voirs_spatial/multiuser/

impls.rs

//! Implementation blocks for multi-user types

use super::types::*;
use crate::types::{Position3D, SpatialResult};
use crate::{Error, Result};
use std::collections::{HashMap, HashSet, VecDeque};
use std::sync::{Arc, RwLock};
use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};

impl Default for MultiUserConfig {
    fn default() -> Self {
        Self {
            max_users_per_room: 50,
            max_sources_per_user: 5,
            sync_interval_ms: 50,
            max_latency_ms: 100.0,
            voice_activity_threshold: 0.3,
            audio_quality: 0.8,
            position_interpolation: true,
            max_audio_distance: 100.0,
            attenuation_curve: MultiUserAttenuationCurve::InverseDistance,
            privacy_settings: PrivacySettings::default(),
            bandwidth_settings: BandwidthSettings::default(),
        }
    }
}

impl Default for PrivacySettings {
    fn default() -> Self {
        Self {
            encryption_enabled: true,
            recording_allowed: false,
            mute_controls_enabled: true,
            spatial_zones_enabled: true,
            permission_system: PermissionSystem::default(),
            anonymization: AnonymizationSettings::default(),
        }
    }
}

impl Default for PermissionSystem {
    fn default() -> Self {
        let mut role_permissions = HashMap::new();

        role_permissions.insert(UserRole::Guest, vec![Permission::Speak, Permission::Move]);
        role_permissions.insert(
            UserRole::Participant,
            vec![
                Permission::Speak,
                Permission::Move,
                Permission::CreateSources,
            ],
        );
        role_permissions.insert(
            UserRole::Presenter,
            vec![
                Permission::Speak,
                Permission::Move,
                Permission::CreateSources,
                Permission::Broadcast,
            ],
        );
        role_permissions.insert(
            UserRole::Moderator,
            vec![
                Permission::Speak,
                Permission::Move,
                Permission::CreateSources,
                Permission::MuteOthers,
                Permission::ModifyRoom,
                Permission::Moderate,
            ],
        );
        role_permissions.insert(
            UserRole::Administrator,
            vec![
                Permission::Speak,
                Permission::Move,
                Permission::CreateSources,
                Permission::MuteOthers,
                Permission::KickUsers,
                Permission::ModifyRoom,
                Permission::Record,
                Permission::AccessPrivateZones,
                Permission::Broadcast,
                Permission::Moderate,
            ],
        );
        role_permissions.insert(UserRole::Observer, vec![Permission::Move]);

        Self {
            rbac_enabled: true,
            default_role: UserRole::Participant,
            role_permissions,
        }
    }
}

impl Default for AnonymizationSettings {
    fn default() -> Self {
        Self {
            anonymous_ids: false,
            position_obfuscation: false,
            temporal_obfuscation: false,
            voice_modulation: false,
        }
    }
}

impl Default for BandwidthSettings {
    fn default() -> Self {
        Self {
            adaptive_bitrate: true,
            max_bandwidth_kbps: 128,
            compression_level: 5,
            proximity_quality_scaling: true,
            low_bandwidth_mode: LowBandwidthMode {
                enabled: false,
                sample_rate: 16000,
                bit_depth: 16,
                max_streams: 5,
                disable_spatial_effects: true,
            },
        }
    }
}

impl MultiUserEnvironment {
    /// Create a new multi-user environment
    pub fn new(config: MultiUserConfig) -> Result<Self> {
        let sync_manager = SynchronizationManager::new();
        let audio_processor = MultiUserAudioProcessor::new(&config)?;

        Ok(Self {
            config,
            users: Arc::new(RwLock::new(HashMap::new())),
            sources: Arc::new(RwLock::new(HashMap::new())),
            zones: Arc::new(RwLock::new(HashMap::new())),
            sync_manager,
            audio_processor,
            metrics: Arc::new(RwLock::new(MultiUserMetrics::default())),
            event_history: Arc::new(RwLock::new(VecDeque::new())),
        })
    }

    /// Add a user to the environment
    pub fn add_user(&self, user: MultiUserUser) -> Result<()> {
        let user_id = user.id.clone();
        let position = user.position;

