codex_memory/backup/

point_in_time_recovery.rs

use super::{BackupConfig, BackupError, BackupMetadata, RecoveryOptions, Result};
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use sqlx::PgPool;
use std::path::{Path, PathBuf};
use std::process::Command;
use std::sync::Arc;
use tokio::fs;
use tracing::{debug, error, info, warn};

/// Point-in-Time Recovery (PITR) manager for database recovery operations
pub struct PointInTimeRecovery {
    config: BackupConfig,
    #[allow(dead_code)]
    db_pool: Arc<PgPool>,
    recovery_status: Arc<tokio::sync::RwLock<RecoveryStatus>>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RecoveryStatus {
    pub is_recovering: bool,
    pub recovery_id: Option<String>,
    pub start_time: Option<DateTime<Utc>>,
    pub progress_percentage: u8,
    pub current_phase: RecoveryPhase,
    pub estimated_completion: Option<DateTime<Utc>>,
    pub error_message: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum RecoveryPhase {
    Initializing,
    RestoringBaseBackup,
    ApplyingWalFiles,
    ValidatingConsistency,
    Finalizing,
    Completed,
    Failed,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RecoveryPlan {
    pub recovery_id: String,
    pub target_time: Option<DateTime<Utc>>,
    pub target_lsn: Option<String>,
    pub base_backup: BackupMetadata,
    pub required_wal_files: Vec<String>,
    pub estimated_duration_minutes: u32,
    pub data_directory: PathBuf,
    pub recovery_conf_path: PathBuf,
}

impl PointInTimeRecovery {
    pub fn new(config: BackupConfig, db_pool: Arc<PgPool>) -> Self {
        let recovery_status = Arc::new(tokio::sync::RwLock::new(RecoveryStatus {
            is_recovering: false,
            recovery_id: None,
            start_time: None,
            progress_percentage: 0,
            current_phase: RecoveryPhase::Initializing,
            estimated_completion: None,
            error_message: None,
        }));

        Self {
            config,
            db_pool,
            recovery_status,
        }
    }

    /// Initialize the PITR system
    pub async fn initialize(&self) -> Result<()> {
        info!("Initializing Point-in-Time Recovery system");

        // Verify recovery prerequisites
        self.verify_recovery_prerequisites().await?;

        info!("PITR system initialized successfully");
        Ok(())
    }

    /// Create a recovery plan for the specified target
    pub async fn create_recovery_plan(
        &self,
        recovery_options: &RecoveryOptions,
        data_directory: PathBuf,
    ) -> Result<RecoveryPlan> {
        info!(
            "Creating recovery plan for target: {:?}",
            recovery_options.target_time
        );

        // Find the appropriate base backup
        let base_backup = self.find_base_backup_for_recovery(recovery_options).await?;

        // Identify required WAL files
        let required_wal_files = self
            .identify_required_wal_files(&base_backup, recovery_options)
            .await?;

        // Estimate recovery duration
        let estimated_duration = self.estimate_recovery_duration(&base_backup, &required_wal_files);

        let recovery_plan = RecoveryPlan {
            recovery_id: uuid::Uuid::new_v4().to_string(),
            target_time: recovery_options.target_time,
            target_lsn: recovery_options.target_lsn.clone(),
            base_backup,
            required_wal_files,
            estimated_duration_minutes: estimated_duration,
            data_directory,
            recovery_conf_path: self.config.backup_directory.join("recovery.conf"),
        };

        info!(
            "Recovery plan created: {} (estimated duration: {} minutes)",
            recovery_plan.recovery_id, recovery_plan.estimated_duration_minutes
        );

        Ok(recovery_plan)
    }

    /// Execute a point-in-time recovery
    pub async fn execute_recovery(&self, recovery_plan: RecoveryPlan) -> Result<()> {
        info!(
            "Starting point-in-time recovery: {}",
            recovery_plan.recovery_id
        );

        // Update recovery status
        {
            let mut status = self.recovery_status.write().await;
            status.is_recovering = true;
            status.recovery_id = Some(recovery_plan.recovery_id.clone());
            status.start_time = Some(Utc::now());
            status.progress_percentage = 0;
            status.current_phase = RecoveryPhase::Initializing;
            status.estimated_completion = Some(
                Utc::now()
                    + chrono::Duration::minutes(recovery_plan.estimated_duration_minutes as i64),
            );
        }

        let result = self.execute_recovery_steps(&recovery_plan).await;

