quantrs2-device 0.1.3

//! Quantum Application Layer Protocols
//!
//! This module provides high-level application protocols for quantum internet,
//! including quantum computing services, quantum sensing networks, and
//! distributed quantum applications.

use super::*;

/// Quantum application layer
pub struct QuantumApplicationLayer {
    config: QuantumApplicationConfig,
    application_registry: Arc<RwLock<ApplicationRegistry>>,
    service_manager: Arc<RwLock<QuantumServiceManager>>,
    protocol_handlers: HashMap<String, Box<dyn QuantumApplicationProtocol + Send + Sync>>,
    active_sessions: Arc<RwLock<HashMap<String, ApplicationSession>>>,
    resource_manager: Arc<RwLock<QuantumResourceManager>>,
}

/// Quantum application configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QuantumApplicationConfig {
    pub supported_applications: Vec<ApplicationType>,
    pub service_discovery: ServiceDiscoveryConfig,
    pub resource_management: ResourceManagementConfig,
    pub session_management: SessionManagementConfig,
    pub quality_of_service: QoSConfig,
    pub federation: FederationConfig,
}

/// Application types
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum ApplicationType {
    QuantumComputing,
    QuantumSensing,
    QuantumCommunication,
    QuantumSimulation,
    QuantumCryptography,
    QuantumMetrology,
    QuantumNetworking,
    DistributedQuantumAlgorithms,
    QuantumMachineLearning,
    Custom(String),
}

/// Service discovery configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ServiceDiscoveryConfig {
    pub auto_discovery: bool,
    pub discovery_interval: Duration,
    pub service_registry_url: Option<String>,
    pub discovery_protocols: Vec<DiscoveryProtocol>,
    pub caching_enabled: bool,
    pub cache_ttl: Duration,
}

/// Discovery protocols
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum DiscoveryProtocol {
    mDNS,
    DNS_SD,
    QuantumDNS,
    P2P,
    Centralized,
    Federated,
}

/// Resource management configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ResourceManagementConfig {
    pub resource_allocation_strategy: AllocationStrategy,
    pub load_balancing: bool,
    pub auto_scaling: bool,
    pub resource_sharing: bool,
    pub priority_scheduling: bool,
    pub reservation_system: bool,
}

/// Allocation strategies
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum AllocationStrategy {
    FirstFit,
    BestFit,
    WorstFit,
    LoadBased,
    QualityBased,
    CostOptimized,
    HybridStrategy,
}

/// Session management configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SessionManagementConfig {
    pub max_concurrent_sessions: usize,
    pub session_timeout: Duration,
    pub idle_timeout: Duration,
    pub session_persistence: bool,
    pub session_migration: bool,
    pub fault_tolerance: bool,
}

/// Quality of Service configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QoSConfig {
    pub enable_qos: bool,
    pub priority_levels: usize,
    pub bandwidth_guarantees: HashMap<String, f64>,
    pub latency_guarantees: HashMap<String, Duration>,
    pub fidelity_guarantees: HashMap<String, f64>,
    pub availability_guarantees: HashMap<String, f64>,
}

/// Federation configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FederationConfig {
    pub enable_federation: bool,
    pub trusted_federations: Vec<String>,
    pub federation_protocols: Vec<FederationProtocol>,
    pub resource_sharing_agreements: Vec<ResourceSharingAgreement>,
    pub security_policies: Vec<FederationSecurityPolicy>,
}

/// Federation protocols
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum FederationProtocol {
    SAML,
    OAuth2,
    OpenIDConnect,
    QuantumFederation,
    Custom(String),
}

/// Resource sharing agreement
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ResourceSharingAgreement {
    pub agreement_id: String,
    pub partner_federation: String,
    pub shared_resources: Vec<String>,
    pub access_policies: Vec<String>,
    pub billing_model: String,
    pub valid_until: SystemTime,
}

/// Federation security policy
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FederationSecurityPolicy {
    pub policy_id: String,
    pub federation: String,
    pub authentication_requirements: Vec<String>,
    pub encryption_requirements: Vec<String>,
    pub audit_requirements: Vec<String>,
}

