using GermanApp.Application.DTOs;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

namespace GermanApp.Application.Interfaces;

/// <summary>
/// Interface for user progress report services.
/// Part of the Application layer.
/// </summary>
public interface IUserReportService
{
    /// <summary>
    /// Generates a progress report for a specific user.
    /// </summary>
    /// <param name="userId">The user ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>User progress report</returns>
    Task<UserProgressReportDto> GenerateUserReportAsync(int userId, CancellationToken cancellationToken = default);

    /// <summary>
    /// Generates progress reports for all users.
    /// </summary>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>List of all user progress reports</returns>
    Task<IReadOnlyList<UserProgressReportDto>> GenerateAllUserReportsAsync(CancellationToken cancellationToken = default);

    /// <summary>
    /// Gets lesson completion data for a user.
    /// </summary>
    /// <param name="userId">The user ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>List of lesson completion data</returns>
    Task<IReadOnlyList<LessonCompletionDto>> GetUserLessonProgressAsync(int userId, CancellationToken cancellationToken = default);

    /// <summary>
    /// Gets quiz results for a user.
    /// </summary>
    /// <param name="userId">The user ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>List of quiz results</returns>
    Task<IReadOnlyList<UserQuizResultDto>> GetUserQuizResultsAsync(int userId, CancellationToken cancellationToken = default);

    /// <summary>
    /// Exports user reports as CSV.
    /// </summary>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>CSV content as string</returns>
    Task<string> ExportReportsAsCsvAsync(CancellationToken cancellationToken = default);
}