import { FreshContext } from "$fresh/server.ts";

const chatConnections = new Set<WebSocket>();

// HTML sanitization
function sanitizeText(text: string): string {
  return text
    .replace(/&/g, "&amp;")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&#039;");
}

// Process and sanitize message object
function processChatMessage(message: string): string {
  try {
    const parsed = JSON.parse(message);

    if (typeof parsed.text === "string") {
      parsed.text = sanitizeText(parsed.text.trim().slice(0, 2000));
    }

    if (typeof parsed.sender === "string") {
      parsed.sender = sanitizeText(parsed.sender.trim().slice(0, 50));
    }

    if (!parsed.timestamp) {
      parsed.timestamp = new Date().toISOString();
    }

    return JSON.stringify(parsed);
  } catch (error) {
    console.error("Invalid message format:", error);
    return JSON.stringify({
      text: "Error: Invalid message format",
      sender: "System",
      timestamp: new Date().toISOString(),
    });
  }
}

// Broadcast current user count to all clients
function broadcastUserCount() {
  const count = chatConnections.size;
  const message = JSON.stringify({
    type: "user_count",
    count: count,
  });

  for (const client of chatConnections) {
    if (client.readyState === WebSocket.OPEN) {
      client.send(message);
    }
  }
}

export const handler = (req: Request, _ctx: FreshContext): Response => {
  const { socket, response } = Deno.upgradeWebSocket(req);

  socket.onopen = () => {
    chatConnections.add(socket);
    console.log(`New connection: ${chatConnections.size} users connected`);
    broadcastUserCount();
  };

  // Handle messages
  socket.onmessage = (event) => {
    const sanitizedMessage = processChatMessage(event.data);

    for (const client of chatConnections) {
      if (client.readyState === WebSocket.OPEN) {
        client.send(sanitizedMessage);
      }
    }
  };

  socket.onclose = () => {
    chatConnections.delete(socket);
    console.log(`Connection closed: ${chatConnections.size} users connected`);
    broadcastUserCount();
  };

  return response;
};