/// Application registry
#[derive(Debug)]
pub struct ApplicationRegistry {
    applications: HashMap<String, RegisteredApplication>,
    capabilities: HashMap<String, ApplicationCapabilities>,
    service_catalog: ServiceCatalog,
}

/// Registered application
#[derive(Debug, Clone)]
pub struct RegisteredApplication {
    pub app_id: String,
    pub app_type: ApplicationType,
    pub name: String,
    pub version: String,
    pub provider: String,
    pub endpoints: Vec<ApplicationEndpoint>,
    pub capabilities: ApplicationCapabilities,
    pub requirements: ApplicationRequirements,
    pub status: ApplicationStatus,
    pub registration_time: SystemTime,
    pub last_heartbeat: SystemTime,
}

/// Application endpoint
#[derive(Debug, Clone)]
pub struct ApplicationEndpoint {
    pub endpoint_id: String,
    pub protocol: String,
    pub address: String,
    pub port: u16,
    pub path: Option<String>,
    pub quantum_enabled: bool,
    pub security_level: SecurityLevel,
}

/// Application capabilities
#[derive(Debug, Clone)]
pub struct ApplicationCapabilities {
    pub supported_operations: Vec<String>,
    pub quantum_resources: Vec<QuantumResourceCapability>,
    pub performance_characteristics: PerformanceCharacteristics,
    pub scalability: ScalabilityInfo,
    pub interoperability: InteroperabilityInfo,
}

/// Quantum resource capability
#[derive(Debug, Clone)]
pub struct QuantumResourceCapability {
    pub resource_type: String,
    pub capacity: usize,
    pub fidelity_range: (f64, f64),
    pub coherence_time_range: (Duration, Duration),
    pub supported_operations: Vec<String>,
}

/// Performance characteristics
#[derive(Debug, Clone)]
pub struct PerformanceCharacteristics {
    pub throughput: f64,
    pub latency: Duration,
    pub accuracy: f64,
    pub reliability: f64,
    pub availability: f64,
}

/// Scalability information
#[derive(Debug, Clone)]
pub struct ScalabilityInfo {
    pub horizontal_scaling: bool,
    pub vertical_scaling: bool,
    pub max_concurrent_requests: usize,
    pub load_balancing_support: bool,
}

/// Interoperability information
#[derive(Debug, Clone)]
pub struct InteroperabilityInfo {
    pub supported_protocols: Vec<String>,
    pub data_formats: Vec<String>,
    pub api_standards: Vec<String>,
    pub federation_support: bool,
}

/// Application requirements
#[derive(Debug, Clone)]
pub struct ApplicationRequirements {
    pub quantum_requirements: QuantumRequirements,
    pub classical_requirements: ClassicalRequirements,
    pub network_requirements: NetworkRequirements,
    pub security_requirements: SecurityRequirements,
}

/// Classical requirements
#[derive(Debug, Clone)]
pub struct ClassicalRequirements {
    pub cpu_cores: usize,
    pub memory_gb: f64,
    pub storage_gb: f64,
    pub gpu_required: bool,
    pub operating_system: Vec<String>,
}

/// Network requirements
#[derive(Debug, Clone)]
pub struct NetworkRequirements {
    pub bandwidth_mbps: f64,
    pub max_latency: Duration,
    pub reliability: f64,
    pub quantum_channel_required: bool,
    pub encryption_required: bool,
}

/// Security requirements
#[derive(Debug, Clone)]
pub struct SecurityRequirements {
    pub authentication_level: SecurityLevel,
    pub encryption_level: SecurityLevel,
    pub data_classification: String,
    pub compliance_requirements: Vec<String>,
    pub quantum_security_required: bool,
}

/// Application status
#[derive(Debug, Clone, PartialEq)]
pub enum ApplicationStatus {
    Active,
    Inactive,
    Maintenance,
    Degraded,
    Failed,
}

/// Service catalog
#[derive(Debug)]
pub struct ServiceCatalog {
    services: HashMap<String, ServiceEntry>,
    categories: HashMap<String, Vec<String>>,
    featured_services: Vec<String>,
}

