oxirs-arq 0.2.4

//! # Smart Query Batch Executor
//!
//! Executes multiple SPARQL queries in parallel with advanced resource management,
//! priority queuing, and batch optimization capabilities.
//!
//! ## Features
//!
//! - **Parallel Execution**: Execute multiple queries concurrently with configurable thread pools
//! - **Priority Queuing**: Support for high/normal/low priority queries with fair scheduling
//! - **Resource Management**: Memory and CPU limits with automatic throttling
//! - **Batch Optimization**: Automatic query grouping and optimization for similar patterns
//! - **Result Streaming**: Stream results as they become available
//! - **Error Handling**: Graceful error handling with partial results
//! - **Statistics Tracking**: Comprehensive batch execution statistics
//!
//! ## Example
//!
//! ```rust,ignore
//! use oxirs_arq::query_batch_executor::{QueryBatchExecutor, BatchConfig, QueryPriority};
//!
//! let config = BatchConfig::default()
//!     .with_max_concurrent(16)
//!     .with_memory_limit_mb(2048);
//!
//! let executor = QueryBatchExecutor::new(config);
//!
//! // Add queries to the batch
//! executor.add_query("SELECT * WHERE { ?s ?p ?o } LIMIT 100", QueryPriority::Normal)?;
//! executor.add_query("ASK { ?s a :Person }", QueryPriority::High)?;
//!
//! // Execute batch and get results
//! let results = executor.execute_batch_async(dataset).await?;
//!
//! println!("Executed {} queries", results.len());
//! ```

use crate::executor::Dataset;
use crate::query_fingerprinting::{FingerprintConfig, QueryFingerprint, QueryFingerprinter};
use crate::system_load_monitor::AdaptiveConcurrencyController;
use anyhow::Result;
use scirs2_core::metrics::{Counter, Gauge, Timer};
use std::collections::{HashMap, VecDeque};
use std::sync::{Arc, Mutex, RwLock};
use std::time::{Duration, Instant};
use tokio::task::JoinHandle;

/// Query priority levels for batch execution
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
pub enum QueryPriority {
    /// High priority - execute first
    High = 3,
    /// Normal priority - standard execution
    #[default]
    Normal = 2,
    /// Low priority - execute when resources available
    Low = 1,
    /// Background priority - execute during idle time
    Background = 0,
}

/// Batch execution mode
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum BatchMode {
    /// Execute all queries in parallel (fastest, highest memory)
    Parallel,
    /// Execute queries sequentially (slowest, lowest memory)
    Sequential,
    /// Execute in optimized batches based on similarity (balanced)
    #[default]
    Optimized,
    /// Execute with adaptive concurrency based on system load
    Adaptive,
}

/// Configuration for batch query execution
#[derive(Debug, Clone)]
pub struct BatchConfig {
    /// Maximum number of concurrent queries
    pub max_concurrent: usize,
    /// Memory limit in megabytes
    pub memory_limit_mb: usize,
    /// CPU usage limit (0.0 - 1.0)
    pub cpu_limit: f64,
    /// Batch execution mode
    pub mode: BatchMode,
    /// Enable query grouping optimization
    pub enable_grouping: bool,
    /// Enable result caching across batch
    pub enable_caching: bool,
    /// Timeout for entire batch
    pub batch_timeout: Duration,
    /// Timeout for individual queries
    pub query_timeout: Duration,
    /// Enable fair scheduling (prevent starvation)
    pub fair_scheduling: bool,
}

impl Default for BatchConfig {
    fn default() -> Self {
        Self {
            max_concurrent: num_cpus::get(),
            memory_limit_mb: 4096,
            cpu_limit: 0.8,
            mode: BatchMode::default(),
            enable_grouping: true,
            enable_caching: true,
            batch_timeout: Duration::from_secs(300), // 5 minutes
            query_timeout: Duration::from_secs(60),  // 1 minute
            fair_scheduling: true,
        }
    }
}

impl BatchConfig {
    /// Set maximum concurrent queries
    pub fn with_max_concurrent(mut self, max: usize) -> Self {
        self.max_concurrent = max.max(1);
        self
    }

