Reset achievements unlocked via SAM after specific date

SAM.Game/Manager.cs

@@ -38,6 +38,7 @@ internal partial class Manager : Form
     {
         private readonly long _GameId;
         private readonly API.Client _SteamClient;
+        private readonly DateTime _SAMStartDate;
 
         private readonly WebClient _IconDownloader = new();
 
@@ -52,7 +53,7 @@ internal partial class Manager : Form
 
         //private API.Callback<APITypes.UserStatsStored> UserStatsStoredCallback;
 
-        public Manager(long gameId, API.Client client)
+        public Manager(long gameId, API.Client client, DateTime samStartDate)
         {
             this.InitializeComponent();
 
@@ -85,6 +86,7 @@ public Manager(long gameId, API.Client client)
 
             this._GameId = gameId;
             this._SteamClient = client;
+            this._SAMStartDate = samStartDate;
 
             this._IconDownloader.DownloadDataCompleted += this.OnIconDownload;
 
@@ -840,6 +842,80 @@ private void OnResetAllStats(object sender, EventArgs e)
             this.RefreshStats();
         }
 
+        private void OnRevertAchievements(object sender, EventArgs e)
+        {
+            int unlockedAchievementCount = 0;
+            int totalAchievementCount = this._AchievementListView.Items.Count;
+
+            if (MessageBox.Show(
+                $"Do you want to reset your achievements after {_SAMStartDate}?",
+                "Warning",
+                MessageBoxButtons.YesNo,
+                MessageBoxIcon.Warning) == DialogResult.No)
+            {
+                return;
+            }
+
+            if (this._AchievementListView.Items.Count == 0 && this._AchievementListView.Items.Count < 5)
+            {
+                return;
+            }
+
+            List<Stats.AchievementInfo> achievements = new();
+            foreach (ListViewItem item in this._AchievementListView.Items)
+            {
+                if (item.Tag is not Stats.AchievementInfo achievementInfo ||
+                    achievementInfo.IsAchieved == false)
+                {
+                    continue;
+                }
+
+                unlockedAchievementCount++;
+
+                // UnlockTime can not be null, because we've already checked if it's achieved.
+                DateTime achievementDate = (DateTime)achievementInfo.UnlockTime;
+
+                if (achievementDate > _SAMStartDate)
+                {
+                    achievementInfo.IsAchieved = false;
+                    achievements.Add(achievementInfo);
+                }
+            }
+
+            if (achievements.Count == 0)
+            {
+                return;
+            }
+
+            if (MessageBox.Show(
+                $"{unlockedAchievementCount} out of {totalAchievementCount} achievements unlocked. There are {achievements.Count} achievements unlocked after {_SAMStartDate}\n" +
+                $"Current Completion Rate: {((unlockedAchievementCount / (float)totalAchievementCount) * 100).ToString("N2", CultureInfo.InvariantCulture)}%\n" +
+                $"Completion Rate After Reset: {(((unlockedAchievementCount - achievements.Count) / (float)totalAchievementCount) * 100).ToString("N2", CultureInfo.InvariantCulture)}%\n" +
+                $"Are you sure?",
+                "Warning",
+                MessageBoxButtons.YesNo,
+                MessageBoxIcon.Warning) == DialogResult.No)
+            {
+                return;
+            }
+
+            foreach (var info in achievements)
+            {
+                if (this._SteamClient.SteamUserStats.SetAchievement(info.Id, info.IsAchieved) == false)
+                {
+                    MessageBox.Show(
+                        this,
+                        $"An error occurred while setting the state for {info.Id}, aborting store.",
+                        "Error",
+                        MessageBoxButtons.OK,
+                        MessageBoxIcon.Error);
+                    return;
+                }
+            }
+
+            Application.Exit();
+        }
+
         private void OnCheckAchievement(object sender, ItemCheckEventArgs e)
         {
             if (sender != this._AchievementListView)

SAM.Game/Program.cs

@@ -32,6 +32,7 @@ internal static class Program
         public static void Main(string[] args)
         {
             long appId;
+            DateTime samStartDate;
 
             if (args.Length == 0)
             {
@@ -49,6 +50,16 @@ public static void Main(string[] args)
                 return;
             }
 
+            if (DateTime.TryParse(args[1], out samStartDate) == false)
+            {
+                MessageBox.Show(
+                    "Could not parse SAM Start Date from command line argument.",
+                    "Error",
+                    MessageBoxButtons.OK,
+                    MessageBoxIcon.Error);
+                return;
+            }
+
             if (API.Steam.GetInstallPath() == Application.StartupPath)
             {
                 MessageBox.Show(
@@ -71,7 +82,7 @@ public static void Main(string[] args)
                     {
                         MessageBox.Show(
                             "Steam is not running. Please start Steam then run this tool again.\n\n" +
-                            "If you have the game through Family Share, the game may be locked due to\n" +
+                            "If you have the game through Family Share, the game may be locked due to\n\n" +
                             "the Family Share account actively playing a game.\n\n" +
                             "(" + e.Message + ")",
                             "Error",
@@ -109,7 +120,7 @@ public static void Main(string[] args)
 
                 Application.EnableVisualStyles();
                 Application.SetCompatibleTextRenderingDefault(false);
-                Application.Run(new Manager(appId, client));
+                Application.Run(new Manager(appId, client, samStartDate));
             }
         }
     }