split notedeck into crates

This splits notedeck into crates, separating the browser chrome and
individual apps:

* notedeck: binary file, browser chrome
* notedeck_columns: our columns app
* enostr: same as before

We still need to do more work to cleanly separate the chrome apis
from the app apis. Soon I will create notedeck-notebook to see what
makes sense to be shared between the apps.

Some obvious ones that come to mind:

1. ImageCache

We will likely want to move this to the notedeck crate, as most apps
will want some kind of image cache. In web browsers, web pages do not
need to worry about this, so we will likely have to do something similar

2. Ndb

Since NdbRef is threadsafe and Ndb is an Arc<NdbRef>, it can be safely
copied to each app. This will simplify things. In the future we might
want to create an abstraction over this? Maybe each app shouldn't have
access to the same database... we assume the data in DBs are all public
anyways, but if we have unwrapped giftwraps that could be a problem.

3. RelayPool / Subscription Manager

The browser should probably maintain these. Then apps can use ken's
high level subscription manager api and not have to worry about
connection pool details

4. Accounts

Accounts and key management should be handled by the chrome. Apps should
only have a simple signer interface.

That's all for now, just something to think about!

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

crates/enostr/src/relay/pool.rs

@@ -0,0 +1,254 @@
+use crate::relay::{Relay, RelayStatus};
+use crate::{ClientMessage, Result};
+use nostrdb::Filter;
+
+use std::collections::BTreeSet;
+use std::time::{Duration, Instant};
+
+use url::Url;
+
+#[cfg(not(target_arch = "wasm32"))]
+use ewebsock::{WsEvent, WsMessage};
+
+#[cfg(not(target_arch = "wasm32"))]
+use tracing::{debug, error};
+
+#[derive(Debug)]
+pub struct PoolEvent<'a> {
+    pub relay: &'a str,
+    pub event: ewebsock::WsEvent,
+}
+
+impl PoolEvent<'_> {
+    pub fn into_owned(self) -> PoolEventBuf {
+        PoolEventBuf {
+            relay: self.relay.to_owned(),
+            event: self.event,
+        }
+    }
+}
+
+pub struct PoolEventBuf {
+    pub relay: String,
+    pub event: ewebsock::WsEvent,
+}
+
+pub struct PoolRelay {
+    pub relay: Relay,
+    pub last_ping: Instant,
+    pub last_connect_attempt: Instant,
+    pub retry_connect_after: Duration,
+}
+
+impl PoolRelay {
+    pub fn new(relay: Relay) -> PoolRelay {
+        PoolRelay {
+            relay,
+            last_ping: Instant::now(),
+            last_connect_attempt: Instant::now(),
+            retry_connect_after: Self::initial_reconnect_duration(),
+        }
+    }
+
+    pub fn initial_reconnect_duration() -> Duration {
+        Duration::from_secs(5)
+    }
+}
+
+pub struct RelayPool {
+    pub relays: Vec<PoolRelay>,
+    pub ping_rate: Duration,
+}
+
+impl Default for RelayPool {
+    fn default() -> Self {
+        RelayPool::new()
+    }
+}
+
+impl RelayPool {
+    // Constructs a new, empty RelayPool.
+    pub fn new() -> RelayPool {
+        RelayPool {
+            relays: vec![],
+            ping_rate: Duration::from_secs(25),
+        }
+    }
+
+    pub fn ping_rate(&mut self, duration: Duration) -> &mut Self {
+        self.ping_rate = duration;
+        self
+    }
+
+    pub fn has(&self, url: &str) -> bool {
+        for relay in &self.relays {
+            if relay.relay.url == url {
+                return true;
+            }
+        }
+
+        false
+    }
+
+    pub fn urls(&self) -> BTreeSet<String> {
+        self.relays
+            .iter()
+            .map(|pool_relay| pool_relay.relay.url.clone())
+            .collect()
+    }
+
+    pub fn send(&mut self, cmd: &ClientMessage) {
+        for relay in &mut self.relays {
+            relay.relay.send(cmd);
+        }
+    }
+
+    pub fn unsubscribe(&mut self, subid: String) {
+        for relay in &mut self.relays {
+            relay.relay.send(&ClientMessage::close(subid.clone()));
+        }
+    }
+
+    pub fn subscribe(&mut self, subid: String, filter: Vec<Filter>) {
+        for relay in &mut self.relays {
+            relay.relay.subscribe(subid.clone(), filter.clone());
+        }
+    }
+
+    /// Keep relay connectiongs alive by pinging relays that haven't been
+    /// pinged in awhile. Adjust ping rate with [`ping_rate`].
+    pub fn keepalive_ping(&mut self, wakeup: impl Fn() + Send + Sync + Clone + 'static) {
+        for relay in &mut self.relays {
+            let now = std::time::Instant::now();
+
+            match relay.relay.status {
+                RelayStatus::Disconnected => {
+                    let reconnect_at = relay.last_connect_attempt + relay.retry_connect_after;
