Several improvements for program loading

-Add command line options for shards
-Set consistent exit codes
-Turn on nullable option and edit code further to conform and reduce warnings
-Update libraries

BirthdayBot.csproj

@@ -3,13 +3,13 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>net6.0</TargetFramework>
-    <Version>3.1.4</Version>
+    <Version>3.2.0</Version>
     <PackageId>BirthdayBot</PackageId>
     <Authors>NoiTheCat</Authors>
     <Description>Discord bot for birthday recognition and reminders.</Description>
     <AssemblyName>BirthdayBot</AssemblyName>
     <RootNamespace>BirthdayBot</RootNamespace>
-    <Nullable>annotations</Nullable>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
@@ -24,10 +24,11 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="CommandLineParser" Version="2.8.0" />
     <PackageReference Include="Discord.Net" Version="3.0.0-dev-20210822.1" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
-    <PackageReference Include="NodaTime" Version="3.0.7" />
-    <PackageReference Include="Npgsql" Version="5.0.10" />
+    <PackageReference Include="NodaTime" Version="3.0.9" />
+    <PackageReference Include="Npgsql" Version="6.0.0-rc.2" />
   </ItemGroup>
 
 </Project>

Configuration.cs

@@ -5,6 +5,9 @@ using System;
 using System.IO;
 using System.Reflection;
 using System.Text.RegularExpressions;
+using CommandLine;
+using CommandLine.Text;
+using System.Diagnostics.CodeAnalysis;
 
 namespace BirthdayBot;
 
@@ -27,15 +30,13 @@ class Configuration {
     public int ShardAmount { get; }
     public int ShardTotal { get; }
 
-    public Configuration() {
-        // Looks for settings.json in the executable directory.
-        var confPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
-        confPath += Path.DirectorySeparatorChar + "settings.json";
+    public Configuration(string[] args) {
+        var cmdline = CmdLineOpts.Parse(args);
 
-        if (!File.Exists(confPath)) {
-            throw new Exception("Settings file not found."
-                + " Create a file in the executable directory named 'settings.json'.");
-        }
+        // Looks for configuration file
+        var confPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) + Path.DirectorySeparatorChar;
+        confPath += cmdline.Config!;
+        if (!File.Exists(confPath)) throw new Exception("Settings file not found in path: " + confPath);
 
         var jc = JObject.Parse(File.ReadAllText(confPath));
 
@@ -44,10 +45,10 @@ class Configuration {
         DBotsToken = ReadConfKey<string>(jc, nameof(DBotsToken), false);
         QuitOnFails = ReadConfKey<bool?>(jc, nameof(QuitOnFails), false) ?? false;
 
-        ShardTotal = ReadConfKey<int?>(jc, nameof(ShardTotal), false) ?? 1;
+        ShardTotal = cmdline.ShardTotal ?? ReadConfKey<int?>(jc, nameof(ShardTotal), false) ?? 1;
         if (ShardTotal < 1) throw new Exception($"'{nameof(ShardTotal)}' must be a positive integer.");
 
-        string shardRangeInput = ReadConfKey<string>(jc, KeyShardRange, false);
+        string shardRangeInput = cmdline.ShardRange ?? ReadConfKey<string>(jc, KeyShardRange, false);
         if (!string.IsNullOrWhiteSpace(shardRangeInput)) {
             Regex srPicker = new(@"(?<low>\d{1,2})[-,]{1}(?<high>\d{1,2})");
             var m = srPicker.Match(shardRangeInput);
@@ -80,9 +81,39 @@ class Configuration {
         Database.DBConnectionString = csb.ToString();
     }
 