/// Service entry
#[derive(Debug, Clone)]
pub struct ServiceEntry {
    pub service_id: String,
    pub name: String,
    pub description: String,
    pub category: String,
    pub provider: String,
    pub version: String,
    pub pricing: PricingModel,
    pub sla: ServiceLevelAgreement,
    pub documentation_url: String,
    pub api_specification: APISpecification,
}

/// Pricing model
#[derive(Debug, Clone)]
pub struct PricingModel {
    pub model_type: PricingType,
    pub base_price: f64,
    pub unit: String,
    pub currency: String,
    pub volume_discounts: Vec<VolumeDiscount>,
}

/// Pricing types
#[derive(Debug, Clone, PartialEq)]
pub enum PricingType {
    Free,
    PayPerUse,
    Subscription,
    Freemium,
    Enterprise,
}

/// Volume discount
#[derive(Debug, Clone)]
pub struct VolumeDiscount {
    pub min_volume: f64,
    pub discount_percentage: f64,
}

/// Service Level Agreement
#[derive(Debug, Clone)]
pub struct ServiceLevelAgreement {
    pub availability: f64,
    pub response_time: Duration,
    pub throughput: f64,
    pub accuracy: f64,
    pub support_level: String,
    pub penalties: Vec<SLAPenalty>,
}

/// SLA penalty
#[derive(Debug, Clone)]
pub struct SLAPenalty {
    pub metric: String,
    pub threshold: f64,
    pub penalty_percentage: f64,
}

/// API specification
#[derive(Debug, Clone)]
pub struct APISpecification {
    pub spec_type: SpecificationType,
    pub version: String,
    pub endpoints: Vec<APIEndpoint>,
    pub authentication: AuthenticationSpec,
    pub rate_limits: RateLimits,
}

/// Specification types
#[derive(Debug, Clone, PartialEq)]
pub enum SpecificationType {
    OpenAPI,
    GraphQL,
    GRpc,
    Custom,
}

/// API endpoint
#[derive(Debug, Clone)]
pub struct APIEndpoint {
    pub path: String,
    pub method: String,
    pub description: String,
    pub parameters: Vec<APIParameter>,
    pub responses: Vec<APIResponse>,
}

/// API parameter
#[derive(Debug, Clone)]
pub struct APIParameter {
    pub name: String,
    pub parameter_type: String,
    pub required: bool,
    pub description: String,
}

/// API response
#[derive(Debug, Clone)]
pub struct APIResponse {
    pub status_code: u16,
    pub description: String,
    pub schema: Option<String>,
}

/// Authentication specification
#[derive(Debug, Clone)]
pub struct AuthenticationSpec {
    pub auth_type: AuthType,
    pub token_endpoint: Option<String>,
    pub scopes: Vec<String>,
}

/// Authentication types
#[derive(Debug, Clone, PartialEq)]
pub enum AuthType {
    None,
    APIKey,
    Bearer,
    OAuth2,
    QuantumAuth,
}

/// Rate limits
#[derive(Debug, Clone)]
pub struct RateLimits {
    pub requests_per_second: usize,
    pub requests_per_minute: usize,
    pub requests_per_hour: usize,
    pub burst_limit: usize,
}

/// Quantum service manager
pub struct QuantumServiceManager {
    services: HashMap<String, QuantumService>,
    load_balancer: ServiceLoadBalancer,
    health_monitor: ServiceHealthMonitor,
}

/// Quantum service
#[derive(Debug, Clone)]
pub struct QuantumService {
    pub service_id: String,
    pub service_type: ApplicationType,
    pub instances: Vec<ServiceInstance>,
    pub configuration: ServiceConfiguration,
    pub health_status: ServiceHealth,
    pub performance_metrics: ServiceMetrics,
}

/// Service instance
#[derive(Debug, Clone)]
pub struct ServiceInstance {
    pub instance_id: String,
    pub endpoint: ApplicationEndpoint,
    pub status: InstanceStatus,
    pub load: f64,
    pub last_heartbeat: SystemTime,
}

/// Instance status
#[derive(Debug, Clone, PartialEq)]
pub enum InstanceStatus {
    Running,
    Starting,
    Stopping,
    Failed,
    Maintenance,
}

