using GermanApp.Domain.Entities;

namespace GermanApp.Domain.Interfaces;

/// <summary>
/// Generic repository interface for domain entities.
/// All repositories should implement this interface.
/// </summary>
/// <typeparam name="TEntity">The entity type</typeparam>
/// <typeparam name="TId">The identifier type (usually int or Guid)</typeparam>
public interface IRepository<TEntity, TId> where TEntity : class
{
    /// <summary>
    /// Gets an entity by its identifier.
    /// </summary>
    Task<TEntity?> GetByIdAsync(TId id, CancellationToken cancellationToken = default);

    /// <summary>
    /// Gets all entities.
    /// </summary>
    Task<IReadOnlyList<TEntity>> GetAllAsync(CancellationToken cancellationToken = default);

    /// <summary>
    /// Adds a new entity.
    /// </summary>
    Task<TEntity> AddAsync(TEntity entity, CancellationToken cancellationToken = default);

    /// <summary>
    /// Updates an existing entity.
    /// </summary>
    Task UpdateAsync(TEntity entity, CancellationToken cancellationToken = default);

    /// <summary>
    /// Deletes an entity.
    /// </summary>
    Task DeleteAsync(TEntity entity, CancellationToken cancellationToken = default);

    /// <summary>
    /// Checks if an entity with the given identifier exists.
    /// </summary>
    Task<bool> ExistsAsync(TId id, CancellationToken cancellationToken = default);
}

/// <summary>
/// Repository interface for Lesson entities.
/// </summary>
public interface ILessonRepository : IRepository<Lesson, int>
{
    /// <summary>
    /// Gets lessons by level.
    /// </summary>
    Task<IReadOnlyList<Lesson>> GetByLevelAsync(int level, CancellationToken cancellationToken = default);

    /// <summary>
    /// Gets beginner-level lessons.
    /// </summary>
    Task<IReadOnlyList<Lesson>> GetBeginnerLessonsAsync(CancellationToken cancellationToken = default);

    /// <summary>
    /// Gets advanced-level lessons.
    /// </summary>
    Task<IReadOnlyList<Lesson>> GetAdvancedLessonsAsync(CancellationToken cancellationToken = default);
}