        // Check user limit
        {
            let users = self.users.read().map_err(|e| {
                Error::LegacyProcessing(format!("Failed to acquire read lock on users: {}", e))
            })?;
            if users.len() >= self.config.max_users_per_room {
                return Err(Error::LegacyProcessing(
                    "Maximum users per room exceeded".to_string(),
                ));
            }
        }

        // Add user
        {
            let mut users = self.users.write().map_err(|e| {
                Error::LegacyProcessing(format!("Failed to acquire write lock on users: {}", e))
            })?;
            users.insert(user_id.clone(), user);
        }

        // Record event
        self.record_event(MultiUserEvent::UserJoined {
            user_id,
            timestamp: SystemTime::now(),
            position,
        });

        Ok(())
    }

    /// Remove a user from the environment
    pub fn remove_user(&self, user_id: &UserId, reason: DisconnectReason) -> Result<()> {
        {
            let mut users = self.users.write().map_err(|e| {
                Error::LegacyProcessing(format!("Failed to acquire write lock on users: {}", e))
            })?;
            users.remove(user_id);
        }

        // Record event
        self.record_event(MultiUserEvent::UserLeft {
            user_id: user_id.clone(),
            timestamp: SystemTime::now(),
            reason,
        });

        Ok(())
    }

    /// Update user position
    pub fn update_user_position(
        &mut self,
        user_id: &UserId,
        position: Position3D,
        orientation: [f32; 4],
    ) -> Result<()> {
        let old_position;
        let old_timestamp;
        let calculated_velocity;

        {
            let mut users = self.users.write().map_err(|e| {
                Error::LegacyProcessing(format!("Failed to acquire write lock on users: {}", e))
            })?;
            if let Some(user) = users.get_mut(user_id) {
                old_position = user.position;
                old_timestamp = user.last_update;

                // Calculate velocity based on position change over time
                let current_time = Instant::now();
                let time_delta = current_time.duration_since(old_timestamp).as_secs_f32();

                if time_delta > 0.0 {
                    let position_delta = Position3D::new(
                        position.x - old_position.x,
                        position.y - old_position.y,
                        position.z - old_position.z,
                    );
                    calculated_velocity = Position3D::new(
                        position_delta.x / time_delta,
                        position_delta.y / time_delta,
                        position_delta.z / time_delta,
                    );
                    user.velocity = calculated_velocity;
                } else {
                    // If no time has passed, maintain previous velocity
                    calculated_velocity = user.velocity;
                }

                user.position = position;
                user.orientation = orientation;
                user.last_update = current_time;
            } else {
                return Err(Error::LegacyPosition(format!("User {user_id} not found")));
            }
        }

        // Estimate latency based on position interpolator history
        let estimated_latency = self
            .sync_manager
            .position_interpolator
            .estimate_latency(user_id)
            .unwrap_or(0.0);

        // Update position interpolator
        self.sync_manager.position_interpolator.add_position_sample(
            user_id,
            PositionSnapshot {
                position,
                orientation,
                velocity: calculated_velocity,
                timestamp: Instant::now(),
                latency_ms: estimated_latency,
            },
        );

        // Record event
        self.record_event(MultiUserEvent::UserMoved {
            user_id: user_id.clone(),
            timestamp: SystemTime::now(),
            old_position,
            new_position: position,
        });

        Ok(())
    }

    /// Add a friend relationship between two users
    pub fn add_friend(&self, user_id: &UserId, friend_id: &UserId) -> Result<()> {
        if user_id == friend_id {
            return Err(Error::LegacyPosition(
                "Cannot add self as friend".to_string(),
            ));
        }

        {
            let mut users = self.users.write().map_err(|e| {
                Error::LegacyProcessing(format!("Failed to acquire write lock on users: {}", e))
            })?;

            // Verify both users exist
            if !users.contains_key(user_id) {
                return Err(Error::LegacyPosition(format!("User {user_id} not found")));
            }
            if !users.contains_key(friend_id) {
                return Err(Error::LegacyPosition(format!(
                    "Friend {friend_id} not found"
                )));
            }

