DeutschLernen/GermanApp/Presentation/Controllers/LessonsController.cs

using GermanApp.Application.DTOs;
using GermanApp.Application.Services;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;

namespace GermanApp.Presentation.Controllers;

/// <summary>
/// API controller for managing lessons.
/// This is part of the Presentation layer.
/// </summary>
[ApiController]
[Route("api/[controller]")]
[Authorize]
public class LessonsController : ControllerBase
{
    private readonly LessonService _lessonService;
    private readonly ProgressService _progressService;

    public LessonsController(LessonService lessonService, ProgressService progressService)
    {
        _lessonService = lessonService;
        _progressService = progressService;
    }

    /// <summary>
    /// Gets all lessons.
    /// </summary>
    /// <returns>List of all lessons</returns>
    [HttpGet]
    public async Task<IActionResult> GetAllLessonsAsync(CancellationToken cancellationToken = default)
    {
        var lessons = await _lessonService.GetAllLessonsAsync(cancellationToken);
        return Ok(lessons);
    }

    /// <summary>
    /// Gets all lessons ordered by level and lesson order.
    /// </summary>
    /// <returns>List of all lessons in order</returns>
    [HttpGet("ordered")]
    public async Task<IActionResult> GetAllOrderedLessonsAsync(CancellationToken cancellationToken = default)
    {
        var lessons = await _lessonService.GetAllOrderedLessonsAsync(cancellationToken);
        return Ok(lessons);
    }

    /// <summary>
    /// Gets a specific lesson by its ID.
    /// </summary>
    /// <param name="id">The lesson ID</param>
    /// <returns>The lesson with the specified ID</returns>
    [HttpGet("{id}")]
    public async Task<IActionResult> GetLessonByIdAsync(int id, CancellationToken cancellationToken = default)
    {
        var lesson = await _lessonService.GetLessonByIdAsync(id, cancellationToken);
        if (lesson == null)
            return NotFound();
        return Ok(lesson);
    }

    /// <summary>
    /// Gets lessons by level ID.
    /// </summary>
    /// <param name="levelId">The level ID</param>
    /// <returns>List of lessons for the specified level</returns>
    [HttpGet("by-level/{levelId}")]
    public async Task<IActionResult> GetLessonsByLevelAsync(int levelId, CancellationToken cancellationToken = default)
    {
        var lessons = await _lessonService.GetLessonsByLevelAsync(levelId, cancellationToken);
        return Ok(lessons);
    }

    /// <summary>
    /// Gets beginner lessons (A1 and A2 - levels 1 and 2).
    /// </summary>
    /// <returns>List of beginner lessons</returns>
    [HttpGet("beginner")]
    public async Task<IActionResult> GetBeginnerLessonsAsync(CancellationToken cancellationToken = default)
    {
        var lessons = await _lessonService.GetBeginnerLessonsAsync(cancellationToken);
        return Ok(lessons);
    }

    /// <summary>
    /// Gets advanced lessons (B2 and C1 - levels 4 and 5).
    /// </summary>
    /// <returns>List of advanced lessons</returns>
    [HttpGet("advanced")]
    public async Task<IActionResult> GetAdvancedLessonsAsync(CancellationToken cancellationToken = default)
    {
        var lessons = await _lessonService.GetAdvancedLessonsAsync(cancellationToken);
        return Ok(lessons);
    }

    /// <summary>
    /// Creates a new lesson.
    /// </summary>
    /// <param name="dto">The lesson data</param>
    /// <returns>The created lesson</returns>
    [HttpPost]
    [Authorize(Roles = "Admin")]
    public async Task<IActionResult> CreateLessonAsync(CreateLessonDto dto, CancellationToken cancellationToken = default)
    {
        var lesson = await _lessonService.CreateLessonAsync(dto, cancellationToken);
        return CreatedAtAction(nameof(GetLessonByIdAsync), new { id = lesson.Id }, lesson);
    }

    /// <summary>
    /// Updates an existing lesson.
    /// </summary>
    /// <param name="id">The lesson ID</param>
    /// <param name="dto">The updated lesson data</param>
    /// <returns>The updated lesson</returns>
    [HttpPut("{id}")]
    [Authorize(Roles = "Admin")]
    public async Task<IActionResult> UpdateLessonAsync(int id, UpdateLessonDto dto, CancellationToken cancellationToken = default)
    {
        var lesson = await _lessonService.UpdateLessonAsync(id, dto, cancellationToken);
        if (lesson == null)
            return NotFound();
        return Ok(lesson);
    }

    /// <summary>
    /// Deletes a lesson by its ID.
    /// </summary>
    /// <param name="id">The lesson ID</param>
    /// <returns>No content on success</returns>
    [HttpDelete("{id}")]
    [Authorize(Roles = "Admin")]
    public async Task<IActionResult> DeleteLessonAsync(int id, CancellationToken cancellationToken = default)
    {
        var result = await _lessonService.DeleteLessonAsync(id, cancellationToken);
        if (!result)
            return NotFound();
        return NoContent();
    }

    /// <summary>
    /// Gets the first lesson in a level.
    /// </summary>
    /// <param name="levelId">The level ID</param>
    /// <returns>The first lesson in the level</returns>
    [HttpGet("first/{levelId}")]
    public async Task<IActionResult> GetFirstLessonInLevelAsync(int levelId, CancellationToken cancellationToken = default)
    {
        var lesson = await _lessonService.GetFirstLessonInLevelAsync(levelId, cancellationToken);
        if (lesson == null)
            return NotFound();
        return Ok(lesson);
    }

    /// <summary>
    /// Gets the next lesson after the specified one.
    /// </summary>
    /// <param name="currentLessonId">The current lesson ID</param>
    /// <returns>The next lesson</returns>
    [HttpGet("next/{currentLessonId}")]
    public async Task<IActionResult> GetNextLessonAsync(int currentLessonId, CancellationToken cancellationToken = default)
    {
        var lesson = await _lessonService.GetNextLessonAsync(currentLessonId, cancellationToken);
        if (lesson == null)
            return NotFound();
        return Ok(lesson);
    }

    /// <summary>
    /// Gets lessons that the user can access (based on completion of previous lessons).
    /// </summary>
    /// <param name="userId">The user ID</param>
    /// <returns>List of accessible lessons for the user</returns>
    [HttpGet("accessible/{userId}")]
    [Authorize]
    public async Task<IActionResult> GetAccessibleLessonsAsync(int userId, CancellationToken cancellationToken = default)
    {
        var lessons = await _lessonService.GetAccessibleLessonsAsync(userId, cancellationToken);
        return Ok(lessons);
    }

    /// <summary>
    /// Checks if the next lesson is unlocked for a user.
    /// </summary>
    /// <param name="userId">The user ID</param>
    /// <param name="currentLessonId">The current lesson ID</param>
    /// <returns>True if the next lesson is unlocked</returns>
    [HttpGet("unlocked/{userId}/{currentLessonId}")]
    [Authorize]
    public async Task<IActionResult> IsNextLessonUnlockedAsync(int userId, int currentLessonId, CancellationToken cancellationToken = default)
    {
        var isUnlocked = await _progressService.IsNextLessonUnlockedAsync(userId, currentLessonId, cancellationToken);
        return Ok(isUnlocked);
    }
}