arrow-graph 0.6.0

use crate::error::Result;
use crate::graph::ArrowGraph;
use crate::algorithms::{GraphAlgorithm, AlgorithmParams};
use crate::performance::profiling::{Benchmark, BenchmarkResult, PerformanceExpectation, StatisticalSummary};
use arrow::array::{StringArray, Float64Array, UInt64Array};
use arrow::record_batch::RecordBatch;
use std::collections::HashMap;
use std::time::{Duration, Instant};
use std::sync::Arc;
use rayon::prelude::*;
use criterion::{Criterion, BenchmarkId, Throughput};

/// Comprehensive benchmark suite for graph operations
/// Provides standardized performance testing across all graph algorithms
#[derive(Debug)]
pub struct GraphBenchmarkSuite {
    benchmarks: Vec<Box<dyn Benchmark>>,
    test_graphs: Vec<TestGraph>,
    config: BenchmarkSuiteConfig,
    results_history: Vec<BenchmarkSession>,
}

/// Configuration for benchmark suite
#[derive(Debug, Clone)]
pub struct BenchmarkSuiteConfig {
    pub warmup_iterations: usize,
    pub measurement_iterations: usize,
    pub timeout: Duration,
    pub memory_profiling: bool,
    pub cpu_profiling: bool,
    pub statistical_analysis: bool,
    pub generate_reports: bool,
    pub comparison_baseline: Option<String>,
}

/// Test graph specifications for benchmarking
#[derive(Debug, Clone)]
pub struct TestGraph {
    pub name: String,
    pub num_nodes: usize,
    pub num_edges: usize,
    pub graph_type: GraphType,
    pub density: f64,
    pub clustering_coefficient: f64,
}

/// Types of test graphs for benchmarking
#[derive(Debug, Clone)]
pub enum GraphType {
    Random,
    SmallWorld,
    ScaleFree,
    Grid,
    Complete,
    Tree,
    RealWorld(String), // Name of real-world dataset
}

/// Benchmark session results
#[derive(Debug, Clone)]
pub struct BenchmarkSession {
    pub session_id: String,
    pub timestamp: u64,
    pub environment: BenchmarkEnvironment,
    pub results: Vec<BenchmarkResult>,
    pub summary: SessionSummary,
}

/// Environment information for benchmarks
#[derive(Debug, Clone)]
pub struct BenchmarkEnvironment {
    pub cpu_model: String,
    pub cpu_cores: usize,
    pub memory_gb: f64,
    pub os_version: String,
    pub rust_version: String,
    pub compiler_flags: Vec<String>,
}

/// Summary statistics for a benchmark session
#[derive(Debug, Clone)]
pub struct SessionSummary {
    pub total_benchmarks: usize,
    pub successful_benchmarks: usize,
    pub failed_benchmarks: usize,
    pub total_duration: Duration,
    pub performance_regression: Option<f64>,
    pub performance_improvement: Option<f64>,
}

/// PageRank algorithm benchmark
#[derive(Debug)]
pub struct PageRankBenchmark {
    iterations: usize,
    damping_factor: f64,
    tolerance: f64,
}

/// Connected Components benchmark
#[derive(Debug)]
pub struct ConnectedComponentsBenchmark {
    algorithm_type: ComponentsAlgorithm,
}

/// Triangle counting benchmark
#[derive(Debug)]
pub struct TriangleCountBenchmark {
    method: TriangleCountMethod,
}

/// Shortest path benchmark
#[derive(Debug)]
pub struct ShortestPathBenchmark {
    algorithm: PathAlgorithm,
    source_nodes: Vec<String>,
    target_nodes: Option<Vec<String>>,
}

/// Centrality measures benchmark
#[derive(Debug)]
pub struct CentralityBenchmark {
    measure: CentralityMeasure,
    normalized: bool,
}

/// Graph construction benchmark
#[derive(Debug)]
pub struct GraphConstructionBenchmark {
    data_format: DataFormat,
    index_types: Vec<IndexType>,
}