    /// Set memory limit in megabytes
    pub fn with_memory_limit_mb(mut self, limit: usize) -> Self {
        self.memory_limit_mb = limit;
        self
    }

    /// Set CPU usage limit (0.0 - 1.0)
    pub fn with_cpu_limit(mut self, limit: f64) -> Self {
        self.cpu_limit = limit.clamp(0.0, 1.0);
        self
    }

    /// Set batch execution mode
    pub fn with_mode(mut self, mode: BatchMode) -> Self {
        self.mode = mode;
        self
    }

    /// Enable or disable query grouping
    pub fn with_grouping(mut self, enabled: bool) -> Self {
        self.enable_grouping = enabled;
        self
    }

    /// Enable or disable result caching
    pub fn with_caching(mut self, enabled: bool) -> Self {
        self.enable_caching = enabled;
        self
    }

    /// Set batch timeout
    pub fn with_batch_timeout(mut self, timeout: Duration) -> Self {
        self.batch_timeout = timeout;
        self
    }

    /// Set individual query timeout
    pub fn with_query_timeout(mut self, timeout: Duration) -> Self {
        self.query_timeout = timeout;
        self
    }
}

/// A query in the batch with metadata
#[derive(Debug, Clone)]
pub struct BatchQuery {
    /// Query ID (auto-assigned)
    pub id: String,
    /// SPARQL query string
    pub query: String,
    /// Query priority
    pub priority: QueryPriority,
    /// Query fingerprint for grouping
    pub fingerprint: Option<QueryFingerprint>,
    /// Submission timestamp
    pub submitted_at: Instant,
    /// Execution start time
    pub started_at: Option<Instant>,
    /// Execution completion time
    pub completed_at: Option<Instant>,
}

/// Result of a batch query execution
#[derive(Debug, Clone)]
pub struct BatchQueryResult {
    /// Query ID
    pub id: String,
    /// Execution success status
    pub success: bool,
    /// Query results (if successful)
    pub results: Option<String>, // Serialized results
    /// Error message (if failed)
    pub error: Option<String>,
    /// Execution duration
    pub duration: Duration,
    /// Number of results
    pub result_count: usize,
}

/// Statistics for batch execution
#[derive(Debug, Clone)]
pub struct BatchStatistics {
    /// Total number of queries in batch
    pub total_queries: usize,
    /// Number of successful queries
    pub successful_queries: usize,
    /// Number of failed queries
    pub failed_queries: usize,
    /// Total execution time
    pub total_duration: Duration,
    /// Average query execution time
    pub avg_duration: Duration,
    /// Min query execution time
    pub min_duration: Duration,
    /// Max query execution time
    pub max_duration: Duration,
    /// Total results returned
    pub total_results: usize,
    /// Queries per second throughput
    pub throughput: f64,
    /// Peak memory usage (MB)
    pub peak_memory_mb: f64,
    /// Average CPU usage
    pub avg_cpu_usage: f64,
    /// Number of queries cached
    pub cached_queries: usize,
    /// Number of query groups (if grouping enabled)
    pub query_groups: usize,
}

impl BatchStatistics {
    /// Create empty statistics
    pub fn new() -> Self {
        Self {
            total_queries: 0,
            successful_queries: 0,
            failed_queries: 0,
            total_duration: Duration::from_secs(0),
            avg_duration: Duration::from_secs(0),
            min_duration: Duration::MAX,
            max_duration: Duration::from_secs(0),
            total_results: 0,
            throughput: 0.0,
            peak_memory_mb: 0.0,
            avg_cpu_usage: 0.0,
            cached_queries: 0,
            query_groups: 0,
        }
    }

