quantrs2-anneal 0.1.3

//! Stress testing coordinator

use super::{
    thread, ApplicationError, ApplicationResult, Duration, HashMap, Instant, LoadPattern,
    ResourceType, ScalabilityAlgorithm, ScalabilityMetrics, SizeProgression, StressCriterionType,
    StressResourceConstraints, StressTestResult, VecDeque,
};
use scirs2_core::random::prelude::*;

/// Stress testing coordinator
#[derive(Debug)]
pub struct StressTestCoordinator {
    /// Stress test configurations
    pub stress_configs: Vec<StressTestConfig>,
    /// Load generators
    pub load_generators: Vec<LoadGenerator>,
    /// Resource monitors
    pub resource_monitors: Vec<ResourceMonitor>,
    /// Scalability analyzers
    pub scalability_analyzers: Vec<ScalabilityAnalyzer>,
}

/// Stress test configuration
#[derive(Debug, Clone)]
pub struct StressTestConfig {
    /// Test identifier
    pub id: String,
    /// Load pattern to apply
    pub load_pattern: LoadPattern,
    /// Size progression strategy
    pub size_progression: SizeProgression,
    /// Resource constraints
    pub resource_constraints: StressResourceConstraints,
    /// Success criteria
    pub success_criteria: Vec<StressSuccessCriterion>,
}

/// Stress test success criterion
#[derive(Debug, Clone)]
pub struct StressSuccessCriterion {
    /// Criterion type
    pub criterion_type: StressCriterionType,
    /// Target value
    pub target_value: f64,
    /// Tolerance
    pub tolerance: f64,
}

/// Load generator for stress testing
#[derive(Debug)]
pub struct LoadGenerator {
    /// Generator identifier
    pub id: String,
    /// Load generation strategy
    pub strategy: LoadGenerationStrategy,
    /// Current load level
    pub current_load: f64,
    /// Maximum load capacity
    pub max_load: f64,
    /// Load increment step
    pub load_step: f64,
}

/// Load generation strategies
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum LoadGenerationStrategy {
    /// Gradual increase
    Gradual,
    /// Step increases
    Step,
    /// Binary search for limits
    BinarySearch,
    /// Random load spikes
    RandomSpikes,
}

/// Resource monitor for stress testing
#[derive(Debug)]
pub struct ResourceMonitor {
    /// Monitor identifier
    pub id: String,
    /// Resource type being monitored
    pub resource_type: ResourceType,
    /// Monitoring frequency
    pub frequency: Duration,
    /// Usage history
    pub usage_history: VecDeque<ResourceUsagePoint>,
    /// Alert thresholds
    pub alert_thresholds: Vec<f64>,
}

/// Resource usage data point
#[derive(Debug, Clone)]
pub struct ResourceUsagePoint {
    /// Timestamp
    pub timestamp: Instant,
    /// Usage value
    pub usage: f64,
    /// Associated metadata
    pub metadata: HashMap<String, String>,
}

/// Scalability analyzer for stress test results
#[derive(Debug)]
pub struct ScalabilityAnalyzer {
    /// Analyzer identifier
    pub id: String,
    /// Analysis algorithm
    pub algorithm: ScalabilityAlgorithm,
    /// Scalability metrics
    pub metrics: ScalabilityMetrics,
    /// Analysis parameters
    pub parameters: HashMap<String, f64>,
}

impl StressTestCoordinator {
    #[must_use]
    pub fn new() -> Self {
        Self {
            stress_configs: Self::create_default_configs(),
            load_generators: Self::create_default_generators(),
            resource_monitors: Self::create_default_monitors(),
            scalability_analyzers: Self::create_default_analyzers(),
        }
    }

