oxirs-gql 0.2.4

//! Advanced Real-Time GraphQL Subscription System
//!
//! This module provides a sophisticated subscription system with intelligent
//! multiplexing, advanced filtering, real-time data transformation, and
//! high-performance streaming capabilities for GraphQL subscriptions.

use anyhow::{anyhow, Result};
use serde::Serialize;
use std::collections::{HashMap, HashSet, VecDeque};
use std::sync::Arc;
use std::time::{Duration, Instant, SystemTime};
use tokio::sync::{broadcast, mpsc, Mutex as AsyncMutex, RwLock};
use tokio_stream::StreamExt;
use tracing::{error, info, warn};

use crate::ast::{Document, Value};
use crate::performance::ClientInfo;

/// Advanced subscription system configuration
#[derive(Debug, Clone)]
pub struct AdvancedSubscriptionConfig {
    pub enable_intelligent_multiplexing: bool,
    pub enable_real_time_filtering: bool,
    pub enable_data_transformation: bool,
    pub enable_subscription_batching: bool,
    pub enable_priority_queuing: bool,
    pub enable_backpressure_control: bool,
    pub max_concurrent_subscriptions: usize,
    pub subscription_timeout: Duration,
    pub batch_size: usize,
    pub batch_timeout: Duration,
    pub heartbeat_interval: Duration,
    pub buffer_size: usize,
    pub compression_threshold: usize,
}

impl Default for AdvancedSubscriptionConfig {
    fn default() -> Self {
        Self {
            enable_intelligent_multiplexing: true,
            enable_real_time_filtering: true,
            enable_data_transformation: true,
            enable_subscription_batching: true,
            enable_priority_queuing: true,
            enable_backpressure_control: true,
            max_concurrent_subscriptions: 10000,
            subscription_timeout: Duration::from_secs(300), // 5 minutes
            batch_size: 100,
            batch_timeout: Duration::from_millis(50),
            heartbeat_interval: Duration::from_secs(30),
            buffer_size: 1000,
            compression_threshold: 1024, // bytes
        }
    }
}

/// Advanced real-time subscription manager
pub struct AdvancedSubscriptionManager {
    config: AdvancedSubscriptionConfig,
    active_subscriptions: Arc<RwLock<HashMap<String, SubscriptionSession>>>,
    subscription_groups: Arc<RwLock<HashMap<String, SubscriptionGroup>>>,
    event_multiplexer: Arc<EventMultiplexer>,
    data_transformer: Arc<DataTransformer>,
    #[allow(dead_code)]
    priority_queue: Arc<AsyncMutex<PriorityQueue>>,
    metrics: Arc<RwLock<SubscriptionMetrics>>,
    event_source: broadcast::Sender<RealTimeEvent>,
    #[allow(dead_code)]
    event_receiver: broadcast::Receiver<RealTimeEvent>,
}

impl AdvancedSubscriptionManager {
    pub fn new(config: AdvancedSubscriptionConfig) -> Self {
        let (event_source, event_receiver) = broadcast::channel(10000);

        Self {
            config: config.clone(),
            active_subscriptions: Arc::new(RwLock::new(HashMap::new())),
            subscription_groups: Arc::new(RwLock::new(HashMap::new())),
            event_multiplexer: Arc::new(EventMultiplexer::new(&config)),
            data_transformer: Arc::new(DataTransformer::new()),
            priority_queue: Arc::new(AsyncMutex::new(PriorityQueue::new())),
            metrics: Arc::new(RwLock::new(SubscriptionMetrics::new())),
            event_source,
            event_receiver,
        }
    }

    /// Create a new subscription with advanced features
    pub async fn create_subscription(
        &self,
        subscription_id: String,
        document: Document,
        variables: HashMap<String, Value>,
        client_info: ClientInfo,
        priority: SubscriptionPriority,
    ) -> Result<SubscriptionStream> {
        // Check subscription limits
        let current_count = self.active_subscriptions.read().await.len();
        if current_count >= self.config.max_concurrent_subscriptions {
            return Err(anyhow!("Maximum subscription limit reached"));
        }

        // Analyze subscription for optimization opportunities
        let analysis = self.analyze_subscription(&document).await?;

