// Chicago TDD Tests for Notification & Messaging Hub
// Comprehensive test suite with ≤2ns budget validation

#[cfg(test)]
mod notification_messaging_hub_tests {
    use std::time::Instant;

    // Mock implementations for testing
    struct TestMessage {
        id: String,
        body: String,
        channel: String,
        priority: String,
    }

    struct TestDeliveryAttempt {
        message_id: String,
        status: String,
        provider: String,
        attempt_number: u32,
    }

    struct TestRateLimit {
        channel: String,
        max_per_minute: u32,
        current_count: u32,
    }

    // ==================== Message Creation Tests ====================

    #[test]
    fn test_message_creation_basic() {
        let start = Instant::now();

        let message = TestMessage {
            id: "msg-001".to_string(),
            body: "Test notification".to_string(),
            channel: "email".to_string(),
            priority: "medium".to_string(),
        };

        assert_eq!(message.id, "msg-001");
        assert_eq!(message.body, "Test notification");
        assert_eq!(message.channel, "email");
        assert_eq!(message.priority, "medium");

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_message_with_priority() {
        let start = Instant::now();

        let message = TestMessage {
            id: "msg-002".to_string(),
            body: "Urgent alert".to_string(),
            channel: "sms".to_string(),
            priority: "critical".to_string(),
        };

        assert_eq!(message.priority, "critical");
        assert_eq!(message.channel, "sms");

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_message_channels() {
        let start = Instant::now();

        let channels = vec!["email", "sms", "push", "webhook", "slack", "teams"];

        for channel in channels {
            let message = TestMessage {
                id: format!("msg-{}", channel),
                body: format!("{} message", channel),
                channel: channel.to_string(),
                priority: "medium".to_string(),
            };

            assert_eq!(message.channel, channel);
        }

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    // ==================== Delivery Status Tests ====================

    #[test]
    fn test_delivery_attempt_creation() {
        let start = Instant::now();

        let attempt = TestDeliveryAttempt {
            message_id: "msg-001".to_string(),
            status: "pending".to_string(),
            provider: "sendgrid".to_string(),
            attempt_number: 1,
        };

        assert_eq!(attempt.message_id, "msg-001");
        assert_eq!(attempt.status, "pending");
        assert_eq!(attempt.provider, "sendgrid");
        assert_eq!(attempt.attempt_number, 1);

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_delivery_status_progression() {
        let start = Instant::now();

        let statuses = vec![
            "pending", "queued", "sending", "delivered"
        ];

        for (i, status) in statuses.iter().enumerate() {
            let attempt = TestDeliveryAttempt {
                message_id: "msg-001".to_string(),
                status: status.to_string(),
                provider: "sendgrid".to_string(),
                attempt_number: (i + 1) as u32,
            };

            assert_eq!(attempt.status, *status);
        }

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_delivery_failure_handling() {
        let start = Instant::now();

        let attempt = TestDeliveryAttempt {
            message_id: "msg-001".to_string(),
            status: "failed".to_string(),
            provider: "sendgrid".to_string(),
            attempt_number: 3,
        };

        assert_eq!(attempt.status, "failed");
        assert!(attempt.attempt_number <= 3);

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    // ==================== Rate Limiting Tests ====================

    #[test]
    fn test_rate_limit_configuration() {
        let start = Instant::now();

        let rate_limit = TestRateLimit {
            channel: "email".to_string(),
            max_per_minute: 100,
            current_count: 0,
        };

        assert_eq!(rate_limit.max_per_minute, 100);
        assert_eq!(rate_limit.current_count, 0);

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_rate_limit_check_within_limit() {
        let start = Instant::now();

        let rate_limit = TestRateLimit {
            channel: "email".to_string(),
            max_per_minute: 100,
            current_count: 50,
        };

        let within_limit = rate_limit.current_count < rate_limit.max_per_minute;
        assert!(within_limit);

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_rate_limit_check_exceeded() {
        let start = Instant::now();

        let rate_limit = TestRateLimit {
            channel: "sms".to_string(),
            max_per_minute: 50,
            current_count: 55,
        };

        let within_limit = rate_limit.current_count < rate_limit.max_per_minute;
        assert!(!within_limit);

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_rate_limit_per_channel() {
        let start = Instant::now();

        let limits = vec![
            ("email", 100),
            ("sms", 50),
            ("push", 1000),
            ("webhook", 100),
        ];

        for (channel, max) in limits {
            let rate_limit = TestRateLimit {
                channel: channel.to_string(),
                max_per_minute: max,
                current_count: 0,
            };

            assert_eq!(rate_limit.max_per_minute, max);
        }

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    // ==================== Provider Tests ====================

    #[test]
    fn test_provider_selection() {
        let start = Instant::now();

        let providers = vec![
            ("sendgrid", "email"),
            ("twilio", "sms"),
            ("fcm", "push"),
            ("slack", "slack"),
        ];

        for (provider, channel) in providers {
            let attempt = TestDeliveryAttempt {
                message_id: "msg-001".to_string(),
                status: "pending".to_string(),
                provider: provider.to_string(),
                attempt_number: 1,
            };

            assert_eq!(attempt.provider, provider);
        }

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_provider_failover() {
        let start = Instant::now();

        let providers = vec!["sendgrid", "aws-ses", "mailgun"];

        for (i, provider) in providers.iter().enumerate() {
            let attempt = TestDeliveryAttempt {
                message_id: "msg-001".to_string(),
                status: if i == providers.len() - 1 { "delivered" } else { "failed" }.to_string(),
                provider: provider.to_string(),
                attempt_number: (i + 1) as u32,
            };

            if i < providers.len() - 1 {
                assert_eq!(attempt.status, "failed");
            } else {
                assert_eq!(attempt.status, "delivered");
            }
        }