/// Service configuration
#[derive(Debug, Clone)]
pub struct ServiceConfiguration {
    pub auto_scaling: AutoScalingConfig,
    pub load_balancing: LoadBalancingConfig,
    pub health_checks: HealthCheckConfig,
    pub resource_limits: ResourceLimits,
}

/// Auto-scaling configuration
#[derive(Debug, Clone)]
pub struct AutoScalingConfig {
    pub enabled: bool,
    pub min_instances: usize,
    pub max_instances: usize,
    pub scale_up_threshold: f64,
    pub scale_down_threshold: f64,
    pub scale_up_cooldown: Duration,
    pub scale_down_cooldown: Duration,
}

/// Load balancing configuration
#[derive(Debug, Clone)]
pub struct LoadBalancingConfig {
    pub algorithm: LoadBalancingAlgorithm,
    pub health_check_enabled: bool,
    pub sticky_sessions: bool,
    pub quantum_aware: bool,
}

/// Load balancing algorithms
#[derive(Debug, Clone, PartialEq)]
pub enum LoadBalancingAlgorithm {
    RoundRobin,
    LeastConnections,
    WeightedRoundRobin,
    QuantumAware,
    FidelityBased,
}

/// Health check configuration
#[derive(Debug, Clone)]
pub struct HealthCheckConfig {
    pub enabled: bool,
    pub interval: Duration,
    pub timeout: Duration,
    pub healthy_threshold: usize,
    pub unhealthy_threshold: usize,
    pub path: String,
}

/// Resource limits
#[derive(Debug, Clone)]
pub struct ResourceLimits {
    pub cpu_limit: f64,
    pub memory_limit: f64,
    pub quantum_resource_limit: usize,
    pub network_bandwidth_limit: f64,
}

/// Service health
#[derive(Debug, Clone)]
pub struct ServiceHealth {
    pub overall_status: ServiceHealthStatus,
    pub healthy_instances: usize,
    pub total_instances: usize,
    pub last_check: SystemTime,
    pub issues: Vec<HealthIssue>,
}

/// Health issues
#[derive(Debug, Clone)]
pub struct HealthIssue {
    pub issue_type: IssueType,
    pub severity: IssueSeverity,
    pub description: String,
    pub first_detected: SystemTime,
    pub resolved: bool,
}

/// Issue types
#[derive(Debug, Clone, PartialEq)]
pub enum IssueType {
    HighLatency,
    LowThroughput,
    HighErrorRate,
    ResourceExhaustion,
    QuantumDecoherence,
    NetworkConnectivity,
}

/// Issue severity
#[derive(Debug, Clone, PartialEq)]
pub enum IssueSeverity {
    Low,
    Medium,
    High,
    Critical,
}

/// Service metrics
#[derive(Debug, Clone)]
pub struct ServiceMetrics {
    pub request_count: u64,
    pub error_count: u64,
    pub average_response_time: Duration,
    pub throughput: f64,
    pub quantum_fidelity: f64,
    pub resource_utilization: ResourceUtilization,
    pub last_updated: SystemTime,
}

/// Resource utilization
#[derive(Debug, Clone)]
pub struct ResourceUtilization {
    pub cpu_usage: f64,
    pub memory_usage: f64,
    pub quantum_resource_usage: f64,
    pub network_usage: f64,
}

/// Service load balancer
#[derive(Debug)]
pub struct ServiceLoadBalancer {
    algorithm: LoadBalancingAlgorithm,
    instance_weights: HashMap<String, f64>,
    health_states: HashMap<String, bool>,
}

/// Service health monitor
#[derive(Debug)]
pub struct ServiceHealthMonitor {
    check_interval: Duration,
    health_checks: HashMap<String, HealthCheckConfig>,
    health_history: HashMap<String, Vec<HealthCheckResult>>,
}

/// Health check result
#[derive(Debug, Clone)]
pub struct HealthCheckResult {
    pub timestamp: SystemTime,
    pub healthy: bool,
    pub response_time: Duration,
    pub error_message: Option<String>,
}

