quantrs2-tytan 0.1.3

//! Fault detection types for Real-time Quantum Computing Integration
//!
//! This module provides fault detection and recovery types.

use serde::{Deserialize, Serialize};
use std::collections::{HashMap, VecDeque};
use std::time::{Duration, SystemTime};

use super::config::RealtimeConfig;
use super::state::SystemState;
use super::types::{FaultDetectionMethod, FaultType, IssueSeverity, RecoveryStepType};

/// Automated fault detection and recovery system
pub struct FaultDetectionSystem {
    /// Fault detectors
    pub(crate) fault_detectors: Vec<FaultDetector>,
    /// Recovery procedures
    pub(crate) recovery_procedures: HashMap<FaultType, RecoveryProcedure>,
    /// Fault history
    pub(crate) fault_history: VecDeque<FaultEvent>,
    /// Recovery statistics
    pub(crate) recovery_stats: RecoveryStatistics,
}

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

impl FaultDetectionSystem {
    pub fn new() -> Self {
        Self {
            fault_detectors: vec![],
            recovery_procedures: HashMap::new(),
            fault_history: VecDeque::new(),
            recovery_stats: RecoveryStatistics::default(),
        }
    }

    pub fn check_for_faults(
        &mut self,
        system_state: &SystemState,
        config: &RealtimeConfig,
    ) -> Result<(), String> {
        // Check for various fault conditions
        self.check_performance_degradation(system_state, config)?;
        self.check_resource_exhaustion(system_state, config)?;
        self.check_hardware_issues(system_state, config)?;
        Ok(())
    }

    fn check_performance_degradation(
        &mut self,
        system_state: &SystemState,
        _config: &RealtimeConfig,
    ) -> Result<(), String> {
        if system_state.performance_summary.performance_score < 0.5 {
            self.detect_fault(
                FaultType::PerformanceDegradation,
                IssueSeverity::High,
                "Performance score below threshold".to_string(),
            )?;
        }
        Ok(())
    }

    fn check_resource_exhaustion(
        &mut self,
        system_state: &SystemState,
        config: &RealtimeConfig,
    ) -> Result<(), String> {
        if system_state.resource_utilization.cpu_utilization > config.alert_thresholds.cpu_threshold
        {
            self.detect_fault(
                FaultType::PerformanceDegradation,
                IssueSeverity::Medium,
                "High CPU utilization".to_string(),
            )?;
        }
        Ok(())
    }

    const fn check_hardware_issues(
        &self,
        _system_state: &SystemState,
        _config: &RealtimeConfig,
    ) -> Result<(), String> {
        // Check for hardware-related issues
        Ok(())
    }

    fn detect_fault(
        &mut self,
        fault_type: FaultType,
        severity: IssueSeverity,
        description: String,
    ) -> Result<(), String> {
        let fault_event = FaultEvent {
            timestamp: SystemTime::now(),
            fault_type: fault_type.clone(),
            severity,
            affected_components: vec!["system".to_string()],
            detection_method: "threshold_based".to_string(),
            description,
            recovery_action: None,
            recovery_success: None,
        };

        self.fault_history.push_back(fault_event);
        if self.fault_history.len() > 10000 {
            self.fault_history.pop_front();
        }

        // Attempt automatic recovery if enabled
        self.attempt_recovery(&fault_type)?;

        Ok(())
    }

    fn attempt_recovery(&mut self, fault_type: &FaultType) -> Result<(), String> {
        if let Some(_procedure) = self.recovery_procedures.get(fault_type) {
            // Execute recovery procedure
            println!("Executing recovery procedure for fault: {fault_type:?}");
            // Implementation would execute actual recovery steps
            self.recovery_stats.successful_recoveries += 1;
        }
        Ok(())
    }
}

/// Fault detector
#[derive(Debug, Clone)]
pub struct FaultDetector {
    /// Detector name
    pub name: String,
    /// Detection method
    pub detection_method: FaultDetectionMethod,
    /// Monitoring targets
    pub targets: Vec<String>,
    /// Detection threshold
    pub threshold: f64,
    /// Check interval
    pub check_interval: Duration,
}

/// Fault event
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FaultEvent {
    /// Event timestamp
    pub timestamp: SystemTime,
    /// Fault type
    pub fault_type: FaultType,
    /// Severity
    pub severity: IssueSeverity,
    /// Affected components
    pub affected_components: Vec<String>,
    /// Detection method
    pub detection_method: String,
    /// Fault description
    pub description: String,
    /// Recovery action taken
    pub recovery_action: Option<String>,
    /// Recovery success
    pub recovery_success: Option<bool>,
}

/// Recovery procedure
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RecoveryProcedure {
    /// Procedure name
    pub name: String,
    /// Recovery steps
    pub steps: Vec<RecoveryStep>,
    /// Success criteria
    pub success_criteria: Vec<SuccessCriterion>,
    /// Rollback procedure
    pub rollback_procedure: Option<Vec<RecoveryStep>>,
    /// Maximum attempts
    pub max_attempts: usize,
}

/// Recovery step
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RecoveryStep {
    /// Step name
    pub name: String,
    /// Step type
    pub step_type: RecoveryStepType,
    /// Parameters
    pub parameters: HashMap<String, String>,
    /// Timeout
    pub timeout: Duration,
    /// Retry on failure
    pub retry_on_failure: bool,
}

/// Success criterion for recovery
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SuccessCriterion {
    /// Metric to check
    pub metric: String,
    /// Expected value or range
    pub expected_value: ExpectedValue,
    /// Check timeout
    pub timeout: Duration,
}

/// Expected value types
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ExpectedValue {
    Exact(f64),
    Range(f64, f64),
    LessThan(f64),
    GreaterThan(f64),
    Boolean(bool),
}

/// Recovery statistics
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RecoveryStatistics {
    /// Total faults detected
    pub total_faults: usize,
    /// Successful recoveries
    pub successful_recoveries: usize,
    /// Failed recoveries
    pub failed_recoveries: usize,
    /// Average recovery time
    pub average_recovery_time: Duration,
    /// Recovery success rate by fault type
    pub success_rate_by_type: HashMap<FaultType, f64>,
}

impl Default for RecoveryStatistics {
    fn default() -> Self {
        Self {
            total_faults: 0,
            successful_recoveries: 0,
            failed_recoveries: 0,
            average_recovery_time: Duration::ZERO,
            success_rate_by_type: HashMap::new(),
        }
    }
}