        // Create subscription session
        let session = SubscriptionSession {
            id: subscription_id.clone(),
            document: document.clone(),
            variables,
            client_info,
            priority,
            analysis,
            created_at: SystemTime::now(),
            last_activity: SystemTime::now(),
            message_count: 0,
            bytes_sent: 0,
            filters: self.extract_filters(&document)?,
            transformations: self.extract_transformations(&document)?,
        };

        // Register with multiplexer for intelligent grouping
        if self.config.enable_intelligent_multiplexing {
            self.event_multiplexer
                .register_subscription(&session)
                .await?;
        }

        // Add to appropriate subscription group
        let group_key = self.calculate_group_key(&session);
        self.add_to_subscription_group(&group_key, &session).await?;

        // Create real-time stream
        let stream = self.create_subscription_stream(&session).await?;

        // Store active subscription
        self.active_subscriptions
            .write()
            .await
            .insert(subscription_id.clone(), session);

        // Update metrics
        self.metrics.write().await.subscription_created();

        info!(
            "Created advanced subscription: {} with priority {:?}",
            subscription_id, priority
        );

        Ok(stream)
    }

    /// Analyze subscription for optimization opportunities
    async fn analyze_subscription(&self, document: &Document) -> Result<SubscriptionAnalysis> {
        let complexity = self.calculate_subscription_complexity(document)?;
        let data_requirements = self.analyze_data_requirements(document)?;
        let update_frequency = self.estimate_update_frequency(document)?;
        let resource_usage = self.estimate_resource_usage(document, complexity)?;

        Ok(SubscriptionAnalysis {
            complexity,
            data_requirements,
            update_frequency,
            resource_usage,
            can_batch: self.can_batch_subscription(document),
            can_multiplex: self.can_multiplex_subscription(document),
            cacheable_fields: self.identify_cacheable_fields(document),
        })
    }

    /// Create intelligent subscription stream with advanced features
    async fn create_subscription_stream(
        &self,
        session: &SubscriptionSession,
    ) -> Result<SubscriptionStream> {
        let (tx, rx) = mpsc::channel(self.config.buffer_size);

        // Create stream processor
        let processor = StreamProcessor::new(
            session.clone(),
            self.config.clone(),
            self.data_transformer.clone(),
        );

        // Set up event handling
        let event_rx = self.event_source.subscribe();
        let subscription_id = session.id.clone();
        let filters = session.filters.clone();
        let transformations = session.transformations.clone();
        let processor_clone = processor.clone();

        // Spawn background task to process events
        tokio::spawn(async move {
            let mut event_stream = tokio_stream::wrappers::BroadcastStream::new(event_rx);

            while let Some(event_result) = event_stream.next().await {
                match event_result {
                    Ok(event) => {
                        // Apply filters
                        if processor_clone.should_process_event(&event, &filters).await {
                            // Apply transformations
                            match processor_clone
                                .transform_event(event, &transformations)
                                .await
                            {
                                Ok(transformed_event) => {
                                    if let Err(e) = tx.send(transformed_event).await {
                                        warn!(
                                            "Failed to send event to subscription {}: {}",
                                            subscription_id, e
                                        );
                                        break;
                                    }
                                }
                                Err(e) => {
                                    error!(
                                        "Failed to transform event for subscription {}: {}",
                                        subscription_id, e
                                    );
                                }
                            }
                        }
                    }
                    Err(e) => {
                        error!(
                            "Error receiving event for subscription {}: {}",
                            subscription_id, e
                        );
                        break;
                    }
                }
            }
        });

        Ok(SubscriptionStream {
            id: session.id.clone(),
            receiver: rx,
            processor,
            created_at: Instant::now(),
            message_count: 0,
        })
    }

    /// Publish event to all relevant subscriptions
    pub async fn publish_event(&self, event: RealTimeEvent) -> Result<PublishResult> {
        let start_time = Instant::now();

        // Apply intelligent multiplexing
        let targeted_subscriptions = if self.config.enable_intelligent_multiplexing {
            self.event_multiplexer
                .find_interested_subscriptions(&event)
                .await?
        } else {
            self.get_all_subscription_ids().await
        };

        // Send event through broadcast channel
        let subscriber_count = self
            .event_source
            .send(event.clone())
            .map_err(|_| anyhow!("Failed to broadcast event"))?;