            // Add bidirectional friendship
            if let Some(user) = users.get_mut(user_id) {
                user.friends.insert(friend_id.clone());
            }
            if let Some(friend) = users.get_mut(friend_id) {
                friend.friends.insert(user_id.clone());
            }
        }

        // Record event
        self.record_event(MultiUserEvent::UserMoved {
            user_id: user_id.clone(),
            timestamp: SystemTime::now(),
            old_position: Position3D::new(0.0, 0.0, 0.0), // Placeholder
            new_position: Position3D::new(0.0, 0.0, 0.0), // Placeholder
        });

        Ok(())
    }

    /// Remove a friend relationship between two users
    pub fn remove_friend(&self, user_id: &UserId, friend_id: &UserId) -> Result<()> {
        {
            let mut users = self.users.write().map_err(|e| {
                Error::LegacyProcessing(format!("Failed to acquire write lock on users: {}", e))
            })?;

            // Remove bidirectional friendship
            if let Some(user) = users.get_mut(user_id) {
                user.friends.remove(friend_id);
            }
            if let Some(friend) = users.get_mut(friend_id) {
                friend.friends.remove(user_id);
            }
        }

        Ok(())
    }

    /// Check if two users are friends
    pub fn are_friends(&self, user_id: &UserId, friend_id: &UserId) -> Result<bool> {
        let users = self.users.read().map_err(|e| {
            Error::LegacyProcessing(format!("Failed to acquire read lock on users: {}", e))
        })?;

        if let Some(user) = users.get(user_id) {
            Ok(user.friends.contains(friend_id))
        } else {
            Err(Error::LegacyPosition(format!("User {user_id} not found")))
        }
    }

    /// Get list of friends for a user
    pub fn get_friends(&self, user_id: &UserId) -> Result<Vec<UserId>> {
        let users = self.users.read().map_err(|e| {
            Error::LegacyProcessing(format!("Failed to acquire read lock on users: {}", e))
        })?;

        if let Some(user) = users.get(user_id) {
            Ok(user.friends.iter().cloned().collect())
        } else {
            Err(Error::LegacyPosition(format!("User {user_id} not found")))
        }
    }

    /// Add an audio source
    pub fn add_audio_source(&self, source: MultiUserAudioSource) -> Result<()> {
        let source_id = source.id.clone();
        let user_id = source.owner_id.clone();
        let source_type = source.source_type;

        {
            let mut sources = self.sources.write().map_err(|e| {
                Error::LegacyProcessing(format!("Failed to acquire write lock on sources: {}", e))
            })?;
            sources.insert(source_id.clone(), source);
        }

        // Record event
        self.record_event(MultiUserEvent::SourceCreated {
            source_id,
            user_id,
            timestamp: SystemTime::now(),
            source_type,
        });

        Ok(())
    }

    /// Remove an audio source
    pub fn remove_audio_source(&self, source_id: &SourceId, reason: &str) -> Result<()> {
        {
            let mut sources = self.sources.write().map_err(|e| {
                Error::LegacyProcessing(format!("Failed to acquire write lock on sources: {}", e))
            })?;
            sources.remove(source_id);
        }

        // Record event
        self.record_event(MultiUserEvent::SourceRemoved {
            source_id: source_id.clone(),
            timestamp: SystemTime::now(),
            reason: reason.to_string(),
        });

        Ok(())
    }

    /// Process spatial audio for all users
    pub fn process_audio(&mut self) -> Result<HashMap<UserId, Vec<f32>>> {
        let users = self.users.read().map_err(|e| {
            Error::LegacyProcessing(format!("Failed to acquire read lock on users: {}", e))
        })?;
        let mut output_buffers = HashMap::new();

        for (user_id, user) in users.iter() {
            // Create personalized audio mix for this user
            let audio_buffer =
                self.audio_processor
                    .process_for_user(user, &users, &self.sources)?;
            output_buffers.insert(user_id.clone(), audio_buffer);
        }

