codex_memory/backup/

disaster_recovery.rs

use super::{BackupConfig, BackupError, BackupMetadata, Result};
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use sqlx::PgPool;
use std::collections::HashMap;
use std::sync::Arc;
use tokio::fs;
use tracing::{debug, error, info, warn};

/// Comprehensive disaster recovery system for database and infrastructure
pub struct DisasterRecoveryManager {
    config: BackupConfig,
    #[allow(dead_code)]
    db_pool: Arc<PgPool>,
    dr_status: Arc<tokio::sync::RwLock<DisasterRecoveryStatus>>,
    runbooks: HashMap<DisasterType, DisasterRunbook>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DisasterRecoveryStatus {
    pub is_in_disaster_mode: bool,
    pub disaster_id: Option<String>,
    pub disaster_type: Option<DisasterType>,
    pub started_at: Option<DateTime<Utc>>,
    pub estimated_completion: Option<DateTime<Utc>>,
    pub current_phase: DisasterRecoveryPhase,
    pub rto_target_minutes: u32,
    pub rpo_target_minutes: u32,
    pub actual_rto_minutes: Option<u32>,
    pub actual_rpo_minutes: Option<u32>,
}

#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Hash)]
pub enum DisasterType {
    DatabaseCorruption,
    HardwareFailure,
    DataCenterOutage,
    CyberAttack,
    HumanError,
    NetworkFailure,
    PowerFailure,
    NaturalDisaster,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum DisasterRecoveryPhase {
    Assessment,
    Planning,
    Execution,
    Validation,
    Cutover,
    Monitoring,
    Completed,
    Failed,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DisasterRunbook {
    pub disaster_type: DisasterType,
    pub steps: Vec<DisasterRecoveryStep>,
    pub estimated_duration_minutes: u32,
    pub required_resources: Vec<String>,
    pub escalation_contacts: Vec<String>,
    pub validation_checks: Vec<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DisasterRecoveryStep {
    pub step_number: u32,
    pub description: String,
    pub estimated_duration_minutes: u32,
    pub automated: bool,
    pub dependencies: Vec<u32>,
    pub validation_criteria: Vec<String>,
    pub rollback_instructions: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DisasterRecoveryPlan {
    pub disaster_id: String,
    pub disaster_type: DisasterType,
    pub detection_time: DateTime<Utc>,
    pub recovery_target_time: DateTime<Utc>,
    pub selected_backup: BackupMetadata,
    pub recovery_steps: Vec<DisasterRecoveryStep>,
    pub estimated_total_duration_minutes: u32,
    pub alternative_plans: Vec<AlternativePlan>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AlternativePlan {
    pub plan_id: String,
    pub description: String,
    pub estimated_duration_minutes: u32,
    pub data_loss_risk: DataLossRisk,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum DataLossRisk {
    None,
    Minimal,
    Moderate,
    High,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DisasterRecoveryTest {
    pub test_id: String,
    pub test_type: DisasterType,
    pub scheduled_time: DateTime<Utc>,
    pub executed_time: Option<DateTime<Utc>>,
    pub duration_minutes: Option<u32>,
    pub success: Option<bool>,
    pub issues_identified: Vec<String>,
    pub improvements_recommended: Vec<String>,
}

impl DisasterRecoveryManager {
    pub fn new(config: BackupConfig, db_pool: Arc<PgPool>) -> Self {
        let dr_status = Arc::new(tokio::sync::RwLock::new(DisasterRecoveryStatus {
            is_in_disaster_mode: false,
            disaster_id: None,
            disaster_type: None,
            started_at: None,
            estimated_completion: None,
            current_phase: DisasterRecoveryPhase::Assessment,
            rto_target_minutes: config.rto_minutes,
            rpo_target_minutes: config.rpo_minutes,
            actual_rto_minutes: None,
            actual_rpo_minutes: None,
        }));

        let runbooks = Self::create_default_runbooks();

        Self {
            config,
            db_pool,
            dr_status,
            runbooks,
        }
    }

    /// Initialize the disaster recovery system
    pub async fn initialize(&self) -> Result<()> {
        info!("Initializing disaster recovery system");