    /// Calculate derived statistics
    pub fn calculate_derived(&mut self) {
        if self.total_queries > 0 {
            let total_secs = self.total_duration.as_secs_f64();
            if total_secs > 0.0 {
                self.throughput = self.total_queries as f64 / total_secs;
            }

            if self.successful_queries > 0 {
                self.avg_duration = self.total_duration / self.successful_queries as u32;
            }
        }
    }

    /// Success rate (0.0 - 1.0)
    pub fn success_rate(&self) -> f64 {
        if self.total_queries == 0 {
            return 0.0;
        }
        self.successful_queries as f64 / self.total_queries as f64
    }

    /// Cache hit rate (0.0 - 1.0)
    pub fn cache_hit_rate(&self) -> f64 {
        if self.total_queries == 0 {
            return 0.0;
        }
        self.cached_queries as f64 / self.total_queries as f64
    }
}

impl Default for BatchStatistics {
    fn default() -> Self {
        Self::new()
    }
}

/// Smart query batch executor
pub struct QueryBatchExecutor {
    /// Configuration
    config: BatchConfig,
    /// Queued queries
    queue: Arc<Mutex<VecDeque<BatchQuery>>>,
    /// Query results (reserved for future streaming/event notification)
    #[allow(dead_code)]
    results: Arc<RwLock<HashMap<String, BatchQueryResult>>>,
    /// Query fingerprinter for grouping
    fingerprinter: QueryFingerprinter,
    /// Result cache
    cache: Arc<RwLock<HashMap<String, String>>>, // fingerprint -> results
    /// Execution statistics
    stats: Arc<RwLock<BatchStatistics>>,
    /// Metrics
    queries_executed: Counter,
    queries_failed: Counter,
    batch_duration: Timer,
    active_queries: Gauge,
}

impl QueryBatchExecutor {
    /// Create a new batch executor
    pub fn new(config: BatchConfig) -> Self {
        Self {
            config,
            queue: Arc::new(Mutex::new(VecDeque::new())),
            results: Arc::new(RwLock::new(HashMap::new())),
            fingerprinter: QueryFingerprinter::new(FingerprintConfig::default()),
            cache: Arc::new(RwLock::new(HashMap::new())),
            stats: Arc::new(RwLock::new(BatchStatistics::new())),
            queries_executed: Counter::new("batch_queries_executed".to_string()),
            queries_failed: Counter::new("batch_queries_failed".to_string()),
            batch_duration: Timer::new("batch_execution_duration".to_string()),
            active_queries: Gauge::new("batch_active_queries".to_string()),
        }
    }

    /// Add a query to the batch
    pub fn add_query(&self, query: impl Into<String>, priority: QueryPriority) -> Result<String> {
        let query = query.into();
        let id = format!("query_{}", uuid::Uuid::new_v4());

        // Calculate fingerprint for grouping
        let fingerprint = if self.config.enable_grouping {
            Some(self.fingerprinter.fingerprint(&query)?)
        } else {
            None
        };

        let batch_query = BatchQuery {
            id: id.clone(),
            query,
            priority,
            fingerprint,
            submitted_at: Instant::now(),
            started_at: None,
            completed_at: None,
        };

        let mut queue = self.queue.lock().expect("lock poisoned");

        // Insert based on priority (maintain priority order)
        if self.config.fair_scheduling {
            // Fair scheduling: append to end of priority group
            let insert_pos = queue
                .iter()
                .rposition(|q| q.priority >= priority)
                .map(|pos| pos + 1)
                .unwrap_or(0);
            queue.insert(insert_pos, batch_query);
        } else {
            // Strict priority: insert at front of priority group
            let insert_pos = queue
                .iter()
                .position(|q| q.priority < priority)
                .unwrap_or(queue.len());
            queue.insert(insert_pos, batch_query);
        }

        Ok(id)
    }

    /// Add multiple queries at once
    pub fn add_queries(&self, queries: Vec<(String, QueryPriority)>) -> Result<Vec<String>> {
        queries
            .into_iter()
            .map(|(q, p)| self.add_query(q, p))
            .collect()
    }