+                    if now > reconnect_at {
+                        relay.last_connect_attempt = now;
+                        let next_duration = Duration::from_millis(
+                            ((relay.retry_connect_after.as_millis() as f64) * 1.5) as u64,
+                        );
+                        debug!(
+                            "bumping reconnect duration from {:?} to {:?} and retrying connect",
+                            relay.retry_connect_after, next_duration
+                        );
+                        relay.retry_connect_after = next_duration;
+                        if let Err(err) = relay.relay.connect(wakeup.clone()) {
+                            error!("error connecting to relay: {}", err);
+                        }
+                    } else {
+                        // let's wait a bit before we try again
+                    }
+                }
+
+                RelayStatus::Connected => {
+                    relay.retry_connect_after = PoolRelay::initial_reconnect_duration();
+
+                    let should_ping = now - relay.last_ping > self.ping_rate;
+                    if should_ping {
+                        debug!("pinging {}", relay.relay.url);
+                        relay.relay.ping();
+                        relay.last_ping = Instant::now();
+                    }
+                }
+
+                RelayStatus::Connecting => {
+                    // cool story bro
+                }
+            }
+        }
+    }
+
+    pub fn send_to(&mut self, cmd: &ClientMessage, relay_url: &str) {
+        for relay in &mut self.relays {
+            let relay = &mut relay.relay;
+            if relay.url == relay_url {
+                relay.send(cmd);
+                return;
+            }
+        }
+    }
+
+    // Adds a websocket url to the RelayPool.
+    pub fn add_url(
+        &mut self,
+        url: String,
+        wakeup: impl Fn() + Send + Sync + Clone + 'static,
+    ) -> Result<()> {
+        let url = Self::canonicalize_url(url);
+        // Check if the URL already exists in the pool.
+        if self.has(&url) {
+            return Ok(());
+        }
+        let relay = Relay::new(url, wakeup)?;
+        let pool_relay = PoolRelay::new(relay);
+
+        self.relays.push(pool_relay);
+
+        Ok(())
+    }
+
+    pub fn add_urls(
+        &mut self,
+        urls: BTreeSet<String>,
+        wakeup: impl Fn() + Send + Sync + Clone + 'static,
+    ) -> Result<()> {
+        for url in urls {
+            self.add_url(url, wakeup.clone())?;
+        }
+        Ok(())
+    }
+
+    pub fn remove_urls(&mut self, urls: &BTreeSet<String>) {
+        self.relays
+            .retain(|pool_relay| !urls.contains(&pool_relay.relay.url));
+    }
+
+    // standardize the format (ie, trailing slashes)
+    fn canonicalize_url(url: String) -> String {
+        match Url::parse(&url) {
+            Ok(parsed_url) => parsed_url.to_string(),
+            Err(_) => url, // If parsing fails, return the original URL.
+        }
+    }
+
+    /// Attempts to receive a pool event from a list of relays. The
+    /// function searches each relay in the list in order, attempting to
+    /// receive a message from each. If a message is received, return it.
+    /// If no message is received from any relays, None is returned.
+    pub fn try_recv(&mut self) -> Option<PoolEvent<'_>> {
+        for relay in &mut self.relays {
+            let relay = &mut relay.relay;
+            if let Some(event) = relay.receiver.try_recv() {
+                match &event {
+                    WsEvent::Opened => {
+                        relay.status = RelayStatus::Connected;
+                    }
+                    WsEvent::Closed => {
+                        relay.status = RelayStatus::Disconnected;
+                    }
+                    WsEvent::Error(err) => {
+                        error!("{:?}", err);
+                        relay.status = RelayStatus::Disconnected;
+                    }
+                    WsEvent::Message(ev) => {
+                        // let's just handle pongs here.
+                        // We only need to do this natively.
+                        #[cfg(not(target_arch = "wasm32"))]
+                        if let WsMessage::Ping(ref bs) = ev {
+                            debug!("pong {}", &relay.url);
+                            relay.sender.send(WsMessage::Pong(bs.to_owned()));
+                        }
+                    }
+                }
+                return Some(PoolEvent {
+                    event,
+                    relay: &relay.url,
+                });
+            }
+        }
+
+        None
+    }
+}