        // Verify DR prerequisites
        self.verify_dr_prerequisites().await?;

        // Create DR workspace
        let dr_workspace = self.config.backup_directory.join("disaster_recovery");
        fs::create_dir_all(&dr_workspace).await?;

        // Initialize communication channels
        self.setup_communication_channels().await?;

        // Schedule regular DR tests
        self.schedule_dr_tests().await?;

        info!("Disaster recovery system initialized");
        Ok(())
    }

    /// Detect and assess a potential disaster
    pub async fn assess_disaster(
        &self,
        disaster_type: DisasterType,
        details: String,
    ) -> Result<DisasterRecoveryPlan> {
        info!("Assessing disaster: {:?} - {}", disaster_type, details);

        let disaster_id = uuid::Uuid::new_v4().to_string();
        let detection_time = Utc::now();

        // Update DR status
        {
            let mut status = self.dr_status.write().await;
            status.is_in_disaster_mode = true;
            status.disaster_id = Some(disaster_id.clone());
            status.disaster_type = Some(disaster_type.clone());
            status.started_at = Some(detection_time);
            status.current_phase = DisasterRecoveryPhase::Assessment;
        }

        // Assess impact and determine recovery strategy
        let _impact_assessment = self.assess_impact(&disaster_type).await?;

        // Select appropriate backup for recovery
        let selected_backup = self.select_recovery_backup(&disaster_type).await?;

        // Get runbook for this disaster type
        let runbook =
            self.runbooks
                .get(&disaster_type)
                .ok_or_else(|| BackupError::RecoveryFailed {
                    message: format!("No runbook available for disaster type: {disaster_type:?}"),
                })?;

        // Calculate recovery target time based on RTO
        let recovery_target_time =
            detection_time + chrono::Duration::minutes(self.config.rto_minutes as i64);

        // Create disaster recovery plan
        let recovery_plan = DisasterRecoveryPlan {
            disaster_id: disaster_id.clone(),
            disaster_type: disaster_type.clone(),
            detection_time,
            recovery_target_time,
            selected_backup,
            recovery_steps: runbook.steps.clone(),
            estimated_total_duration_minutes: runbook.estimated_duration_minutes,
            alternative_plans: self.generate_alternative_plans(&disaster_type).await?,
        };

        // Update estimated completion time
        {
            let mut status = self.dr_status.write().await;
            status.estimated_completion = Some(
                detection_time
                    + chrono::Duration::minutes(
                        recovery_plan.estimated_total_duration_minutes as i64,
                    ),
            );
        }

        info!(
            "Disaster assessment completed: {} (estimated recovery: {} minutes)",
            disaster_id, recovery_plan.estimated_total_duration_minutes
        );

        Ok(recovery_plan)
    }

    /// Execute disaster recovery plan
    pub async fn execute_disaster_recovery(&self, plan: DisasterRecoveryPlan) -> Result<()> {
        info!("Executing disaster recovery plan: {}", plan.disaster_id);

        // Update status
        {
            let mut status = self.dr_status.write().await;
            status.current_phase = DisasterRecoveryPhase::Planning;
        }

        // Send notifications to stakeholders
        self.notify_stakeholders(&plan).await?;

        // Execute recovery steps
        for (index, step) in plan.recovery_steps.iter().enumerate() {
            info!(
                "Executing DR step {}: {}",
                step.step_number, step.description
            );

            // Update progress
            let progress_phase = match index {
                0..=1 => DisasterRecoveryPhase::Planning,
                2..=4 => DisasterRecoveryPhase::Execution,
                5..=6 => DisasterRecoveryPhase::Validation,
                7..=8 => DisasterRecoveryPhase::Cutover,
                _ => DisasterRecoveryPhase::Monitoring,
            };

            {
                let mut status = self.dr_status.write().await;
                status.current_phase = progress_phase;
            }

            // Execute step
            match self.execute_recovery_step(step, &plan).await {
                Ok(_) => {
                    info!("DR step {} completed successfully", step.step_number);
                }
                Err(e) => {
                    error!("DR step {} failed: {}", step.step_number, e);

