Mizuki/Services/LoginService.cs

using System.Security.Claims;
using Microsoft.AspNetCore.Authentication;
using Mizuki.Database.Models;

namespace Mizuki.Services;

/// <summary>
/// The login service for Mizuki.
/// </summary>
public class LoginService(
    IHttpContextAccessor httpContextAccessor,
    UserService userService)
{
    /// <summary>
    /// Logs in as a given user.
    /// </summary>
    /// <param name="user">The user.</param>
    public async Task LoginAsUser(
        User user)
    {
        var claims = new List<Claim>
        {
            new(ClaimTypes.NameIdentifier, user.Id.ToString()),
            new(ClaimTypes.Name, user.Username)
        };

        var claimsIdentity = new ClaimsIdentity(claims, "MizukiAuth");
        await httpContextAccessor.HttpContext!
            .SignInAsync(
                "MizukiAuth",
                new ClaimsPrincipal(claimsIdentity),
                new AuthenticationProperties());
    }

    /// <summary>
    /// Logs out.
    /// </summary>
    public async Task Logout()
    {
        await httpContextAccessor.HttpContext!
            .SignOutAsync("MizukiAuth");
    }

    /// <summary>
    /// Gets the active user.
    /// </summary>
    /// <returns>The active user.</returns>
    public async Task<User> GetActiveUser()
    {
        var username = httpContextAccessor.HttpContext!
            .User
            .FindFirst(ClaimTypes.Name)!
            .ToString();

        return await userService.GetUserForUsername(username);
    }
}