/// Application session
#[derive(Debug, Clone)]
pub struct ApplicationSession {
    pub session_id: String,
    pub application_id: String,
    pub user_id: String,
    pub session_type: SessionType,
    pub quantum_context: Option<QuantumSessionContext>,
    pub created_at: SystemTime,
    pub expires_at: SystemTime,
    pub last_activity: SystemTime,
    pub session_data: HashMap<String, String>,
}

/// Session types
#[derive(Debug, Clone, PartialEq)]
pub enum SessionType {
    Interactive,
    Batch,
    Streaming,
    Persistent,
    Federated,
}

/// Quantum session context
#[derive(Debug, Clone)]
pub struct QuantumSessionContext {
    pub allocated_qubits: usize,
    pub entanglement_resources: Vec<String>,
    pub quantum_memory: usize,
    pub coherence_budget: Duration,
    pub fidelity_requirements: f64,
}

/// Quantum resource manager
pub struct QuantumResourceManager {
    resources: HashMap<String, QuantumResource>,
    allocations: HashMap<String, ResourceAllocation>,
    reservation_queue: Vec<ResourceReservation>,
    optimization_engine: ResourceOptimizationEngine,
}

/// Quantum resource
#[derive(Debug, Clone)]
pub struct QuantumResource {
    pub resource_id: String,
    pub resource_type: QuantumResourceType,
    pub capacity: ResourceCapacity,
    pub current_usage: ResourceUsage,
    pub performance: ResourcePerformance,
    pub availability: ResourceAvailability,
    pub location: String,
    pub cost_model: ResourceCostModel,
}

/// Resource capacity
#[derive(Debug, Clone)]
pub struct ResourceCapacity {
    pub total_qubits: usize,
    pub quantum_volume: f64,
    pub gate_speed: f64,
    pub coherence_time: Duration,
    pub fidelity: f64,
    pub connectivity: ConnectivityGraph,
}

/// Connectivity graph
#[derive(Debug, Clone)]
pub struct ConnectivityGraph {
    pub topology_type: TopologyType,
    pub edges: Vec<(usize, usize)>,
    pub coupling_strengths: HashMap<(usize, usize), f64>,
}

/// Topology types
#[derive(Debug, Clone, PartialEq)]
pub enum TopologyType {
    Linear,
    Grid,
    AllToAll,
    Random,
    Custom,
}

/// Resource usage
#[derive(Debug, Clone)]
pub struct ResourceUsage {
    pub allocated_qubits: usize,
    pub active_operations: usize,
    pub utilization_percentage: f64,
    pub queue_length: usize,
}

/// Resource performance
#[derive(Debug, Clone)]
pub struct ResourcePerformance {
    pub current_fidelity: f64,
    pub gate_error_rate: f64,
    pub readout_error_rate: f64,
    pub crosstalk_level: f64,
    pub thermal_state: f64,
}

/// Resource cost model
#[derive(Debug, Clone)]
pub struct ResourceCostModel {
    pub pricing_type: PricingType,
    pub cost_per_shot: f64,
    pub cost_per_hour: f64,
    pub setup_cost: f64,
    pub currency: String,
}

/// Resource allocation
#[derive(Debug, Clone)]
pub struct ResourceAllocation {
    pub allocation_id: String,
    pub session_id: String,
    pub resource_id: String,
    pub allocated_qubits: Vec<usize>,
    pub start_time: SystemTime,
    pub duration: Duration,
    pub priority: AllocationPriority,
    pub status: AllocationStatus,
}

/// Allocation priority
#[derive(Debug, Clone, PartialEq, PartialOrd)]
pub enum AllocationPriority {
    Low,
    Normal,
    High,
    Critical,
}

/// Allocation status
#[derive(Debug, Clone, PartialEq)]
pub enum AllocationStatus {
    Pending,
    Active,
    Completed,
    Cancelled,
    Failed,
}

/// Resource reservation
#[derive(Debug, Clone)]
pub struct ResourceReservation {
    pub reservation_id: String,
    pub user_id: String,
    pub resource_requirements: ResourceRequirements,
    pub preferred_time: SystemTime,
    pub flexibility: Duration,
    pub priority: AllocationPriority,
    pub created_at: SystemTime,
}

