fraiseql-server 2.0.0-alpha.1

//! Disaster recovery utilities.

use std::time::SystemTime;

/// Disaster Recovery Runbook
///
/// This module provides utilities and documentation for recovering from data loss.
///
/// ## Recovery Procedure (RTO: 1 hour, RPO: Last hourly backup)
///
/// ### Step 1: Assess Damage (5-10 min)
/// - Determine what data was lost
/// - Identify last known good backup
/// - Notify stakeholders of estimated RTO
///
/// ### Step 2: PostgreSQL Recovery (10-20 min)
/// ```bash
/// # Stop all applications
/// systemctl stop fraiseql-server
///
/// # Restore from hourly backup
/// psql fraiseql < /var/backups/fraiseql/postgres/postgres-1234567890.sql.gz
///
/// # Recover WAL files if point-in-time recovery needed
/// # (requires WAL archiving configured)
/// pg_wal_replay last_wal_segment.tar.gz
///
/// # Run maintenance
/// psql fraiseql -c "ANALYZE; VACUUM;"
/// ```
///
/// ### Step 3: Redis Recovery (5-10 min)
/// ```bash
/// # Stop Redis client connections
/// redis-cli SHUTDOWN SAVE
///
/// # Restore from daily dump
/// cp /var/backups/fraiseql/redis/redis-1234567890.rdb /var/lib/redis/dump.rdb
///
/// # Start Redis
/// systemctl start redis-server
///
/// # Verify keys
/// redis-cli DBSIZE
/// ```
///
/// ### Step 4: ClickHouse Recovery (10-20 min)
/// ```bash
/// # Stop ClickHouse
/// systemctl stop clickhouse-server
///
/// # Restore backup files
/// tar -xzf /var/backups/fraiseql/clickhouse/clickhouse-1234567890.tar.gz \
///   -C /var/lib/clickhouse/
///
/// # Start ClickHouse
/// systemctl start clickhouse-server
///
/// # Attach tables
/// clickhouse-client -q "ATTACH TABLE fraiseql_events..."
/// ```
///
/// ### Step 5: Elasticsearch Recovery (10-20 min)
/// ```bash
/// # Restore from snapshot
/// curl -X POST "localhost:9200/_snapshot/default/elasticsearch-1234567890/_restore"
///
/// # Monitor recovery
/// curl "localhost:9200/_recovery?v"
///
/// # Verify indices
/// curl "localhost:9200/_cat/indices"
/// ```
///
/// ### Step 6: Verification & Restart (5-10 min)
/// ```bash
/// # Check data consistency
/// # Run application-level consistency checks
///
/// # Start application
/// systemctl start fraiseql-server
///
/// # Monitor logs
/// journalctl -u fraiseql-server -f
/// ```
///
/// ## Testing Recovery
///
/// **Quarterly DR Test Schedule**:
/// - Q1: PostgreSQL recovery drill
/// - Q2: Redis recovery drill
/// - Q3: ClickHouse recovery drill
/// - Q4: Full disaster recovery simulation
///
/// **Test Procedure**:
/// 1. Take a backup
/// 2. Restore to isolated environment (dev/staging)
/// 3. Run full test suite
/// 4. Document any issues found
/// 5. Update runbook if needed
///
/// ## Backup Retention Policy
///
/// | Store | Frequency | Retention | Strategy |
/// |-------|-----------|-----------|----------|
/// | PostgreSQL | Hourly | 30 days | Full backup + WAL |
/// | Redis | Daily | 7 days | RDB snapshot + AOF |
/// | ClickHouse | Daily | 7 days | Native snapshots |
/// | Elasticsearch | Daily | 7 days | Snapshot API |
///
/// ## Critical Contacts
///
/// In case of major data loss:
/// - DBA: (escalate to data recovery team)
/// - DevOps: (coordinate infrastructure changes)
/// - Engineering Lead: (assess impact and prioritize recovery)
use serde::{Deserialize, Serialize};

/// Recovery status for a single data store.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RecoveryStatus {
    /// Name of data store
    pub store_name: String,

    /// Current recovery step (1-6)
    pub step: u32,

    /// Step name
    pub step_name: String,

    /// Recovery progress (0-100)
    pub progress_percent: u32,

    /// Estimated time remaining (seconds)
    pub estimated_time_remaining_secs: u64,

    /// Any errors encountered
    pub errors: Vec<String>,

    /// Recovery start timestamp
    pub started_at: i64,
}

impl RecoveryStatus {
    /// Create new recovery status.
    pub fn new(store_name: String) -> Self {
        Self {
            store_name,
            step: 1,
            step_name: "Assessing damage".to_string(),
            progress_percent: 0,
            estimated_time_remaining_secs: 3600, // 1 hour RTO
            errors: Vec::new(),
            started_at: SystemTime::now()
                .duration_since(SystemTime::UNIX_EPOCH)
                .map(|d| d.as_secs() as i64)
                .unwrap_or(0),
        }
    }

