feat: add SMTP notifier plugin

src/proxy_pool/plugins/builtin/notifiers/smtp.py

@@ -0,0 +1,86 @@
+from __future__ import annotations
+
+from email.message import EmailMessage
+
+import aiosmtplib
+
+from proxy_pool.config import Settings
+from proxy_pool.plugins.protocols import Event
+
+
+class SmtpNotifier:
+    name = "smtp"
+    subscribes_to = [
+        "proxy.pool_low",
+        "source.failed",
+        "credits.low_balance",
+        "credits.exhausted",
+    ]
+
+    def __init__(
+        self,
+        host: str,
+        port: int,
+        user: str,
+        password: str,
+        to_address: str,
+    ) -> None:
+        self._host = host
+        self._port = port
+        self._user = user
+        self._password = password
+        self._to = to_address
+
+    async def notify(self, event: Event) -> None:
+        msg = EmailMessage()
+        msg["Subject"] = f"[ProxyPool] {event.type}"
+        msg["From"] = self._user
+        msg["To"] = self._to
+        msg.set_content(self._format_body(event))
+
+        await aiosmtplib.send(
+            msg,
+            hostname=self._host,
+            port=self._port,
+            username=self._user,
+            password=self._password,
+            use_tls=True,
+        )
+
+    async def health_check(self) -> bool:
+        try:
+            client = aiosmtplib.SMTP(
+                hostname=self._host,
+                port=self._port,
+            )
+            await client.connect()
+            await client.quit()
+        except Exception:
+            return False
+        else:
+            return True
+
+    @staticmethod
+    def _format_body(event: Event) -> str:
+        lines = [
+            f"Event: {event.type}",
+            f"Time: {event.timestamp.isoformat()}",
+            "",
+        ]
+        for key, value in event.payload.items():
+            lines.append(f"  {key}: {value}")
+        return "\n".join(lines)
+
+
+def create_plugin(settings: Settings) -> SmtpNotifier | None:
+    notify = settings.notification
+    if not notify.smtp_host or not notify.smtp_user:
+        return None
+
+    return SmtpNotifier(
+        host=notify.smtp_host,
+        port=notify.smtp_port,
+        user=notify.smtp_user,
+        password=notify.smtp_password or "",
+        to_address=notify.alert_email or notify.smtp_user,
+    )