DeutschLernen/GermanApp/Presentation/Controllers/LevelsController.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 CEFR levels.
/// This is part of the Presentation layer.
/// </summary>
[ApiController]
[Route("api/[controller]")]
[Authorize]
public class LevelsController : ControllerBase
{
    private readonly LevelService _levelService;

    public LevelsController(LevelService levelService)
    {
        _levelService = levelService;
    }

    /// <summary>
    /// Gets all CEFR levels ordered by their sort order.
    /// </summary>
    /// <returns>List of all levels</returns>
    [HttpGet]
    public async Task<IActionResult> GetAllLevelsAsync(CancellationToken cancellationToken = default)
    {
        var levels = await _levelService.GetAllLevelsAsync(cancellationToken);
        return Ok(levels);
    }

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

    /// <summary>
    /// Gets a level by its code (e.g., "A1", "B2").
    /// </summary>
    /// <param name="code">The level code</param>
    /// <returns>The level with the specified code</returns>
    [HttpGet("by-code/{code}")]
    public async Task<IActionResult> GetLevelByCodeAsync(string code, CancellationToken cancellationToken = default)
    {
        var level = await _levelService.GetLevelByCodeAsync(code, cancellationToken);
        if (level == null)
            return NotFound();
        return Ok(level);
    }

    /// <summary>
    /// Creates a new CEFR level.
    /// </summary>
    /// <param name="dto">The level data</param>
    /// <returns>The created level</returns>
    [HttpPost]
    [Authorize(Roles = "Admin")]
    public async Task<IActionResult> CreateLevelAsync(CreateLevelDto dto, CancellationToken cancellationToken = default)
    {
        var level = await _levelService.CreateLevelAsync(dto, cancellationToken);
        return CreatedAtAction(nameof(GetLevelByIdAsync), new { id = level.Id }, level);
    }

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

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

    /// <summary>
    /// Gets the first level (lowest order number) - typically A1.
    /// </summary>
    /// <returns>The first level</returns>
    [HttpGet("first")]
    public async Task<IActionResult> GetFirstLevelAsync(CancellationToken cancellationToken = default)
    {
        var level = await _levelService.GetFirstLevelAsync(cancellationToken);
        if (level == null)
            return NotFound();
        return Ok(level);
    }

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