        // Update final status
        {
            let mut status = self.recovery_status.write().await;
            match &result {
                Ok(_) => {
                    status.current_phase = RecoveryPhase::Completed;
                    status.progress_percentage = 100;
                    status.is_recovering = false;
                }
                Err(e) => {
                    status.current_phase = RecoveryPhase::Failed;
                    status.error_message = Some(e.to_string());
                    status.is_recovering = false;
                }
            }
        }

        match result {
            Ok(_) => {
                info!(
                    "Point-in-time recovery completed successfully: {}",
                    recovery_plan.recovery_id
                );
                Ok(())
            }
            Err(e) => {
                error!("Point-in-time recovery failed: {}", e);
                Err(e)
            }
        }
    }

    /// Validate that a recovery is possible to the specified target
    pub async fn validate_recovery_target(
        &self,
        recovery_options: &RecoveryOptions,
    ) -> Result<bool> {
        debug!(
            "Validating recovery target: {:?}",
            recovery_options.target_time
        );

        // Check if we have a base backup that covers the target time
        let base_backup_exists = self
            .find_base_backup_for_recovery(recovery_options)
            .await
            .is_ok();

        if !base_backup_exists {
            warn!("No suitable base backup found for recovery target");
            return Ok(false);
        }

        // Check if required WAL files are available
        let base_backup = self.find_base_backup_for_recovery(recovery_options).await?;
        let wal_files_available = self
            .check_wal_files_availability(&base_backup, recovery_options)
            .await?;

        if !wal_files_available {
            warn!("Required WAL files not available for recovery target");
            return Ok(false);
        }

        info!("Recovery target is valid and achievable");
        Ok(true)
    }

    /// Get current recovery status
    pub async fn get_recovery_status(&self) -> RecoveryStatus {
        self.recovery_status.read().await.clone()
    }

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

        {
            let mut status = self.recovery_status.write().await;
            if status.is_recovering {
                status.current_phase = RecoveryPhase::Failed;
                status.error_message = Some("Recovery cancelled by user".to_string());
                status.is_recovering = false;
            }
        }

        // In a real implementation, this would stop the PostgreSQL recovery process
        // and clean up any temporary files

        info!("Recovery operation cancelled");
        Ok(())
    }

    /// Test recovery procedure without actually performing recovery
    pub async fn test_recovery(
        &self,
        recovery_options: &RecoveryOptions,
    ) -> Result<RecoveryTestResult> {
        info!("Testing recovery procedure");

        let start_time = Utc::now();
        let temp_dir = self.create_temporary_test_directory().await?;

        // Create recovery plan
        let recovery_plan = self
            .create_recovery_plan(recovery_options, temp_dir.clone())
            .await?;

        // Validate all components are available
        let base_backup_valid = self
            .validate_base_backup(&recovery_plan.base_backup)
            .await?;
        let wal_files_valid = self
            .validate_wal_files(&recovery_plan.required_wal_files)
            .await?;

        // Test restoration steps without actually starting PostgreSQL
        let restoration_feasible = self.test_restoration_steps(&recovery_plan).await?;

        // Cleanup test directory
        if temp_dir.exists() {
            fs::remove_dir_all(&temp_dir).await?;
        }

        let test_duration = Utc::now().signed_duration_since(start_time);

        let test_result = RecoveryTestResult {
            test_id: uuid::Uuid::new_v4().to_string(),
            test_time: start_time,
            duration_seconds: test_duration.num_seconds() as u32,
            base_backup_valid,
            wal_files_valid,
            restoration_feasible,
            estimated_recovery_time_minutes: recovery_plan.estimated_duration_minutes,
            issues_found: Vec::new(), // Would be populated with any issues discovered
        };

        info!(
            "Recovery test completed in {} seconds",
            test_result.duration_seconds
        );
        Ok(test_result)
    }

    // Private helper methods

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

        // Check if backup directory exists and is accessible
        if !self.config.backup_directory.exists() {
            return Err(BackupError::ConfigurationError {
                message: "Backup directory does not exist".to_string(),
            });
        }

        // Check if WAL archive directory exists and is accessible
        if !self.config.wal_archive_directory.exists() {
            return Err(BackupError::ConfigurationError {
                message: "WAL archive directory does not exist".to_string(),
            });
        }

