Add helper class to simplify documentation sharing

UserInterface/CommandDocumentation.cs

@@ -0,0 +1,52 @@
+using Discord;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace BirthdayBot.UserInterface
+{
+    internal class CommandDocumentation
+    {
+        public string[] Commands { get; }
+        public string Usage { get; }
+        public string Examples { get; }
+
+        public CommandDocumentation(IEnumerable<string> commands, string usage, string examples)
+        {
+            var cmds = new List<string>();
+            foreach (var item in commands) cmds.Add(CommandsCommon.CommandPrefix + item);
+            if (cmds.Count == 0) throw new ArgumentException(nameof(commands));
+            Commands = cmds.ToArray();
+            Usage = usage ?? throw new ArgumentException(nameof(usage));
+            Examples = examples;
+        }
+
+        /// <summary>
+        /// Returns a string that can be inserted into a help or usage message.
+        /// </summary>
+        public string Export()
+        {
+            var result = new StringBuilder();
+            foreach (var item in Commands) result.Append(", `" + item + "`");
+            result.Remove(0, 2);
+            result.Insert(0, '●');
+            result.AppendLine();
+            result.Append("» " + Usage);
+            if (Examples != null)
+            {
+                result.AppendLine();
+                result.Append("» Examples: " + Examples);
+            }
+            return result.ToString();
+        }
+
+        /// <summary>
+        /// Creates an embeddable message containing the command documentation.
+        /// </summary>
+        public Embed UsageEmbed => new EmbedBuilder()
+        {
+            Author = new EmbedAuthorBuilder() { Name = "Usage" },
+            Description = Export()
+        }.Build();
+    }
+}