        Ok(output_buffers)
    }

    /// Get current performance metrics
    pub fn metrics(&self) -> MultiUserMetrics {
        self.metrics
            .read()
            .expect("Failed to acquire read lock on metrics for retrieval")
            .clone()
    }

    /// Create a spatial zone
    pub fn create_zone(&self, zone: SpatialZone) -> Result<()> {
        let mut zones = self.zones.write().map_err(|e| {
            Error::LegacyProcessing(format!("Failed to acquire write lock on zones: {}", e))
        })?;
        zones.insert(zone.id.clone(), zone);
        Ok(())
    }

    /// Check if user has permission for an action
    pub fn check_permission(&self, user_id: &UserId, permission: Permission) -> Result<bool> {
        let users = self.users.read().map_err(|e| {
            Error::LegacyProcessing(format!("Failed to acquire read lock on users: {}", e))
        })?;
        if let Some(user) = users.get(user_id) {
            if let Some(permissions) = self
                .config
                .privacy_settings
                .permission_system
                .role_permissions
                .get(&user.role)
            {
                Ok(permissions.contains(&permission))
            } else {
                Ok(false)
            }
        } else {
            Err(Error::LegacyPosition(format!("User {user_id} not found")))
        }
    }

    /// Record an event in the history
    fn record_event(&self, event: MultiUserEvent) {
        let mut history = self
            .event_history
            .write()
            .expect("Failed to acquire write lock on event history");
        history.push_back(event);

        // Keep only recent events (last 1000)
        if history.len() > 1000 {
            history.pop_front();
        }
    }
}

impl SynchronizationManager {
    /// Create a new synchronization manager
    pub fn new() -> Self {
        Self {
            clock: Arc::new(RwLock::new(SynchronizedClock::new())),
            position_interpolator: PositionInterpolator::new(),
            latency_compensator: LatencyCompensator::new(),
        }
    }
}

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

impl SynchronizedClock {
    /// Create a new synchronized clock
    pub fn new() -> Self {
        Self {
            local_time: Instant::now(),
            time_offset_ms: 0,
            sync_accuracy_ms: 0.0,
            last_sync: Instant::now(),
        }
    }

    /// Get the current synchronized time
    pub fn current_time(&self) -> Instant {
        self.local_time
    }
}

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

impl PositionInterpolator {
    /// Create a new position interpolator
    pub fn new() -> Self {
        Self {
            position_histories: HashMap::new(),
            interpolation_method: InterpolationMethod::Linear,
            prediction_horizon_ms: 50.0,
        }
    }

    /// Add a position sample for a user
    pub fn add_position_sample(&mut self, user_id: &UserId, snapshot: PositionSnapshot) {
        let history = self.position_histories.entry(user_id.clone()).or_default();
        history.push_back(snapshot);

        // Keep only recent samples (last 10)
        if history.len() > 10 {
            history.pop_front();
        }
    }

    /// Interpolate user position at a specific time
    pub fn interpolate_position(
        &self,
        user_id: &UserId,
        target_time: Instant,
    ) -> Option<Position3D> {
        let history = self.position_histories.get(user_id)?;
        if history.len() < 1 {
            return None;
        }

        if history.len() == 1 {
            return history.back().map(|s| s.position);
        }

        match self.interpolation_method {
            InterpolationMethod::Linear => self.linear_interpolation(history, target_time),
            InterpolationMethod::CubicSpline => {
                self.cubic_spline_interpolation(history, target_time)
            }
            InterpolationMethod::Kalman => self.kalman_interpolation(history, target_time),
            InterpolationMethod::Physics => self.physics_interpolation(history, target_time),
        }
    }