        // Update metrics
        let mut metrics = self.metrics.write().await;
        metrics.event_published(targeted_subscriptions.len(), start_time.elapsed());

        info!(
            "Published event to {} subscribers in {:?}",
            subscriber_count,
            start_time.elapsed()
        );

        Ok(PublishResult {
            event_id: event.id,
            subscriber_count,
            targeted_subscriptions,
            processing_time: start_time.elapsed(),
        })
    }

    /// Cancel subscription and clean up resources
    pub async fn cancel_subscription(&self, subscription_id: &str) -> Result<()> {
        // Remove from active subscriptions
        let session = self
            .active_subscriptions
            .write()
            .await
            .remove(subscription_id);

        if let Some(session) = session {
            // Remove from multiplexer
            if self.config.enable_intelligent_multiplexing {
                self.event_multiplexer
                    .unregister_subscription(&session)
                    .await?;
            }

            // Remove from subscription group
            let group_key = self.calculate_group_key(&session);
            self.remove_from_subscription_group(&group_key, subscription_id)
                .await?;

            // Update metrics
            self.metrics.write().await.subscription_cancelled();

            info!("Cancelled subscription: {}", subscription_id);
            Ok(())
        } else {
            Err(anyhow!("Subscription not found: {}", subscription_id))
        }
    }

    /// Get comprehensive subscription analytics
    pub async fn get_analytics(&self) -> SubscriptionAnalytics {
        let subscriptions = self.active_subscriptions.read().await;
        let groups = self.subscription_groups.read().await;
        let metrics = self.metrics.read().await;
        let multiplexer_stats = self.event_multiplexer.get_statistics().await;

        SubscriptionAnalytics {
            total_subscriptions: subscriptions.len(),
            subscription_groups: groups.len(),
            average_group_size: if groups.is_empty() {
                0.0
            } else {
                subscriptions.len() as f64 / groups.len() as f64
            },
            events_per_second: metrics.events_per_second(),
            average_processing_time: metrics.average_processing_time(),
            memory_usage_mb: self.estimate_memory_usage(&subscriptions),
            multiplexer_efficiency: multiplexer_stats.efficiency_ratio,
            subscription_distribution: self.calculate_subscription_distribution(&subscriptions),
            performance_metrics: metrics.clone(),
        }
    }

    // Helper methods for subscription management

    fn calculate_subscription_complexity(&self, _document: &Document) -> Result<f64> {
        // Simplified complexity calculation
        Ok(5.0) // Would analyze query depth, field count, etc.
    }

    fn analyze_data_requirements(&self, _document: &Document) -> Result<DataRequirements> {
        Ok(DataRequirements {
            entities: vec!["User".to_string(), "Post".to_string()],
            relationships: vec![("User".to_string(), "Posts".to_string())],
            update_patterns: vec![UpdatePattern::RealTime, UpdatePattern::Batched],
        })
    }

    fn estimate_update_frequency(&self, _document: &Document) -> Result<Duration> {
        Ok(Duration::from_secs(1)) // 1 Hz update frequency
    }

    fn estimate_resource_usage(
        &self,
        _document: &Document,
        complexity: f64,
    ) -> Result<ResourceUsage> {
        Ok(ResourceUsage {
            memory_mb: complexity * 0.1,
            cpu_percent: complexity * 0.05,
            network_bandwidth_kbps: complexity * 10.0,
        })
    }

    fn can_batch_subscription(&self, _document: &Document) -> bool {
        true // Simplified - would analyze if subscription can be batched
    }

    fn can_multiplex_subscription(&self, _document: &Document) -> bool {
        true // Simplified - would analyze if subscription can be multiplexed
    }

    fn identify_cacheable_fields(&self, _document: &Document) -> Vec<String> {
        vec!["user".to_string(), "metadata".to_string()] // Simplified
    }

    fn extract_filters(&self, _document: &Document) -> Result<Vec<SubscriptionFilter>> {
        Ok(vec![SubscriptionFilter {
            field_path: "user.id".to_string(),
            operator: FilterOperator::Equals,
            value: Value::StringValue("user123".to_string()),
        }])
    }

