oxirs-arq 0.2.4

//! Advanced Caching Integration for OxiRS ARQ Query Engine
//!
//! This module integrates the shared advanced caching system with the ARQ query processor
//! to provide high-performance caching for query plans, results, and intermediate computations.

use crate::{
    algebra::{Algebra, Solution, Term, Variable},
    query::Query,
    Result,
};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::hash::{Hash, Hasher};
use std::sync::Arc;
use std::time::Duration;

// Import the shared cache from parent engine module
// For now, we'll define basic cache traits locally until the module structure is fixed
pub trait CacheKey: Clone + std::hash::Hash + Eq + Send + Sync {}
pub trait CacheValue: Clone + Send + Sync {}

// Implement CacheKey for String
impl CacheKey for String {}

// Implement CacheValue for StatisticsSnapshot
impl CacheValue for StatisticsSnapshot {}

// Placeholder for AdvancedCache until shared_cache is properly imported
#[derive(Debug)]
pub struct AdvancedCache<K, V> {
    _phantom: std::marker::PhantomData<(K, V)>,
}

impl<K: CacheKey, V: CacheValue> AdvancedCache<K, V> {
    pub fn new(_config: AdvancedCacheConfig) -> Self {
        Self {
            _phantom: std::marker::PhantomData,
        }
    }

    pub fn get(&self, _key: &K) -> Option<V> {
        None
    }

    pub fn put(&self, _key: K, _value: V) -> Result<()> {
        Ok(())
    }

    pub fn warm_cache(&self) -> Result<()> {
        Ok(())
    }

    pub fn clear(&self) {
        // No-op for placeholder
    }
}

// Placeholder for AdvancedCacheConfig
#[derive(Debug, Clone)]
pub struct AdvancedCacheConfig {
    pub l1_cache_size: usize,
    pub l2_cache_size: usize,
    pub l3_cache_size: usize,
    pub enable_compression: bool,
}

impl Default for AdvancedCacheConfig {
    fn default() -> Self {
        Self {
            l1_cache_size: 1024,
            l2_cache_size: 4096,
            l3_cache_size: 16384,
            enable_compression: false,
        }
    }
}

/// ARQ-specific cache configuration
#[derive(Debug, Clone)]
pub struct ArqCacheConfig {
    /// Query plan cache configuration
    pub query_plan_cache: AdvancedCacheConfig,
    /// Query result cache configuration
    pub query_result_cache: AdvancedCacheConfig,
    /// BGP evaluation cache configuration
    pub bgp_cache: AdvancedCacheConfig,
    /// Statistics cache configuration
    pub statistics_cache: AdvancedCacheConfig,
    /// Enable cross-query optimization caching
    pub enable_cross_query_caching: bool,
    /// Maximum query result size to cache (bytes)
    pub max_result_size: usize,
    /// Query similarity threshold for result reuse
    pub query_similarity_threshold: f64,
}

impl Default for ArqCacheConfig {
    fn default() -> Self {
        let base_config = AdvancedCacheConfig {
            l1_cache_size: 5000, // Smaller for query plans
            l2_cache_size: 20000,
            l3_cache_size: 100000,
            ..Default::default()
        };

        let result_config = AdvancedCacheConfig {
            l1_cache_size: 1000, // Results can be large
            l2_cache_size: 5000,
            l3_cache_size: 20000,
            enable_compression: true,
        };

        Self {
            query_plan_cache: base_config.clone(),
            query_result_cache: result_config,
            bgp_cache: base_config.clone(),
            statistics_cache: base_config,
            enable_cross_query_caching: true,
            max_result_size: 10 * 1024 * 1024, // 10MB
            query_similarity_threshold: 0.8,
        }
    }
}

/// Cached query plan
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CachedQueryPlan {
    /// The optimized algebra
    pub algebra: Algebra,
    /// Estimated execution cost
    pub estimated_cost: f64,
    /// Optimization metadata
    pub optimization_metadata: OptimizationMetadata,
    /// Statistics used for optimization
    pub statistics_snapshot: StatisticsSnapshot,
}

/// Optimization metadata
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct OptimizationMetadata {
    /// Optimizations applied
    pub optimizations_applied: Vec<String>,
    /// Optimization time
    pub optimization_time_ms: u64,
    /// Selectivity estimates
    pub selectivity_estimates: HashMap<String, f64>,
    /// Join order decisions
    pub join_order: Vec<String>,
}

/// Statistics snapshot for cache validation
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StatisticsSnapshot {
    /// Dataset size when cached
    pub dataset_size: usize,
    /// Predicate cardinalities
    pub predicate_cardinalities: HashMap<String, usize>,
    /// Snapshot timestamp
    pub timestamp: u64,
    /// Statistics version
    pub version: String,
}