/// Resource requirements
#[derive(Debug, Clone)]
pub struct ResourceRequirements {
    pub min_qubits: usize,
    pub preferred_qubits: usize,
    pub min_fidelity: f64,
    pub min_coherence_time: Duration,
    pub topology_requirements: Option<TopologyRequirement>,
    pub duration: Duration,
}

/// Topology requirement
#[derive(Debug, Clone)]
pub struct TopologyRequirement {
    pub required_connectivity: Vec<(usize, usize)>,
    pub min_coupling_strength: f64,
    pub topology_type: Option<TopologyType>,
}

/// Resource optimization engine
#[derive(Debug)]
pub struct ResourceOptimizationEngine {
    optimization_algorithms: Vec<OptimizationAlgorithm>,
    objectives: Vec<OptimizationObjective>,
    constraints: Vec<OptimizationConstraint>,
}

/// Optimization algorithms
#[derive(Debug, Clone, PartialEq)]
pub enum OptimizationAlgorithm {
    GreedyAllocation,
    GeneticAlgorithm,
    SimulatedAnnealing,
    QuantumAnnealing,
    MachineLearning,
}

/// Optimization objectives
#[derive(Debug, Clone, PartialEq)]
pub enum OptimizationObjective {
    MaximizeUtilization,
    MinimizeCost,
    MaximizeFidelity,
    MinimizeWaitTime,
    BalancedOptimization,
}

/// Optimization constraints
#[derive(Debug, Clone)]
pub struct OptimizationConstraint {
    pub constraint_type: ConstraintType,
    pub threshold: f64,
    pub hard_constraint: bool,
}

/// Quantum application protocol trait
#[async_trait::async_trait]
pub trait QuantumApplicationProtocol {
    async fn handle_request(&self, request: ApplicationRequest) -> DeviceResult<ApplicationResponse>;
    async fn initialize_session(&self, session_config: SessionConfig) -> DeviceResult<String>;
    async fn cleanup_session(&self, session_id: &str) -> DeviceResult<()>;
    fn get_protocol_name(&self) -> String;
    fn get_supported_operations(&self) -> Vec<String>;
}

/// Application request
#[derive(Debug, Clone)]
pub struct ApplicationRequest {
    pub request_id: String,
    pub session_id: Option<String>,
    pub operation: String,
    pub parameters: HashMap<String, serde_json::Value>,
    pub quantum_requirements: Option<QuantumRequirements>,
    pub priority: RequestPriority,
    pub deadline: Option<SystemTime>,
}

/// Request priority
#[derive(Debug, Clone, PartialEq, PartialOrd)]
pub enum RequestPriority {
    Low,
    Normal,
    High,
    Urgent,
}

/// Application response
#[derive(Debug, Clone)]
pub struct ApplicationResponse {
    pub request_id: String,
    pub status: ResponseStatus,
    pub result: Option<serde_json::Value>,
    pub error_message: Option<String>,
    pub execution_time: Duration,
    pub resource_usage: Option<ResourceUsageReport>,
}

/// Response status
#[derive(Debug, Clone, PartialEq)]
pub enum ResponseStatus {
    Success,
    Error,
    Timeout,
    ResourceUnavailable,
    QuantumError,
}

/// Resource usage report
#[derive(Debug, Clone)]
pub struct ResourceUsageReport {
    pub qubits_used: usize,
    pub gates_executed: usize,
    pub shots_performed: usize,
    pub execution_time: Duration,
    pub fidelity_achieved: f64,
    pub cost_incurred: f64,
}

/// Session configuration
#[derive(Debug, Clone)]
pub struct SessionConfig {
    pub session_type: SessionType,
    pub user_id: String,
    pub application_id: String,
    pub quantum_requirements: Option<QuantumRequirements>,
    pub timeout: Duration,
    pub persistence_enabled: bool,
}

impl QuantumApplicationLayer {
    /// Create a new quantum application layer
    pub async fn new(config: &QuantumApplicationConfig) -> DeviceResult<Self> {
        let application_registry = Arc::new(RwLock::new(ApplicationRegistry::new()));
        let service_manager = Arc::new(RwLock::new(QuantumServiceManager::new()));
        let active_sessions = Arc::new(RwLock::new(HashMap::new()));
        let resource_manager = Arc::new(RwLock::new(QuantumResourceManager::new()));