                    // Attempt rollback if available
                    if let Some(rollback) = &step.rollback_instructions {
                        warn!("Attempting rollback: {}", rollback);
                        // Execute rollback logic here
                    }

                    return Err(e);
                }
            }
        }

        // Final validation
        self.validate_recovery(&plan).await?;

        // Complete recovery
        let completion_time = Utc::now();
        let actual_rto = completion_time
            .signed_duration_since(plan.detection_time)
            .num_minutes() as u32;

        {
            let mut status = self.dr_status.write().await;
            status.current_phase = DisasterRecoveryPhase::Completed;
            status.actual_rto_minutes = Some(actual_rto);
            status.is_in_disaster_mode = false;
        }

        info!(
            "Disaster recovery completed successfully: {} (actual RTO: {} minutes)",
            plan.disaster_id, actual_rto
        );

        // Post-recovery monitoring
        self.start_post_recovery_monitoring().await?;

        Ok(())
    }

    /// Test disaster recovery procedures
    pub async fn test_disaster_recovery(
        &self,
        disaster_type: DisasterType,
    ) -> Result<DisasterRecoveryTest> {
        info!("Testing disaster recovery for: {:?}", disaster_type);

        let test_id = uuid::Uuid::new_v4().to_string();
        let start_time = Utc::now();

        let mut test_result = DisasterRecoveryTest {
            test_id: test_id.clone(),
            test_type: disaster_type.clone(),
            scheduled_time: start_time,
            executed_time: Some(start_time),
            duration_minutes: None,
            success: None,
            issues_identified: Vec::new(),
            improvements_recommended: Vec::new(),
        };

        // Create test disaster scenario
        let test_plan = self
            .assess_disaster(disaster_type, "DR Test Scenario".to_string())
            .await?;

        // Execute test in isolated environment
        match self
            .execute_test_recovery(&test_plan, &mut test_result)
            .await
        {
            Ok(_) => {
                test_result.success = Some(true);
                info!("DR test completed successfully");
            }
            Err(e) => {
                test_result.success = Some(false);
                test_result.issues_identified.push(e.to_string());
                warn!("DR test failed: {}", e);
            }
        }

        let end_time = Utc::now();
        test_result.duration_minutes =
            Some(end_time.signed_duration_since(start_time).num_minutes() as u32);

        // Generate improvement recommendations
        test_result.improvements_recommended =
            self.generate_test_recommendations(&test_result).await;

        // Store test results
        self.store_test_results(&test_result).await?;

        info!(
            "DR test completed: {} (duration: {} minutes)",
            test_id,
            test_result.duration_minutes.unwrap_or(0)
        );

        Ok(test_result)
    }

    /// Get current disaster recovery status
    pub async fn get_dr_status(&self) -> DisasterRecoveryStatus {
        self.dr_status.read().await.clone()
    }

    /// Cancel ongoing disaster recovery
    pub async fn cancel_disaster_recovery(&self) -> Result<()> {
        info!("Cancelling disaster recovery operation");

        {
            let mut status = self.dr_status.write().await;
            if status.is_in_disaster_mode {
                status.current_phase = DisasterRecoveryPhase::Failed;
                status.is_in_disaster_mode = false;
            }
        }

        info!("Disaster recovery cancelled");
        Ok(())
    }

    /// Generate disaster recovery documentation
    pub async fn generate_dr_documentation(&self) -> Result<String> {
        info!("Generating disaster recovery documentation");

        let mut documentation = String::new();
        documentation.push_str("# Disaster Recovery Procedures\n\n");

        for (disaster_type, runbook) in &self.runbooks {
            documentation.push_str(&format!("## {disaster_type:?} Recovery\n\n"));
            documentation.push_str(&format!(
                "**Estimated Duration:** {} minutes\n\n",
                runbook.estimated_duration_minutes
            ));
            documentation.push_str("**Steps:**\n\n");

            for step in &runbook.steps {
                documentation.push_str(&format!(
                    "{}. {} ({}min) {}\n",
                    step.step_number,
                    step.description,
                    step.estimated_duration_minutes,
                    if step.automated {
                        "[AUTOMATED]"
                    } else {
                        "[MANUAL]"
                    }
                ));
            }

            documentation.push_str("\n---\n\n");
        }

        documentation.push_str(&format!(
            "**RTO Target:** {} minutes\n",
            self.config.rto_minutes
        ));
        documentation.push_str(&format!(
            "**RPO Target:** {} minutes\n",
            self.config.rpo_minutes
        ));