/// Cached query result
#[derive(Debug, Clone)]
pub struct CachedQueryResult {
    /// Result solutions
    pub solutions: Vec<Solution>,
    /// Result metadata
    pub metadata: QueryResultMetadata,
    /// Result size in bytes
    pub size_bytes: usize,
}

/// Query result metadata
#[derive(Debug, Clone)]
pub struct QueryResultMetadata {
    /// Execution time when cached
    pub execution_time: Duration,
    /// Dataset version when executed
    pub dataset_version: String,
    /// Variables in result
    pub variables: Vec<Variable>,
    /// Total solution count
    pub solution_count: usize,
    /// Whether result is complete or partial
    pub is_complete: bool,
}

/// Cache key for query plans
#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct QueryPlanCacheKey {
    /// Normalized query hash
    pub query_hash: u64,
    /// Dataset schema hash
    pub schema_hash: u64,
    /// Optimization level
    pub optimization_level: OptimizationLevel,
    /// Configuration parameters
    pub config_hash: u64,
}

/// Cache key for query results
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct QueryResultCacheKey {
    /// Query signature
    pub query_signature: QuerySignature,
    /// Dataset version
    pub dataset_version: String,
    /// Parameter bindings (for parameterized queries)
    pub parameter_bindings: HashMap<String, String>,
}

impl std::hash::Hash for QueryResultCacheKey {
    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
        self.query_signature.hash(state);
        self.dataset_version.hash(state);
        // Hash the parameter bindings in a deterministic way
        let mut sorted_params: Vec<_> = self.parameter_bindings.iter().collect();
        sorted_params.sort_by_key(|(k, _)| *k);
        for (k, v) in sorted_params {
            k.hash(state);
            v.hash(state);
        }
    }
}

/// Query signature for result caching
#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct QuerySignature {
    /// Canonical query form
    pub canonical_form: String,
    /// Variable set
    pub variables: Vec<String>,
    /// Operation type
    pub operation_type: QueryOperationType,
    /// Complexity score
    pub complexity_score: u32,
}

/// Query operation types
#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
pub enum QueryOperationType {
    Select,
    Construct,
    Ask,
    Describe,
    Update,
}

/// Optimization levels
#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
pub enum OptimizationLevel {
    Basic,
    Standard,
    Aggressive,
    Custom(u32),
}

/// Cache key for BGP evaluations
#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct BgpCacheKey {
    /// BGP pattern hash
    pub pattern_hash: u64,
    /// Variable bindings
    pub bindings_hash: u64,
    /// Graph context
    pub graph_context: Option<String>,
}

/// Cached BGP result
#[derive(Debug, Clone)]
pub struct CachedBgpResult {
    /// Solutions found
    pub solutions: Vec<Solution>,
    /// Evaluation metadata
    pub metadata: BgpEvaluationMetadata,
}

/// BGP evaluation metadata
#[derive(Debug, Clone)]
pub struct BgpEvaluationMetadata {
    /// Evaluation time
    pub evaluation_time: Duration,
    /// Solutions count
    pub solution_count: usize,
    /// Index hits
    pub index_hits: usize,
    /// Selectivity achieved
    pub selectivity: f64,
}

/// Advanced cache manager for ARQ
pub struct ArqCacheManager {
    /// Query plan cache
    query_plan_cache: Arc<AdvancedCache<QueryPlanCacheKey, CachedQueryPlan>>,
    /// Query result cache
    query_result_cache: Arc<AdvancedCache<QueryResultCacheKey, CachedQueryResult>>,
    /// BGP evaluation cache
    bgp_cache: Arc<AdvancedCache<BgpCacheKey, CachedBgpResult>>,
    /// Statistics cache
    statistics_cache: Arc<AdvancedCache<String, StatisticsSnapshot>>,
    /// Configuration
    config: ArqCacheConfig,
    /// Cache statistics
    cache_stats: Arc<std::sync::RwLock<ArqCacheStatistics>>,
}

/// ARQ cache statistics
#[derive(Debug, Clone, Default)]
pub struct ArqCacheStatistics {
    /// Query plan cache hits
    pub plan_cache_hits: usize,
    /// Query plan cache misses
    pub plan_cache_misses: usize,
    /// Result cache hits
    pub result_cache_hits: usize,
    /// Result cache misses
    pub result_cache_misses: usize,
    /// BGP cache hits
    pub bgp_cache_hits: usize,
    /// BGP cache misses
    pub bgp_cache_misses: usize,
    /// Total time saved (milliseconds)
    pub time_saved_ms: u64,
    /// Average cache lookup time
    pub avg_lookup_time_us: f64,
    /// Cache efficiency score
    pub efficiency_score: f64,
}

impl ArqCacheManager {
    /// Create new ARQ cache manager
    pub fn new(config: ArqCacheConfig) -> Self {
        Self {
            query_plan_cache: Arc::new(AdvancedCache::new(config.query_plan_cache.clone())),
            query_result_cache: Arc::new(AdvancedCache::new(config.query_result_cache.clone())),
            bgp_cache: Arc::new(AdvancedCache::new(config.bgp_cache.clone())),
            statistics_cache: Arc::new(AdvancedCache::new(config.statistics_cache.clone())),
            config,
            cache_stats: Arc::new(std::sync::RwLock::new(ArqCacheStatistics::default())),
        }
    }

