From ff476f12dc28d0eabff58f24217f6b75022a974f Mon Sep 17 00:00:00 2001
From: Butterfly Dev <dev@butterfly.local>
Date: Tue, 7 Apr 2026 03:08:36 +0000
Subject: [PATCH] =?UTF-8?q?server:=20state.rs=20=E2=80=94=20AppState=20wit?=
 =?UTF-8?q?h=20DashMap=20sessions/agents,=20FrameBuffer=20ring=20for=20lat?=
 =?UTF-8?q?e-joiners?=
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---
 server/src/state.rs | 153 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 server/src/state.rs

diff --git a/server/src/state.rs b/server/src/state.rs
new file mode 100644
index 0000000..1574990
--- /dev/null
+++ b/server/src/state.rs
@@ -0,0 +1,153 @@
+use std::sync::Arc;
+use std::time::Instant;
+
+use dashmap::DashMap;
+use log::info;
+
+use crate::models::{AgentConnection, Session, SessionStatus};
+
+/// Global shared state accessible from every request / WS handler via `web::Data`.
+#[derive(Debug)]
+pub struct AppState {
+    /// All sessions keyed by session id.
+    pub sessions: DashMap<String, Session>,
+    /// Connected agents keyed by agent id.
+    pub agents: DashMap<String, AgentConnection>,
+    /// Server start time for uptime calculations.
+    pub started_at: Instant,
+    /// Configured max sessions.
+    pub max_sessions: usize,
+    /// Configured idle timeout in seconds.
+    pub idle_timeout_secs: u64,
+    /// Configured frame buffer size.
+    pub frame_buffer_size: usize,
+    /// Per-session frame buffers (session_id → ring of latest base64 frames).
+    pub frame_buffers: DashMap<String, Arc<FrameBuffer>>,
+}
+
+/// Simple circular buffer that keeps the *N* most recent display frames.
+/// Viewers that connect mid-stream can pull the latest frame immediately
+/// instead of waiting for the next one from the agent.
+pub struct FrameBuffer {
+    frames: parking_lot::Mutex<Vec<String>>,
+    capacity: usize,
+}
+
+impl FrameBuffer {
+    pub fn new(capacity: usize) -> Self {
+        Self {
+            frames: parking_lot::Mutex::new(Vec::with_capacity(capacity)),
+            capacity,
+        }
+    }
+
+    /// Push a base64-encoded frame, evicting the oldest when full.
+    pub fn push(&self, frame: String) {
+        let mut buf = self.frames.lock();
+        if buf.len() >= self.capacity {
+            buf.remove(0);
+        }
+        buf.push(frame);
+    }
+
+    /// Return the most recent frame, if any.
+    pub fn latest(&self) -> Option<String> {
+        let buf = self.frames.lock();
+        buf.last().cloned()
+    }
+}
+
+impl AppState {
+    pub fn new(max_sessions: usize, idle_timeout_secs: u64, frame_buffer_size: usize) -> Arc<Self> {
+        Arc::new(Self {
+            sessions: DashMap::new(),
+            agents: DashMap::new(),
+            started_at: Instant::now(),
+            max_sessions,
+            idle_timeout_secs,
+            frame_buffer_size,
+            frame_buffers: DashMap::new(),
+        })
+    }
+
+    /// Create a brand-new session and return its id.
+    pub fn create_session(self: &Arc<Self>) -> Result<Session, &'static str> {
+        if self.sessions.len() >= self.max_sessions {
+            return Err("max sessions reached");
+        }
+        let id = uuid::Uuid::new_v4().to_string();
+        let session = Session::new(id.clone());
+        self.frame_buffers.insert(id.clone(), Arc::new(FrameBuffer::new(self.frame_buffer_size)));
+        self.sessions.insert(id.clone(), session.clone());
+        info!("session created: {}", id);
+        Ok(session)
+    }
+
+    /// Look up a session by id.
+    pub fn get_session(&self, id: &str) -> Option<Session> {
+        self.sessions.get(id).map(|r| r.value().clone())
+    }
+
+    /// Remove a session (and its frame buffer).
+    pub fn remove_session(&self, id: &str) -> bool {
+        let removed = self.sessions.remove(id).is_some();
+        self.frame_buffers.remove(id);
+        if removed {
+            info!("session removed: {}", id);
+        }
+        removed
+    }
+
+    /// Mark a session as active once the agent starts streaming.
+    pub fn activate_session(&self, session_id: &str, resolution: Option<&str>) {
+        if let Some(mut s) = self.sessions.get_mut(session_id) {
+            s.status = SessionStatus::Active;
+            s.display_active = true;
+            s.resolution = resolution.map(String::from);
+            info!("session activated: {}", session_id);
+        }
+    }
+
+    /// Register a newly connected agent.
+    pub fn register_agent(&self, agent: AgentConnection) {
+        info!("agent registered: {} for session {}", agent.agent_id, agent.session_id);
+        self.agents.insert(agent.agent_id.clone(), agent);
+    }
+
+    /// Unregister an agent and mark its session as disconnected.
+    pub fn unregister_agent(&self, agent_id: &str) {
+        if let Some((_, agent)) = self.agents.remove(agent_id) {
+            // Mark the session as disconnected if no other agents are connected for it.
+            let session_id = agent.session_id.clone();
+            let still_has_agent = self
+                .agents
+                .iter()
+                .any(|r| r.session_id == session_id && r.agent_id != agent_id);
+            if !still_has_agent {
+                if let Some(mut s) = self.sessions.get_mut(&session_id) {
+                    s.status = SessionStatus::Disconnected;
+                    s.display_active = false;
+                    s.audio_active = false;
+                }
+            }
+            info!("agent unregistered: {} (session {})", agent_id, session_id);
+        }
+    }
+
+    /// Push a display frame into the session's circular buffer.
+    pub fn push_frame(&self, session_id: &str, frame: String) {
+        if let Some(buf) = self.frame_buffers.get(session_id) {
+            buf.push(frame);
+        }
+    }
+
+    /// Return counts for health-check.
+    pub fn stats(&self) -> (usize, usize) {
+        let active: usize = self
+            .sessions
+            .iter()
+            .filter(|r| r.status == SessionStatus::Active)
+            .count();
+        (self.sessions.len(), self.agents.len())
+    }
+}