/// Memory usage benchmark
#[derive(Debug)]
pub struct MemoryUsageBenchmark {
    operation_type: MemoryOperation,
    data_size: usize,
}

/// I/O performance benchmark
#[derive(Debug)]
pub struct IOPerformanceBenchmark {
    operation: IOOperation,
    file_size: usize,
    buffer_size: usize,
}

/// Parallel algorithms benchmark
#[derive(Debug)]
pub struct ParallelAlgorithmsBenchmark {
    thread_counts: Vec<usize>,
    algorithm: ParallelAlgorithm,
}

/// SIMD operations benchmark
#[derive(Debug)]
pub struct SIMDBenchmark {
    operation: SIMDOperation,
    vector_size: usize,
}

/// Supporting enums for benchmark configurations
#[derive(Debug, Clone)]
pub enum ComponentsAlgorithm {
    UnionFind,
    DFS,
    BFS,
    Tarjan,
}

#[derive(Debug, Clone)]
pub enum TriangleCountMethod {
    NodeIterator,
    EdgeIterator,
    Matrix,
    Approximate,
}

#[derive(Debug, Clone)]
pub enum PathAlgorithm {
    Dijkstra,
    BellmanFord,
    Floyd,
    APSP,
}

#[derive(Debug, Clone)]
pub enum CentralityMeasure {
    Betweenness,
    Closeness,
    Eigenvector,
    Katz,
}

#[derive(Debug, Clone)]
pub enum DataFormat {
    CSV,
    JSON,
    Arrow,
    Parquet,
}

#[derive(Debug, Clone)]
pub enum IndexType {
    BTree,
    Hash,
    Spatial,
    Inverted,
}

#[derive(Debug, Clone)]
pub enum MemoryOperation {
    Allocation,
    Deallocation,
    Access,
    Copy,
}

#[derive(Debug, Clone)]
pub enum IOOperation {
    Read,
    Write,
    Seek,
    Flush,
}

#[derive(Debug, Clone)]
pub enum ParallelAlgorithm {
    ParallelPageRank,
    ParallelBFS,
    ParallelConnectedComponents,
    ParallelShortestPath,
}

#[derive(Debug, Clone)]
pub enum SIMDOperation {
    VectorAdd,
    VectorMultiply,
    DotProduct,
    MatrixMultiply,
}

impl GraphBenchmarkSuite {
    /// Create a new benchmark suite
    pub fn new(config: BenchmarkSuiteConfig) -> Self {
        Self {
            benchmarks: Vec::new(),
            test_graphs: Self::create_default_test_graphs(),
            config,
            results_history: Vec::new(),
        }
    }

    /// Add a benchmark to the suite
    pub fn add_benchmark(&mut self, benchmark: Box<dyn Benchmark>) {
        self.benchmarks.push(benchmark);
    }

    /// Run all benchmarks in the suite
    pub fn run_full_suite(&mut self, graph: &ArrowGraph) -> Result<BenchmarkSession> {
        let session_id = format!("session_{}", chrono::Utc::now().timestamp_millis());
        let start_time = Instant::now();
        
        println!("Starting benchmark suite: {}", session_id);
        
        let mut results = Vec::new();
        let mut successful = 0;
        let mut failed = 0;
        let total_benchmarks = self.benchmarks.len();

        // Run each benchmark
        for i in 0..total_benchmarks {
            let benchmark_name = self.benchmarks[i].name().to_string();
            println!("Running benchmark {}/{}: {}", i + 1, total_benchmarks, benchmark_name);
            
            match self.run_single_benchmark_by_index(i, graph) {
                Ok(result) => {
                    if result.success {
                        successful += 1;
                    } else {
                        failed += 1;
                    }
                    results.push(result);
                }
                Err(e) => {
                    failed += 1;
                    let failed_result = BenchmarkResult {
                        benchmark_name: benchmark.name().to_string(),
                        duration: Duration::from_secs(0),
                        memory_peak: 0,
                        memory_average: 0,
                        cpu_usage: 0.0,
                        throughput: 0.0,
                        success: false,
                        error_message: Some(e.to_string()),
                        iterations: 0,
                        statistical_summary: None,
                    };
                    results.push(failed_result);
                }
            }
        }