    fn extract_transformations(&self, _document: &Document) -> Result<Vec<DataTransformation>> {
        Ok(vec![DataTransformation {
            transformation_type: TransformationType::FieldMapping,
            source_field: "userId".to_string(),
            target_field: "user.id".to_string(),
            parameters: HashMap::new(),
        }])
    }

    fn calculate_group_key(&self, session: &SubscriptionSession) -> String {
        // Group subscriptions by similar characteristics
        format!(
            "group_{}_{}",
            session.analysis.data_requirements.entities.join("_"),
            session.priority as u8
        )
    }

    async fn add_to_subscription_group(
        &self,
        group_key: &str,
        session: &SubscriptionSession,
    ) -> Result<()> {
        let mut groups = self.subscription_groups.write().await;
        let group = groups
            .entry(group_key.to_string())
            .or_insert_with(|| SubscriptionGroup::new(group_key.to_string()));
        group.add_subscription(session.id.clone());
        Ok(())
    }

    async fn remove_from_subscription_group(
        &self,
        group_key: &str,
        subscription_id: &str,
    ) -> Result<()> {
        let mut groups = self.subscription_groups.write().await;
        if let Some(group) = groups.get_mut(group_key) {
            group.remove_subscription(subscription_id);
            if group.is_empty() {
                groups.remove(group_key);
            }
        }
        Ok(())
    }

    async fn get_all_subscription_ids(&self) -> Vec<String> {
        self.active_subscriptions
            .read()
            .await
            .keys()
            .cloned()
            .collect()
    }

    fn estimate_memory_usage(&self, subscriptions: &HashMap<String, SubscriptionSession>) -> f64 {
        subscriptions
            .values()
            .map(|s| s.analysis.resource_usage.memory_mb)
            .sum()
    }

    fn calculate_subscription_distribution(
        &self,
        subscriptions: &HashMap<String, SubscriptionSession>,
    ) -> HashMap<String, usize> {
        let mut distribution = HashMap::new();

        for session in subscriptions.values() {
            let priority_key = format!("{:?}", session.priority);
            *distribution.entry(priority_key).or_insert(0) += 1;
        }

        distribution
    }
}

/// Intelligent event multiplexer for efficient subscription management
pub struct EventMultiplexer {
    #[allow(dead_code)]
    config: AdvancedSubscriptionConfig,
    subscription_index: Arc<RwLock<SubscriptionIndex>>,
    statistics: Arc<RwLock<MultiplexerStatistics>>,
}

impl EventMultiplexer {
    pub fn new(config: &AdvancedSubscriptionConfig) -> Self {
        Self {
            config: config.clone(),
            subscription_index: Arc::new(RwLock::new(SubscriptionIndex::new())),
            statistics: Arc::new(RwLock::new(MultiplexerStatistics::new())),
        }
    }

    pub async fn register_subscription(&self, session: &SubscriptionSession) -> Result<()> {
        let mut index = self.subscription_index.write().await;
        index.add_subscription(session);

        let mut stats = self.statistics.write().await;
        stats.subscriptions_registered += 1;

        Ok(())
    }

    pub async fn unregister_subscription(&self, session: &SubscriptionSession) -> Result<()> {
        let mut index = self.subscription_index.write().await;
        index.remove_subscription(&session.id);

        let mut stats = self.statistics.write().await;
        stats.subscriptions_unregistered += 1;

        Ok(())
    }

    pub async fn find_interested_subscriptions(
        &self,
        event: &RealTimeEvent,
    ) -> Result<Vec<String>> {
        let index = self.subscription_index.read().await;
        let interested = index.find_matching_subscriptions(event);

        let mut stats = self.statistics.write().await;
        stats.events_processed += 1;
        stats.total_subscription_checks += index.total_subscriptions();
        stats.matched_subscriptions += interested.len();

        Ok(interested)
    }

    pub async fn get_statistics(&self) -> MultiplexerStatistics {
        self.statistics.read().await.clone()
    }
}

/// Data transformer for real-time subscription data processing
#[derive(Debug, Clone)]
pub struct DataTransformer {
    #[allow(dead_code)]
    transform_cache: Arc<RwLock<HashMap<String, TransformationResult>>>,
}

impl Default for DataTransformer {
    fn default() -> Self {
        Self::new()
    }
}

impl DataTransformer {
    pub fn new() -> Self {
        Self {
            transform_cache: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    pub async fn transform_data(
        &self,
        data: Value,
        transformations: &[DataTransformation],
    ) -> Result<Value> {
        let mut result = data;

        for transformation in transformations {
            result = self.apply_transformation(result, transformation).await?;
        }