    /// Get number of queued queries
    pub fn queue_size(&self) -> usize {
        self.queue.lock().expect("lock poisoned").len()
    }

    /// Clear the queue
    pub fn clear_queue(&self) {
        self.queue.lock().expect("lock poisoned").clear();
    }

    /// Get batch statistics
    pub fn statistics(&self) -> BatchStatistics {
        self.stats.read().expect("lock poisoned").clone()
    }

    /// Execute the batch (async version)
    pub async fn execute_batch_async<D: Dataset + Send + Sync + 'static>(
        &self,
        dataset: Arc<D>,
    ) -> Result<Vec<BatchQueryResult>> {
        let start_time = Instant::now();

        // Get all queries from queue
        let queries: Vec<BatchQuery> = {
            let mut queue = self.queue.lock().expect("lock poisoned");
            queue.drain(..).collect()
        };

        if queries.is_empty() {
            return Ok(Vec::new());
        }

        // Update stats
        {
            let mut stats = self.stats.write().expect("lock poisoned");
            stats.total_queries = queries.len();
        }

        // Execute based on mode
        let results = match self.config.mode {
            BatchMode::Parallel => self.execute_parallel(queries, dataset).await?,
            BatchMode::Sequential => self.execute_sequential(queries, dataset).await?,
            BatchMode::Optimized => self.execute_optimized(queries, dataset).await?,
            BatchMode::Adaptive => self.execute_adaptive(queries, dataset).await?,
        };

        // Calculate final statistics
        let duration = start_time.elapsed();
        {
            let mut stats = self.stats.write().expect("lock poisoned");
            stats.total_duration = duration;
            stats.calculate_derived();
        }

        self.batch_duration.observe(duration);

        Ok(results)
    }

    /// Execute all queries in parallel
    async fn execute_parallel<D: Dataset + Send + Sync + 'static>(
        &self,
        queries: Vec<BatchQuery>,
        dataset: Arc<D>,
    ) -> Result<Vec<BatchQueryResult>> {
        let semaphore = Arc::new(tokio::sync::Semaphore::new(self.config.max_concurrent));
        let mut handles: Vec<JoinHandle<BatchQueryResult>> = Vec::new();

        for query in queries {
            let permit = semaphore.clone().acquire_owned().await?;
            let dataset = dataset.clone();
            let timeout = self.config.query_timeout;
            let cache = self.cache.clone();
            let enable_caching = self.config.enable_caching;
            let fingerprint = query.fingerprint.clone();

            self.active_queries.inc();

            let handle = tokio::spawn(async move {
                let result = Self::execute_single_query(
                    query,
                    dataset,
                    timeout,
                    cache,
                    enable_caching,
                    fingerprint,
                )
                .await;
                drop(permit);
                result
            });

            handles.push(handle);
        }

        // Collect results
        let mut results = Vec::new();
        for handle in handles {
            match handle.await {
                Ok(result) => {
                    self.update_stats(&result);
                    results.push(result);
                }
                Err(e) => {
                    eprintln!("Task failed: {}", e);
                    self.queries_failed.inc();
                }
            }
            self.active_queries.dec();
        }

        Ok(results)
    }

    /// Execute queries sequentially
    async fn execute_sequential<D: Dataset + Send + Sync + 'static>(
        &self,
        queries: Vec<BatchQuery>,
        dataset: Arc<D>,
    ) -> Result<Vec<BatchQueryResult>> {
        let mut results = Vec::new();

        for query in queries {
            self.active_queries.inc();

            let result = Self::execute_single_query(
                query,
                dataset.clone(),
                self.config.query_timeout,
                self.cache.clone(),
                self.config.enable_caching,
                None,
            )
            .await;

            self.update_stats(&result);
            results.push(result);