    /// Get cached query plan
    pub fn get_query_plan(&self, key: &QueryPlanCacheKey) -> Option<CachedQueryPlan> {
        let start_time = std::time::Instant::now();
        let result = self.query_plan_cache.get(key);

        {
            let mut stats = self.cache_stats.write().expect("lock poisoned");
            if result.is_some() {
                stats.plan_cache_hits += 1;
            } else {
                stats.plan_cache_misses += 1;
            }
            self.update_avg_lookup_time(&mut stats, start_time.elapsed());
        }

        result
    }

    /// Cache query plan
    pub fn cache_query_plan(&self, key: QueryPlanCacheKey, plan: CachedQueryPlan) -> Result<()> {
        self.query_plan_cache.put(key, plan)?;
        Ok(())
    }

    /// Get cached query result
    pub fn get_query_result(&self, key: &QueryResultCacheKey) -> Option<CachedQueryResult> {
        let start_time = std::time::Instant::now();

        // Validate cache key freshness
        if !self.is_result_cache_valid(key) {
            return None;
        }

        let result = self.query_result_cache.get(key);

        {
            let mut stats = self.cache_stats.write().expect("lock poisoned");
            if let Some(ref cached_result) = result {
                stats.result_cache_hits += 1;
                stats.time_saved_ms += cached_result.metadata.execution_time.as_millis() as u64;
            } else {
                stats.result_cache_misses += 1;
            }
            self.update_avg_lookup_time(&mut stats, start_time.elapsed());
        }

        result
    }

    /// Cache query result
    pub fn cache_query_result(
        &self,
        key: QueryResultCacheKey,
        result: CachedQueryResult,
    ) -> Result<()> {
        // Check size limits
        if result.size_bytes > self.config.max_result_size {
            return Ok(()); // Don't cache oversized results
        }

        self.query_result_cache.put(key, result)?;
        Ok(())
    }

    /// Get cached BGP result
    pub fn get_bgp_result(&self, key: &BgpCacheKey) -> Option<CachedBgpResult> {
        let start_time = std::time::Instant::now();
        let result = self.bgp_cache.get(key);

        {
            let mut stats = self.cache_stats.write().expect("lock poisoned");
            if result.is_some() {
                stats.bgp_cache_hits += 1;
            } else {
                stats.bgp_cache_misses += 1;
            }
            self.update_avg_lookup_time(&mut stats, start_time.elapsed());
        }

        result
    }

    /// Cache BGP result
    pub fn cache_bgp_result(&self, key: BgpCacheKey, result: CachedBgpResult) -> Result<()> {
        self.bgp_cache.put(key, result)?;
        Ok(())
    }

    /// Create query plan cache key
    pub fn create_plan_cache_key(
        &self,
        query: &Query,
        schema_hash: u64,
        optimization_level: OptimizationLevel,
    ) -> QueryPlanCacheKey {
        let query_hash = self.hash_query(query);
        let config_hash = self.hash_config();

        QueryPlanCacheKey {
            query_hash,
            schema_hash,
            optimization_level,
            config_hash,
        }
    }

    /// Create query result cache key
    pub fn create_result_cache_key(
        &self,
        query: &Query,
        dataset_version: String,
        parameter_bindings: HashMap<String, String>,
    ) -> QueryResultCacheKey {
        let query_signature = self.create_query_signature(query);

        QueryResultCacheKey {
            query_signature,
            dataset_version,
            parameter_bindings,
        }
    }

    /// Create BGP cache key
    pub fn create_bgp_cache_key(
        &self,
        pattern_hash: u64,
        bindings: &HashMap<Variable, Term>,
        graph_context: Option<&str>,
    ) -> BgpCacheKey {
        let bindings_hash = self.hash_bindings(bindings);

        BgpCacheKey {
            pattern_hash,
            bindings_hash,
            graph_context: graph_context.map(|s| s.to_string()),
        }
    }

    /// Get cache statistics
    pub fn get_statistics(&self) -> ArqCacheStatistics {
        let stats = self.cache_stats.read().expect("lock poisoned");
        stats.clone()
    }

    /// Warm caches based on query patterns
    pub fn warm_caches(&self) -> Result<()> {
        // Warm query plan cache
        self.query_plan_cache.warm_cache()?;

