Return existing user code rather than creating a new unique one

Bot/InviteTracker.fs

@@ -40,6 +40,27 @@ let getInvites () = async {
         |> Map.ofList
 }
 
+let getInvitesFromUser discordId = async {
+    let! invites =
+        connStr
+        |> Sql.connect
+        |> Sql.parameters [ "did" , Sql.string (string discordId) ]
+        |> Sql.query """
+                SELECT code, count FROM invite
+                WHERE inviter = @did
+           """
+        |> Sql.executeAsync (fun read -> {
+                Code = read.string "code"
+                Inviter = discordId
+                Count = read.int "count"
+            })
+        |> Async.AwaitTask
+    return
+        invites
+        |> List.map (fun inv -> (inv.Code , (inv.Inviter , inv.Count)))
+        |> Map.ofList
+}
+
 let createInvite inviter code =
     connStr
     |> Sql.connect
@@ -288,21 +309,27 @@ let handleCreateInvite (ctx : IDiscordContext) =
         let builder = DiscordInteractionResponseBuilder().AsEphemeral(true)
         do! ctx.Respond(InteractionResponseType.DeferredChannelMessageWithSource, builder)
 
-        let channel = ctx.GetGuild().Channels.[GuildEnvironment.channelWelcome]
-        let! invite = channel.CreateInviteAsync(max_age = 0, unique = true)
+        let user = ctx.GetDiscordMember()
 
-        // When a player generates an invite code but it hasn't expired, it generates the same code, creating a duplicate entry
-        // so catch the exception thrown because the code column is unique
-        try
-            let! _ = createInvite (ctx.GetDiscordMember().Id) invite.Code
-            return ()
-        with ex ->
-            printfn "%A" ex.Message
-            ()
+        let! code =
+            task {
+                let! invites = getInvitesFromUser user.Id
+                match invites |> Map.toList with
+                | [] ->
+                    let channel = ctx.GetGuild().Channels.[GuildEnvironment.channelWelcome]
+                    let! invite = channel.CreateInviteAsync(max_age = 0, unique = true)
+
+                    try do! createInvite (ctx.GetDiscordMember().Id) invite.Code |> Async.Ignore
+                    with ex -> printfn "%A" ex.Message
+
+                    return invite.Code
+                | invite::_ ->
+                    return invite |> fst
+            }
 
         let msg =
             DiscordFollowupMessageBuilder()
-                .WithContent($"https://discord.gg/{invite.Code}")
+                .WithContent($"https://discord.gg/{code}")
                 .AsEphemeral(true)
 
         do! ctx.FollowUp(msg)