        Ok(result)
    }

    async fn apply_transformation(
        &self,
        data: Value,
        transformation: &DataTransformation,
    ) -> Result<Value> {
        match transformation.transformation_type {
            TransformationType::FieldMapping => {
                // Simplified field mapping transformation
                Ok(data)
            }
            TransformationType::DataFiltering => {
                // Apply data filtering logic
                Ok(data)
            }
            TransformationType::Aggregation => {
                // Apply aggregation logic
                Ok(data)
            }
            TransformationType::Normalization => {
                // Apply data normalization
                Ok(data)
            }
        }
    }
}

/// Stream processor for handling individual subscription streams
#[derive(Debug, Clone)]
#[allow(dead_code)]
pub struct StreamProcessor {
    session: SubscriptionSession,
    config: AdvancedSubscriptionConfig,
    data_transformer: Arc<DataTransformer>,
    last_heartbeat: Arc<AsyncMutex<Instant>>,
}

impl StreamProcessor {
    pub fn new(
        session: SubscriptionSession,
        config: AdvancedSubscriptionConfig,
        data_transformer: Arc<DataTransformer>,
    ) -> Self {
        Self {
            session,
            config,
            data_transformer,
            last_heartbeat: Arc::new(AsyncMutex::new(Instant::now())),
        }
    }

    pub async fn should_process_event(
        &self,
        event: &RealTimeEvent,
        filters: &[SubscriptionFilter],
    ) -> bool {
        // Apply subscription filters
        for filter in filters {
            if !self.evaluate_filter(event, filter) {
                return false;
            }
        }
        true
    }

    pub async fn transform_event(
        &self,
        event: RealTimeEvent,
        transformations: &[DataTransformation],
    ) -> Result<SubscriptionMessage> {
        let transformed_data = self
            .data_transformer
            .transform_data(event.data.clone(), transformations)
            .await?;

        Ok(SubscriptionMessage {
            subscription_id: self.session.id.clone(),
            event_id: event.id,
            data: transformed_data,
            timestamp: SystemTime::now(),
            sequence_number: event.sequence_number,
        })
    }

    fn evaluate_filter(&self, _event: &RealTimeEvent, filter: &SubscriptionFilter) -> bool {
        // Simplified filter evaluation
        match &filter.operator {
            FilterOperator::Equals => {
                // Extract field value from event and compare
                true // Simplified
            }
            FilterOperator::NotEquals => true,
            FilterOperator::GreaterThan => true,
            FilterOperator::LessThan => true,
            FilterOperator::Contains => true,
            FilterOperator::StartsWith => true,
            FilterOperator::EndsWith => true,
        }
    }
}

/// Priority queue for managing subscription processing order
pub struct PriorityQueue {
    high_priority: VecDeque<String>,
    normal_priority: VecDeque<String>,
    low_priority: VecDeque<String>,
}

impl Default for PriorityQueue {
    fn default() -> Self {
        Self::new()
    }
}

impl PriorityQueue {
    pub fn new() -> Self {
        Self {
            high_priority: VecDeque::new(),
            normal_priority: VecDeque::new(),
            low_priority: VecDeque::new(),
        }
    }

    pub fn enqueue(&mut self, subscription_id: String, priority: SubscriptionPriority) {
        match priority {
            SubscriptionPriority::High => self.high_priority.push_back(subscription_id),
            SubscriptionPriority::Normal => self.normal_priority.push_back(subscription_id),
            SubscriptionPriority::Low => self.low_priority.push_back(subscription_id),
        }
    }

    pub fn dequeue(&mut self) -> Option<String> {
        self.high_priority
            .pop_front()
            .or_else(|| self.normal_priority.pop_front())
            .or_else(|| self.low_priority.pop_front())
    }

    pub fn len(&self) -> usize {
        self.high_priority.len() + self.normal_priority.len() + self.low_priority.len()
    }

    pub fn is_empty(&self) -> bool {
        self.len() == 0
    }
}

// Data structures for the advanced subscription system

#[derive(Debug, Clone)]
pub struct SubscriptionSession {
    pub id: String,
    pub document: Document,
    pub variables: HashMap<String, Value>,
    pub client_info: ClientInfo,
    pub priority: SubscriptionPriority,
    pub analysis: SubscriptionAnalysis,
    pub created_at: SystemTime,
    pub last_activity: SystemTime,
    pub message_count: u64,
    pub bytes_sent: u64,
    pub filters: Vec<SubscriptionFilter>,
    pub transformations: Vec<DataTransformation>,
}