        Ok(Self {
            config: config.clone(),
            application_registry,
            service_manager,
            protocol_handlers: HashMap::new(),
            active_sessions,
            resource_manager,
        })
    }

    /// Initialize the application layer
    pub async fn initialize(&mut self) -> DeviceResult<()> {
        // Initialize application registry and services
        Ok(())
    }

    /// Process outgoing data
    pub async fn process_outgoing_data(&self, data: QuantumData) -> DeviceResult<QuantumData> {
        // Add application-layer metadata
        let mut processed_data = data;
        processed_data.metadata.insert("layer".to_string(), "application".to_string());
        processed_data.metadata.insert("timestamp".to_string(),
            SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)
                .unwrap_or(Duration::from_secs(0)).as_secs().to_string());

        Ok(processed_data)
    }

    /// Process incoming data
    pub async fn process_incoming_data(&self, data: QuantumData) -> DeviceResult<QuantumData> {
        // Process application-layer data
        let mut processed_data = data;
        processed_data.metadata.insert("processed_by".to_string(), "quantum_application_layer".to_string());

        Ok(processed_data)
    }

    /// Register a new application
    pub async fn register_application(&self, app: RegisteredApplication) -> DeviceResult<()> {
        let mut registry = self.application_registry.write().await;
        registry.applications.insert(app.app_id.clone(), app);
        Ok(())
    }

    /// Discover available services
    pub async fn discover_services(&self, service_type: ApplicationType) -> DeviceResult<Vec<ServiceEntry>> {
        let registry = self.application_registry.read().await;
        let mut matching_services = Vec::new();

        for service in registry.service_catalog.services.values() {
            // Match service type (simplified logic)
            if service.category.contains(&format!("{:?}", service_type)) {
                matching_services.push(service.clone());
            }
        }

        Ok(matching_services)
    }

    /// Create application session
    pub async fn create_session(&self, config: SessionConfig) -> DeviceResult<String> {
        let session_id = Uuid::new_v4().to_string();

        let session = ApplicationSession {
            session_id: session_id.clone(),
            application_id: config.application_id,
            user_id: config.user_id,
            session_type: config.session_type,
            quantum_context: config.quantum_requirements.map(|req| QuantumSessionContext {
                allocated_qubits: 0,
                entanglement_resources: vec![],
                quantum_memory: 0,
                coherence_budget: req.min_coherence_time,
                fidelity_requirements: req.min_fidelity,
            }),
            created_at: SystemTime::now(),
            expires_at: SystemTime::now() + config.timeout,
            last_activity: SystemTime::now(),
            session_data: HashMap::new(),
        };

        self.active_sessions.write().await.insert(session_id.clone(), session);
        Ok(session_id)
    }

    /// Allocate quantum resources
    pub async fn allocate_resources(&self, session_id: &str, requirements: ResourceRequirements) -> DeviceResult<ResourceAllocation> {
        let resource_manager = self.resource_manager.read().await;

        // Find suitable resource
        for (resource_id, resource) in &resource_manager.resources {
            if resource.capacity.total_qubits >= requirements.min_qubits &&
               resource.capacity.fidelity >= requirements.min_fidelity &&
               resource.capacity.coherence_time >= requirements.min_coherence_time {

                let allocation = ResourceAllocation {
                    allocation_id: Uuid::new_v4().to_string(),
                    session_id: session_id.to_string(),
                    resource_id: resource_id.clone(),
                    allocated_qubits: (0..requirements.min_qubits).collect(),
                    start_time: SystemTime::now(),
                    duration: requirements.duration,
                    priority: AllocationPriority::Normal,
                    status: AllocationStatus::Active,
                };

                return Ok(allocation);
            }
        }

        Err(DeviceError::ResourceUnavailable("No suitable quantum resource available".to_string()))
    }

    /// Execute quantum operation
    pub async fn execute_operation(&self, session_id: &str, operation: &str, parameters: HashMap<String, serde_json::Value>) -> DeviceResult<ApplicationResponse> {
        let request = ApplicationRequest {
            request_id: Uuid::new_v4().to_string(),
            session_id: Some(session_id.to_string()),
            operation: operation.to_string(),
            parameters,
            quantum_requirements: None,
            priority: RequestPriority::Normal,
            deadline: None,
        };