            self.active_queries.dec();
        }

        Ok(results)
    }

    /// Execute queries in optimized batches (group similar queries)
    async fn execute_optimized<D: Dataset + Send + Sync + 'static>(
        &self,
        queries: Vec<BatchQuery>,
        dataset: Arc<D>,
    ) -> Result<Vec<BatchQueryResult>> {
        // Group queries by fingerprint
        let mut groups: HashMap<String, Vec<BatchQuery>> = HashMap::new();

        for query in queries {
            let key = query
                .fingerprint
                .as_ref()
                .map(|f| f.hash.clone())
                .unwrap_or_else(|| query.id.clone());

            groups.entry(key).or_default().push(query);
        }

        // Update group count
        {
            let mut stats = self.stats.write().expect("lock poisoned");
            stats.query_groups = groups.len();
        }

        // Execute each group in parallel
        let mut all_results = Vec::new();

        for (_key, group) in groups {
            let group_results = self.execute_parallel(group, dataset.clone()).await?;
            all_results.extend(group_results);
        }

        Ok(all_results)
    }

    /// Execute with adaptive concurrency based on system load
    async fn execute_adaptive<D: Dataset + Send + Sync + 'static>(
        &self,
        queries: Vec<BatchQuery>,
        dataset: Arc<D>,
    ) -> Result<Vec<BatchQueryResult>> {
        use tokio::sync::Semaphore;

        // Create adaptive concurrency controller
        let controller = Arc::new(
            AdaptiveConcurrencyController::new(self.config.max_concurrent)
                .with_thresholds(0.75, 0.40) // High load: 75%, Low load: 40%
                .with_adjustment_interval(Duration::from_secs(5)),
        );

        // Create semaphore for concurrency control
        let initial_permits = controller.current_concurrency();
        let semaphore = Arc::new(Semaphore::new(initial_permits));

        // Spawn background task to adjust semaphore permits based on load
        let controller_clone = Arc::clone(&controller);
        let semaphore_clone = Arc::clone(&semaphore);
        let adjustment_task = tokio::spawn(async move {
            loop {
                tokio::time::sleep(Duration::from_secs(5)).await;

                // Update concurrency based on system load
                controller_clone.update_concurrency();
                let new_concurrency = controller_clone.current_concurrency();

                // Adjust semaphore permits (add or remove as needed)
                let current_permits = semaphore_clone.available_permits();
                if new_concurrency > current_permits {
                    // Add permits
                    semaphore_clone.add_permits(new_concurrency - current_permits);
                }
                // Note: Can't easily remove permits, but new queries will naturally throttle
            }
        });

        // Execute all queries with adaptive concurrency control
        let mut tasks = Vec::new();

        for query in queries {
            let dataset_clone = Arc::clone(&dataset);
            let cache_clone = Arc::clone(&self.cache);
            let timeout = self.config.query_timeout;
            let enable_caching = self.config.enable_caching;
            let fingerprint = query.fingerprint.clone();
            let semaphore_clone = Arc::clone(&semaphore);

            let task = tokio::spawn(async move {
                // Acquire permit (adaptive concurrency control)
                let _permit = semaphore_clone.acquire().await.expect("Semaphore closed");

                // Execute query
                Self::execute_single_query(
                    query,
                    dataset_clone,
                    timeout,
                    cache_clone,
                    enable_caching,
                    fingerprint,
                )
                .await
            });

            tasks.push(task);
        }

        // Wait for all queries to complete
        let mut results = Vec::with_capacity(tasks.len());
        for task in tasks {
            match task.await {
                Ok(result) => results.push(result),
                Err(e) => {
                    // Task panicked or was cancelled
                    eprintln!("Task execution error: {}", e);
                }
            }
        }

        // Stop adjustment task
        adjustment_task.abort();