        // Verify PostgreSQL tools are available
        self.verify_postgresql_tools().await?;

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

    async fn verify_postgresql_tools(&self) -> Result<()> {
        debug!("Verifying PostgreSQL tools availability");

        // Check pg_restore
        let output = Command::new("pg_restore")
            .arg("--version")
            .output()
            .map_err(|e| BackupError::ConfigurationError {
                message: format!("pg_restore not found: {e}"),
            })?;

        if !output.status.success() {
            return Err(BackupError::ConfigurationError {
                message: "pg_restore is not working properly".to_string(),
            });
        }

        debug!("PostgreSQL tools verified");
        Ok(())
    }

    async fn find_base_backup_for_recovery(
        &self,
        recovery_options: &RecoveryOptions,
    ) -> Result<BackupMetadata> {
        debug!("Finding suitable base backup for recovery");

        // This would query the backup metadata store to find the most recent
        // full backup that was completed before the target recovery time

        // For this implementation, we'll create a mock backup metadata
        let mock_backup = BackupMetadata {
            id: "recovery-base-backup".to_string(),
            backup_type: super::BackupType::Full,
            status: super::BackupStatus::Completed,
            start_time: recovery_options.target_time.unwrap_or_else(Utc::now)
                - chrono::Duration::hours(1),
            end_time: Some(
                recovery_options.target_time.unwrap_or_else(Utc::now)
                    - chrono::Duration::minutes(30),
            ),
            size_bytes: 1024 * 1024 * 1024,           // 1GB
            compressed_size_bytes: 512 * 1024 * 1024, // 512MB
            file_path: self.config.backup_directory.join("base_backup.sql"),
            checksum: "mock_checksum".to_string(),
            database_name: "codex_memory".to_string(),
            wal_start_lsn: Some("0/1000000".to_string()),
            wal_end_lsn: Some("0/2000000".to_string()),
            encryption_enabled: self.config.enable_encryption,
            replication_status: std::collections::HashMap::new(),
            verification_status: None,
        };

        Ok(mock_backup)
    }

    async fn identify_required_wal_files(
        &self,
        _base_backup: &BackupMetadata,
        _recovery_options: &RecoveryOptions,
    ) -> Result<Vec<String>> {
        debug!("Identifying required WAL files for recovery");

        // This would analyze the WAL archive directory to find all WAL files
        // needed from the base backup's end LSN to the target recovery point

        let mut required_files = Vec::new();

        // Mock WAL files for demonstration
        for i in 1..10 {
            required_files.push(format!("00000001000000000000000{i:X}"));
        }

        debug!("Identified {} required WAL files", required_files.len());
        Ok(required_files)
    }

    fn estimate_recovery_duration(
        &self,
        base_backup: &BackupMetadata,
        wal_files: &[String],
    ) -> u32 {
        // Estimate recovery time based on backup size and number of WAL files
        let base_restore_minutes = (base_backup.size_bytes / (100 * 1024 * 1024)) as u32; // 100MB per minute
        let wal_apply_minutes = wal_files.len() as u32; // 1 minute per WAL file

        std::cmp::max(5, base_restore_minutes + wal_apply_minutes) // At least 5 minutes
    }

    async fn execute_recovery_steps(&self, recovery_plan: &RecoveryPlan) -> Result<()> {
        // Phase 1: Prepare data directory
        self.update_recovery_phase(RecoveryPhase::RestoringBaseBackup, 10)
            .await;
        self.prepare_data_directory(&recovery_plan.data_directory)
            .await?;

        // Phase 2: Restore base backup
        self.update_recovery_phase(RecoveryPhase::RestoringBaseBackup, 30)
            .await;
        self.restore_base_backup(&recovery_plan.base_backup, &recovery_plan.data_directory)
            .await?;

        // Phase 3: Configure recovery
        self.update_recovery_phase(RecoveryPhase::ApplyingWalFiles, 50)
            .await;
        self.create_recovery_configuration(recovery_plan).await?;

        // Phase 4: Apply WAL files
        self.update_recovery_phase(RecoveryPhase::ApplyingWalFiles, 80)
            .await;
        self.apply_wal_files(
            &recovery_plan.required_wal_files,
            &recovery_plan.data_directory,
        )
        .await?;

        // Phase 5: Validate consistency
        self.update_recovery_phase(RecoveryPhase::ValidatingConsistency, 90)
            .await;
        self.validate_recovery_consistency(&recovery_plan.data_directory)
            .await?;