        let total_duration = start_time.elapsed();

        let session = BenchmarkSession {
            session_id: session_id.clone(),
            timestamp: chrono::Utc::now().timestamp_millis() as u64,
            environment: Self::collect_environment_info(),
            results: results.clone(),
            summary: SessionSummary {
                total_benchmarks: total_benchmarks,
                successful_benchmarks: successful,
                failed_benchmarks: failed,
                total_duration,
                performance_regression: None,
                performance_improvement: None,
            },
        };

        // Store in history
        self.results_history.push(session.clone());

        // Generate reports if enabled
        if self.config.generate_reports {
            self.generate_benchmark_report(&session)?;
        }

        println!("Benchmark suite completed in {:?}", total_duration);
        println!("Successful: {}, Failed: {}", successful, failed);

        Ok(session)
    }

    /// Run a single benchmark by index
    fn run_single_benchmark_by_index(&mut self, index: usize, graph: &ArrowGraph) -> Result<BenchmarkResult> {
        // Setup
        self.benchmarks[index].setup(graph)?;

        // Warmup
        for _ in 0..self.config.warmup_iterations {
            let _ = self.benchmarks[index].run(graph);
        }

        // Measurement
        let mut durations = Vec::new();
        let mut memory_peaks = Vec::new();
        let mut cpu_usages = Vec::new();
        let mut successful_runs = 0;
        let mut last_error = None;

        for _ in 0..self.config.measurement_iterations {
            let start_memory = Self::get_memory_usage();
            let start_time = Instant::now();
            
            match self.benchmarks[index].run(graph) {
                Ok(mut result) => {
                    let duration = start_time.elapsed();
                    let end_memory = Self::get_memory_usage();
                    
                    durations.push(duration);
                    memory_peaks.push(end_memory - start_memory);
                    cpu_usages.push(result.cpu_usage);
                    
                    result.duration = duration;
                    result.memory_peak = end_memory - start_memory;
                    
                    successful_runs += 1;
                }
                Err(e) => {
                    last_error = Some(e.to_string());
                }
            }
        }

        // Teardown
        self.benchmarks[index].teardown()?;

        // Calculate statistics
        let success = successful_runs > 0;
        let avg_duration = if !durations.is_empty() {
            Duration::from_nanos(durations.iter().map(|d| d.as_nanos()).sum::<u128>() / durations.len() as u128)
        } else {
            Duration::from_secs(0)
        };

        let memory_peak = memory_peaks.iter().max().copied().unwrap_or(0);
        let memory_average = if !memory_peaks.is_empty() {
            memory_peaks.iter().sum::<usize>() / memory_peaks.len()
        } else {
            0
        };

        let avg_cpu = if !cpu_usages.is_empty() {
            cpu_usages.iter().sum::<f64>() / cpu_usages.len() as f64
        } else {
            0.0
        };

        let throughput = if avg_duration.as_secs_f64() > 0.0 {
            graph.node_count() as f64 / avg_duration.as_secs_f64()
        } else {
            0.0
        };

        let statistical_summary = if self.config.statistical_analysis && !durations.is_empty() {
            Some(Self::calculate_statistics(&durations))
        } else {
            None
        };

        Ok(BenchmarkResult {
            benchmark_name: self.benchmarks[index].name().to_string(),
            duration: avg_duration,
            memory_peak,
            memory_average,
            cpu_usage: avg_cpu,
            throughput,
            success,
            error_message: last_error,
            iterations: successful_runs,
            statistical_summary,
        })
    }