        Ok(results)
    }

    /// Execute a single query
    async fn execute_single_query<D: Dataset + Send + Sync + 'static>(
        mut query: BatchQuery,
        _dataset: Arc<D>,
        timeout: Duration,
        cache: Arc<RwLock<HashMap<String, String>>>,
        enable_caching: bool,
        _fingerprint: Option<QueryFingerprint>,
    ) -> BatchQueryResult {
        query.started_at = Some(Instant::now());
        let start = Instant::now();

        // Check cache
        if enable_caching {
            if let Some(fp) = &query.fingerprint {
                if let Some(cached) = cache.read().expect("lock poisoned").get(&fp.hash) {
                    query.completed_at = Some(Instant::now());
                    return BatchQueryResult {
                        id: query.id,
                        success: true,
                        results: Some(cached.clone()),
                        error: None,
                        duration: start.elapsed(),
                        result_count: cached.lines().count(),
                    };
                }
            }
        }

        // Execute query with timeout
        let result = tokio::time::timeout(timeout, async {
            // Simulate query execution
            // In production, this would call the actual query executor
            tokio::time::sleep(Duration::from_millis(10)).await;
            Ok::<String, anyhow::Error>(format!("Results for: {}", query.query))
        })
        .await;

        query.completed_at = Some(Instant::now());
        let duration = start.elapsed();

        match result {
            Ok(Ok(results)) => {
                // Cache results
                if enable_caching {
                    if let Some(fp) = &query.fingerprint {
                        cache
                            .write()
                            .expect("lock poisoned")
                            .insert(fp.hash.clone(), results.clone());
                    }
                }

                BatchQueryResult {
                    id: query.id,
                    success: true,
                    results: Some(results.clone()),
                    error: None,
                    duration,
                    result_count: results.lines().count(),
                }
            }
            Ok(Err(e)) => BatchQueryResult {
                id: query.id,
                success: false,
                results: None,
                error: Some(e.to_string()),
                duration,
                result_count: 0,
            },
            Err(_) => BatchQueryResult {
                id: query.id,
                success: false,
                results: None,
                error: Some("Query timeout".to_string()),
                duration,
                result_count: 0,
            },
        }
    }

    /// Update statistics with query result
    fn update_stats(&self, result: &BatchQueryResult) {
        let mut stats = self.stats.write().expect("lock poisoned");

        if result.success {
            stats.successful_queries += 1;
            self.queries_executed.inc();

            stats.total_results += result.result_count;

            if result.duration < stats.min_duration {
                stats.min_duration = result.duration;
            }
            if result.duration > stats.max_duration {
                stats.max_duration = result.duration;
            }
        } else {
            stats.failed_queries += 1;
            self.queries_failed.inc();
        }
    }
}

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

    #[test]
    fn test_batch_config_builder() {
        let config = BatchConfig::default()
            .with_max_concurrent(32)
            .with_memory_limit_mb(8192)
            .with_cpu_limit(0.9)
            .with_mode(BatchMode::Parallel);

        assert_eq!(config.max_concurrent, 32);
        assert_eq!(config.memory_limit_mb, 8192);
        assert_eq!(config.cpu_limit, 0.9);
        assert_eq!(config.mode, BatchMode::Parallel);
    }

    #[test]
    fn test_priority_ordering() {
        assert!(QueryPriority::High > QueryPriority::Normal);
        assert!(QueryPriority::Normal > QueryPriority::Low);
        assert!(QueryPriority::Low > QueryPriority::Background);
    }

    #[test]
    fn test_batch_statistics() {
        let mut stats = BatchStatistics::new();
        stats.total_queries = 100;
        stats.successful_queries = 95;
        stats.failed_queries = 5;
        stats.total_duration = Duration::from_secs(10);
        stats.cached_queries = 20;

        stats.calculate_derived();

        assert_eq!(stats.success_rate(), 0.95);
        assert_eq!(stats.cache_hit_rate(), 0.2);
        assert_eq!(stats.throughput, 10.0); // 100 queries / 10 seconds
    }

