//! Performance Benchmarks for APT-OSTree
//! 
//! This module provides comprehensive performance testing for critical
//! apt-ostree operations including dependency resolution, package operations,
//! and OSTree integration.

use criterion::{black_box, criterion_group, criterion_main, Criterion, BenchmarkId};
use std::time::Instant;
use tracing::{info, warn};
use apt_ostree::DependencyResolver;
use apt_ostree::dependency_resolver::DebPackageMetadata;
use apt_ostree::error::AptOstreeResult;

/// Benchmark dependency resolution performance
fn benchmark_dependency_resolution(c: &mut Criterion) {
    let mut group = c.benchmark_group("dependency_resolution");
    
    // Test with different package counts
    for package_count in [10, 50, 100, 500, 1000] {
        group.bench_with_input(
            BenchmarkId::new("resolve_dependencies", package_count),
            &package_count,
            |b, &count| {
                b.iter(|| {
                    let mut resolver = create_test_resolver(count);
                    black_box(resolver.resolve_dependencies(&["test-package".to_string()]))
                });
            },
        );
    }
    
    group.finish();
}

/// Benchmark package installation simulation
fn benchmark_package_installation(c: &mut Criterion) {
    let mut group = c.benchmark_group("package_installation");
    
    // Test with different package sizes
    for package_size in ["small", "medium", "large"] {
        group.bench_with_input(
            BenchmarkId::new("install_package", package_size),
            &package_size,
            |b, &size| {
                b.iter(|| {
                    black_box(simulate_package_installation(size))
                });
            },
        );
    }
    
    group.finish();
}

/// Benchmark OSTree operations
fn benchmark_ostree_operations(c: &mut Criterion) {
    let mut group = c.benchmark_group("ostree_operations");
    
    // Test commit creation
    group.bench_function("create_commit", |b| {
        b.iter(|| {
            black_box(simulate_ostree_commit())
        });
    });
    
    // Test deployment
    group.bench_function("deploy_commit", |b| {
        b.iter(|| {
            black_box(simulate_ostree_deployment())
        });
    });
    
    group.finish();
}

/// Benchmark memory usage under load
fn benchmark_memory_usage(c: &mut Criterion) {
    let mut group = c.benchmark_group("memory_usage");
    
    // Test with different data sizes
    for data_size in [1_000, 10_000, 100_000, 1_000_000] {
        group.bench_with_input(
            BenchmarkId::new("memory_usage", data_size),
            &data_size,
            |b, &size| {
                b.iter(|| {
                    black_box(measure_memory_usage(size))
                });
            },
        );
    }
    
    group.finish();
}

/// Benchmark concurrent operations
fn benchmark_concurrent_operations(c: &mut Criterion) {
    let mut group = c.benchmark_group("concurrent_operations");
    
    // Test with different thread counts
    for thread_count in [1, 2, 4, 8, 16] {
        group.bench_with_input(
            BenchmarkId::new("concurrent_package_ops", thread_count),
            &thread_count,
            |b, &threads| {
                b.iter(|| {
                    black_box(simulate_concurrent_operations(threads))
                });
            },
        );
    }
    
    group.finish();
}

/// Benchmark error handling performance
fn benchmark_error_handling(c: &mut Criterion) {
    let mut group = c.benchmark_group("error_handling");
    
    // Test different error scenarios
    let error_scenarios = ["network_timeout", "permission_denied", "package_not_found", "dependency_conflict"];
    
    for scenario in error_scenarios {
        group.bench_with_input(
            BenchmarkId::new("error_handling", scenario),
            &scenario,
            |b, &scenario| {
                b.iter(|| {
                    black_box(simulate_error_scenario(scenario))
                });
            },
        );
    }
    
    group.finish();
}

// Helper functions for benchmarks

/// Create a test dependency resolver with specified package count
fn create_test_resolver(package_count: usize) -> DependencyResolver {
    let mut resolver = DependencyResolver::new();
    
    // Add test packages with dependencies
    for i in 0..package_count {
        let package_name = format!("package-{}", i);
        let dependencies = if i > 0 {
            vec![format!("package-{}", i - 1)]
        } else {
            vec![]
        };
        
        let package = DebPackageMetadata {
            name: package_name,
            version: "1.0.0".to_string(),
            architecture: "amd64".to_string(),
            depends: dependencies,
            conflicts: vec![],
            provides: vec![],
            breaks: vec![],
            replaces: vec![],
        };
        
        resolver.add_available_packages(vec![package]);
    }
    
    resolver
}

/// Simulate package installation
fn simulate_package_installation(package_size: &str) -> AptOstreeResult<()> {
    // Simulate different package sizes
    let operation_count = match package_size {
        "small" => 10,
        "medium" => 100,
        "large" => 1000,
        _ => 100,
    };
    
    for _ in 0..operation_count {
        // Simulate package operation
        std::thread::sleep(std::time::Duration::from_micros(100));
    }
    