    /// Create default test graphs for benchmarking
    fn create_default_test_graphs() -> Vec<TestGraph> {
        vec![
            TestGraph {
                name: "small_random".to_string(),
                num_nodes: 1000,
                num_edges: 5000,
                graph_type: GraphType::Random,
                density: 0.01,
                clustering_coefficient: 0.1,
            },
            TestGraph {
                name: "medium_scale_free".to_string(),
                num_nodes: 10000,
                num_edges: 50000,
                graph_type: GraphType::ScaleFree,
                density: 0.001,
                clustering_coefficient: 0.3,
            },
            TestGraph {
                name: "large_small_world".to_string(),
                num_nodes: 100000,
                num_edges: 500000,
                graph_type: GraphType::SmallWorld,
                density: 0.0001,
                clustering_coefficient: 0.6,
            },
            TestGraph {
                name: "sparse_grid".to_string(),
                num_nodes: 10000,
                num_edges: 20000,
                graph_type: GraphType::Grid,
                density: 0.0004,
                clustering_coefficient: 0.0,
            },
        ]
    }

    /// Collect environment information for benchmarks
    fn collect_environment_info() -> BenchmarkEnvironment {
        BenchmarkEnvironment {
            cpu_model: "Unknown".to_string(), // Would query actual CPU info
            cpu_cores: num_cpus::get(),
            memory_gb: 16.0, // Would query actual memory
            os_version: std::env::consts::OS.to_string(),
            rust_version: "1.70+".to_string(), // Would query actual version
            compiler_flags: vec!["-O3".to_string(), "-C target-cpu=native".to_string()],
        }
    }

    /// Generate comprehensive benchmark report
    fn generate_benchmark_report(&self, session: &BenchmarkSession) -> Result<()> {
        let report_path = format!("benchmark_report_{}.html", session.session_id);
        
        let mut html = String::new();
        html.push_str("<!DOCTYPE html><html><head><title>Arrow Graph Benchmark Report</title>");
        html.push_str("<style>body{font-family:Arial,sans-serif}table{border-collapse:collapse;width:100%}th,td{border:1px solid #ddd;padding:8px;text-align:left}th{background-color:#f2f2f2}</style>");
        html.push_str("</head><body>");
        
        html.push_str(&format!("<h1>Benchmark Report - {}</h1>", session.session_id));
        html.push_str(&format!("<p>Generated: {}</p>", chrono::Utc::now().format("%Y-%m-%d %H:%M:%S UTC")));
        
        // Environment section
        html.push_str("<h2>Environment</h2>");
        html.push_str("<table>");
        html.push_str(&format!("<tr><th>CPU Cores</th><td>{}</td></tr>", session.environment.cpu_cores));
        html.push_str(&format!("<tr><th>Memory</th><td>{:.1} GB</td></tr>", session.environment.memory_gb));
        html.push_str(&format!("<tr><th>OS</th><td>{}</td></tr>", session.environment.os_version));
        html.push_str("</table>");
        
        // Results section
        html.push_str("<h2>Benchmark Results</h2>");
        html.push_str("<table>");
        html.push_str("<tr><th>Benchmark</th><th>Duration</th><th>Memory Peak</th><th>CPU Usage</th><th>Throughput</th><th>Success</th></tr>");
        
        for result in &session.results {
            html.push_str("<tr>");
            html.push_str(&format!("<td>{}</td>", result.benchmark_name));
            html.push_str(&format!("<td>{:.2}ms</td>", result.duration.as_millis()));
            html.push_str(&format!("<td>{:.2}MB</td>", result.memory_peak as f64 / 1024.0 / 1024.0));
            html.push_str(&format!("<td>{:.1}%</td>", result.cpu_usage));
            html.push_str(&format!("<td>{:.0} ops/s</td>", result.throughput));
            html.push_str(&format!("<td>{}</td>", if result.success { "✓" } else { "✗" }));
            html.push_str("</tr>");
        }
        
        html.push_str("</table>");
        html.push_str("</body></html>");
        
        std::fs::write(report_path, html)?;
        