        Ok(documentation)
    }

    // Private helper methods

    fn create_default_runbooks() -> HashMap<DisasterType, DisasterRunbook> {
        let mut runbooks = HashMap::new();

        // Database Corruption runbook
        let db_corruption_runbook = DisasterRunbook {
            disaster_type: DisasterType::DatabaseCorruption,
            steps: vec![
                DisasterRecoveryStep {
                    step_number: 1,
                    description: "Assess corruption extent".to_string(),
                    estimated_duration_minutes: 10,
                    automated: true,
                    dependencies: vec![],
                    validation_criteria: vec!["Corruption scope identified".to_string()],
                    rollback_instructions: None,
                },
                DisasterRecoveryStep {
                    step_number: 2,
                    description: "Stop application services".to_string(),
                    estimated_duration_minutes: 5,
                    automated: true,
                    dependencies: vec![1],
                    validation_criteria: vec!["All services stopped".to_string()],
                    rollback_instructions: Some("Restart services".to_string()),
                },
                DisasterRecoveryStep {
                    step_number: 3,
                    description: "Restore from latest backup".to_string(),
                    estimated_duration_minutes: 30,
                    automated: true,
                    dependencies: vec![2],
                    validation_criteria: vec!["Database restored successfully".to_string()],
                    rollback_instructions: None,
                },
                DisasterRecoveryStep {
                    step_number: 4,
                    description: "Apply WAL files for point-in-time recovery".to_string(),
                    estimated_duration_minutes: 15,
                    automated: true,
                    dependencies: vec![3],
                    validation_criteria: vec!["WAL files applied".to_string()],
                    rollback_instructions: None,
                },
                DisasterRecoveryStep {
                    step_number: 5,
                    description: "Validate data integrity".to_string(),
                    estimated_duration_minutes: 10,
                    automated: true,
                    dependencies: vec![4],
                    validation_criteria: vec!["Data integrity verified".to_string()],
                    rollback_instructions: None,
                },
                DisasterRecoveryStep {
                    step_number: 6,
                    description: "Restart application services".to_string(),
                    estimated_duration_minutes: 5,
                    automated: true,
                    dependencies: vec![5],
                    validation_criteria: vec!["Services running normally".to_string()],
                    rollback_instructions: Some("Stop services".to_string()),
                },
            ],
            estimated_duration_minutes: 75,
            required_resources: vec!["Database backup".to_string(), "WAL archives".to_string()],
            escalation_contacts: vec!["dba-team@company.com".to_string()],
            validation_checks: vec![
                "Database is accessible".to_string(),
                "Data integrity verified".to_string(),
                "Application functions normally".to_string(),
            ],
        };

        runbooks.insert(DisasterType::DatabaseCorruption, db_corruption_runbook);

        // Add more runbooks for other disaster types...

        runbooks
    }

    async fn verify_dr_prerequisites(&self) -> Result<()> {
        debug!("Verifying disaster recovery prerequisites");

        // Verify backups are available
        if !self.config.backup_directory.exists() {
            return Err(BackupError::ConfigurationError {
                message: "Backup directory not accessible".to_string(),
            });
        }

        // Verify communication channels
        // This would test notification systems, paging, etc.

        debug!("DR prerequisites verified");
        Ok(())
    }

    async fn setup_communication_channels(&self) -> Result<()> {
        debug!("Setting up disaster recovery communication channels");

        // In production, this would configure:
        // - Email notifications
        // - SMS/paging systems
        // - Slack/Teams integrations
        // - Incident management systems

        debug!("Communication channels configured");
        Ok(())
    }

    async fn schedule_dr_tests(&self) -> Result<()> {
        debug!("Scheduling regular DR tests");

