> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/juuaaann456/DMI-Practica06/llms.txt
> Use this file to discover all available pages before exploring further.

# Domain layer

> The domain layer defines the core business rules of Cinemapedia through entities, abstract datasources, and repository contracts.

The domain layer is the innermost ring of the architecture. It contains no framework imports and no knowledge of how data is fetched or displayed. Everything else depends on it.

## Structure

```
lib/domain/
├── entities/
│   └── movie.dart
├── datasources/
│   └── movies_datasource.dart
└── repositories/
    └── movies_repository.dart
```

## The `Movie` entity

`Movie` is the canonical representation of a film throughout the application. It is a plain Dart class with no serialization logic or external dependencies.

```dart theme={null}
class Movie {
  final bool adult;
  final String backdropPath;
  final List<int> genreIds;
  final int id;
  final String originalLanguage;
  final String originalTitle;
  final String overview;
  final double popularity;
  final String posterPath;
  final DateTime releaseDate;
  final String title;
  final bool video;
  final double voteAverage;
  final int voteCount;

  Movie({
    required this.adult,
    required this.backdropPath,
    required this.genreIds,
    required this.id,
    required this.originalLanguage,
    required this.originalTitle,
    required this.overview,
    required this.popularity,
    required this.posterPath,
    required this.releaseDate,
    required this.title,
    required this.video,
    required this.voteAverage,
    required this.voteCount,
  });
}
```

### Field reference

| Field              | Type        | Description                       |
| ------------------ | ----------- | --------------------------------- |
| `id`               | `int`       | Unique TheMovieDB identifier      |
| `title`            | `String`    | Localized movie title             |
| `originalTitle`    | `String`    | Title in the original language    |
| `overview`         | `String`    | Plot summary                      |
| `posterPath`       | `String`    | Full URL to the poster image      |
| `backdropPath`     | `String`    | Full URL to the backdrop image    |
| `releaseDate`      | `DateTime`  | Theatrical release date           |
| `voteAverage`      | `double`    | Average user rating (0–10)        |
| `voteCount`        | `int`       | Total number of ratings           |
| `popularity`       | `double`    | TheMovieDB popularity score       |
| `genreIds`         | `List<int>` | Genre identifiers                 |
| `originalLanguage` | `String`    | ISO 639-1 language code           |
| `adult`            | `bool`      | Whether the film is adult-rated   |
| `video`            | `bool`      | Whether a video clip is available |

<Note>
  `posterPath` and `backdropPath` on the domain entity are already full URLs. The infrastructure mapper is responsible for constructing them — the domain entity never knows about the image CDN.
</Note>

## Abstract datasource

`MoviesDatasource` is an abstract class that declares what operations any data source must support. The domain defines the contract; the infrastructure fulfills it.

```dart theme={null}
import 'package:cinemapedia_220083/domain/entities/movie.dart';

abstract class MoviesDatasource {
  Future<List<Movie>> getNowPlaying({int page = 1});
  Future<List<Movie>> getPopular({int page = 1});
  Future<List<Movie>> getUpcoming({int page = 1});
  Future<List<Movie>> getTopRated({int page = 1});
  Future<List<Movie>> getMexicanMovies({int page = 1});
}
```

All methods accept a `page` parameter that defaults to `1`, enabling pagination without forcing callers to supply it.

## Abstract repository

`MoviesRepository` mirrors the datasource contract. The extra abstraction layer allows the application to swap datasources or add caching inside a repository implementation without changing the presentation layer.

```dart theme={null}
import 'package:cinemapedia_220083/domain/entities/movie.dart';

abstract class MoviesRepository {
  Future<List<Movie>> getNowPlaying({int page = 1});
  Future<List<Movie>> getPopular({int page = 1});
  Future<List<Movie>> getUpcoming({int page = 1});
  Future<List<Movie>> getTopRated({int page = 1});
  Future<List<Movie>> getMexicanMovies({int page = 1});
}
```

<Tip>
  The repository and datasource abstractions look identical here, but they serve different purposes. The datasource is about raw data access; the repository is where business logic (caching, merging sources, error handling) would live as the app grows.
</Tip>