From 3917dda658241e198cf6661b6989f9b33e77176d Mon Sep 17 00:00:00 2001
From: Oliver Booth <git@olivr.me>
Date: Sun, 25 Feb 2024 14:18:41 +0000
Subject: [PATCH] feat: add permission system to User

---
 OliverBooth/Data/Blog/BlogContext.cs          |  1 -
 OliverBooth/Data/Permission.cs                | 37 ++++++++++++++++
 OliverBooth/Data/PermissionListConverter.cs   | 42 +++++++++++++++++++
 .../Web/Configuration/UserConfiguration.cs    |  1 +
 OliverBooth/Data/Web/IUser.cs                 | 24 +++++++++++
 OliverBooth/Data/Web/User.cs                  | 17 ++++++++
 OliverBooth/Data/Web/WebContext.cs            |  1 -
 7 files changed, 121 insertions(+), 2 deletions(-)
 create mode 100644 OliverBooth/Data/Permission.cs
 create mode 100644 OliverBooth/Data/PermissionListConverter.cs

diff --git a/OliverBooth/Data/Blog/BlogContext.cs b/OliverBooth/Data/Blog/BlogContext.cs
index c20282b..4d9db4f 100644
--- a/OliverBooth/Data/Blog/BlogContext.cs
+++ b/OliverBooth/Data/Blog/BlogContext.cs
@@ -1,6 +1,5 @@
 using Microsoft.EntityFrameworkCore;
 using OliverBooth.Data.Blog.Configuration;
-using OliverBooth.Data.Web;
 
 namespace OliverBooth.Data.Blog;
 
diff --git a/OliverBooth/Data/Permission.cs b/OliverBooth/Data/Permission.cs
new file mode 100644
index 0000000..6ad2376
--- /dev/null
+++ b/OliverBooth/Data/Permission.cs
@@ -0,0 +1,37 @@
+namespace OliverBooth.Data;
+
+/// <summary>
+///     Represents a permission.
+/// </summary>
+public struct Permission
+{
+    /// <summary>
+    ///     Represents a permission that grants all scopes.
+    /// </summary>
+    public static readonly Permission Administrator = new("*");
+    
+    /// <summary>
+    ///     Initializes a new instance of the <see cref="Permission" /> struct.
+    /// </summary>
+    /// <param name="name">The name of the permission.</param>
+    /// <param name="isAllowed">
+    ///     <see langword="true" /> if the permission is allowed; otherwise, <see langword="false" />.
+    /// </param>
+    public Permission(string name, bool isAllowed = true)
+    {
+        Name = name;
+        IsAllowed = isAllowed;
+    }
+
+    /// <summary>
+    ///     Gets the name of this permission.
+    /// </summary>
+    /// <value>The name.</value>
+    public string Name { get; }
+
+    /// <summary>
+    ///     Gets a value indicating whether this permission is allowed.
+    /// </summary>
+    /// <value><see langword="true" /> if the permission is allowed; otherwise, <see langword="false" />.</value>
+    public bool IsAllowed { get; }
+}
diff --git a/OliverBooth/Data/PermissionListConverter.cs b/OliverBooth/Data/PermissionListConverter.cs
new file mode 100644
index 0000000..3dd86a2
--- /dev/null
+++ b/OliverBooth/Data/PermissionListConverter.cs
@@ -0,0 +1,42 @@
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+namespace OliverBooth.Data;
+
+internal sealed class PermissionListConverter : ValueConverter<IReadOnlyList<Permission>, string>
+{
+    public PermissionListConverter() : this(';')
+    {
+    }
+
+    public PermissionListConverter(char separator) :
+        base(v => ToProvider(v, separator),
+            s => FromProvider(s, separator))
+    {
+    }
+
+    private static IReadOnlyList<Permission> FromProvider(string source, char separator = ';')
+    {
+        var permissions = new List<Permission>();
+
+        foreach (string permission in source.Split(separator))
+        {
+            string name = permission;
+            var allowed = true;
+
+            if (name.Length > 1 && name[0] == '-')
+            {
+                name = name[1..];
+                allowed = false;
+            }
+
+            permissions.Add(new Permission(name, allowed));
+        }
+
+        return permissions.AsReadOnly();
+    }
+
+    private static string ToProvider(IEnumerable<Permission> permissions, char separator = ';')
+    {
+        return string.Join(separator, permissions.Select(p => $"{(p.IsAllowed ? "-" : "")}{p.Name}"));
+    }
+}
diff --git a/OliverBooth/Data/Web/Configuration/UserConfiguration.cs b/OliverBooth/Data/Web/Configuration/UserConfiguration.cs
index 5c20fe0..c6be0cc 100644
--- a/OliverBooth/Data/Web/Configuration/UserConfiguration.cs
+++ b/OliverBooth/Data/Web/Configuration/UserConfiguration.cs
@@ -18,5 +18,6 @@ internal sealed class UserConfiguration : IEntityTypeConfiguration<User>
         builder.Property(e => e.Salt).HasMaxLength(255).IsRequired();
         builder.Property(e => e.Registered).IsRequired();
         builder.Property(e => e.Totp);
+        builder.Property(e => e.Permissions).HasConversion<PermissionListConverter>();
     }
 }
diff --git a/OliverBooth/Data/Web/IUser.cs b/OliverBooth/Data/Web/IUser.cs
index e021546..83f4aa8 100644
--- a/OliverBooth/Data/Web/IUser.cs
+++ b/OliverBooth/Data/Web/IUser.cs
@@ -35,6 +35,12 @@ public interface IUser
     /// <value>The registration date and time.</value>
     DateTimeOffset Registered { get; }
 