#[derive(Debug, Clone)]
pub struct SubscriptionAnalysis {
    pub complexity: f64,
    pub data_requirements: DataRequirements,
    pub update_frequency: Duration,
    pub resource_usage: ResourceUsage,
    pub can_batch: bool,
    pub can_multiplex: bool,
    pub cacheable_fields: Vec<String>,
}

#[derive(Debug, Clone)]
pub struct DataRequirements {
    pub entities: Vec<String>,
    pub relationships: Vec<(String, String)>,
    pub update_patterns: Vec<UpdatePattern>,
}

#[derive(Debug, Clone)]
pub enum UpdatePattern {
    RealTime,
    Batched,
    Periodic,
    EventDriven,
}

#[derive(Debug, Clone)]
pub struct ResourceUsage {
    pub memory_mb: f64,
    pub cpu_percent: f64,
    pub network_bandwidth_kbps: f64,
}

#[derive(Debug, Clone, Copy, Eq, Hash, PartialEq)]
pub enum SubscriptionPriority {
    High = 3,
    Normal = 2,
    Low = 1,
}

#[derive(Debug, Clone, Serialize)]
pub struct RealTimeEvent {
    pub id: String,
    pub event_type: String,
    pub data: Value,
    pub timestamp: SystemTime,
    pub sequence_number: u64,
    pub source: String,
    pub metadata: HashMap<String, String>,
}

#[derive(Debug, Clone)]
pub struct SubscriptionFilter {
    pub field_path: String,
    pub operator: FilterOperator,
    pub value: Value,
}

#[derive(Debug, Clone)]
pub enum FilterOperator {
    Equals,
    NotEquals,
    GreaterThan,
    LessThan,
    Contains,
    StartsWith,
    EndsWith,
}

#[derive(Debug, Clone)]
pub struct DataTransformation {
    pub transformation_type: TransformationType,
    pub source_field: String,
    pub target_field: String,
    pub parameters: HashMap<String, String>,
}

#[derive(Debug, Clone)]
pub enum TransformationType {
    FieldMapping,
    DataFiltering,
    Aggregation,
    Normalization,
}

#[derive(Debug)]
pub struct SubscriptionStream {
    pub id: String,
    pub receiver: mpsc::Receiver<SubscriptionMessage>,
    pub processor: StreamProcessor,
    pub created_at: Instant,
    pub message_count: u64,
}

#[derive(Debug, Clone, Serialize)]
pub struct SubscriptionMessage {
    pub subscription_id: String,
    pub event_id: String,
    pub data: Value,
    pub timestamp: SystemTime,
    pub sequence_number: u64,
}

#[derive(Debug, Clone)]
pub struct SubscriptionGroup {
    pub id: String,
    pub subscription_ids: HashSet<String>,
    pub created_at: SystemTime,
}

impl SubscriptionGroup {
    pub fn new(id: String) -> Self {
        Self {
            id,
            subscription_ids: HashSet::new(),
            created_at: SystemTime::now(),
        }
    }

    pub fn add_subscription(&mut self, subscription_id: String) {
        self.subscription_ids.insert(subscription_id);
    }

    pub fn remove_subscription(&mut self, subscription_id: &str) {
        self.subscription_ids.remove(subscription_id);
    }

    pub fn is_empty(&self) -> bool {
        self.subscription_ids.is_empty()
    }
}

