From 12fef7cbaf2073f9cc349ed765ea140be0259d8e Mon Sep 17 00:00:00 2001
From: Paweł Bernaciak <pawelbernaciak@zohomail.eu>
Date: Sat, 21 Oct 2023 11:55:33 +0200
Subject: Basic API auth and Google login

---
 .../Elements.Backend/Controllers/AuthController.cs | 106 +++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 backend/Elements.Backend/Controllers/AuthController.cs

(limited to 'backend/Elements.Backend/Controllers/AuthController.cs')

diff --git a/backend/Elements.Backend/Controllers/AuthController.cs b/backend/Elements.Backend/Controllers/AuthController.cs
new file mode 100644
index 0000000..56e7c3b
--- /dev/null
+++ b/backend/Elements.Backend/Controllers/AuthController.cs
@@ -0,0 +1,106 @@
+using System.Runtime.Serialization;
+using System.Security.Claims;
+using System.Text.Json;
+using Elements.Data;
+using Elements.Data.Models;
+using Google.Apis.Auth;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Authentication.Cookies;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+
+namespace Elements.Backend.Controllers;
+
+[ApiController]
+[Route("[controller]/[action]")]
+public class AuthController : ControllerBase
+{
+    private readonly IConfiguration _config;
+    private readonly ApplicationDbContext _dbContext;
+
+    public AuthController(IConfiguration config, ApplicationDbContext dbContext)
+    {
+        _config = config;
+        _dbContext = dbContext;
+    }
+
+    public class LoginModel
+    {
+        public required string GoogleToken { get; init; }
+    }
+
+    [HttpPost]
+    public async Task<IActionResult> Login([FromBody] LoginModel model)
+    {
+        GoogleJsonWebSignature.Payload? payload = await VerifyGoogleIdToken(model.GoogleToken);
+        if (payload == null)
+            return Unauthorized();
+
+        User? user = await _dbContext.Users.SingleOrDefaultAsync(u => u.GoogleId == payload.Subject);
+        if (user != null)
+        {
+            //Check if user's name changed and update if it did
+            if (user.Name != payload.Name)
+                user.Name = payload.Name;
+        }
+        else
+        {
+            user = new User()
+            {
+                Name = payload.Name,
+                GoogleId = payload.Subject,
+                Elements = new List<Element>()
+            };
+
+            await _dbContext.Users.AddAsync(user);
+        }
+
+        await _dbContext.SaveChangesAsync();
+
+        List<Claim> claims = new()
+        {
+            new Claim("id", user.Id.ToString()),
+            new Claim(ClaimTypes.Role, "User")
+        };
+        ClaimsIdentity claimsIdentity = new(claims, CookieAuthenticationDefaults.AuthenticationScheme);
+
+        AuthenticationProperties authProperties = new()
+        {
+            IsPersistent = true,
+            AllowRefresh = true
+        };
+
+        await HttpContext.SignInAsync(
+            CookieAuthenticationDefaults.AuthenticationScheme,
+            new ClaimsPrincipal(claimsIdentity),
+            authProperties);
+
+        var response = new
+        {
+            Id = user.Id.ToString()
+        };
+        
+        return Ok(JsonSerializer.Serialize(response));
+    }
+    
+    [HttpPost]
+    public async Task<IActionResult> Logout()
+    {
+        await HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);
+        return Ok();
+    }
+
+    private async Task<GoogleJsonWebSignature.Payload?> VerifyGoogleIdToken(string token)
+    {
+        try
+        {
+            GoogleJsonWebSignature.Payload? payload = await GoogleJsonWebSignature.ValidateAsync(token);
+            return payload;
+        }
+        catch (InvalidJwtException)
+        {
+            return null;
+        }
+    }
+}
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