+    /// <summary>
+    ///     Gets the permissions this user is granted.
+    /// </summary>
+    /// <value>A read-only view of the permissions this user is granted.</value>
+    IReadOnlyList<Permission> Permissions { get; }
+
     /// <summary>
     ///     Gets the user's TOTP token.
     /// </summary>
@@ -48,6 +54,24 @@ public interface IUser
     /// <returns>The URL of the user's avatar.</returns>
     Uri GetAvatarUrl(int size = 28);
 
+    /// <summary>
+    ///     Determines whether the user has the specified permission.
+    /// </summary>
+    /// <param name="permission">The permission to test.</param>
+    /// <returns>
+    ///     <see langword="true" /> if the user has the specified permission; otherwise, <see langword="false" />.
+    /// </returns>
+    bool HasPermission(Permission permission);
+
+    /// <summary>
+    ///     Determines whether the user has the specified permission.
+    /// </summary>
+    /// <param name="permission">The permission to test.</param>
+    /// <returns>
+    ///     <see langword="true" /> if the user has the specified permission; otherwise, <see langword="false" />.
+    /// </returns>
+    bool HasPermission(string permission);
+
     /// <summary>
     ///     Returns a value indicating whether the specified password is valid for the user.
     /// </summary>
diff --git a/OliverBooth/Data/Web/User.cs b/OliverBooth/Data/Web/User.cs
index d713b0a..c8eaa66 100644
--- a/OliverBooth/Data/Web/User.cs
+++ b/OliverBooth/Data/Web/User.cs
@@ -24,6 +24,9 @@ internal sealed class User : IUser, IBlogAuthor
     /// <inheritdoc cref="IUser.Id" />
     public Guid Id { get; private set; } = Guid.NewGuid();
 
+    /// <inheritdoc />
+    public IReadOnlyList<Permission> Permissions { get; private set; } = ArraySegment<Permission>.Empty;
+
     /// <inheritdoc />
     public DateTimeOffset Registered { get; private set; } = DateTimeOffset.UtcNow;
 
@@ -75,6 +78,20 @@ internal sealed class User : IUser, IBlogAuthor
         return new Uri($"https://www.gravatar.com/avatar/{builder}?size={size}");
     }
 
+    /// <inheritdoc />
+    public bool HasPermission(Permission permission)
+    {
+        return HasPermission(permission.Name);
+    }
+
+    /// <inheritdoc />
+    public bool HasPermission(string permission)
+    {
+        return (Permissions.Any(p => p.IsAllowed && p.Name == permission) ||
+                Permissions.Any(p => p is { IsAllowed: true, Name: "*" })) &&
+               !Permissions.Any(p => !p.IsAllowed && p.Name == permission);
+    }
+
     /// <inheritdoc />
     public bool TestCredentials(string password)
     {
diff --git a/OliverBooth/Data/Web/WebContext.cs b/OliverBooth/Data/Web/WebContext.cs
index c445a3b..9f884c6 100644
--- a/OliverBooth/Data/Web/WebContext.cs
+++ b/OliverBooth/Data/Web/WebContext.cs
@@ -1,5 +1,4 @@
 using Microsoft.EntityFrameworkCore;
-using OliverBooth.Data.Blog.Configuration;
 using OliverBooth.Data.Web.Configuration;
 
 namespace OliverBooth.Data.Web;