DeutschLernen/GermanApp/Presentation/Endpoints/LessonsEndpoints.cs

using GermanApp.Application.DTOs;
using GermanApp.Application.UseCases.Commands;
using GermanApp.Domain.Entities;
using GermanApp.Domain.Interfaces;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;

namespace GermanApp.Presentation.Endpoints;

/// <summary>
/// Minimal API endpoints for Lesson resources.
/// This is part of the Presentation layer.
/// </summary>
public static class LessonsEndpoints
{
    public static void MapLessonsEndpoints(this WebApplication app)
    {
        var group = app.MapGroup("/api/lessons");

        // GET /api/lessons
        group.MapGet("/", async ([FromServices] ILessonRepository repository) =>
        {
            var lessons = await repository.GetAllAsync();
            return Results.Ok(lessons.Select(l => l.ToDto()));
        })
        .WithName("GetAllLessons")
        .WithOpenApi(operation => new(operation)
        {
            Summary = "Get all lessons",
            Description = "Retrieves all available German lessons"
        });

        // GET /api/lessons/{id}
        group.MapGet("/{id}", async ([FromRoute] int id, [FromServices] ILessonRepository repository) =>
        {
            var lesson = await repository.GetByIdAsync(id);
            return lesson is null ? Results.NotFound() : Results.Ok(lesson.ToDto());
        })
        .WithName("GetLessonById")
        .WithOpenApi(operation => new(operation)
        {
            Summary = "Get lesson by ID",
            Description = "Retrieves a specific lesson by its identifier"
        });

        // GET /api/lessons/beginner
        group.MapGet("/beginner", async ([FromServices] ILessonRepository repository) =>
        {
            // Beginner lessons are A1 (level 1) and A2 (level 2)
            var beginnerLessons = new List<Lesson>();
            var level1Lessons = await repository.GetByLevelAsync(1);
            var level2Lessons = await repository.GetByLevelAsync(2);
            beginnerLessons.AddRange(level1Lessons);
            beginnerLessons.AddRange(level2Lessons);
            return Results.Ok(beginnerLessons.OrderBy(l => l.LevelId).ThenBy(l => l.Order).Select(l => l.ToDto()));
        })
        .WithName("GetBeginnerLessons")
        .WithOpenApi(operation => new(operation)
        {
            Summary = "Get beginner lessons",
            Description = "Retrieves all lessons at beginner level (A1-A2)"
        });

        // GET /api/lessons/advanced
        group.MapGet("/advanced", async ([FromServices] ILessonRepository repository) =>
        {
            // Advanced lessons are B2 (level 4) and C1 (level 5)
            var advancedLessons = new List<Lesson>();
            var level4Lessons = await repository.GetByLevelAsync(4);
            var level5Lessons = await repository.GetByLevelAsync(5);
            advancedLessons.AddRange(level4Lessons);
            advancedLessons.AddRange(level5Lessons);
            return Results.Ok(advancedLessons.OrderBy(l => l.LevelId).ThenBy(l => l.Order).Select(l => l.ToDto()));
        })
        .WithName("GetAdvancedLessons")
        .WithOpenApi(operation => new(operation)
        {
            Summary = "Get advanced lessons",
            Description = "Retrieves all lessons at advanced level (B2-C1)"
        });

        // GET /api/lessons/level/{level}
        group.MapGet("/level/{level}", async ([FromRoute] int level, [FromServices] ILessonRepository repository) =>
        {
            var lessons = await repository.GetByLevelAsync(level);
            return Results.Ok(lessons.Select(l => l.ToDto()));
        })
        .WithName("GetLessonsByLevel")
        .WithOpenApi(operation => new(operation)
        {
            Summary = "Get lessons by level",
            Description = "Retrieves all lessons at a specific proficiency level"
        });

        // POST /api/lessons
        group.MapPost("/", async (
            [FromBody] CreateLessonDto dto,
            [FromServices] ICommandHandler<CreateLessonCommand, LessonDto> handler,
            CancellationToken cancellationToken) =>
        {
            var command = new CreateLessonCommand(dto);
            var result = await handler.Handle(command, cancellationToken);
            return Results.Created($"/api/lessons/{result.Id}", result);
        })
        .RequireAuthorization()
        .WithName("CreateLesson")
        .WithOpenApi(operation => new(operation)
        {
            Summary = "Create a new lesson",
            Description = "Creates a new German lesson"
        });

        // PUT /api/lessons/{id}
        group.MapPut("/{id}", async (
            [FromRoute] int id,
            [FromBody] UpdateLessonDto dto,
            [FromServices] ILessonRepository repository) =>
        {
            var existingLesson = await repository.GetByIdAsync(id);
            if (existingLesson is null)
                return Results.NotFound();

            // Map DTO to entity
            existingLesson.UpdateFromDto(dto);
            await repository.UpdateAsync(existingLesson);

            return Results.Ok(existingLesson.ToDto());
        })
        .RequireAuthorization()
        .WithName("UpdateLesson")
        .WithOpenApi(operation => new(operation)
        {
            Summary = "Update a lesson",
            Description = "Updates an existing lesson"
        });

        // DELETE /api/lessons/{id}
        group.MapDelete("/{id}", async ([FromRoute] int id, [FromServices] ILessonRepository repository) =>
        {
            var lesson = await repository.GetByIdAsync(id);
            if (lesson is null)
                return Results.NotFound();

            await repository.DeleteAsync(lesson);
            return Results.NoContent();
        })
        .RequireAuthorization()
        .WithName("DeleteLesson")
        .WithOpenApi(operation => new(operation)
        {
            Summary = "Delete a lesson",
            Description = "Deletes a lesson by its identifier"
        });
    }
}