chore: rewrite the backend (not tested) (#203)

* wip: refactor

* refactor

* clean up

* .

* rename

* add relay auth

* .

* .

* optimize

* .

* clean up

* add encryption crate

* .

* .

* .

* .

* .

* add encryption crate

* .

* refactor nip4e

* .

* fix endless loop

* fix metadata fetching

crates/state/src/tracker.rs

@@ -0,0 +1,50 @@
+use std::collections::{HashMap, HashSet};
+use std::sync::OnceLock;
+
+use nostr_sdk::prelude::*;
+
+static INITIALIZED_AT: OnceLock<Timestamp> = OnceLock::new();
+
+pub fn initialized_at() -> &'static Timestamp {
+    INITIALIZED_AT.get_or_init(Timestamp::now)
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct EventTracker {
+    /// Tracking events that have failed to unwrap
+    pub failed_unwrap_events: Vec<Event>,
+
+    /// Tracking events that have been resent by Coop in the current session
+    pub resent_ids: Vec<Output<EventId>>,
+
+    /// Temporarily store events that need to be resent later
+    pub resend_queue: HashMap<EventId, RelayUrl>,
+
+    /// Tracking events sent by Coop in the current session
+    pub sent_ids: HashSet<EventId>,
+
+    /// Tracking events seen on which relays in the current session
+    pub seen_on_relays: HashMap<EventId, HashSet<RelayUrl>>,
+}
+
+impl EventTracker {
+    pub fn failed_unwrap_events(&self) -> &Vec<Event> {
+        &self.failed_unwrap_events
+    }
+
+    pub fn resent_ids(&self) -> &Vec<Output<EventId>> {
+        &self.resent_ids
+    }
+
+    pub fn resend_queue(&self) -> &HashMap<EventId, RelayUrl> {
+        &self.resend_queue
+    }
+
+    pub fn sent_ids(&self) -> &HashSet<EventId> {
+        &self.sent_ids
+    }
+
+    pub fn seen_on_relays(&self) -> &HashMap<EventId, HashSet<RelayUrl>> {
+        &self.seen_on_relays
+    }
+}