    /// Move to next step.
    pub fn next_step(&mut self) -> bool {
        if self.step >= 6 {
            return false;
        }

        self.step += 1;
        self.step_name = match self.step {
            1 => "Assessing damage",
            2 => "Restoring PostgreSQL",
            3 => "Restoring Redis",
            4 => "Restoring ClickHouse",
            5 => "Restoring Elasticsearch",
            6 => "Verification and restart",
            _ => "Unknown",
        }
        .to_string();

        self.progress_percent = (self.step * 16) + 1; // Rough progress estimate

        true
    }

    /// Record an error.
    pub fn add_error(&mut self, error: String) {
        self.errors.push(error);
    }

    /// Check if recovery is complete.
    pub fn is_complete(&self) -> bool {
        self.step >= 6 && self.errors.is_empty()
    }

    /// Check if recovery is failed.
    pub fn is_failed(&self) -> bool {
        !self.errors.is_empty()
    }
}

/// Recovery checklist item.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RecoveryChecklistItem {
    /// Item ID
    pub id: String,

    /// Item description
    pub description: String,

    /// Whether item is completed
    pub completed: bool,

    /// Notes
    pub notes: Option<String>,
}

/// Complete recovery checklist.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct RecoveryChecklist {
    /// Checklist items
    pub items: Vec<RecoveryChecklistItem>,
}

impl RecoveryChecklist {
    /// Create new recovery checklist.
    pub fn new() -> Self {
        Self {
            items: vec![
                RecoveryChecklistItem {
                    id:          "assess".to_string(),
                    description: "Assess data loss and impact".to_string(),
                    completed:   false,
                    notes:       None,
                },
                RecoveryChecklistItem {
                    id:          "notify".to_string(),
                    description: "Notify stakeholders of RTO/RPO".to_string(),
                    completed:   false,
                    notes:       None,
                },
                RecoveryChecklistItem {
                    id:          "postgres".to_string(),
                    description: "Restore PostgreSQL from backup".to_string(),
                    completed:   false,
                    notes:       None,
                },
                RecoveryChecklistItem {
                    id:          "redis".to_string(),
                    description: "Restore Redis from dump".to_string(),
                    completed:   false,
                    notes:       None,
                },
                RecoveryChecklistItem {
                    id:          "clickhouse".to_string(),
                    description: "Restore ClickHouse from snapshot".to_string(),
                    completed:   false,
                    notes:       None,
                },
                RecoveryChecklistItem {
                    id:          "elasticsearch".to_string(),
                    description: "Restore Elasticsearch indices".to_string(),
                    completed:   false,
                    notes:       None,
                },
                RecoveryChecklistItem {
                    id:          "verify".to_string(),
                    description: "Verify data integrity and consistency".to_string(),
                    completed:   false,
                    notes:       None,
                },
                RecoveryChecklistItem {
                    id:          "test".to_string(),
                    description: "Run acceptance tests".to_string(),
                    completed:   false,
                    notes:       None,
                },
                RecoveryChecklistItem {
                    id:          "restart".to_string(),
                    description: "Restart all services".to_string(),
                    completed:   false,
                    notes:       None,
                },
                RecoveryChecklistItem {
                    id:          "monitor".to_string(),
                    description: "Monitor applications for issues".to_string(),
                    completed:   false,
                    notes:       None,
                },
            ],
        }
    }

    /// Mark item as complete.
    pub fn complete_item(&mut self, id: &str, notes: Option<String>) -> bool {
        for item in &mut self.items {
            if item.id == id {
                item.completed = true;
                item.notes = notes;
                return true;
            }
        }
        false
    }

    /// Get completion percentage.
    pub fn completion_percent(&self) -> u32 {
        let completed = self.items.iter().filter(|i| i.completed).count();
        ((completed as u32 * 100) / self.items.len() as u32).min(100)
    }

    /// Check if all items completed.
    pub fn is_complete(&self) -> bool {
        self.items.iter().all(|i| i.completed)
    }
}

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

    #[test]
    fn test_recovery_status_steps() {
        let mut status = RecoveryStatus::new("postgres".to_string());
        assert_eq!(status.step, 1);

        status.next_step();
        assert_eq!(status.step, 2);
        assert_eq!(status.step_name, "Restoring PostgreSQL");

        for _ in 0..4 {
            status.next_step();
        }
        assert_eq!(status.step, 6);
        assert!(!status.next_step()); // Can't go beyond step 6
    }

    #[test]
    fn test_recovery_status_complete() {
        let mut status = RecoveryStatus::new("postgres".to_string());
        for _ in 0..5 {
            status.next_step();
        }
        assert!(status.is_complete());
    }

    #[test]
    fn test_recovery_checklist() {
        let mut checklist = RecoveryChecklist::new();
        assert_eq!(checklist.completion_percent(), 0);

        checklist.complete_item("assess", Some("Data loss confirmed".to_string()));
        assert!(checklist.completion_percent() > 0);

        for item in &mut checklist.items {
            item.completed = true;
        }
        assert!(checklist.is_complete());
        assert_eq!(checklist.completion_percent(), 100);
    }
}