using GermanApp.Domain.Entities;

namespace GermanApp.Application.DTOs;

/// <summary>
/// Data Transfer Object for Lesson - used for API responses.
/// This is a read-only representation of a Lesson entity.
/// </summary>
public record LessonDto(
    int Id,
    string Title,
    string Description,
    int Level,
    string LevelDescription,
    DateTime CreatedAt,
    DateTime? UpdatedAt);

/// <summary>
/// Data Transfer Object for creating a new Lesson.
/// </summary>
public record CreateLessonDto(
    string Title,
    string Description,
    int Level);

/// <summary>
/// Data Transfer Object for updating an existing Lesson.
/// </summary>
public record UpdateLessonDto(
    string Title,
    string Description,
    int Level);

/// <summary>
/// Extension methods for mapping between Lesson entity and DTOs.
/// </summary>
public static class LessonDtoExtensions
{
    public static LessonDto ToDto(this Lesson lesson) => new(
        lesson.Id,
        lesson.Title,
        lesson.Description,
        lesson.Level,
        GetLevelDescription(lesson.Level),
        lesson.CreatedAt,
        lesson.UpdatedAt);

    private static string GetLevelDescription(int level) => level switch
    {
        1 => "A1 (Beginner)",
        2 => "A2 (Elementary)",
        3 => "B1 (Intermediate)",
        4 => "B2 (Upper Intermediate)",
        5 => "C1 (Advanced)",
        _ => "Unknown"
    };

    public static Lesson ToEntity(this CreateLessonDto dto) =>
        Lesson.Create(dto.Title, dto.Description, dto.Level);
}