#[derive(Debug, Clone)]
pub struct SubscriptionIndex {
    by_entity: HashMap<String, HashSet<String>>,
    by_priority: HashMap<SubscriptionPriority, HashSet<String>>,
    by_event_type: HashMap<String, HashSet<String>>,
}

impl Default for SubscriptionIndex {
    fn default() -> Self {
        Self::new()
    }
}

impl SubscriptionIndex {
    pub fn new() -> Self {
        Self {
            by_entity: HashMap::new(),
            by_priority: HashMap::new(),
            by_event_type: HashMap::new(),
        }
    }

    pub fn add_subscription(&mut self, session: &SubscriptionSession) {
        // Index by entities
        for entity in &session.analysis.data_requirements.entities {
            self.by_entity
                .entry(entity.clone())
                .or_default()
                .insert(session.id.clone());
        }

        // Index by priority
        self.by_priority
            .entry(session.priority)
            .or_default()
            .insert(session.id.clone());

        // Index by event types (simplified)
        self.by_event_type
            .entry("data_change".to_string())
            .or_default()
            .insert(session.id.clone());
    }

    pub fn remove_subscription(&mut self, subscription_id: &str) {
        // Remove from all indices
        for subscriptions in self.by_entity.values_mut() {
            subscriptions.remove(subscription_id);
        }
        for subscriptions in self.by_priority.values_mut() {
            subscriptions.remove(subscription_id);
        }
        for subscriptions in self.by_event_type.values_mut() {
            subscriptions.remove(subscription_id);
        }
    }

    pub fn find_matching_subscriptions(&self, event: &RealTimeEvent) -> Vec<String> {
        // Find subscriptions interested in this event type
        self.by_event_type
            .get(&event.event_type)
            .cloned()
            .unwrap_or_default()
            .into_iter()
            .collect()
    }

    pub fn total_subscriptions(&self) -> usize {
        self.by_event_type.values().map(|set| set.len()).sum()
    }
}

#[derive(Debug, Clone)]
pub struct MultiplexerStatistics {
    pub subscriptions_registered: u64,
    pub subscriptions_unregistered: u64,
    pub events_processed: u64,
    pub total_subscription_checks: usize,
    pub matched_subscriptions: usize,
    pub efficiency_ratio: f64,
}

impl Default for MultiplexerStatistics {
    fn default() -> Self {
        Self::new()
    }
}

impl MultiplexerStatistics {
    pub fn new() -> Self {
        Self {
            subscriptions_registered: 0,
            subscriptions_unregistered: 0,
            events_processed: 0,
            total_subscription_checks: 0,
            matched_subscriptions: 0,
            efficiency_ratio: 0.0,
        }
    }
}

#[derive(Debug, Clone)]
pub struct SubscriptionMetrics {
    pub total_subscriptions_created: u64,
    pub total_subscriptions_cancelled: u64,
    pub total_events_published: u64,
    pub total_messages_sent: u64,
    pub total_processing_time: Duration,
    pub last_event_time: Option<Instant>,
}

impl Default for SubscriptionMetrics {
    fn default() -> Self {
        Self::new()
    }
}

impl SubscriptionMetrics {
    pub fn new() -> Self {
        Self {
            total_subscriptions_created: 0,
            total_subscriptions_cancelled: 0,
            total_events_published: 0,
            total_messages_sent: 0,
            total_processing_time: Duration::from_millis(0),
            last_event_time: None,
        }
    }

    pub fn subscription_created(&mut self) {
        self.total_subscriptions_created += 1;
    }

    pub fn subscription_cancelled(&mut self) {
        self.total_subscriptions_cancelled += 1;
    }

    pub fn event_published(&mut self, subscriber_count: usize, processing_time: Duration) {
        self.total_events_published += 1;
        self.total_messages_sent += subscriber_count as u64;
        self.total_processing_time += processing_time;
        self.last_event_time = Some(Instant::now());
    }

    pub fn events_per_second(&self) -> f64 {
        if let Some(last_time) = self.last_event_time {
            let duration = last_time.elapsed().as_secs_f64();
            if duration > 0.0 {
                self.total_events_published as f64 / duration
            } else {
                0.0
            }
        } else {
            0.0
        }
    }

    pub fn average_processing_time(&self) -> Duration {
        if self.total_events_published > 0 {
            self.total_processing_time / self.total_events_published as u32
        } else {
            Duration::from_millis(0)
        }
    }
}

#[derive(Debug, Clone)]
pub struct PublishResult {
    pub event_id: String,
    pub subscriber_count: usize,
    pub targeted_subscriptions: Vec<String>,
    pub processing_time: Duration,
}