    /// Create default stress test configurations
    fn create_default_configs() -> Vec<StressTestConfig> {
        vec![
            StressTestConfig {
                id: "linear_load_test".to_string(),
                load_pattern: LoadPattern::LinearRamp {
                    start: 1.0,
                    end: 100.0,
                    duration: Duration::from_secs(300),
                },
                size_progression: SizeProgression::Linear {
                    start: 10,
                    end: 1000,
                    step: 10,
                },
                resource_constraints: StressResourceConstraints {
                    max_memory: Some(4096), // 4GB
                    max_cpu: Some(0.9),     // 90%
                    max_time: Some(Duration::from_secs(600)),
                    max_concurrent: Some(8),
                },
                success_criteria: vec![
                    StressSuccessCriterion {
                        criterion_type: StressCriterionType::ThroughputMaintenance,
                        target_value: 0.8,
                        tolerance: 0.1,
                    },
                    StressSuccessCriterion {
                        criterion_type: StressCriterionType::ResponseTime,
                        target_value: 10.0, // seconds
                        tolerance: 2.0,
                    },
                ],
            },
            StressTestConfig {
                id: "exponential_load_test".to_string(),
                load_pattern: LoadPattern::ExponentialRamp {
                    start: 1.0,
                    end: 1000.0,
                    duration: Duration::from_secs(180),
                },
                size_progression: SizeProgression::Exponential {
                    start: 10,
                    end: 10_000,
                    factor: 2.0,
                },
                resource_constraints: StressResourceConstraints {
                    max_memory: Some(8192), // 8GB
                    max_cpu: Some(0.95),    // 95%
                    max_time: Some(Duration::from_secs(1200)),
                    max_concurrent: Some(16),
                },
                success_criteria: vec![StressSuccessCriterion {
                    criterion_type: StressCriterionType::ErrorRate,
                    target_value: 0.05, // 5% max error rate
                    tolerance: 0.02,
                }],
            },
            StressTestConfig {
                id: "spike_load_test".to_string(),
                load_pattern: LoadPattern::Spike {
                    base_load: 10.0,
                    spike_load: 200.0,
                    spike_duration: Duration::from_secs(30),
                },
                size_progression: SizeProgression::Custom(vec![50, 100, 200, 500, 1000, 2000]),
                resource_constraints: StressResourceConstraints {
                    max_memory: Some(2048), // 2GB
                    max_cpu: Some(0.8),     // 80%
                    max_time: Some(Duration::from_secs(300)),
                    max_concurrent: Some(4),
                },
                success_criteria: vec![StressSuccessCriterion {
                    criterion_type: StressCriterionType::RecoveryTime,
                    target_value: 60.0, // seconds
                    tolerance: 15.0,
                }],
            },
        ]
    }

    /// Create default load generators
    fn create_default_generators() -> Vec<LoadGenerator> {
        vec![
            LoadGenerator {
                id: "gradual_generator".to_string(),
                strategy: LoadGenerationStrategy::Gradual,
                current_load: 0.0,
                max_load: 1000.0,
                load_step: 1.0,
            },
            LoadGenerator {
                id: "step_generator".to_string(),
                strategy: LoadGenerationStrategy::Step,
                current_load: 0.0,
                max_load: 500.0,
                load_step: 10.0,
            },
            LoadGenerator {
                id: "binary_search_generator".to_string(),
                strategy: LoadGenerationStrategy::BinarySearch,
                current_load: 0.0,
                max_load: 2000.0,
                load_step: 50.0,
            },
        ]
    }

    /// Create default resource monitors
    fn create_default_monitors() -> Vec<ResourceMonitor> {
        vec![
            ResourceMonitor {
                id: "cpu_monitor".to_string(),
                resource_type: ResourceType::CPU,
                frequency: Duration::from_secs(1),
                usage_history: VecDeque::new(),
                alert_thresholds: vec![0.7, 0.85, 0.95],
            },
            ResourceMonitor {
                id: "memory_monitor".to_string(),
                resource_type: ResourceType::Memory,
                frequency: Duration::from_secs(2),
                usage_history: VecDeque::new(),
                alert_thresholds: vec![0.8, 0.9, 0.98],
            },
            ResourceMonitor {
                id: "disk_io_monitor".to_string(),
                resource_type: ResourceType::DiskIO,
                frequency: Duration::from_secs(5),
                usage_history: VecDeque::new(),
                alert_thresholds: vec![100.0, 500.0, 1000.0], // MB/s
            },
        ]
    }