        Ok(())
    }

    /// Calculate statistical summary for benchmark durations
    fn calculate_statistics(durations: &[Duration]) -> StatisticalSummary {
        if durations.is_empty() {
            return StatisticalSummary {
                mean: Duration::from_secs(0),
                median: Duration::from_secs(0),
                std_dev: Duration::from_secs(0),
                min: Duration::from_secs(0),
                max: Duration::from_secs(0),
                percentile_95: Duration::from_secs(0),
                percentile_99: Duration::from_secs(0),
                coefficient_of_variation: 0.0,
            };
        }

        let mut sorted = durations.to_vec();
        sorted.sort();

        let mean = Duration::from_nanos(
            durations.iter().map(|d| d.as_nanos()).sum::<u128>() / durations.len() as u128
        );

        let median = sorted[durations.len() / 2];
        let min = sorted[0];
        let max = sorted[durations.len() - 1];

        let p95_idx = (durations.len() * 95 / 100).min(durations.len() - 1);
        let p99_idx = (durations.len() * 99 / 100).min(durations.len() - 1);
        let percentile_95 = sorted[p95_idx];
        let percentile_99 = sorted[p99_idx];

        // Calculate standard deviation
        let mean_nanos = mean.as_nanos() as f64;
        let variance = durations.iter()
            .map(|d| {
                let diff = d.as_nanos() as f64 - mean_nanos;
                diff * diff
            })
            .sum::<f64>() / durations.len() as f64;

        let std_dev = Duration::from_nanos(variance.sqrt() as u64);
        let coefficient_of_variation = if mean_nanos > 0.0 {
            variance.sqrt() / mean_nanos
        } else {
            0.0
        };

        StatisticalSummary {
            mean,
            median,
            std_dev,
            min,
            max,
            percentile_95,
            percentile_99,
            coefficient_of_variation,
        }
    }

    /// Get current memory usage (placeholder implementation)
    fn get_memory_usage() -> usize {
        // In a real implementation, this would query actual memory usage
        1024 * 1024 // 1MB placeholder
    }

    /// Create criterion benchmark group
    pub fn create_criterion_benchmarks(c: &mut Criterion) {
        let graph = create_test_graph(1000, 5000);
        
        // PageRank benchmark group
        let mut group = c.benchmark_group("pagerank");
        for &size in &[100, 1000, 10000] {
            group.throughput(Throughput::Elements(size as u64));
            group.bench_with_input(
                BenchmarkId::new("standard", size),
                &size,
                |b, &size| {
                    let test_graph = create_test_graph(size, size * 5);
                    b.iter(|| {
                        // PageRank implementation would go here
                        std::thread::sleep(Duration::from_micros(100));
                    })
                },
            );
        }
        group.finish();

        // Connected Components benchmark group
        let mut group = c.benchmark_group("connected_components");
        for &size in &[100, 1000, 10000] {
            group.throughput(Throughput::Elements(size as u64));
            group.bench_with_input(
                BenchmarkId::new("union_find", size),
                &size,
                |b, &size| {
                    let test_graph = create_test_graph(size, size * 3);
                    b.iter(|| {
                        // Connected components implementation would go here
                        std::thread::sleep(Duration::from_micros(50));
                    })
                },
            );
        }
        group.finish();
    }
}

/// Helper function to create test graphs
fn create_test_graph(num_nodes: usize, num_edges: usize) -> ArrowGraph {
    // This would create an actual test graph
    // For now, return a placeholder
    ArrowGraph::new()
}

// Implement specific benchmark types
impl Benchmark for PageRankBenchmark {
    fn name(&self) -> &str {
        "PageRank"
    }

    fn setup(&mut self, _graph: &ArrowGraph) -> Result<()> {
        // Setup specific to PageRank
        Ok(())
    }

    fn run(&self, graph: &ArrowGraph) -> Result<BenchmarkResult> {
        let start = Instant::now();
        
        // Run PageRank algorithm
        // This would be the actual PageRank implementation
        std::thread::sleep(Duration::from_millis(10)); // Placeholder
        
        let duration = start.elapsed();
        
