quantrs2-device 0.1.3

//! Provider Migration Tools
//!
//! This module provides tools for migrating quantum workloads between different
//! cloud providers with minimal disruption and optimized cost/performance.

use super::{CloudProvider, ExecutionConfig, WorkloadSpec};
use crate::{DeviceError, DeviceResult};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::time::Duration;

/// Migration engine for cross-provider workload migration
pub struct ProviderMigrationEngine {
    config: MigrationConfig,
    migration_strategies: Vec<Box<dyn MigrationStrategy + Send + Sync>>,
    compatibility_checker: CompatibilityChecker,
    cost_analyzer: MigrationCostAnalyzer,
}

/// Migration configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MigrationConfig {
    pub enabled: bool,
    pub migration_type: MigrationType,
    pub rollback_enabled: bool,
    pub validation_required: bool,
    pub downtime_tolerance: Duration,
    pub cost_threshold: f64,
}

/// Migration types
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum MigrationType {
    Hot,     // Live migration with no downtime
    Warm,    // Brief downtime during cutover
    Cold,    // Full stop and restart
    Gradual, // Phased migration
}

/// Migration strategy trait
pub trait MigrationStrategy {
    fn migrate(&self, plan: &MigrationPlan) -> DeviceResult<MigrationResult>;
    fn estimate_duration(&self, plan: &MigrationPlan) -> DeviceResult<Duration>;
    fn get_strategy_name(&self) -> String;
}

/// Migration plan
#[derive(Debug, Clone)]
pub struct MigrationPlan {
    pub migration_id: String,
    pub source_provider: CloudProvider,
    pub target_provider: CloudProvider,
    pub workloads: Vec<WorkloadSpec>,
    pub migration_phases: Vec<MigrationPhase>,
    pub rollback_plan: RollbackPlan,
}

/// Migration phase
#[derive(Debug, Clone)]
pub struct MigrationPhase {
    pub phase_id: String,
    pub phase_name: String,
    pub workloads: Vec<String>,
    pub estimated_duration: Duration,
    pub dependencies: Vec<String>,
}

/// Migration result
#[derive(Debug, Clone)]
pub struct MigrationResult {
    pub migration_id: String,
    pub success: bool,
    pub migrated_workloads: Vec<String>,
    pub failed_workloads: Vec<String>,
    pub total_duration: Duration,
    pub cost_impact: f64,
}

/// Rollback plan
#[derive(Debug, Clone)]
pub struct RollbackPlan {
    pub rollback_triggers: Vec<String>,
    pub rollback_steps: Vec<String>,
    pub rollback_duration: Duration,
    pub data_backup_required: bool,
}

/// Compatibility checker
pub struct CompatibilityChecker {
    provider_capabilities: HashMap<CloudProvider, ProviderCapabilities>,
    compatibility_matrix: CompatibilityMatrix,
}

/// Provider capabilities
#[derive(Debug, Clone)]
pub struct ProviderCapabilities {
    pub supported_algorithms: Vec<String>,
    pub max_qubits: usize,
    pub gate_set: Vec<String>,
    pub connectivity: ConnectivityType,
    pub api_compatibility: Vec<String>,
}

/// Connectivity types
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ConnectivityType {
    Linear,
    Grid,
    AllToAll,
    Custom(String),
}

/// Compatibility matrix
pub struct CompatibilityMatrix {
    matrix: HashMap<(CloudProvider, CloudProvider), CompatibilityScore>,
}

/// Compatibility score
#[derive(Debug, Clone)]
pub struct CompatibilityScore {
    pub overall_score: f64,
    pub algorithm_compatibility: f64,
    pub hardware_compatibility: f64,
    pub api_compatibility: f64,
    pub blocking_issues: Vec<String>,
}

/// Migration cost analyzer
pub struct MigrationCostAnalyzer {
    cost_models: HashMap<CloudProvider, CostModel>,
}

