MemoServ: add SET NOTIFY and SET LIMIT

SET NOTIFY {ON|OFF} controls whether you're told about new memos on login;
SET LIMIT <n>|NONE sets your mailbox cap (honoured on SEND, NONE = the
network default). New memo_notify/memo_limit account fields + one
MemoPrefsSet event.

modules/memoserv/src/lib.rs

@@ -24,6 +24,8 @@ mod info;
 mod sendall;
 #[path = "ignore.rs"]
 mod ignore;
+#[path = "set.rs"]
+mod set;
 
 const BLURB: &str = "MemoServ delivers messages to registered users, online or not. You must be identified to use it.";
 
@@ -40,6 +42,7 @@ const TOPICS: &[HelpEntry] = &[
     HelpEntry { cmd: "INFO", summary: "your mailbox summary", detail: "Syntax: \x02INFO\x02\nShows how many memos you have, how many are unread, and your capacity." },
     HelpEntry { cmd: "SENDALL", summary: "memo every account (admin)", detail: "Syntax: \x02SENDALL <text>\x02\nLeaves a memo on every registered account. Requires the admin privilege." },
     HelpEntry { cmd: "IGNORE", summary: "block memos from an account", detail: "Syntax: \x02IGNORE ADD <nick> | DEL <nick> | LIST\x02\nMemos from an ignored account are silently dropped." },
+    HelpEntry { cmd: "SET", summary: "your memo preferences", detail: "Syntax: \x02SET NOTIFY {ON|OFF}\x02, \x02SET LIMIT <n>|NONE\x02\nControls new-memo notifications and your mailbox size cap." },
 ];
 
 pub struct MemoServ {
@@ -83,6 +86,7 @@ impl Service for MemoServ {
             Some("INFO") => info::handle(me, from, account, ctx, db),
             Some("SENDALL") => sendall::handle(me, from, account, args, ctx, db),
             Some("IGNORE") => ignore::handle(me, from, account, args, ctx, db),
+            Some("SET") => set::handle(me, from, account, args, ctx, db),
             Some(other) => ctx.notice(me, from.uid, format!("I don't know the command \x02{other}\x02. Try \x02HELP\x02.")),
             None => {}
         }

modules/memoserv/src/send.rs

@@ -14,7 +14,8 @@ pub fn handle(me: &str, from: &Sender, account: &str, args: &[&str], ctx: &mut S
         ctx.notice(me, from.uid, format!("\x02{target}\x02 isn't registered."));
         return;
     };
-    if db.memo_list(&dest).len() >= MAX_MEMOS {
+    let limit = db.memo_limit_of(&dest).unwrap_or(MAX_MEMOS as u32) as usize;
+    if db.memo_list(&dest).len() >= limit {
         ctx.notice(me, from.uid, format!("\x02{target}\x02's mailbox is full — they'll need to clear some memos first."));
         return;
     }

modules/memoserv/src/set.rs

@@ -0,0 +1,38 @@
+use echo_api::{Sender, ServiceCtx, Store};
+
+// SET NOTIFY {ON|OFF} | SET LIMIT <n>|NONE: your MemoServ preferences.
+pub fn handle(me: &str, from: &Sender, account: &str, args: &[&str], ctx: &mut ServiceCtx, db: &mut dyn Store) {
+    match args.get(1).map(|s| s.to_ascii_uppercase()).as_deref() {
+        Some("NOTIFY") => {
+            let on = match args.get(2).map(|s| s.to_ascii_uppercase()).as_deref() {
+                Some("ON") => true,
+                Some("OFF") => false,
+                _ => {
+                    ctx.notice(me, from.uid, "Syntax: SET NOTIFY {ON|OFF}");
+                    return;
+                }
+            };
+            db.set_memo_notify(account, on);
+            ctx.notice(me, from.uid, format!("New-memo notification is now \x02{}\x02.", if on { "on" } else { "off" }));
+        }
+        Some("LIMIT") => {
+            let limit = match args.get(2) {
+                None => None,
+                Some(&n) if n.eq_ignore_ascii_case("NONE") || n.eq_ignore_ascii_case("OFF") => None,
+                Some(&n) => match n.parse::<u32>() {
+                    Ok(v) if v <= super::MAX_MEMOS as u32 => Some(v),
+                    _ => {
+                        ctx.notice(me, from.uid, format!("The limit must be a number from 0 to {}, or NONE.", super::MAX_MEMOS));
+                        return;
+                    }
+                },
+            };
+            db.set_memo_limit(account, limit);
+            match limit {
+                Some(v) => ctx.notice(me, from.uid, format!("Your mailbox limit is now \x02{v}\x02.")),
+                None => ctx.notice(me, from.uid, format!("Your mailbox limit is now the network default (\x02{}\x02).", super::MAX_MEMOS)),
+            }
+        }
+        _ => ctx.notice(me, from.uid, "Syntax: SET NOTIFY {ON|OFF} | SET LIMIT <n>|NONE"),
+    }
+}

modules/nickserv/src/identify.rs

@@ -65,7 +65,7 @@ pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx, db:
             }
             // Let them know about waiting memos.
             let unread = db.unread_memos(&account);
-            if unread > 0 {
+            if unread > 0 && db.memo_notify_on(&account) {
                 ctx.notice(me, from.uid, format!("You have \x02{unread}\x02 new memo(s). Read them with \x02/msg MemoServ READ NEW\x02."));
             }
         }