-    private static T ReadConfKey<T>(JObject jc, string key, bool failOnEmpty) {
-        if (jc.ContainsKey(key)) return jc[key].Value<T>();
+    private static T? ReadConfKey<T>(JObject jc, string key, [DoesNotReturnIf(true)] bool failOnEmpty) {
+        if (jc.ContainsKey(key)) return jc[key]!.Value<T>();
         if (failOnEmpty) throw new Exception($"'{key}' must be specified.");
         return default;
     }
+
+    private class CmdLineOpts {
+        [Option('c', "config", Default = "settings.json",
+            HelpText = "Custom path to instance configuration, relative from executable directory.")]
+        public string? Config { get; set; }
+
+        [Option("shardtotal",
+            HelpText = "Total number of shards online. MUST be the same for all instances.\n"
+            + "This value overrides the config file value.")]
+        public int? ShardTotal { get; set; }
+
+        [Option("shardrange", HelpText = "Shard range for this instance to handle.\n"
+            + "This value overrides the config file value.")]
+        public string? ShardRange { get; set; }
+
+        public static CmdLineOpts Parse(string[] args) {
+            // Do not automatically print help message
+            var clp = new Parser(c => c.HelpWriter = null);
+
+            CmdLineOpts? result = null;
+            var r = clp.ParseArguments<CmdLineOpts>(args);
+            r.WithParsed(parsed => result = parsed);
+            r.WithNotParsed(err => {
+                    var ht = HelpText.AutoBuild(r);
+                    Console.WriteLine(ht.ToString());
+                    Environment.Exit((int)Program.ExitCodes.BadCommand);
+                });
+            return result!;
+        }
+    }
 }

Program.cs

@@ -5,7 +5,7 @@ using System.Threading.Tasks;
 namespace BirthdayBot;
 
 class Program {
-    private static ShardManager _bot;
+    private static ShardManager? _bot;
     private static readonly DateTimeOffset _botStartTime = DateTimeOffset.UtcNow;
 
     /// <summary>
@@ -13,13 +13,20 @@ class Program {
     /// </summary>
     public static string BotUptime => (DateTimeOffset.UtcNow - _botStartTime).ToString("d' days, 'hh':'mm':'ss");
 
-    static async Task Main() {
-        var cfg = new Configuration();
+    static async Task Main(string[] args) {
+        Configuration? cfg = null;
+        try {
+            cfg = new Configuration(args);
+        } catch (Exception ex) {
+            Console.WriteLine(ex);
+            Environment.Exit((int)ExitCodes.ConfigError);
+        }
+        
         try {
             await Database.DoInitialDatabaseSetupAsync();
         } catch (Npgsql.NpgsqlException e) {
             Console.WriteLine("Error when attempting to connect to database: " + e.Message);
-            Environment.Exit(1);
+            Environment.Exit((int)ExitCodes.DatabaseError);
         }
         
         Console.CancelKeyPress += OnCancelKeyPressed;
@@ -38,7 +45,7 @@ class Program {
             Console.WriteLine($"{ts:u} [{source}] {item}");
     }
 
-    private static void OnCancelKeyPressed(object sender, ConsoleCancelEventArgs e) {
+    private static void OnCancelKeyPressed(object? sender, ConsoleCancelEventArgs e) {
         e.Cancel = true;
         Log("Shutdown", "Captured cancel key; sending shutdown.");
         ProgramStop();
@@ -50,11 +57,21 @@ class Program {
         _stopping = true;
         Log("Shutdown", "Commencing shutdown...");
 
-        var dispose = Task.Run(_bot.Dispose);
+        var dispose = Task.Run(_bot!.Dispose);
         if (!dispose.Wait(90000)) {
             Log("Shutdown", "Normal shutdown has not concluded after 90 seconds. Will force quit.");
-            Environment.ExitCode += 0x200;
+            Environment.ExitCode &= (int)ExitCodes.ForcedExit;
         }
         Environment.Exit(Environment.ExitCode);
     }
+
+    [Flags]
+    public enum ExitCodes {
+        Normal = 0x0,
+        ForcedExit = 0x1,
+        ConfigError = 0x2,
+        DatabaseError = 0x4,
+        DeadShardThreshold = 0x8,
+        BadCommand = 0x10,
+    }
 }

ShardManager.cs

@@ -213,7 +213,7 @@ class ShardManager : IDisposable {
                     _destroyedShards++;
                 }
                 if (Config.QuitOnFails && _destroyedShards > MaxDestroyedShards) {
-                    Environment.ExitCode = 0x04;
+                    Environment.ExitCode = (int)Program.ExitCodes.DeadShardThreshold;
                     Program.ProgramStop();
                 } else {
                     // Start up any missing shards