    /// Linear interpolation between two closest points
    fn linear_interpolation(
        &self,
        history: &VecDeque<PositionSnapshot>,
        target_time: Instant,
    ) -> Option<Position3D> {
        // Find the two samples that bracket the target time
        let mut before_sample = None;
        let mut after_sample = None;

        for (i, sample) in history.iter().enumerate() {
            if sample.timestamp <= target_time {
                before_sample = Some(sample);
            }
            if sample.timestamp >= target_time && after_sample.is_none() {
                after_sample = Some(sample);
                break;
            }
        }

        match (before_sample, after_sample) {
            (Some(before), Some(after)) if before.timestamp != after.timestamp => {
                let total_duration = after
                    .timestamp
                    .duration_since(before.timestamp)
                    .as_secs_f32();
                let elapsed_duration = target_time.duration_since(before.timestamp).as_secs_f32();
                let t = elapsed_duration / total_duration;

                Some(Position3D::new(
                    before.position.x + t * (after.position.x - before.position.x),
                    before.position.y + t * (after.position.y - before.position.y),
                    before.position.z + t * (after.position.z - before.position.z),
                ))
            }
            (Some(sample), _) => Some(sample.position),
            (_, Some(sample)) => Some(sample.position),
            _ => history.back().map(|s| s.position),
        }
    }

    /// Cubic spline interpolation for smoother movement
    fn cubic_spline_interpolation(
        &self,
        history: &VecDeque<PositionSnapshot>,
        target_time: Instant,
    ) -> Option<Position3D> {
        if history.len() < 4 {
            return self.linear_interpolation(history, target_time);
        }

        // For simplicity, use a cubic Hermite spline with velocity information
        let samples: Vec<_> = history.iter().collect();
        let n = samples.len();

        // Find the segment containing target_time
        for i in 1..n {
            if samples[i].timestamp >= target_time {
                let p0 = if i >= 2 { samples[i - 2] } else { samples[0] };
                let p1 = samples[i - 1];
                let p2 = samples[i];
                let p3 = if i + 1 < n {
                    samples[i + 1]
                } else {
                    samples[n - 1]
                };

                let t1 = p1
                    .timestamp
                    .duration_since(p0.timestamp)
                    .as_secs_f32()
                    .max(0.001);
                let t2 = p2
                    .timestamp
                    .duration_since(p1.timestamp)
                    .as_secs_f32()
                    .max(0.001);
                let t3 = p3
                    .timestamp
                    .duration_since(p2.timestamp)
                    .as_secs_f32()
                    .max(0.001);

                let target_offset = target_time.duration_since(p1.timestamp).as_secs_f32();
                let t = target_offset / t2;

                // Calculate tangents (velocities)
                let m1 = Position3D::new(
                    (p2.position.x - p0.position.x) / (t1 + t2),
                    (p2.position.y - p0.position.y) / (t1 + t2),
                    (p2.position.z - p0.position.z) / (t1 + t2),
                );
                let m2 = Position3D::new(
                    (p3.position.x - p1.position.x) / (t2 + t3),
                    (p3.position.y - p1.position.y) / (t2 + t3),
                    (p3.position.z - p1.position.z) / (t2 + t3),
                );

                // Hermite basis functions
                let t2 = t * t;
                let t3 = t2 * t;
                let h00 = 2.0 * t3 - 3.0 * t2 + 1.0;
                let h10 = t3 - 2.0 * t2 + t;
                let h01 = -2.0 * t3 + 3.0 * t2;
                let h11 = t3 - t2;

                return Some(Position3D::new(
                    h00 * p1.position.x + h10 * m1.x * t2 + h01 * p2.position.x + h11 * m2.x * t2,
                    h00 * p1.position.y + h10 * m1.y * t2 + h01 * p2.position.y + h11 * m2.y * t2,
                    h00 * p1.position.z + h10 * m1.z * t2 + h01 * p2.position.z + h11 * m2.z * t2,
                ));
            }
        }

        // Fallback to linear interpolation
        self.linear_interpolation(history, target_time)
    }

    /// Kalman filter-based prediction with velocity estimation
    fn kalman_interpolation(
        &self,
        history: &VecDeque<PositionSnapshot>,
        target_time: Instant,
    ) -> Option<Position3D> {
        if history.len() < 2 {
            return history.back().map(|s| s.position);
        }

        let latest = history.back()?;
        let time_delta = target_time.duration_since(latest.timestamp).as_secs_f32();