        // Phase 6: Finalize
        self.update_recovery_phase(RecoveryPhase::Finalizing, 95)
            .await;
        self.finalize_recovery(recovery_plan).await?;

        Ok(())
    }

    async fn update_recovery_phase(&self, phase: RecoveryPhase, progress: u8) {
        let mut status = self.recovery_status.write().await;
        status.current_phase = phase;
        status.progress_percentage = progress;
    }

    async fn prepare_data_directory(&self, data_directory: &Path) -> Result<()> {
        debug!("Preparing data directory: {}", data_directory.display());

        // Create or clean the data directory
        if data_directory.exists() {
            warn!("Data directory exists, cleaning it for recovery");
            fs::remove_dir_all(data_directory).await?;
        }

        fs::create_dir_all(data_directory).await?;
        Ok(())
    }

    async fn restore_base_backup(
        &self,
        backup: &BackupMetadata,
        data_directory: &Path,
    ) -> Result<()> {
        debug!("Restoring base backup: {}", backup.id);

        if !backup.file_path.exists() {
            return Err(BackupError::RecoveryFailed {
                message: format!("Base backup file not found: {}", backup.file_path.display()),
            });
        }

        // Use pg_restore to restore the backup
        let mut cmd = Command::new("pg_restore");
        cmd.arg("--verbose")
            .arg("--no-privileges")
            .arg("--no-owner")
            .arg("--dbname")
            .arg(data_directory.to_string_lossy().as_ref())
            .arg(&backup.file_path);

        let output = cmd.output().map_err(|e| BackupError::RecoveryFailed {
            message: format!("Failed to execute pg_restore: {e}"),
        })?;

        if !output.status.success() {
            let error_msg = String::from_utf8_lossy(&output.stderr);
            return Err(BackupError::RecoveryFailed {
                message: format!("pg_restore failed: {error_msg}"),
            });
        }

        info!("Base backup restored successfully");
        Ok(())
    }

    async fn create_recovery_configuration(&self, recovery_plan: &RecoveryPlan) -> Result<()> {
        debug!("Creating recovery configuration");

        let mut recovery_conf = String::new();

        // Set recovery target
        if let Some(target_time) = &recovery_plan.target_time {
            recovery_conf.push_str(&format!(
                "recovery_target_time = '{}'\n",
                target_time.format("%Y-%m-%d %H:%M:%S")
            ));
        }

        if let Some(target_lsn) = &recovery_plan.target_lsn {
            recovery_conf.push_str(&format!("recovery_target_lsn = '{target_lsn}'\n"));
        }

        // Set WAL archive location
        recovery_conf.push_str(&format!(
            "restore_command = 'cp {}/{{}} {{}}'\n",
            self.config.wal_archive_directory.display()
        ));

        // Write recovery configuration
        fs::write(&recovery_plan.recovery_conf_path, recovery_conf).await?;

        debug!("Recovery configuration created");
        Ok(())
    }

    async fn apply_wal_files(&self, wal_files: &[String], _data_directory: &Path) -> Result<()> {
        debug!("Applying {} WAL files", wal_files.len());

        // In a real implementation, this would involve starting PostgreSQL
        // in recovery mode and letting it apply the WAL files automatically

        for (index, wal_file) in wal_files.iter().enumerate() {
            debug!("Processing WAL file: {}", wal_file);

            // Update progress
            let progress = 50 + (30 * index / wal_files.len()) as u8;
            self.update_recovery_phase(RecoveryPhase::ApplyingWalFiles, progress)
                .await;

            // Simulate WAL file application
            tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
        }

        info!("WAL files applied successfully");
        Ok(())
    }

    async fn validate_recovery_consistency(&self, data_directory: &Path) -> Result<()> {
        debug!("Validating recovery consistency");

        // This would perform consistency checks on the recovered database
        // For now, just check that the data directory exists and has content
        if !data_directory.exists() {
            return Err(BackupError::RecoveryFailed {
                message: "Data directory does not exist after recovery".to_string(),
            });
        }

        // Check for basic PostgreSQL files
        let pg_version_file = data_directory.join("PG_VERSION");
        if !pg_version_file.exists() {
            return Err(BackupError::RecoveryFailed {
                message: "Recovery validation failed: PG_VERSION file not found".to_string(),
            });
        }

        info!("Recovery consistency validation passed");
        Ok(())
    }

    async fn finalize_recovery(&self, recovery_plan: &RecoveryPlan) -> Result<()> {
        debug!("Finalizing recovery");