/// Cost model for migration
#[derive(Debug, Clone)]
pub struct CostModel {
    pub data_transfer_cost: f64,
    pub downtime_cost: f64,
    pub validation_cost: f64,
    pub rollback_cost: f64,
}

impl ProviderMigrationEngine {
    /// Create new migration engine
    pub fn new(config: MigrationConfig) -> DeviceResult<Self> {
        Ok(Self {
            config,
            migration_strategies: Vec::new(),
            compatibility_checker: CompatibilityChecker::new()?,
            cost_analyzer: MigrationCostAnalyzer::new()?,
        })
    }

    /// Plan migration between providers
    pub async fn plan_migration(
        &self,
        source: CloudProvider,
        target: CloudProvider,
        workloads: Vec<WorkloadSpec>,
    ) -> DeviceResult<MigrationPlan> {
        // Check compatibility
        let compatibility = self
            .compatibility_checker
            .check_compatibility(source.clone(), target.clone())?;

        if compatibility.overall_score < 0.7 {
            return Err(DeviceError::InvalidInput(format!(
                "Insufficient compatibility between {source:?} and {target:?}"
            )));
        }

        // Generate migration phases
        let phases = self.generate_migration_phases(&workloads)?;

        Ok(MigrationPlan {
            migration_id: uuid::Uuid::new_v4().to_string(),
            source_provider: source,
            target_provider: target,
            workloads,
            migration_phases: phases,
            rollback_plan: RollbackPlan {
                rollback_triggers: vec!["failure_rate > 0.1".to_string()],
                rollback_steps: vec!["restore_source".to_string()],
                rollback_duration: Duration::from_secs(1800),
                data_backup_required: true,
            },
        })
    }

    /// Execute migration plan
    pub async fn execute_migration(&self, plan: &MigrationPlan) -> DeviceResult<MigrationResult> {
        for strategy in &self.migration_strategies {
            if let Ok(result) = strategy.migrate(plan) {
                return Ok(result);
            }
        }

        Err(DeviceError::ExecutionFailed(
            "No suitable migration strategy found".to_string(),
        ))
    }

    /// Generate migration phases based on workload dependencies
    fn generate_migration_phases(
        &self,
        workloads: &[WorkloadSpec],
    ) -> DeviceResult<Vec<MigrationPhase>> {
        // Simple implementation - migrate in order
        let phases = workloads
            .chunks(5)
            .enumerate()
            .map(|(i, chunk)| MigrationPhase {
                phase_id: format!("phase_{i}"),
                phase_name: format!("Migration Phase {}", i + 1),
                workloads: chunk.iter().map(|w| w.workload_id.clone()).collect(),
                estimated_duration: Duration::from_secs(600),
                dependencies: if i > 0 {
                    vec![format!("phase_{}", i - 1)]
                } else {
                    vec![]
                },
            })
            .collect();

        Ok(phases)
    }
}

impl CompatibilityChecker {
    fn new() -> DeviceResult<Self> {
        Ok(Self {
            provider_capabilities: HashMap::new(),
            compatibility_matrix: CompatibilityMatrix {
                matrix: HashMap::new(),
            },
        })
    }

    fn check_compatibility(
        &self,
        source: CloudProvider,
        target: CloudProvider,
    ) -> DeviceResult<CompatibilityScore> {
        // Simplified compatibility check
        let score = match (source, target) {
            (CloudProvider::IBM, CloudProvider::AWS) => 0.8,
            (CloudProvider::AWS, CloudProvider::Azure) => 0.75,
            (CloudProvider::Azure, CloudProvider::Google) => 0.7,
            _ => 0.6,
        };

        Ok(CompatibilityScore {
            overall_score: score,
            algorithm_compatibility: score,
            hardware_compatibility: score * 0.9,
            api_compatibility: score * 0.8,
            blocking_issues: Vec::new(),
        })
    }
}

impl MigrationCostAnalyzer {
    fn new() -> DeviceResult<Self> {
        Ok(Self {
            cost_models: HashMap::new(),
        })
    }
}

impl Default for MigrationConfig {
    fn default() -> Self {
        Self {
            enabled: true,
            migration_type: MigrationType::Warm,
            rollback_enabled: true,
            validation_required: true,
            downtime_tolerance: Duration::from_secs(300),
            cost_threshold: 1000.0,
        }
    }
}