    /// Create default scalability analyzers
    fn create_default_analyzers() -> Vec<ScalabilityAnalyzer> {
        vec![
            ScalabilityAnalyzer {
                id: "linear_scalability".to_string(),
                algorithm: ScalabilityAlgorithm::LinearRegression,
                metrics: ScalabilityMetrics {
                    scalability_factor: 0.0,
                    efficiency_ratio: 0.0,
                    breaking_point: None,
                    theoretical_max: None,
                },
                parameters: HashMap::new(),
            },
            ScalabilityAnalyzer {
                id: "power_law_scalability".to_string(),
                algorithm: ScalabilityAlgorithm::PowerLaw,
                metrics: ScalabilityMetrics {
                    scalability_factor: 0.0,
                    efficiency_ratio: 0.0,
                    breaking_point: None,
                    theoretical_max: None,
                },
                parameters: {
                    let mut params = HashMap::new();
                    params.insert("exponent_range".to_string(), 2.0);
                    params
                },
            },
        ]
    }

    /// Run stress test
    pub fn run_stress_test(&mut self, config_id: &str) -> ApplicationResult<StressTestResult> {
        let config = self
            .stress_configs
            .iter()
            .find(|c| c.id == config_id)
            .ok_or_else(|| {
                ApplicationError::ConfigurationError(format!(
                    "Stress test config not found: {config_id}"
                ))
            })?
            .clone();

        println!("Starting stress test: {}", config.id);
        let start_time = Instant::now();

        // Initialize monitors
        self.start_monitoring()?;

        // Run the stress test
        let result = self.execute_stress_test(&config)?;

        // Stop monitoring
        self.stop_monitoring()?;

        let execution_time = start_time.elapsed();
        println!("Stress test completed in {execution_time:?}");

        Ok(StressTestResult {
            test_id: config.id,
            max_load: result.max_load_achieved,
            breaking_point: result.breaking_point,
            resource_utilization: result.resource_utilization,
            throughput: result.throughput,
            success_rate: result.success_rate,
            scalability_metrics: result.scalability_metrics,
        })
    }

    /// Execute stress test with given configuration
    fn execute_stress_test(
        &self,
        config: &StressTestConfig,
    ) -> ApplicationResult<StressTestExecutionResult> {
        let mut max_load_achieved = 0.0f64;
        let mut breaking_point = None;
        let mut successful_tests = 0;
        let mut total_tests = 0;
        let mut throughput_sum = 0.0;

        // Generate test sizes based on progression
        let test_sizes = self.generate_test_sizes(&config.size_progression);

        for size in &test_sizes {
            total_tests += 1;

            // Generate load based on pattern
            let load = self.generate_load(&config.load_pattern, total_tests)?;
            max_load_achieved = max_load_achieved.max(load);

            // Run test at this size and load
            let test_result = self.run_stress_test_instance(*size, load, config)?;

            if test_result.success {
                successful_tests += 1;
                throughput_sum += test_result.throughput;
            } else {
                if breaking_point.is_none() {
                    breaking_point = Some(*size);
                }
                // Check if we should continue or stop
                if !self.should_continue_after_failure(&test_result, config) {
                    break;
                }
            }

            // Check resource constraints
            if self.check_resource_constraints_exceeded(&config.resource_constraints)? {
                println!("Resource constraints exceeded, stopping test");
                break;
            }
        }

        let success_rate = if total_tests > 0 {
            f64::from(successful_tests) / total_tests as f64
        } else {
            0.0
        };

        let average_throughput = if successful_tests > 0 {
            throughput_sum / f64::from(successful_tests)
        } else {
            0.0
        };

        // Analyze scalability
        let scalability_metrics = self.analyze_scalability(&test_sizes[..total_tests])?;

        // Get resource utilization
        let resource_utilization = self.get_resource_utilization();

        Ok(StressTestExecutionResult {
            max_load_achieved,
            breaking_point,
            success_rate,
            throughput: average_throughput,
            scalability_metrics,
            resource_utilization,
        })
    }

    /// Generate test sizes based on progression strategy
    fn generate_test_sizes(&self, progression: &SizeProgression) -> Vec<usize> {
        match progression {
            SizeProgression::Linear { start, end, step } => {
                (*start..=*end).step_by(*step).collect()
            }
            SizeProgression::Exponential { start, end, factor } => {
                let mut sizes = Vec::new();
                let mut current = *start;
                while current <= *end {
                    sizes.push(current);
                    current = (current as f64 * factor) as usize;
                }
                sizes
            }
            SizeProgression::Custom(sizes) => sizes.clone(),
        }
    }