        // In production, this would set up automated DR testing
        // For now, just log the intention
        info!("DR tests should be scheduled monthly");

        Ok(())
    }

    async fn assess_impact(&self, disaster_type: &DisasterType) -> Result<String> {
        debug!("Assessing impact for disaster type: {:?}", disaster_type);

        let impact = match disaster_type {
            DisasterType::DatabaseCorruption => {
                "Data corruption detected, immediate recovery required"
            }
            DisasterType::HardwareFailure => "Hardware failure, failover to backup systems needed",
            DisasterType::DataCenterOutage => "Data center unavailable, activate DR site",
            DisasterType::CyberAttack => "Security breach detected, isolate and recover",
            DisasterType::HumanError => "Human error caused data loss, restore from backup",
            DisasterType::NetworkFailure => "Network connectivity lost, check alternative routes",
            DisasterType::PowerFailure => "Power outage, switch to backup power",
            DisasterType::NaturalDisaster => "Natural disaster, activate remote DR site",
        };

        Ok(impact.to_string())
    }

    async fn select_recovery_backup(
        &self,
        _disaster_type: &DisasterType,
    ) -> Result<BackupMetadata> {
        debug!("Selecting appropriate backup for recovery");

        // This would query the backup metadata to find the best backup
        // For now, return a mock backup
        Ok(BackupMetadata {
            id: "disaster-recovery-backup".to_string(),
            backup_type: super::BackupType::Full,
            status: super::BackupStatus::Completed,
            start_time: Utc::now() - chrono::Duration::hours(2),
            end_time: Some(Utc::now() - chrono::Duration::hours(1)),
            size_bytes: 2 * 1024 * 1024 * 1024,        // 2GB
            compressed_size_bytes: 1024 * 1024 * 1024, // 1GB
            file_path: self
                .config
                .backup_directory
                .join("disaster_recovery_backup.sql"),
            checksum: "disaster_recovery_checksum".to_string(),
            database_name: "codex_memory".to_string(),
            wal_start_lsn: Some("0/3000000".to_string()),
            wal_end_lsn: Some("0/4000000".to_string()),
            encryption_enabled: self.config.enable_encryption,
            replication_status: HashMap::new(),
            verification_status: None,
        })
    }

    async fn generate_alternative_plans(
        &self,
        disaster_type: &DisasterType,
    ) -> Result<Vec<AlternativePlan>> {
        debug!("Generating alternative recovery plans");

        let mut alternatives = Vec::new();

        match disaster_type {
            DisasterType::DatabaseCorruption => {
                alternatives.push(AlternativePlan {
                    plan_id: "quick-restore".to_string(),
                    description: "Quick restore from most recent backup (may lose recent data)"
                        .to_string(),
                    estimated_duration_minutes: 30,
                    data_loss_risk: DataLossRisk::Moderate,
                });

                alternatives.push(AlternativePlan {
                    plan_id: "full-pitr".to_string(),
                    description: "Full point-in-time recovery with WAL replay".to_string(),
                    estimated_duration_minutes: 60,
                    data_loss_risk: DataLossRisk::Minimal,
                });
            }
            _ => {
                // Add alternatives for other disaster types
            }
        }

        Ok(alternatives)
    }

    async fn notify_stakeholders(&self, _plan: &DisasterRecoveryPlan) -> Result<()> {
        debug!("Notifying stakeholders of disaster recovery initiation");

        // In production, this would send notifications to:
        // - Operations team
        // - Management
        // - Customer support
        // - External partners if needed

        info!("Stakeholders notified of disaster recovery initiation");
        Ok(())
    }

    async fn execute_recovery_step(
        &self,
        step: &DisasterRecoveryStep,
        _plan: &DisasterRecoveryPlan,
    ) -> Result<()> {
        debug!("Executing recovery step: {}", step.description);

        if step.automated {
            // Execute automated step
            match step.step_number {
                1 => self.assess_system_state().await?,
                2 => self.stop_services().await?,
                3 => self.restore_database().await?,
                4 => self.apply_wal_files().await?,
                5 => self.validate_data().await?,
                6 => self.start_services().await?,
                _ => {
                    warn!("Unknown automated step: {}", step.step_number);
                }
            }
        } else {
            // Manual step - would require human intervention
            warn!(
                "Manual step required: {} - {}",
                step.step_number, step.description
            );