    #[test]
    fn test_add_query() {
        let executor = QueryBatchExecutor::new(BatchConfig::default());

        let id1 = executor
            .add_query("SELECT * WHERE { ?s ?p ?o }", QueryPriority::Normal)
            .unwrap();
        let id2 = executor
            .add_query("ASK { ?s a :Person }", QueryPriority::High)
            .unwrap();

        assert_eq!(executor.queue_size(), 2);
        assert_ne!(id1, id2);

        // High priority query should be first
        let queue = executor.queue.lock().expect("lock should not be poisoned");
        assert_eq!(queue[0].priority, QueryPriority::High);
        assert_eq!(queue[1].priority, QueryPriority::Normal);
    }

    #[test]
    fn test_add_multiple_queries() {
        let executor = QueryBatchExecutor::new(BatchConfig::default());

        let queries = vec![
            (
                "SELECT ?s WHERE { ?s ?p ?o }".to_string(),
                QueryPriority::Normal,
            ),
            (
                "SELECT ?p WHERE { ?s ?p ?o }".to_string(),
                QueryPriority::Low,
            ),
            (
                "SELECT ?o WHERE { ?s ?p ?o }".to_string(),
                QueryPriority::High,
            ),
        ];

        let ids = executor.add_queries(queries).unwrap();
        assert_eq!(ids.len(), 3);
        assert_eq!(executor.queue_size(), 3);
    }

    #[test]
    fn test_clear_queue() {
        let executor = QueryBatchExecutor::new(BatchConfig::default());

        executor
            .add_query("SELECT * WHERE { ?s ?p ?o }", QueryPriority::Normal)
            .unwrap();
        executor
            .add_query("ASK { ?s a :Person }", QueryPriority::High)
            .unwrap();

        assert_eq!(executor.queue_size(), 2);

        executor.clear_queue();
        assert_eq!(executor.queue_size(), 0);
    }

    #[test]
    fn test_batch_modes() {
        let modes = vec![
            BatchMode::Parallel,
            BatchMode::Sequential,
            BatchMode::Optimized,
            BatchMode::Adaptive,
        ];

        for mode in modes {
            let config = BatchConfig::default().with_mode(mode);
            assert_eq!(config.mode, mode);
        }
    }

    #[test]
    fn test_fair_scheduling() {
        let config = BatchConfig {
            fair_scheduling: true,
            ..Default::default()
        };

        let executor = QueryBatchExecutor::new(config);

        // Add queries with mixed priorities
        executor.add_query("Q1", QueryPriority::Normal).unwrap();
        executor.add_query("Q2", QueryPriority::High).unwrap();
        executor.add_query("Q3", QueryPriority::Normal).unwrap();
        executor.add_query("Q4", QueryPriority::High).unwrap();

        let queue = executor.queue.lock().expect("lock should not be poisoned");

        // With fair scheduling, order should be: High, High, Normal, Normal
        assert_eq!(queue[0].priority, QueryPriority::High);
        assert_eq!(queue[1].priority, QueryPriority::High);
        assert_eq!(queue[2].priority, QueryPriority::Normal);
        assert_eq!(queue[3].priority, QueryPriority::Normal);
    }

    #[test]
    fn test_config_limits() {
        let config = BatchConfig::default()
            .with_max_concurrent(0) // Should be clamped to 1
            .with_cpu_limit(1.5); // Should be clamped to 1.0

        assert_eq!(config.max_concurrent, 1);
        assert_eq!(config.cpu_limit, 1.0);
    }

    #[test]
    fn test_batch_query_timing() {
        let query = BatchQuery {
            id: "test".to_string(),
            query: "SELECT * WHERE { ?s ?p ?o }".to_string(),
            priority: QueryPriority::Normal,
            fingerprint: None,
            submitted_at: Instant::now(),
            started_at: None,
            completed_at: None,
        };

        assert!(query.started_at.is_none());
        assert!(query.completed_at.is_none());
    }
}