        // Warm result cache
        self.query_result_cache.warm_cache()?;

        // Warm BGP cache
        self.bgp_cache.warm_cache()?;

        Ok(())
    }

    /// Clear all caches
    pub fn clear_all_caches(&self) {
        self.query_plan_cache.clear();
        self.query_result_cache.clear();
        self.bgp_cache.clear();
        self.statistics_cache.clear();

        // Reset statistics
        {
            let mut stats = self.cache_stats.write().expect("lock poisoned");
            *stats = ArqCacheStatistics::default();
        }
    }

    /// Invalidate caches based on dataset changes
    pub fn invalidate_on_dataset_change(&self, _changed_predicates: &[String]) -> Result<()> {
        // Implementation would invalidate relevant cache entries
        // For now, clear all caches as a conservative approach
        self.clear_all_caches();
        Ok(())
    }

    // Private helper methods
    fn hash_query(&self, query: &Query) -> u64 {
        // Create a canonical hash of the query
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        // This would hash the normalized query structure
        format!("{query:?}").hash(&mut hasher);
        hasher.finish()
    }

    fn hash_config(&self) -> u64 {
        // Hash relevant configuration parameters
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        self.config
            .query_similarity_threshold
            .to_bits()
            .hash(&mut hasher);
        self.config.enable_cross_query_caching.hash(&mut hasher);
        hasher.finish()
    }

    fn hash_bindings(&self, bindings: &HashMap<Variable, Term>) -> u64 {
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        // Sort bindings for consistent hashing
        let mut sorted_bindings: Vec<_> = bindings.iter().collect();
        sorted_bindings.sort_by_key(|(var, _)| var.as_str());

        for (var, term) in sorted_bindings {
            var.hash(&mut hasher);
            format!("{term:?}").hash(&mut hasher);
        }

        hasher.finish()
    }

    fn create_query_signature(&self, query: &Query) -> QuerySignature {
        // Extract canonical form and metadata
        QuerySignature {
            canonical_form: format!("{query:?}"), // Simplified
            variables: query
                .select_variables
                .iter()
                .map(|v| v.as_str().to_string())
                .collect(),
            operation_type: self.determine_operation_type(query),
            complexity_score: self.calculate_complexity_score(query),
        }
    }

    fn determine_operation_type(&self, _query: &Query) -> QueryOperationType {
        // Determine query type based on query structure
        QueryOperationType::Select // Simplified
    }

    fn calculate_complexity_score(&self, _query: &Query) -> u32 {
        // Calculate query complexity score
        100 // Simplified
    }

    fn is_result_cache_valid(&self, _key: &QueryResultCacheKey) -> bool {
        // Check if cached result is still valid
        // This would check dataset version, timestamps, etc.
        true // Simplified
    }

    fn update_avg_lookup_time(&self, stats: &mut ArqCacheStatistics, lookup_time: Duration) {
        let total_lookups = stats.plan_cache_hits
            + stats.plan_cache_misses
            + stats.result_cache_hits
            + stats.result_cache_misses
            + stats.bgp_cache_hits
            + stats.bgp_cache_misses;

        let lookup_time_us = lookup_time.as_micros() as f64;

        if total_lookups == 1 {
            stats.avg_lookup_time_us = lookup_time_us;
        } else {
            stats.avg_lookup_time_us = (stats.avg_lookup_time_us * (total_lookups - 1) as f64
                + lookup_time_us)
                / total_lookups as f64;
        }

        // Update efficiency score
        let hit_rate = (stats.plan_cache_hits + stats.result_cache_hits + stats.bgp_cache_hits)
            as f64
            / total_lookups.max(1) as f64;
        stats.efficiency_score =
            hit_rate * 0.7 + (1.0 - stats.avg_lookup_time_us / 1000.0).max(0.0) * 0.3;
    }
}

// Implement cache traits
impl CacheKey for QueryPlanCacheKey {}
impl CacheValue for CachedQueryPlan {}
impl CacheKey for QueryResultCacheKey {}
impl CacheValue for CachedQueryResult {}
impl CacheKey for BgpCacheKey {}
impl CacheValue for CachedBgpResult {}

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

    #[test]
    fn test_arq_cache_manager_creation() {
        let config = ArqCacheConfig::default();
        let cache_manager = ArqCacheManager::new(config);

        let stats = cache_manager.get_statistics();
        assert_eq!(stats.plan_cache_hits, 0);
        assert_eq!(stats.result_cache_hits, 0);
    }

    #[test]
    fn test_cache_key_creation() {
        let config = ArqCacheConfig::default();
        let _cache_manager = ArqCacheManager::new(config);

        // Test would create actual query and test key creation
        // This is a placeholder test structure
    }
}