Refactor API endpoints into modules

src/ASTRAIN.Api/Services/UserProvisioning.cs

@@ -0,0 +1,60 @@
+using System.Text.RegularExpressions;
+using ASTRAIN.Api.Data;
+using ASTRAIN.Shared.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace ASTRAIN.Api.Services;
+
+/// <summary>
+/// Provides helper methods for ensuring and validating application users.
+/// </summary>
+internal static class UserProvisioning
+{
+    /// <summary>
+    /// Ensures a user exists in the database and returns the user record.
+    /// </summary>
+    /// <param name="db">The application database context.</param>
+    /// <param name="userId">Optional user id to validate or create.</param>
+    /// <returns>The existing or newly created user.</returns>
+    public static async Task<User> EnsureUserAsync(AppDbContext db, string? userId)
+    {
+        if (!string.IsNullOrWhiteSpace(userId) && IsValidUserId(userId))
+        {
+            var existing = await db.Users.FirstOrDefaultAsync(u => u.Id == userId);
+            if (existing is not null)
+            {
+                return existing;
+            }
+
+            var created = new User { Id = userId };
+            db.Users.Add(created);
+            await db.SaveChangesAsync();
+            return created;
+        }
+
+        while (true)
+        {
+            var newId = UserKeyGenerator.Generate(8);
+            var exists = await db.Users.AnyAsync(u => u.Id == newId);
+            if (exists)
+            {
+                continue;
+            }
+
+            var user = new User { Id = newId };
+            db.Users.Add(user);
+            await db.SaveChangesAsync();
+            return user;
+        }
+    }
+
+    /// <summary>
+    /// Determines whether a user id matches the expected format.
+    /// </summary>
+    /// <param name="userId">The user id to validate.</param>
+    /// <returns><c>true</c> if the id is valid; otherwise <c>false</c>.</returns>
+    public static bool IsValidUserId(string userId)
+    {
+        return Regex.IsMatch(userId, "^[A-Za-z0-9]{8}$");
+    }
+}