auradb 0.1.0

//! Compaction module for LSM tree management
//! 
//! This module will implement flexible LSM (FLSM) with tiered/leveled compaction,
//! RL-driven policy selection, and I/O rate limiting.
//! 
//! Planned for M2-M3 milestones.

use crate::error::{Error, Result};

/// Compaction strategy type
#[derive(Debug, Clone)]
pub enum CompactionStrategy {
    /// Leveled compaction (RocksDB-style)
    Leveled,
    /// Tiered compaction
    Tiered,
    /// Flexible LSM (can switch between strategies)
    Flexible,
}

/// Compaction task information
#[derive(Debug, Clone)]
pub struct CompactionTask {
    /// Task ID
    pub id: u64,
    /// Source level
    pub source_level: u32,
    /// Target level
    pub target_level: u32,
    /// Input files
    pub input_files: Vec<String>,
    /// Output file
    pub output_file: String,
    /// Priority
    pub priority: u32,
}

/// Compaction manager for orchestrating LSM compaction
pub struct CompactionManager {
    // TODO: Implement compaction management functionality
}

impl CompactionManager {
    /// Create a new compaction manager
    pub fn new() -> Self {
        Self {}
    }
    
    /// Schedule a compaction task
    pub fn schedule_task(&mut self, _task: CompactionTask) -> Result<()> {
        // TODO: Implement
        Ok(())
    }
    
    /// Get pending compaction tasks
    pub fn get_pending_tasks(&self) -> Vec<CompactionTask> {
        // TODO: Implement
        Vec::new()
    }
    
    /// Run compaction tasks
    pub fn run_compaction(&mut self) -> Result<()> {
        // TODO: Implement
        Ok(())
    }
}

/// RL agent for compaction policy selection
pub struct RlCompactionAgent {
    // TODO: Implement RL agent functionality
}

impl RlCompactionAgent {
    /// Create a new RL agent
    pub fn new() -> Self {
        Self {}
    }
    
    /// Observe current state
    pub fn observe_state(&mut self) -> Result<()> {
        // TODO: Implement
        Ok(())
    }
    
    /// Select action based on current state
    pub fn select_action(&self) -> CompactionStrategy {
        // TODO: Implement
        CompactionStrategy::Leveled
    }
    
    /// Update policy based on reward
    pub fn update_policy(&mut self, _reward: f64) -> Result<()> {
        // TODO: Implement
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    fn test_compaction_manager_creation() {
        let manager = CompactionManager::new();
        assert!(manager.get_pending_tasks().is_empty());
    }
    
    #[test]
    fn test_rl_agent_creation() {
        let agent = RlCompactionAgent::new();
        assert!(matches!(agent.select_action(), CompactionStrategy::Leveled));
    }
}