ubiquity-database 0.1.1

//! Memory pool implementations for 7-wide parallel processing

use async_trait::async_trait;
use std::collections::HashMap;
use std::path::PathBuf;
use std::sync::Arc;
use tokio::sync::RwLock;
use crate::{DatabaseConfig, DatabaseError, MemoryPool, MemoryPoolManager, PoolStats};

/// SQLite-based memory pools using file storage
pub struct SqliteMemoryPools {
    pools: Vec<Arc<SqliteMemoryPool>>,
    config: DatabaseConfig,
}

impl SqliteMemoryPools {
    pub async fn new(config: DatabaseConfig) -> Result<Self, DatabaseError> {
        // Create pool directory
        tokio::fs::create_dir_all(&config.sqlite.pool_directory).await?;
        
        // Create 7 pools
        let mut pools = Vec::with_capacity(config.memory_pools.pool_count);
        for i in 0..config.memory_pools.pool_count {
            let pool = SqliteMemoryPool::new(
                config.sqlite.pool_directory.join(format!("pool_{}.db", i)),
                config.memory_pools.max_pool_size_mb,
            ).await?;
            pools.push(Arc::new(pool));
        }
        
        Ok(Self { pools, config })
    }
}

#[async_trait]
impl MemoryPoolManager for SqliteMemoryPools {
    async fn get_pool(&self, index: usize) -> Result<Box<dyn MemoryPool>, DatabaseError> {
        if index >= self.pools.len() {
            return Err(DatabaseError::InvalidPoolIndex(index));
        }
        Ok(Box::new(self.pools[index].clone()))
    }
    
    async fn get_pool_for_key(&self, key: &str) -> Result<Box<dyn MemoryPool>, DatabaseError> {
        // Simple consistent hashing
        let hash = seahash::hash(key.as_bytes());
        let index = (hash as usize) % self.pools.len();
        self.get_pool(index).await
    }
    
    async fn all_stats(&self) -> Result<Vec<PoolStats>, DatabaseError> {
        let mut stats = Vec::new();
        for pool in &self.pools {
            stats.push(pool.stats().await?);
        }
        Ok(stats)
    }
    
    async fn rebalance(&self) -> Result<(), DatabaseError> {
        // SQLite pools don't need rebalancing
        Ok(())
    }
}

/// Individual SQLite memory pool
#[derive(Clone)]
pub struct SqliteMemoryPool {
    pool: Arc<sqlx::SqlitePool>,
    stats: Arc<RwLock<PoolStats>>,
    max_size_bytes: usize,
}

impl SqliteMemoryPool {
    async fn new(path: PathBuf, max_size_mb: usize) -> Result<Self, DatabaseError> {
        let pool = sqlx::SqlitePool::connect(&format!("sqlite:{}", path.display())).await?;
        
        // Create table
        sqlx::query(
            "CREATE TABLE IF NOT EXISTS memory_pool (
                key TEXT PRIMARY KEY,
                value BLOB NOT NULL,
                created_at INTEGER NOT NULL,
                accessed_at INTEGER NOT NULL,
                access_count INTEGER DEFAULT 1
            )"
        )
        .execute(&pool)
        .await?;
        
        // Create indices
        sqlx::query("CREATE INDEX IF NOT EXISTS idx_accessed_at ON memory_pool(accessed_at)")
            .execute(&pool)
            .await?;
        
        let stats = PoolStats {
            size: 0,
            items: 0,
            hits: 0,
            misses: 0,
            evictions: 0,
        };
        
        Ok(Self {
            pool: Arc::new(pool),
            stats: Arc::new(RwLock::new(stats)),
            max_size_bytes: max_size_mb * 1024 * 1024,
        })
    }
}

#[async_trait]
impl MemoryPool for SqliteMemoryPool {
    async fn store(&self, key: &str, value: &[u8]) -> Result<(), DatabaseError> {
        let now = chrono::Utc::now().timestamp();
        
        // Check if we need to evict
        let current_size = self.get_total_size().await?;
        if current_size + value.len() > self.max_size_bytes {
            self.evict_lru().await?;
        }
        
        sqlx::query(
            "INSERT OR REPLACE INTO memory_pool (key, value, created_at, accessed_at) 
             VALUES (?, ?, ?, ?)"
        )
        .bind(key)
        .bind(value)
        .bind(now)
        .bind(now)
        .execute(&*self.pool)
        .await?;
        
        let mut stats = self.stats.write().await;
        stats.items += 1;
        stats.size += value.len();
        
        Ok(())
    }
    
    async fn retrieve(&self, key: &str) -> Result<Option<Vec<u8>>, DatabaseError> {
        let now = chrono::Utc::now().timestamp();
        
        let result: Option<(Vec<u8>,)> = sqlx::query_as(
            "UPDATE memory_pool 
             SET accessed_at = ?, access_count = access_count + 1 
             WHERE key = ? 
             RETURNING value"
        )
        .bind(now)
        .bind(key)
        .fetch_optional(&*self.pool)
        .await?;
        
        let mut stats = self.stats.write().await;
        if result.is_some() {
            stats.hits += 1;
        } else {
            stats.misses += 1;
        }
        
        Ok(result.map(|r| r.0))
    }
    
    async fn delete(&self, key: &str) -> Result<(), DatabaseError> {
        let result = sqlx::query("DELETE FROM memory_pool WHERE key = ?")
            .bind(key)
            .execute(&*self.pool)
            .await?;
        
        if result.rows_affected() > 0 {
            let mut stats = self.stats.write().await;
            stats.items -= 1;
        }
        
