Add Twilio call queue service with channel allocation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/services/twilio_service.py

@@ -0,0 +1,100 @@
+"""Twilio call queue and media stream service"""
+
+import time
+import threading
+from typing import Optional
+
+
+class TwilioService:
+    """Manages Twilio call queue, channel allocation, and media streams"""
+
+    FIRST_REAL_CHANNEL = 3
+
+    def __init__(self):
+        self._queue: list[dict] = []
+        self.active_calls: dict[str, dict] = {}
+        self._allocated_channels: set[int] = set()
+        self._caller_counter: int = 0
+        self._lock = threading.Lock()
+
+    def add_to_queue(self, call_sid: str, phone: str):
+        with self._lock:
+            self._queue.append({
+                "call_sid": call_sid,
+                "phone": phone,
+                "queued_at": time.time(),
+            })
+        print(f"[Twilio] Caller {phone} added to queue (SID: {call_sid})")
+
+    def remove_from_queue(self, call_sid: str):
+        with self._lock:
+            self._queue = [c for c in self._queue if c["call_sid"] != call_sid]
+        print(f"[Twilio] Caller {call_sid} removed from queue")
+
+    def get_queue(self) -> list[dict]:
+        now = time.time()
+        with self._lock:
+            return [
+                {
+                    "call_sid": c["call_sid"],
+                    "phone": c["phone"],
+                    "wait_time": int(now - c["queued_at"]),
+                }
+                for c in self._queue
+            ]
+
+    def allocate_channel(self) -> int:
+        with self._lock:
+            ch = self.FIRST_REAL_CHANNEL
+            while ch in self._allocated_channels:
+                ch += 1
+            self._allocated_channels.add(ch)
+            return ch
+
+    def release_channel(self, channel: int):
+        with self._lock:
+            self._allocated_channels.discard(channel)
+
+    def take_call(self, call_sid: str) -> dict:
+        caller = None
+        with self._lock:
+            for c in self._queue:
+                if c["call_sid"] == call_sid:
+                    caller = c
+                    break
+            if caller:
+                self._queue = [c for c in self._queue if c["call_sid"] != call_sid]
+
+        if not caller:
+            raise ValueError(f"Call {call_sid} not in queue")
+
+        channel = self.allocate_channel()
+        self._caller_counter += 1
+        name = f"Caller #{self._caller_counter}"
+
+        call_info = {
+            "call_sid": call_sid,
+            "phone": caller["phone"],
+            "channel": channel,
+            "name": name,
+            "started_at": time.time(),
+        }
+        self.active_calls[call_sid] = call_info
+        print(f"[Twilio] {name} ({caller['phone']}) taken on air — channel {channel}")
+        return call_info
+
+    def hangup(self, call_sid: str):
+        call_info = self.active_calls.pop(call_sid, None)
+        if call_info:
+            self.release_channel(call_info["channel"])
+            print(f"[Twilio] {call_info['name']} hung up — channel {call_info['channel']} released")
+
+    def reset(self):
+        with self._lock:
+            for call_info in self.active_calls.values():
+                self._allocated_channels.discard(call_info["channel"])
+            self._queue.clear()
+            self.active_calls.clear()
+            self._allocated_channels.clear()
+            self._caller_counter = 0
+        print("[Twilio] Service reset")