        // Clean up temporary files
        if recovery_plan.recovery_conf_path.exists() {
            fs::remove_file(&recovery_plan.recovery_conf_path).await?;
        }

        info!("Recovery finalized successfully");
        Ok(())
    }

    async fn check_wal_files_availability(
        &self,
        base_backup: &BackupMetadata,
        recovery_options: &RecoveryOptions,
    ) -> Result<bool> {
        let required_files = self
            .identify_required_wal_files(base_backup, recovery_options)
            .await?;

        for wal_file in &required_files {
            let wal_path = self.config.wal_archive_directory.join(wal_file);
            if !wal_path.exists() {
                warn!("Required WAL file not found: {}", wal_file);
                return Ok(false);
            }
        }

        Ok(true)
    }

    async fn create_temporary_test_directory(&self) -> Result<PathBuf> {
        let temp_dir = std::env::temp_dir().join(format!("pitr_test_{}", uuid::Uuid::new_v4()));
        fs::create_dir_all(&temp_dir).await?;
        Ok(temp_dir)
    }

    async fn validate_base_backup(&self, backup: &BackupMetadata) -> Result<bool> {
        debug!("Validating base backup: {}", backup.id);

        // Check if backup file exists
        if !backup.file_path.exists() {
            warn!("Base backup file not found: {}", backup.file_path.display());
            return Ok(false);
        }

        // Verify checksum if available
        if !backup.checksum.is_empty() {
            let calculated_checksum = self.calculate_file_checksum(&backup.file_path).await?;
            if calculated_checksum != backup.checksum {
                warn!("Base backup checksum mismatch");
                return Ok(false);
            }
        }

        Ok(true)
    }

    async fn validate_wal_files(&self, wal_files: &[String]) -> Result<bool> {
        debug!("Validating {} WAL files", wal_files.len());

        for wal_file in wal_files {
            let wal_path = self.config.wal_archive_directory.join(wal_file);
            if !wal_path.exists() {
                warn!("WAL file not found: {}", wal_file);
                return Ok(false);
            }
        }

        Ok(true)
    }

    async fn test_restoration_steps(&self, recovery_plan: &RecoveryPlan) -> Result<bool> {
        debug!("Testing restoration steps");

        // Test data directory creation
        let test_dir = recovery_plan.data_directory.join("test");
        if fs::create_dir_all(&test_dir).await.is_err() {
            return Ok(false);
        }

        // Clean up test directory
        if test_dir.exists() {
            fs::remove_dir_all(&test_dir).await?;
        }

        Ok(true)
    }

    async fn calculate_file_checksum(&self, file_path: &Path) -> Result<String> {
        use sha2::{Digest, Sha256};

        let contents = fs::read(file_path).await?;
        let mut hasher = Sha256::new();
        hasher.update(&contents);
        let result = hasher.finalize();
        Ok(format!("{result:x}"))
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RecoveryTestResult {
    pub test_id: String,
    pub test_time: DateTime<Utc>,
    pub duration_seconds: u32,
    pub base_backup_valid: bool,
    pub wal_files_valid: bool,
    pub restoration_feasible: bool,
    pub estimated_recovery_time_minutes: u32,
    pub issues_found: Vec<String>,
}

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

    #[test]
    fn test_recovery_phase_progression() {
        let phases = [
            RecoveryPhase::Initializing,
            RecoveryPhase::RestoringBaseBackup,
            RecoveryPhase::ApplyingWalFiles,
            RecoveryPhase::ValidatingConsistency,
            RecoveryPhase::Finalizing,
            RecoveryPhase::Completed,
        ];

        for (i, _phase) in phases.iter().enumerate() {
            assert!(i < 6); // Ensure all phases are covered
        }
    }

    #[test]
    fn test_recovery_status_default() {
        let status = RecoveryStatus {
            is_recovering: false,
            recovery_id: None,
            start_time: None,
            progress_percentage: 0,
            current_phase: RecoveryPhase::Initializing,
            estimated_completion: None,
            error_message: None,
        };

        assert!(!status.is_recovering);
        assert_eq!(status.progress_percentage, 0);
        assert!(matches!(status.current_phase, RecoveryPhase::Initializing));
    }
}