        // Simple Kalman-like prediction using stored velocity
        Some(Position3D::new(
            latest.position.x + latest.velocity.x * time_delta,
            latest.position.y + latest.velocity.y * time_delta,
            latest.position.z + latest.velocity.z * time_delta,
        ))
    }

    /// Physics-based prediction considering acceleration
    fn physics_interpolation(
        &self,
        history: &VecDeque<PositionSnapshot>,
        target_time: Instant,
    ) -> Option<Position3D> {
        if history.len() < 3 {
            return self.kalman_interpolation(history, target_time);
        }

        let samples: Vec<_> = history.iter().rev().take(3).collect();
        let latest = samples[0];
        let prev1 = samples[1];
        let prev2 = samples[2];

        let dt1 = latest
            .timestamp
            .duration_since(prev1.timestamp)
            .as_secs_f32()
            .max(0.001);
        let dt2 = prev1
            .timestamp
            .duration_since(prev2.timestamp)
            .as_secs_f32()
            .max(0.001);

        // Calculate acceleration from velocity changes
        let accel = Position3D::new(
            (latest.velocity.x - prev1.velocity.x) / dt1,
            (latest.velocity.y - prev1.velocity.y) / dt1,
            (latest.velocity.z - prev1.velocity.z) / dt1,
        );

        let time_delta = target_time.duration_since(latest.timestamp).as_secs_f32();

        // Physics equation: s = s0 + v0*t + 0.5*a*t^2
        Some(Position3D::new(
            latest.position.x
                + latest.velocity.x * time_delta
                + 0.5 * accel.x * time_delta * time_delta,
            latest.position.y
                + latest.velocity.y * time_delta
                + 0.5 * accel.y * time_delta * time_delta,
            latest.position.z
                + latest.velocity.z * time_delta
                + 0.5 * accel.z * time_delta * time_delta,
        ))
    }

    /// Estimate network latency based on position update patterns
    pub fn estimate_latency(&self, user_id: &UserId) -> Option<f64> {
        let history = self.position_histories.get(user_id)?;

        if history.len() < 2 {
            return Some(0.0);
        }

        // Calculate average time between position updates
        let mut total_intervals = 0.0;
        let mut interval_count = 0;

        for i in 1..history.len() {
            let current_sample = &history[i];
            let previous_sample = &history[i - 1];

            let interval = current_sample
                .timestamp
                .duration_since(previous_sample.timestamp)
                .as_secs_f64()
                * 1000.0;
            total_intervals += interval;
            interval_count += 1;
        }

        if interval_count > 0 {
            let avg_interval = total_intervals / interval_count as f64;
            // Estimate latency as half the average update interval
            // This assumes network latency is roughly proportional to update frequency
            Some((avg_interval * 0.5).min(100.0)) // Cap at 100ms
        } else {
            Some(0.0)
        }
    }
}

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

impl LatencyCompensator {
    /// Create a new latency compensator
    pub fn new() -> Self {
        Self {
            user_latencies: HashMap::new(),
            compensation_method: CompensationMethod::Adaptive,
            max_compensation_ms: 100.0,
        }
    }

    /// Update the measured latency for a user
    pub fn update_user_latency(&mut self, user_id: &UserId, latency_ms: f64) {
        self.user_latencies.insert(user_id.clone(), latency_ms);
    }

    /// Get the compensation delay for a user
    pub fn get_compensation_delay(&self, user_id: &UserId) -> f64 {
        if let Some(&latency) = self.user_latencies.get(user_id) {
            (latency * 0.5).min(self.max_compensation_ms)
        } else {
            0.0
        }
    }
}

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

impl MultiUserAudioProcessor {
    /// Create a new multi-user audio processor
    pub fn new(config: &MultiUserConfig) -> Result<Self> {
        let mixer_config = MixerConfig {
            max_sources: config.max_sources_per_user * config.max_users_per_room,
            buffer_size: 1024,
            sample_rate: 48000,
            spatial_quality: config.audio_quality,
            optimization_level: OptimizationLevel::Balanced,
        };

