add WHOIS command

lib/server/connection.ml

@@ -61,7 +61,7 @@ let reply t (num, params) =
     | None -> "*"
   in
   let always_trailing = match num with
-    | "301" | "332" | "353" -> true
+    | "301" | "311" | "312" | "319" | "332" | "353" -> true
     | _ -> false
   in
   Outbox.send t.outbox
@@ -585,6 +585,49 @@ let on_msg_who t mask =
   reply t ("315", [mask; "End of WHO list"]);
   Ok ()
 
+let list_whois t user =
+  let nick = User.nick user in
+  let { username; hostname; realname } = user.userinfo in
+  begin
+    reply t ("311", [nick; username; hostname; "*"; realname]);
+    reply t ("312", [nick; t.server_info.hostname; t.server_info.hostname]);
+
+    (* RPL_WHOISOPERATOR (313) "<client> <nick> :is an IRC operator" *)
+    (* RPL_WHOISIDLE (317) "<client> <nick> <secs> <signon> :seconds idle, signon time" *)
+
+    (* TODO: concat channel names until message becomes too long *)
+    List.iter
+      (fun (m : membership) ->
+         let chan_str = Router.membership_prefix m.mem_priv ^ Chan.name m.mem_chan in
+         reply t ("319", [nick; chan_str]))
+      (User.membership user);
+
+    reply t ("320", [nick; "is a cat, meow :3"]);
+
+    reply t ("379", [nick; Fmt.str "is using modes +%s"
+                             (Mode.Set.to_string (User.mode user))]);
+
+    Option.iter
+      (fun text ->
+         reply t (away nick text))
+      (User.away user);
+
+    reply t ("318", [nick; "End of /WHOIS list"]);
+  end
+
+let on_msg_whois t nick =
+  let* _me = require_registered t in
+  let* user =
+    try
+      match name_type nick with
+      | `nick -> Ok (Router.find_user t.router nick)
+      | `chan | `invalid -> raise Not_found
+    with Not_found ->
+      Error (nosuchnick nick)
+  in
+  list_whois t user;
+  Ok ()
+
 
 (* welcome and quit *)
 
@@ -784,6 +827,8 @@ let dispatch t = function
   | "AWAY", args -> on_msg_away t (concat_args args)
   | "MODE", tgt :: args when tgt <> "" -> on_msg_mode t tgt args
   | "WHO", mask :: _ when mask <> "" -> on_msg_who t mask
+  | "WHOIS", ([] | [""] | (_ :: "" :: _)) -> Error nonicknamegiven
+  | "WHOIS", ([nick] | (_ :: nick :: _)) -> on_msg_whois t nick
   | ("USER" | "JOIN" | "NAMES" | "PART" | "KICK" | "MODE" | "WHO") as cmd, _ ->
     Error (needmoreparams cmd)
   (* TODO: "LIST" *)
@@ -795,7 +840,6 @@ let dispatch t = function
   (* TODO: "HELP" *)
   (* TODO: "INFO" *)
   (* TODO: "NOTICE" *)
-  (* TODO: "WHOIS" *)
   (* TODO: "WHOWAS" *)
   (* TODO: "KILL" *)
   (* TODO: "REHASH" *)