        Ok(())
    }
    
    async fn list_keys(&self, prefix: &str) -> Result<Vec<String>, DatabaseError> {
        let pattern = format!("{}%", prefix);
        let keys: Vec<(String,)> = sqlx::query_as(
            "SELECT key FROM memory_pool WHERE key LIKE ? ORDER BY key"
        )
        .bind(pattern)
        .fetch_all(&*self.pool)
        .await?;
        
        Ok(keys.into_iter().map(|k| k.0).collect())
    }
    
    async fn stats(&self) -> Result<PoolStats, DatabaseError> {
        Ok(self.stats.read().await.clone())
    }
}

impl SqliteMemoryPool {
    async fn get_total_size(&self) -> Result<usize, DatabaseError> {
        let size: (i64,) = sqlx::query_as(
            "SELECT COALESCE(SUM(LENGTH(value)), 0) FROM memory_pool"
        )
        .fetch_one(&*self.pool)
        .await?;
        
        Ok(size.0 as usize)
    }
    
    async fn evict_lru(&self) -> Result<(), DatabaseError> {
        // Evict 10% of least recently used items
        let count: (i64,) = sqlx::query_as("SELECT COUNT(*) FROM memory_pool")
            .fetch_one(&*self.pool)
            .await?;
        
        let to_evict = (count.0 as f64 * 0.1).ceil() as i64;
        
        sqlx::query(
            "DELETE FROM memory_pool 
             WHERE key IN (
                 SELECT key FROM memory_pool 
                 ORDER BY accessed_at ASC 
                 LIMIT ?
             )"
        )
        .bind(to_evict)
        .execute(&*self.pool)
        .await?;
        
        let mut stats = self.stats.write().await;
        stats.evictions += to_evict as u64;
        stats.items -= to_evict as usize;
        
        Ok(())
    }
}

/// Astra DB-based memory pools using collections
#[cfg(feature = "astra")]
pub struct AstraMemoryPools {
    pools: Vec<Arc<AstraMemoryPool>>,
    config: DatabaseConfig,
}

#[cfg(feature = "astra")]
impl AstraMemoryPools {
    pub async fn new(config: DatabaseConfig) -> Result<Self, DatabaseError> {
        // Would initialize Astra DB collections here
        // For now, return not implemented
        Err(DatabaseError::NotImplemented)
    }
}

#[cfg(feature = "astra")]
#[async_trait]
impl MemoryPoolManager for AstraMemoryPools {
    async fn get_pool(&self, index: usize) -> Result<Box<dyn MemoryPool>, DatabaseError> {
        if index >= self.pools.len() {
            return Err(DatabaseError::InvalidPoolIndex(index));
        }
        Ok(Box::new(self.pools[index].clone()))
    }
    
    async fn get_pool_for_key(&self, key: &str) -> Result<Box<dyn MemoryPool>, DatabaseError> {
        let hash = seahash::hash(key.as_bytes());
        let index = (hash as usize) % self.pools.len();
        self.get_pool(index).await
    }
    
    async fn all_stats(&self) -> Result<Vec<PoolStats>, DatabaseError> {
        let mut stats = Vec::new();
        for pool in &self.pools {
            stats.push(pool.stats().await?);
        }
        Ok(stats)
    }
    
    async fn rebalance(&self) -> Result<(), DatabaseError> {
        // Astra DB handles rebalancing automatically
        Ok(())
    }
}

/// Individual Astra memory pool
#[cfg(feature = "astra")]
#[derive(Clone)]
pub struct AstraMemoryPool {
    collection_name: String,
    stats: Arc<RwLock<PoolStats>>,
}

#[cfg(feature = "astra")]
#[async_trait]
impl MemoryPool for AstraMemoryPool {
    async fn store(&self, _key: &str, _value: &[u8]) -> Result<(), DatabaseError> {
        Err(DatabaseError::NotImplemented)
    }
    
    async fn retrieve(&self, _key: &str) -> Result<Option<Vec<u8>>, DatabaseError> {
        Err(DatabaseError::NotImplemented)
    }
    
    async fn delete(&self, _key: &str) -> Result<(), DatabaseError> {
        Err(DatabaseError::NotImplemented)
    }
    
    async fn list_keys(&self, _prefix: &str) -> Result<Vec<String>, DatabaseError> {
        Err(DatabaseError::NotImplemented)
    }
    
    async fn stats(&self) -> Result<PoolStats, DatabaseError> {
        Ok(self.stats.read().await.clone())
    }
}

// Implement MemoryPool for Arc<SqliteMemoryPool>
#[async_trait]
impl MemoryPool for Arc<SqliteMemoryPool> {
    async fn store(&self, key: &str, value: &[u8]) -> Result<(), DatabaseError> {
        self.as_ref().store(key, value).await
    }
    
    async fn retrieve(&self, key: &str) -> Result<Option<Vec<u8>>, DatabaseError> {
        self.as_ref().retrieve(key).await
    }
    
    async fn delete(&self, key: &str) -> Result<(), DatabaseError> {
        self.as_ref().delete(key).await
    }
    
    async fn list_keys(&self, prefix: &str) -> Result<Vec<String>, DatabaseError> {
        self.as_ref().list_keys(prefix).await
    }
    
    async fn stats(&self) -> Result<PoolStats, DatabaseError> {
        self.as_ref().stats().await
    }
}

mod seahash {
    pub fn hash(data: &[u8]) -> u64 {
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        hasher.write(data);
        hasher.finish()
    }
    
    use std::hash::Hasher;
}