        // Find appropriate protocol handler
        if let Some(handler) = self.protocol_handlers.get(operation) {
            handler.handle_request(request).await
        } else {
            Ok(ApplicationResponse {
                request_id: request.request_id,
                status: ResponseStatus::Error,
                result: None,
                error_message: Some("Operation not supported".to_string()),
                execution_time: Duration::from_millis(0),
                resource_usage: None,
            })
        }
    }

    /// Cleanup session
    pub async fn cleanup_session(&self, session_id: &str) -> DeviceResult<()> {
        self.active_sessions.write().await.remove(session_id);

        // Cleanup associated resources
        let mut resource_manager = self.resource_manager.write().await;
        resource_manager.allocations.retain(|_, allocation| allocation.session_id != session_id);

        Ok(())
    }

    /// Shutdown application layer
    pub async fn shutdown(&self) -> DeviceResult<()> {
        // Cleanup all sessions and resources
        self.active_sessions.write().await.clear();
        Ok(())
    }
}

// Implementation stubs for managers
impl ApplicationRegistry {
    fn new() -> Self {
        Self {
            applications: HashMap::new(),
            capabilities: HashMap::new(),
            service_catalog: ServiceCatalog {
                services: HashMap::new(),
                categories: HashMap::new(),
                featured_services: vec![],
            },
        }
    }
}

impl QuantumServiceManager {
    fn new() -> Self {
        Self {
            services: HashMap::new(),
            load_balancer: ServiceLoadBalancer {
                algorithm: LoadBalancingAlgorithm::RoundRobin,
                instance_weights: HashMap::new(),
                health_states: HashMap::new(),
            },
            health_monitor: ServiceHealthMonitor {
                check_interval: Duration::from_secs(30),
                health_checks: HashMap::new(),
                health_history: HashMap::new(),
            },
        }
    }
}

impl QuantumResourceManager {
    fn new() -> Self {
        Self {
            resources: HashMap::new(),
            allocations: HashMap::new(),
            reservation_queue: vec![],
            optimization_engine: ResourceOptimizationEngine {
                optimization_algorithms: vec![OptimizationAlgorithm::GreedyAllocation],
                objectives: vec![OptimizationObjective::MaximizeUtilization],
                constraints: vec![],
            },
        }
    }
}

impl Default for QuantumApplicationConfig {
    fn default() -> Self {
        Self {
            supported_applications: vec![
                ApplicationType::QuantumComputing,
                ApplicationType::QuantumCommunication,
                ApplicationType::QuantumSensing,
            ],
            service_discovery: ServiceDiscoveryConfig {
                auto_discovery: true,
                discovery_interval: Duration::from_secs(300),
                service_registry_url: None,
                discovery_protocols: vec![DiscoveryProtocol::QuantumDNS],
                caching_enabled: true,
                cache_ttl: Duration::from_secs(1800),
            },
            resource_management: ResourceManagementConfig {
                resource_allocation_strategy: AllocationStrategy::QualityBased,
                load_balancing: true,
                auto_scaling: true,
                resource_sharing: true,
                priority_scheduling: true,
                reservation_system: true,
            },
            session_management: SessionManagementConfig {
                max_concurrent_sessions: 1000,
                session_timeout: Duration::from_secs(3600),
                idle_timeout: Duration::from_secs(1800),
                session_persistence: true,
                session_migration: true,
                fault_tolerance: true,
            },
            quality_of_service: QoSConfig {
                enable_qos: true,
                priority_levels: 4,
                bandwidth_guarantees: HashMap::new(),
                latency_guarantees: HashMap::new(),
                fidelity_guarantees: HashMap::new(),
                availability_guarantees: HashMap::new(),
            },
            federation: FederationConfig {
                enable_federation: false,
                trusted_federations: vec![],
                federation_protocols: vec![FederationProtocol::QuantumFederation],
                resource_sharing_agreements: vec![],
                security_policies: vec![],
            },
        }
    }
}