"""
Tests for PostgreSQL-MQTT Bridge Service

Note: The postgres_mqtt_bridge.py is a complex standalone service with many external
dependencies (PostgreSQL, MQTT broker, Django models). These tests focus on the testable
components and logic without requiring full service infrastructure.

For full integration testing, use the standalone mode with --auto flag.
"""
import json
import tempfile
import os
from django.test import TestCase


class PostgresMQTTBridgeDocumentationTest(TestCase):
    """Documentation tests for PostgreSQL-MQTT Bridge"""

    def test_bridge_purpose_documented(self):
        """Document the purpose of the PostgreSQL-MQTT Bridge"""
        purpose = """
        The PostgreSQL-MQTT Bridge Service bridges queue events to MQTT broker.

        Key Features:
        - AUTO mode: Starts Mosquitto (development/testing)
        - EXTERNAL mode: Connects to existing services (production)
        - Uses PostgreSQL LISTEN/NOTIFY for event delivery
        - Robust connection management with auto-retry
        - Process locking to prevent multiple instances
        - Graceful shutdown and cleanup
        """
        self.assertTrue(len(purpose) > 0)

    def test_message_flow_documented(self):
        """Document the message flow through the bridge"""
        flow = """
        Message Flow:
        1. Django app inserts event into MQTTEventQueue and sends pg_notify
        2. Bridge LISTENs for notifications
        3. Bridge fetches unprocessed events from queue
        4. Bridge publishes message to MQTT broker
        5. Bridge marks events as processed
        6. MQTT subscribers receive the message
        """
        self.assertTrue(len(flow) > 0)


class PostgresMQTTBridgeEventProcessingTest(TestCase):
    """Test event data processing logic"""

    def test_valid_event_structure(self):
        """Test that event structure is valid"""
        event = {
            "topic": "nemo/tools/1/start",
            "payload": '{"event": "tool_usage_start"}',
            "qos": 1,
            "retain": False,
        }
        event_json = json.dumps(event)
        self.assertIsInstance(event_json, str)
        event_parsed = json.loads(event_json)
        self.assertEqual(event_parsed["topic"], "nemo/tools/1/start")
        self.assertEqual(event_parsed["qos"], 1)
        self.assertEqual(event_parsed["retain"], False)

    def test_missing_required_fields(self):
        """Test validation of required event fields"""
        event_no_topic = {"payload": '{"event": "tool_usage_start"}', "qos": 1}
        self.assertNotIn("topic", event_no_topic)
        event_no_payload = {"topic": "nemo/tools/1/start", "qos": 1}
        self.assertNotIn("payload", event_no_payload)


class PostgresMQTTBridgeLockingTest(TestCase):
    """Test process locking mechanism"""

    def test_lock_file_path(self):
        """Test lock file is in correct location"""
        lock_path = os.path.join(tempfile.gettempdir(), "NEMO_mqtt_bridge.lock")
        self.assertTrue(lock_path.startswith(tempfile.gettempdir()))
        self.assertTrue(lock_path.endswith("NEMO_mqtt_bridge.lock"))


class PostgresMQTTBridgeConnectionTest(TestCase):
    """Test connection management concepts"""

    def test_mqtt_connection_parameters(self):
        """Test MQTT connection parameter structure"""
        config = {
            "broker_host": "localhost",
            "broker_port": 1883,
            "keepalive": 60,
            "username": None,
            "password": None,
        }
        self.assertIsInstance(config["broker_host"], str)
        self.assertIsInstance(config["broker_port"], int)

    def test_postgres_connection_parameters(self):
        """Test PostgreSQL connection parameter structure"""
        config = {
            "host": "localhost",
            "port": 5432,
            "dbname": "nemo",
            "user": "nemo",
            "password": "secret",
        }
        self.assertEqual(config["host"], "localhost")
        self.assertEqual(config["port"], 5432)
        self.assertIn("dbname", config)


class PostgresMQTTBridgeOperationalModesTest(TestCase):
    """Test understanding of operational modes"""

    def test_auto_mode_behavior(self):
        """Document AUTO mode behavior"""
        auto_mode_desc = """
        AUTO Mode (Development/Testing):
        - Automatically starts embedded MQTT broker (mqttools, pure Python)
        - Connects to PostgreSQL (Django DATABASES)
        - Ideal for local development and Docker (no separate broker container)

        Start with: python postgres_mqtt_bridge.py --auto
        """
        self.assertTrue("AUTO" in auto_mode_desc)

    def test_external_mode_behavior(self):
        """Document EXTERNAL mode behavior"""
        external_mode_desc = """
        EXTERNAL Mode (Production):
        - Connects to existing PostgreSQL
        - Connects to existing MQTT broker
        - Does not start Mosquitto
        - Ideal for production deployments

        Start with: python postgres_mqtt_bridge.py
        """
        self.assertTrue("EXTERNAL" in external_mode_desc)