            // In a real system, this would pause and wait for confirmation
            tokio::time::sleep(tokio::time::Duration::from_secs(5)).await;
        }

        debug!("Recovery step completed: {}", step.description);
        Ok(())
    }

    async fn validate_recovery(&self, _plan: &DisasterRecoveryPlan) -> Result<()> {
        debug!("Validating disaster recovery");

        // Perform validation checks:
        // - Database connectivity
        // - Data integrity
        // - Application functionality
        // - Performance benchmarks

        info!("Disaster recovery validation completed successfully");
        Ok(())
    }

    async fn start_post_recovery_monitoring(&self) -> Result<()> {
        debug!("Starting post-recovery monitoring");

        // In production, this would:
        // - Increase monitoring frequency
        // - Set up additional alerts
        // - Generate recovery report
        // - Schedule lessons learned session

        info!("Post-recovery monitoring initiated");
        Ok(())
    }

    async fn execute_test_recovery(
        &self,
        _plan: &DisasterRecoveryPlan,
        _test_result: &mut DisasterRecoveryTest,
    ) -> Result<()> {
        debug!("Executing test disaster recovery");

        // Execute recovery steps in test mode
        // This would use test databases and isolated environments

        info!("Test disaster recovery executed successfully");
        Ok(())
    }

    async fn generate_test_recommendations(
        &self,
        _test_result: &DisasterRecoveryTest,
    ) -> Vec<String> {
        vec![
            "Consider automating more recovery steps".to_string(),
            "Improve monitoring and alerting".to_string(),
            "Update recovery documentation".to_string(),
        ]
    }

    async fn store_test_results(&self, _test_result: &DisasterRecoveryTest) -> Result<()> {
        debug!("Storing DR test results");
        // This would store test results in a database for historical tracking
        Ok(())
    }

    // Mock implementations for recovery steps
    async fn assess_system_state(&self) -> Result<()> {
        debug!("Assessing system state");
        Ok(())
    }

    async fn stop_services(&self) -> Result<()> {
        debug!("Stopping services");
        Ok(())
    }

    async fn restore_database(&self) -> Result<()> {
        debug!("Restoring database");
        Ok(())
    }

    async fn apply_wal_files(&self) -> Result<()> {
        debug!("Applying WAL files");
        Ok(())
    }

    async fn validate_data(&self) -> Result<()> {
        debug!("Validating data integrity");
        Ok(())
    }

    async fn start_services(&self) -> Result<()> {
        debug!("Starting services");
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_disaster_types() {
        let disaster_types = [
            DisasterType::DatabaseCorruption,
            DisasterType::HardwareFailure,
            DisasterType::DataCenterOutage,
            DisasterType::CyberAttack,
            DisasterType::HumanError,
            DisasterType::NetworkFailure,
            DisasterType::PowerFailure,
            DisasterType::NaturalDisaster,
        ];

        assert_eq!(disaster_types.len(), 8);
    }

    #[test]
    fn test_disaster_recovery_phases() {
        let phases = [
            DisasterRecoveryPhase::Assessment,
            DisasterRecoveryPhase::Planning,
            DisasterRecoveryPhase::Execution,
            DisasterRecoveryPhase::Validation,
            DisasterRecoveryPhase::Cutover,
            DisasterRecoveryPhase::Monitoring,
            DisasterRecoveryPhase::Completed,
            DisasterRecoveryPhase::Failed,
        ];

        assert_eq!(phases.len(), 8);
    }

    #[test]
    fn test_data_loss_risk_levels() {
        let risk_levels = [
            DataLossRisk::None,
            DataLossRisk::Minimal,
            DataLossRisk::Moderate,
            DataLossRisk::High,
        ];

        assert_eq!(risk_levels.len(), 4);
    }
}