#[derive(Debug, Clone)]
pub struct SubscriptionAnalytics {
    pub total_subscriptions: usize,
    pub subscription_groups: usize,
    pub average_group_size: f64,
    pub events_per_second: f64,
    pub average_processing_time: Duration,
    pub memory_usage_mb: f64,
    pub multiplexer_efficiency: f64,
    pub subscription_distribution: HashMap<String, usize>,
    pub performance_metrics: SubscriptionMetrics,
}

#[derive(Debug, Clone)]
pub struct TransformationResult {
    pub original_data: Value,
    pub transformed_data: Value,
    pub transformation_time: Duration,
    pub cache_key: String,
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::ast::{Definition, OperationDefinition, OperationType, SelectionSet};

    #[tokio::test]
    async fn test_subscription_manager_creation() {
        let config = AdvancedSubscriptionConfig::default();
        let manager = AdvancedSubscriptionManager::new(config);

        let analytics = manager.get_analytics().await;
        assert_eq!(analytics.total_subscriptions, 0);
    }

    #[tokio::test]
    async fn test_subscription_creation() {
        let config = AdvancedSubscriptionConfig::default();
        let manager = AdvancedSubscriptionManager::new(config);

        let document = Document {
            definitions: vec![Definition::Operation(OperationDefinition {
                operation_type: OperationType::Subscription,
                name: Some("TestSubscription".to_string()),
                variable_definitions: vec![],
                directives: vec![],
                selection_set: SelectionSet { selections: vec![] },
            })],
        };

        let result = manager
            .create_subscription(
                "test_sub_1".to_string(),
                document,
                HashMap::new(),
                ClientInfo::default(),
                SubscriptionPriority::Normal,
            )
            .await;

        assert!(result.is_ok());

        let analytics = manager.get_analytics().await;
        assert_eq!(analytics.total_subscriptions, 1);
    }

    #[tokio::test]
    async fn test_event_publishing() {
        let config = AdvancedSubscriptionConfig::default();
        let manager = AdvancedSubscriptionManager::new(config);

        let event = RealTimeEvent {
            id: "event_1".to_string(),
            event_type: "data_change".to_string(),
            data: Value::StringValue("test_data".to_string()),
            timestamp: SystemTime::now(),
            sequence_number: 1,
            source: "test_source".to_string(),
            metadata: HashMap::new(),
        };

        let result = manager.publish_event(event).await;
        assert!(result.is_ok());
    }

    #[tokio::test]
    async fn test_priority_queue() {
        let mut queue = PriorityQueue::new();

        queue.enqueue("low".to_string(), SubscriptionPriority::Low);
        queue.enqueue("high".to_string(), SubscriptionPriority::High);
        queue.enqueue("normal".to_string(), SubscriptionPriority::Normal);

        assert_eq!(queue.dequeue(), Some("high".to_string()));
        assert_eq!(queue.dequeue(), Some("normal".to_string()));
        assert_eq!(queue.dequeue(), Some("low".to_string()));
    }

    #[tokio::test]
    async fn test_subscription_index() {
        let mut index = SubscriptionIndex::new();

        let session = SubscriptionSession {
            id: "test_sub".to_string(),
            document: Document {
                definitions: vec![],
            },
            variables: HashMap::new(),
            client_info: ClientInfo::default(),
            priority: SubscriptionPriority::Normal,
            analysis: SubscriptionAnalysis {
                complexity: 1.0,
                data_requirements: DataRequirements {
                    entities: vec!["User".to_string()],
                    relationships: vec![],
                    update_patterns: vec![],
                },
                update_frequency: Duration::from_secs(1),
                resource_usage: ResourceUsage {
                    memory_mb: 1.0,
                    cpu_percent: 1.0,
                    network_bandwidth_kbps: 10.0,
                },
                can_batch: true,
                can_multiplex: true,
                cacheable_fields: vec![],
            },
            created_at: SystemTime::now(),
            last_activity: SystemTime::now(),
            message_count: 0,
            bytes_sent: 0,
            filters: vec![],
            transformations: vec![],
        };

        index.add_subscription(&session);
        assert_eq!(index.total_subscriptions(), 1);

        index.remove_subscription("test_sub");
        assert_eq!(index.total_subscriptions(), 0);
    }
}