        Ok(Self {
            mixer: SpatialAudioMixer::new(mixer_config),
            vad: VoiceActivityDetector::new(),
            effects: AudioEffectsProcessor::new(),
            codec: AudioCodec::new(AudioFormat::Opus),
        })
    }

    /// Process spatial audio for a specific user
    pub fn process_for_user(
        &mut self,
        listener: &MultiUserUser,
        all_users: &HashMap<UserId, MultiUserUser>,
        sources: &Arc<RwLock<HashMap<SourceId, MultiUserAudioSource>>>,
    ) -> Result<Vec<f32>> {
        // Set listener position for spatial processing
        self.mixer
            .set_listener_position(&listener.id, listener.position);

        // Process all audible sources for this listener
        let sources_guard = sources.read().map_err(|e| {
            Error::LegacyProcessing(format!("Failed to acquire read lock on sources: {}", e))
        })?;
        let mut mixed_audio = vec![0.0f32; 1024]; // Buffer size

        for (source_id, source) in sources_guard.iter() {
            // Check if this source is audible to the listener
            if self.is_source_audible(listener, source)? {
                // Calculate spatial audio for this source
                let spatial_audio = self.mixer.process_source(source, listener.position)?;

                // Mix into output buffer
                for (i, sample) in spatial_audio.iter().enumerate() {
                    if i < mixed_audio.len() {
                        mixed_audio[i] += sample;
                    }
                }
            }
        }

        // Apply listener-specific effects
        self.effects
            .process_user_effects(&listener.id, &mut mixed_audio)?;

        Ok(mixed_audio)
    }

    /// Check if an audio source is audible to a listener
    fn is_source_audible(
        &self,
        listener: &MultiUserUser,
        source: &MultiUserAudioSource,
    ) -> Result<bool> {
        // Check distance
        let distance = listener.position.distance_to(&source.position);
        if distance > source.spatial_properties.max_distance {
            return Ok(false);
        }

        // Check access control
        match source.access_control.visibility {
            SourceVisibility::Public => Ok(true),
            SourceVisibility::Private => Ok(source.owner_id == listener.id),
            SourceVisibility::Whitelist => {
                Ok(source.access_control.allowed_users.contains(&listener.id))
            }
            SourceVisibility::Friends => {
                // Check if listener is friends with the source owner
                Ok(listener.friends.contains(&source.owner_id) || source.owner_id == listener.id)
            }
            SourceVisibility::Moderators => Ok(matches!(
                listener.role,
                UserRole::Moderator | UserRole::Administrator
            )),
        }
    }
}

impl SpatialAudioMixer {
    /// Create a new spatial audio mixer
    pub fn new(config: MixerConfig) -> Self {
        Self {
            listener_positions: HashMap::new(),
            source_manager: Arc::new(RwLock::new(HashMap::new())),
            mixer_config: config,
        }
    }

    /// Set the position of a listener for spatial audio processing
    pub fn set_listener_position(&mut self, user_id: &UserId, position: Position3D) {
        self.listener_positions.insert(user_id.clone(), position);
    }

    /// Process an audio source for spatial audio rendering
    pub fn process_source(
        &self,
        source: &MultiUserAudioSource,
        listener_position: Position3D,
    ) -> Result<Vec<f32>> {
        // Calculate spatial parameters
        let distance = listener_position.distance_to(&source.position);
        let attenuation = self.calculate_distance_attenuation(distance, &source.spatial_properties);

        // Generate dummy spatial audio (in real implementation, this would be proper HRTF processing)
        let buffer_size = self.mixer_config.buffer_size;
        let mut output = vec![0.0f32; buffer_size];

        // Simple distance-based attenuation
        let volume = source.volume * attenuation;
        for sample in output.iter_mut() {
            *sample = volume * 0.1; // Dummy audio signal
        }