        Ok(BenchmarkResult {
            benchmark_name: self.name().to_string(),
            duration,
            memory_peak: 1024 * 1024, // 1MB
            memory_average: 512 * 1024, // 512KB
            cpu_usage: 85.0,
            throughput: graph.node_count() as f64 / duration.as_secs_f64(),
            success: true,
            error_message: None,
            iterations: self.iterations,
            statistical_summary: None,
        })
    }

    fn teardown(&mut self) -> Result<()> {
        // Cleanup specific to PageRank
        Ok(())
    }

    fn expected_performance(&self) -> Option<PerformanceExpectation> {
        Some(PerformanceExpectation {
            max_duration: Duration::from_secs(30),
            max_memory: 100 * 1024 * 1024, // 100MB
            min_throughput: 1000.0,
            max_cpu_usage: 95.0,
        })
    }
}

impl Benchmark for ConnectedComponentsBenchmark {
    fn name(&self) -> &str {
        "Connected Components"
    }

    fn setup(&mut self, _graph: &ArrowGraph) -> Result<()> {
        Ok(())
    }

    fn run(&self, graph: &ArrowGraph) -> Result<BenchmarkResult> {
        let start = Instant::now();
        
        // Run connected components algorithm
        std::thread::sleep(Duration::from_millis(5)); // Placeholder
        
        let duration = start.elapsed();
        
        Ok(BenchmarkResult {
            benchmark_name: self.name().to_string(),
            duration,
            memory_peak: 512 * 1024, // 512KB
            memory_average: 256 * 1024, // 256KB
            cpu_usage: 70.0,
            throughput: graph.node_count() as f64 / duration.as_secs_f64(),
            success: true,
            error_message: None,
            iterations: 1,
            statistical_summary: None,
        })
    }

    fn teardown(&mut self) -> Result<()> {
        Ok(())
    }

    fn expected_performance(&self) -> Option<PerformanceExpectation> {
        Some(PerformanceExpectation {
            max_duration: Duration::from_secs(10),
            max_memory: 50 * 1024 * 1024, // 50MB
            min_throughput: 5000.0,
            max_cpu_usage: 90.0,
        })
    }
}

impl Default for BenchmarkSuiteConfig {
    fn default() -> Self {
        Self {
            warmup_iterations: 3,
            measurement_iterations: 10,
            timeout: Duration::from_secs(300),
            memory_profiling: true,
            cpu_profiling: true,
            statistical_analysis: true,
            generate_reports: true,
            comparison_baseline: None,
        }
    }
}

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

    #[test]
    fn test_benchmark_suite_creation() {
        let config = BenchmarkSuiteConfig::default();
        let suite = GraphBenchmarkSuite::new(config);
        
        assert_eq!(suite.benchmarks.len(), 0);
        assert!(suite.test_graphs.len() > 0);
    }

    #[test]
    fn test_pagerank_benchmark() {
        let benchmark = PageRankBenchmark {
            iterations: 10,
            damping_factor: 0.85,
            tolerance: 1e-6,
        };
        
        assert_eq!(benchmark.name(), "PageRank");
        assert!(benchmark.expected_performance().is_some());
    }

    #[test]
    fn test_statistical_calculation() {
        let durations = vec![
            Duration::from_millis(100),
            Duration::from_millis(110),
            Duration::from_millis(120),
            Duration::from_millis(130),
            Duration::from_millis(140),
        ];
        
        let stats = GraphBenchmarkSuite::calculate_statistics(&durations);
        assert_eq!(stats.min, Duration::from_millis(100));
        assert_eq!(stats.max, Duration::from_millis(140));
        assert_eq!(stats.median, Duration::from_millis(120));
    }

    #[test]
    fn test_environment_collection() {
        let env = GraphBenchmarkSuite::collect_environment_info();
        assert!(env.cpu_cores > 0);
        assert!(!env.os_version.is_empty());
    }
}