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    // ==================== Queue Management Tests ====================

    #[test]
    fn test_message_queueing() {
        let start = Instant::now();

        let queue: Vec<TestMessage> = vec![
            TestMessage {
                id: "msg-001".to_string(),
                body: "Message 1".to_string(),
                channel: "email".to_string(),
                priority: "high".to_string(),
            },
            TestMessage {
                id: "msg-002".to_string(),
                body: "Message 2".to_string(),
                channel: "email".to_string(),
                priority: "medium".to_string(),
            },
        ];

        assert_eq!(queue.len(), 2);
        assert_eq!(queue[0].id, "msg-001");

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_priority_queue_ordering() {
        let start = Instant::now();

        let mut messages = vec![
            ("msg-001", "low"),
            ("msg-002", "critical"),
            ("msg-003", "medium"),
            ("msg-004", "high"),
        ];

        // Sort by priority
        messages.sort_by(|a, b| {
            let priority_order = |p: &str| match p {
                "critical" => 4,
                "high" => 3,
                "medium" => 2,
                "low" => 1,
                _ => 0,
            };
            priority_order(b.1).cmp(&priority_order(a.1))
        });

        assert_eq!(messages[0].0, "msg-002"); // critical
        assert_eq!(messages[1].0, "msg-004"); // high

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    // ==================== Campaign Tests ====================

    #[test]
    fn test_campaign_message_grouping() {
        let start = Instant::now();

        let campaign_id = "campaign-001";
        let messages: Vec<(&str, &str)> = vec![
            ("msg-001", campaign_id),
            ("msg-002", campaign_id),
            ("msg-003", campaign_id),
        ];

        let campaign_messages: Vec<_> = messages
            .iter()
            .filter(|(_, cid)| *cid == campaign_id)
            .collect();

        assert_eq!(campaign_messages.len(), 3);

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_broadcast_vs_targeted_campaigns() {
        let start = Instant::now();

        let broadcast = TestMessage {
            id: "msg-001".to_string(),
            body: "Broadcast message".to_string(),
            channel: "email".to_string(),
            priority: "medium".to_string(),
        };

        let targeted = TestMessage {
            id: "msg-002".to_string(),
            body: "Targeted message".to_string(),
            channel: "email".to_string(),
            priority: "high".to_string(),
        };

        assert!(targeted.priority > broadcast.priority);

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    // ==================== Template Tests ====================

    #[test]
    fn test_template_variable_substitution() {
        let start = Instant::now();

        let template = "Hello {{name}}, your order {{order_id}} is ready!";
        let vars = vec![
            ("name", "John"),
            ("order_id", "12345"),
        ];

        let mut result = template.to_string();
        for (key, value) in vars {
            result = result.replace(&format!("{{{{{}}}}}", key), value);
        }

        assert!(result.contains("Hello John"));
        assert!(result.contains("12345"));

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    // ==================== Analytics Tests ====================

    #[test]
    fn test_delivery_metrics_calculation() {
        let start = Instant::now();

        let attempts = vec![
            ("delivered", 100),
            ("failed", 10),
            ("bounced", 5),
        ];

        let total: u32 = attempts.iter().map(|(_, count)| count).sum();
        let success_rate = (100.0 / total as f64) * 100.0;

        assert_eq!(total, 115);
        assert!(success_rate > 85.0);

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_channel_performance_comparison() {
        let start = Instant::now();

        let channel_metrics = vec![
            ("email", 95.5),
            ("sms", 98.2),
            ("push", 92.1),
        ];

        let best_channel = channel_metrics
            .iter()
            .max_by(|a, b| a.1.partial_cmp(&b.1).unwrap())
            .unwrap();

        assert_eq!(best_channel.0, "sms");

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    // ==================== Integration Tests ====================

    #[test]
    fn test_end_to_end_message_flow() {
        let start = Instant::now();

        // Create message
        let message = TestMessage {
            id: "msg-001".to_string(),
            body: "Test message".to_string(),
            channel: "email".to_string(),
            priority: "high".to_string(),
        };

        // Check rate limit
        let rate_limit = TestRateLimit {
            channel: "email".to_string(),
            max_per_minute: 100,
            current_count: 50,
        };
        let can_send = rate_limit.current_count < rate_limit.max_per_minute;

        // Create delivery attempt
        let attempt = TestDeliveryAttempt {
            message_id: message.id.clone(),
            status: if can_send { "delivered" } else { "queued" }.to_string(),
            provider: "sendgrid".to_string(),
            attempt_number: 1,
        };

        assert!(can_send);
        assert_eq!(attempt.status, "delivered");

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }

    #[test]
    fn test_multi_channel_delivery() {
        let start = Instant::now();

        let channels = vec!["email", "sms", "push"];
        let mut delivery_results = Vec::new();

        for (i, channel) in channels.iter().enumerate() {
            let attempt = TestDeliveryAttempt {
                message_id: format!("msg-{}", i),
                status: "delivered".to_string(),
                provider: format!("provider-{}", channel),
                attempt_number: 1,
            };
            delivery_results.push(attempt);
        }

        assert_eq!(delivery_results.len(), 3);
        assert!(delivery_results.iter().all(|a| a.status == "delivered"));

        let duration = start.elapsed();
        assert!(
            duration.as_nanos() <= 2,
            "Test exceeded 2ns budget: {:?}",
            duration
        );
    }
}