    Ok(())
}

/// Simulate OSTree commit creation
fn simulate_ostree_commit() -> AptOstreeResult<()> {
    // Simulate commit creation time
    std::thread::sleep(std::time::Duration::from_millis(10));
    Ok(())
}

/// Simulate OSTree deployment
fn simulate_ostree_deployment() -> AptOstreeResult<()> {
    // Simulate deployment time
    std::thread::sleep(std::time::Duration::from_millis(50));
    Ok(())
}

/// Measure memory usage for given data size
fn measure_memory_usage(data_size: usize) -> usize {
    // Simulate memory allocation and usage
    let mut data = Vec::with_capacity(data_size);
    for i in 0..data_size {
        data.push(i as u8);
    }
    
    // Return approximate memory usage
    std::mem::size_of_val(&data) + data.capacity()
}

/// Simulate concurrent operations
fn simulate_concurrent_operations(thread_count: usize) -> AptOstreeResult<()> {
    use std::sync::{Arc, Mutex};
    use std::thread;
    
    let counter = Arc::new(Mutex::new(0));
    let mut handles = vec![];
    
    for _ in 0..thread_count {
        let counter = Arc::clone(&counter);
        let handle = thread::spawn(move || {
            let mut count = counter.lock().unwrap();
            *count += 1;
            // Simulate work
            std::thread::sleep(std::time::Duration::from_micros(100));
        });
        handles.push(handle);
    }
    
    for handle in handles {
        handle.join().unwrap();
    }
    
    Ok(())
}

/// Simulate different error scenarios
fn simulate_error_scenario(scenario: &str) -> AptOstreeResult<()> {
    match scenario {
        "network_timeout" => {
            // Simulate network timeout
            std::thread::sleep(std::time::Duration::from_millis(100));
            Err(apt_ostree::error::AptOstreeError::Network("Connection timeout".to_string()))
        }
        "permission_denied" => {
            // Simulate permission error
            Err(apt_ostree::error::AptOstreeError::PermissionDenied("Access denied".to_string()))
        }
        "package_not_found" => {
            // Simulate package not found
            Err(apt_ostree::error::AptOstreeError::PackageNotFound("Package not found".to_string()))
        }
        "dependency_conflict" => {
            // Simulate dependency conflict
            Err(apt_ostree::error::AptOstreeError::DependencyConflict("Conflicting packages".to_string()))
        }
        _ => Ok(()),
    }
}

/// Run comprehensive performance tests
pub fn run_performance_tests() -> AptOstreeResult<()> {
    info!("🚀 Starting comprehensive performance tests...");
    
    let start_time = Instant::now();
    
    // Test dependency resolution performance
    info!("Testing dependency resolution performance...");
    let mut resolver = create_test_resolver(1000);
    let resolution_start = Instant::now();
    let _resolution = resolver.resolve_dependencies(&["package-999".to_string()])?;
    let resolution_time = resolution_start.elapsed();
    info!("✅ Dependency resolution (1000 packages): {:?}", resolution_time);
    
    // Test memory usage
    info!("Testing memory usage...");
    let memory_start = Instant::now();
    let memory_usage = measure_memory_usage(1_000_000);
    let memory_time = memory_start.elapsed();
    info!("✅ Memory usage test: {} bytes in {:?}", memory_usage, memory_time);
    
    // Test concurrent operations
    info!("Testing concurrent operations...");
    let concurrent_start = Instant::now();
    simulate_concurrent_operations(8)?;
    let concurrent_time = concurrent_start.elapsed();
    info!("✅ Concurrent operations (8 threads): {:?}", concurrent_time);
    
    let total_time = start_time.elapsed();
    info!("🎉 All performance tests completed in {:?}", total_time);
    
    Ok(())
}

// Criterion benchmark configuration
criterion_group!(
    benches,
    benchmark_dependency_resolution,
    benchmark_package_installation,
    benchmark_ostree_operations,
    benchmark_memory_usage,
    benchmark_concurrent_operations,
    benchmark_error_handling
);

criterion_main!(benches);

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    fn test_performance_test_runner() {
        let result = run_performance_tests();
        assert!(result.is_ok(), "Performance tests should complete successfully");
    }
    
    #[test]
    fn test_memory_usage_measurement() {
        let usage = measure_memory_usage(1000);
        assert!(usage > 0, "Memory usage should be measurable");
    }
    
    #[test]
    fn test_concurrent_operations() {
        let result = simulate_concurrent_operations(4);
        assert!(result.is_ok(), "Concurrent operations should complete");
    }
}