExistingTileAsync(double lat, double lon, double tileSizeMeters, int zoomLevel, int version) → Task<TileEntity?>`: fuzzy coordinate match (tolerance: 0.0001° lat/lon, 1m tile size)
- `GetTilesByRegionAsync(double lat, double lon, double sizeMeters, int zoomLevel) → Task<IEnumerable<TileEntity>>`: spatial bounding box query with expanded range to cover tile edges
- `InsertAsync(TileEntity tile) → Task<Guid>`: upsert — `ON CONFLICT (latitude, longitude, tile_zoom, tile_size_meters, version) DO UPDATE` file_path, tile_x, tile_y, updated_at
- `UpdateAsync(TileEntity tile) → Task<int>`
- `DeleteAsync(Guid id) → Task<int>`

### TileRepository (implementation)
Constructs a new `NpgsqlConnection` per method call (no connection pooling at the repository level; Npgsql pools connections internally).

## Internal Logic
- `GetTilesByRegionAsync` calculates a bounding box by expanding the requested region by 2 × tile size to ensure edge tiles are included. Uses meters-to-degrees approximation (111,000 m/degree latitude, adjusted for longitude).
- `InsertAsync` uses an upsert pattern to handle duplicate tile downloads gracefully.
- `GetByTileCoordinatesAsync` orders by `version DESC` and takes the latest.

## Dependencies
- NuGet: `Dapper`, `Npgsql`
- `SatelliteProvider.DataAccess.Models.TileEntity`
- `Microsoft.Extensions.Logging`

## Consumers
- `TileService` — all read/write operations
- `Program.cs` (ServeTile, GetTileByLatLon handlers) — `GetByTileCoordinatesAsync`, `InsertAsync`

## Data Models
Operates on `TileEntity`.

## Configuration
Receives connection string via constructor.

## External Integrations
PostgreSQL — SQL queries via Dapper + Npgsql.

## Security
None.

## Tests
No dedicated repository tests.