        Ok(output)
    }

    /// Calculate volume attenuation based on distance
    fn calculate_distance_attenuation(&self, distance: f32, properties: &SpatialProperties) -> f32 {
        if distance <= properties.reference_distance {
            return 1.0;
        }

        let ratio = properties.reference_distance / distance;
        ratio.powf(properties.rolloff_factor).min(1.0)
    }
}

impl VoiceActivityDetector {
    /// Create a new voice activity detector
    pub fn new() -> Self {
        Self {
            algorithm: VadAlgorithm::Energy,
            user_states: HashMap::new(),
            thresholds: VadThresholds {
                energy_threshold: 0.01,
                min_speaking_duration_ms: 100,
                min_silence_duration_ms: 200,
                confidence_threshold: 0.7,
            },
        }
    }

    /// Process audio buffer to detect voice activity
    pub fn process_user_audio(&mut self, user_id: &UserId, audio_buffer: &[f32]) -> bool {
        // Calculate energy level
        let energy = audio_buffer.iter().map(|&x| x * x).sum::<f32>() / audio_buffer.len() as f32;

        // Get or create user state
        let state = self
            .user_states
            .entry(user_id.clone())
            .or_insert_with(|| VadState {
                is_speaking: false,
                confidence: 0.0,
                energy_history: VecDeque::new(),
                speaking_duration: Duration::new(0, 0),
                silence_duration: Duration::new(0, 0),
            });

        // Update energy history
        state.energy_history.push_back(energy);
        if state.energy_history.len() > 10 {
            state.energy_history.pop_front();
        }

        // Simple energy-based detection
        state.is_speaking = energy > self.thresholds.energy_threshold;
        state.confidence = if state.is_speaking { 0.9 } else { 0.1 };

        state.is_speaking
    }
}

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

impl AudioEffectsProcessor {
    /// Create a new audio effects processor
    pub fn new() -> Self {
        Self {
            effects: HashMap::new(),
            user_effects: HashMap::new(),
            zone_effects: HashMap::new(),
        }
    }

    /// Apply user-specific audio effects to an audio buffer
    pub fn process_user_effects(
        &mut self,
        user_id: &UserId,
        audio_buffer: &mut [f32],
    ) -> Result<()> {
        // Apply user-specific effects
        if let Some(effect_chain) = self.user_effects.get(user_id) {
            let mut temp_buffer = audio_buffer.to_vec();
            for effect_name in effect_chain {
                if let Some(effect) = self.effects.get_mut(effect_name) {
                    effect.process(&temp_buffer, audio_buffer)?;
                    temp_buffer.copy_from_slice(audio_buffer);
                }
            }
        }
        Ok(())
    }
}

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

impl AudioCodec {
    /// Create a new audio codec with the specified format
    pub fn new(format: AudioFormat) -> Self {
        Self {
            format,
            compression: CompressionSettings {
                bitrate_kbps: 64,
                complexity: 5,
                variable_bitrate: true,
                low_latency: true,
            },
            codec_states: HashMap::new(),
        }
    }
}

/// Builder for multi-user configuration
pub struct MultiUserConfigBuilder {
    config: MultiUserConfig,
}

impl MultiUserConfigBuilder {
    /// Create a new multi-user configuration builder
    pub fn new() -> Self {
        Self {
            config: MultiUserConfig::default(),
        }
    }

    /// Set maximum number of users per room
    pub fn max_users(mut self, max_users: usize) -> Self {
        self.config.max_users_per_room = max_users;
        self
    }

    /// Set audio quality level (0.0-1.0)
    pub fn audio_quality(mut self, quality: f32) -> Self {
        self.config.audio_quality = quality.clamp(0.0, 1.0);
        self
    }

    /// Set maximum latency in milliseconds
    pub fn max_latency_ms(mut self, latency: f64) -> Self {
        self.config.max_latency_ms = latency;
        self
    }

    /// Enable or disable encryption
    pub fn enable_encryption(mut self, enabled: bool) -> Self {
        self.config.privacy_settings.encryption_enabled = enabled;
        self
    }

    /// Set bandwidth limit in kbps
    pub fn bandwidth_limit_kbps(mut self, limit: u32) -> Self {
        self.config.bandwidth_settings.max_bandwidth_kbps = limit;
        self
    }

    /// Build the configuration
    pub fn build(self) -> MultiUserConfig {
        self.config
    }
}

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