ratelimit: rename module to match filter name

less confusion

Signed-off-by: William Casarin <jb55@jb55.com>

src/filters/ratelimit.rs

@@ -0,0 +1,75 @@
+use crate::{Action, InputMessage, NoteFilter, OutputMessage};
+use serde::Deserialize;
+use std::collections::HashMap;
+use std::time::{Duration, Instant};
+
+pub struct Tokens {
+    pub tokens: i32,
+    pub last_post: Instant,
+}
+
+#[derive(Deserialize, Default)]
+pub struct RateLimit {
+    pub posts_per_minute: i32,
+    pub whitelist: Option<Vec<String>>,
+
+    #[serde(skip)]
+    pub sources: HashMap<String, Tokens>,
+}
+
+impl NoteFilter for RateLimit {
+    fn name(&self) -> &'static str {
+        "ratelimit"
+    }
+
+    fn filter_note(&mut self, msg: &InputMessage) -> OutputMessage {
+        if let Some(whitelist) = &self.whitelist {
+            if whitelist.contains(&msg.source_info) {
+                return OutputMessage::new(msg.event.id.clone(), Action::Accept, None);
+            }
+        }
+
+        if !self.sources.contains_key(&msg.source_info) {
+            self.sources.insert(
+                msg.source_info.to_owned(),
+                Tokens {
+                    last_post: Instant::now(),
+                    tokens: self.posts_per_minute,
+                },
+            );
+            return OutputMessage::new(msg.event.id.clone(), Action::Accept, None);
+        }
+
+        let entry = self.sources.get_mut(&msg.source_info).expect("impossiburu");
+        let now = Instant::now();
+        let mut diff = now - entry.last_post;
+
+        let min = Duration::from_secs(60);
+        if diff > min {
+            diff = min;
+        }
+
+        let percent = (diff.as_secs() as f32) / 60.0;
+        let new_tokens = (percent * self.posts_per_minute as f32).floor() as i32;
+        entry.tokens += new_tokens - 1;
+
+        if entry.tokens <= 0 {
+            entry.tokens = 0;
+        }
+
+        if entry.tokens >= self.posts_per_minute {
+            entry.tokens = self.posts_per_minute - 1;
+        }
+
+        if entry.tokens == 0 {
+            return OutputMessage::new(
+                msg.event.id.clone(),
+                Action::Reject,
+                Some("rate-limited: you are noting too much".to_string()),
+            );
+        }
+
+        entry.last_post = now;
+        OutputMessage::new(msg.event.id.clone(), Action::Accept, None)
+    }
+}