From b0f70fb2a12e78026c3b27eca14762d9b8ca96a3 Mon Sep 17 00:00:00 2001
From: Natsu Kagami <natsukagami@gmail.com>
Date: Sun, 9 Feb 2020 15:02:13 -0500
Subject: [PATCH] Implement server ranks

---
 youmubot-cf/src/lib.rs | 102 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 100 insertions(+), 2 deletions(-)

diff --git a/youmubot-cf/src/lib.rs b/youmubot-cf/src/lib.rs
index 949692b..3f2fc96 100644
--- a/youmubot-cf/src/lib.rs
+++ b/youmubot-cf/src/lib.rs
@@ -1,9 +1,10 @@
 use serenity::{
     framework::standard::{
         macros::{command, group},
-        Args, CommandResult,
+        Args, CommandError as Error, CommandResult,
     },
     model::channel::Message,
+    utils::MessageBuilder,
 };
 use youmubot_prelude::*;
 
@@ -27,7 +28,7 @@ pub fn setup(path: &std::path::Path, data: &mut ShareMap) {
 #[group]
 #[prefix = "cf"]
 #[description = "Codeforces-related commands"]
-#[commands(profile, save)]
+#[commands(profile, save, ranks)]
 #[default_command(profile)]
 pub struct Codeforces;
 
@@ -105,3 +106,100 @@ pub fn save(ctx: &mut Context, m: &Message, mut args: Args) -> CommandResult {
 
     Ok(())
 }
+
+#[command]
+#[description = "See the leaderboard of all people in the server."]
+#[only_in(guilds)]
+#[num_args(0)]
+pub fn ranks(ctx: &mut Context, m: &Message) -> CommandResult {
+    let everyone = {
+        let db = CfSavedUsers::open(&*ctx.data.read());
+        let db = db.borrow()?;
+        db.iter()
+            .map(|(k, v)| (k.clone(), v.clone()))
+            .collect::<Vec<_>>()
+    };
+    let guild = m.guild_id.expect("Guild-only command");
+    let mut ranks = everyone
+        .into_iter()
+        .filter_map(|(id, cf_user)| guild.member(&ctx, id).ok().map(|mem| (mem, cf_user)))
+        .collect::<Vec<_>>();
+    ranks.sort_by(|(_, a), (_, b)| b.rating.unwrap_or(-1).cmp(&a.rating.unwrap_or(-1)));
+
+    if ranks.is_empty() {
+        m.reply(&ctx, "No saved users in this server.")?;
+        return Ok(());
+    }
+
+    const ITEMS_PER_PAGE: usize = 10;
+    let total_pages = (ranks.len() + ITEMS_PER_PAGE - 1) / ITEMS_PER_PAGE;
+    let last_updated = ranks.iter().map(|(_, cfu)| cfu.last_update).min().unwrap();
+
+    ctx.data.get_cloned::<ReactionWatcher>().paginate_fn(
+        ctx.clone(),
+        m.channel_id,
+        |page, e| {
+            let page = page as usize;
+            let start = ITEMS_PER_PAGE * page;
+            let end = ranks.len().min(start + ITEMS_PER_PAGE);
+            if start >= end {
+                return (e, Err(Error::from("No more pages")));
+            }
+            let ranks = &ranks[start..end];
+
+            let handle_width = ranks.iter().map(|(_, cfu)| cfu.handle.len()).max().unwrap();
+            let username_width = ranks
+                .iter()
+                .map(|(mem, _)| mem.distinct().len())
+                .max()
+                .unwrap();
+
+            let mut m = MessageBuilder::new();
+            m.push_line("```");
+
+            // Table header
+            m.push_line(format!(
+                "Rank | Rating | {:hw$} | {:uw$}",
+                "Handle",
+                "Username",
+                hw = handle_width,
+                uw = username_width
+            ));
+            m.push_line(format!(
+                "----------------{:->hw$}---{:->uw$}",
+                "",
+                "",
+                hw = handle_width,
+                uw = username_width
+            ));
+
+            for (id, (mem, cfu)) in ranks.iter().enumerate() {
+                let id = id + start + 1;
+                m.push_line(format!(
+                    "{:>4} | {:>6} | {:hw$} | {:uw$}",
+                    format!("#{}", id),
+                    cfu.rating
+                        .map(|v| v.to_string())
+                        .unwrap_or("----".to_owned()),
+                    cfu.handle,
+                    mem.distinct(),
+                    hw = handle_width,
+                    uw = username_width
+                ));
+            }
+
+            m.push_line("```");
+            m.push(format!(
+                "Page **{}/{}**. Last updated **{}**",
+                page + 1,
+                total_pages,
+                last_updated.to_rfc2822()
+            ));
+
+            (e.content(m.build()), Ok(()))
+        },
+        std::time::Duration::from_secs(60),
+    )?;
+
+    Ok(())
+}