# Module: Common/DTO

## Purpose
Data transfer objects used across all layers — API requests/responses, inter-service communication, and queue messages.

## Public Interface

### GeoPoint
Geographic coordinate with tolerance-based equality.
- `Lat` (double): latitude, JSON property `"lat"`
- `Lon` (double): longitude, JSON property `"lon"`
- Constructor: `GeoPoint()`, `GeoPoint(double lat, double lon)`
- Equality: two points are equal if both coordinates differ by less than `0.00005` (PRECISION_TOLERANCE)
- Operator overloads: `==`, `!=`

### Direction
Result of a directional calculation between two points.
- `Distance` (double): distance in meters
- `Azimuth` (double): bearing in degrees (0–360)

### SatTile
Represents a single map tile with its spatial bounds.
- `X`, `Y` (int): tile coordinates in the slippy map scheme
- `Zoom` (int): zoom level
- `LeftTop`, `BottomRight` (GeoPoint): computed bounding box corners (via `GeoUtils.TileToWorldPos`)
- `Url` (string): download URL
- `FileName → string`: formatted as `{X}.{Y}.{Zoom}.jpg`

### TileMetadata
Metadata about a stored tile (mirrors `TileEntity` but without DB-specific concerns).
- `Id` (Guid), `TileZoom`, `TileX`, `TileY` (int), `Latitude`, `Longitude` (double)
- `TileSizeMeters` (double), `TileSizePixels` (int), `ImageType` (string)
- `Version` (int?), `FilePath` (string)
- `CreatedAt`, `UpdatedAt` (DateTime)

### RegionRequest
Queue message for async region processing.
- `Id` (Guid), `Latitude`, `Longitude` (double), `SizeMeters` (double)
- `ZoomLevel` (int), `StitchTiles` (bool)

### RegionStatus
Response DTO for region status queries.
- `Id` (Guid), `Status` (string), `CsvFilePath`, `SummaryFilePath` (string?)
- `TilesDownloaded`, `TilesReused` (int), `CreatedAt`, `UpdatedAt` (DateTime)

### RoutePoint
Input point in a route creation request.
- `Latitude` (double, JSON: `"lat"`), `Longitude` (double, JSON: `"lon"`)

### RoutePointDto
Output point in a route response (includes computed fields).
- `Latitude`, `Longitude` (double), `PointType` (string: "start"/"end"/"action"/"intermediate")
- `SequenceNumber`, `SegmentIndex` (int), `DistanceFromPrevious` (double?)

### CreateRouteRequest
API request body for route creation.
- `Id` (Guid), `Name` (string), `Description` (string?)
- `RegionSizeMeters` (double), `ZoomLevel` (int)
- `Points` (List\<RoutePoint\>), `Geofences` (Geofences?)
- `RequestMaps` (bool), `CreateTilesZip` (bool)

### RouteResponse
API response for route queries.
- All fields from the route entity plus `Points` (List\<RoutePointDto\>)
- `MapsReady` (bool), `TilesZipPath` (string?)

### GeofencePolygon
Axis-aligned bounding box defined by NW and SE corners.
- `NorthWest` (GeoPoint?), `SouthEast` (GeoPoint?)

### Geofences
Container for multiple geofence polygons.
- `Polygons` (List\<GeofencePolygon\>)

## Internal Logic
- `GeoPoint` uses a precision tolerance of `0.00005` degrees (~5.5 meters) for equality comparison.
- `SatTile` eagerly computes its bounding box corners on construction by calling `GeoUtils.TileToWorldPos`.

## Dependencies
- `GeoPoint`, `Direction` — no imports
- `SatTile` → `SatelliteProvider.Common.Utils.GeoUtils`
- All others — no internal dependencies (or only `System.Text.Json.Serialization`)

## Consumers
- All services, repositories, and API endpoints consume these DTOs
- `RegionRequest` is the message type for `IRegionRequestQueue`

## Data Models
These ARE the data models (DTOs). They map closely to the database entities but are decoupled from the persistence layer.

## Configuration
None consumed directly.

## External Integrations
None.

## Security
None.

## Tests
No dedicated DTO tests.