    /// Generate load based on pattern
    fn generate_load(&self, pattern: &LoadPattern, iteration: usize) -> ApplicationResult<f64> {
        let load = match pattern {
            LoadPattern::Constant(load) => *load,
            LoadPattern::LinearRamp {
                start,
                end,
                duration: _,
            } => {
                // Simplified: just use iteration as progress
                let progress = (iteration as f64 / 100.0).min(1.0);
                start + progress * (end - start)
            }
            LoadPattern::ExponentialRamp {
                start,
                end,
                duration: _,
            } => {
                let progress = (iteration as f64 / 100.0).min(1.0);
                start * ((end / start).powf(progress))
            }
            LoadPattern::Spike {
                base_load,
                spike_load,
                spike_duration: _,
            } => {
                // Simplified: spike every 10 iterations
                if iteration % 10 == 5 {
                    *spike_load
                } else {
                    *base_load
                }
            }
            LoadPattern::Cyclic {
                min_load,
                max_load,
                period: _,
            } => {
                let phase = (iteration as f64 * 0.1).sin();
                min_load + (max_load - min_load) * (phase + 1.0) / 2.0
            }
        };

        Ok(load)
    }

    /// Run individual stress test instance
    fn run_stress_test_instance(
        &self,
        size: usize,
        load: f64,
        _config: &StressTestConfig,
    ) -> ApplicationResult<StressTestInstanceResult> {
        let start_time = Instant::now();

        // Simulate test execution
        let execution_time = Duration::from_millis((size as u64 * load as u64).min(10_000));
        thread::sleep(Duration::from_millis(1)); // Minimal actual delay

        // Simulate success/failure based on size and load
        let stress_factor = (size as f64 * load) / 10_000.0;
        let success_probability = (1.0 - stress_factor * 0.1).max(0.1);
        let success = thread_rng().random::<f64>() < success_probability;

        // Calculate throughput (problems per second)
        let throughput = if success {
            1.0 / execution_time.as_secs_f64()
        } else {
            0.0
        };

        Ok(StressTestInstanceResult {
            size,
            load,
            execution_time,
            success,
            throughput,
            error: if success {
                None
            } else {
                Some("Simulated failure under stress".to_string())
            },
        })
    }

    /// Check if test should continue after failure
    const fn should_continue_after_failure(
        &self,
        _test_result: &StressTestInstanceResult,
        _config: &StressTestConfig,
    ) -> bool {
        // Simplified: continue unless we have consecutive failures
        true
    }

    /// Check if resource constraints are exceeded
    const fn check_resource_constraints_exceeded(
        &self,
        _constraints: &StressResourceConstraints,
    ) -> ApplicationResult<bool> {
        // Simplified implementation
        Ok(false)
    }

    /// Analyze scalability from test results
    const fn analyze_scalability(
        &self,
        _test_sizes: &[usize],
    ) -> ApplicationResult<ScalabilityMetrics> {
        // Simplified scalability analysis
        Ok(ScalabilityMetrics {
            scalability_factor: 0.85,
            efficiency_ratio: 0.90,
            breaking_point: Some(1000),
            theoretical_max: Some(2000),
        })
    }

    /// Get current resource utilization
    fn get_resource_utilization(&self) -> HashMap<ResourceType, f64> {
        let mut utilization = HashMap::new();

        // Simplified resource utilization
        utilization.insert(ResourceType::CPU, 0.75);
        utilization.insert(ResourceType::Memory, 0.60);
        utilization.insert(ResourceType::DiskIO, 0.30);

        utilization
    }

    /// Start resource monitoring
    fn start_monitoring(&self) -> ApplicationResult<()> {
        println!("Starting resource monitoring");
        // Initialize monitoring systems
        Ok(())
    }

    /// Stop resource monitoring
    fn stop_monitoring(&self) -> ApplicationResult<()> {
        println!("Stopping resource monitoring");
        // Clean up monitoring systems
        Ok(())
    }

    /// Add stress test configuration
    pub fn add_config(&mut self, config: StressTestConfig) {
        self.stress_configs.push(config);
    }

    /// Get stress test configuration
    #[must_use]
    pub fn get_config(&self, config_id: &str) -> Option<&StressTestConfig> {
        self.stress_configs.iter().find(|c| c.id == config_id)
    }

    /// Add load generator
    pub fn add_load_generator(&mut self, generator: LoadGenerator) {
        self.load_generators.push(generator);
    }

    /// Add resource monitor
    pub fn add_resource_monitor(&mut self, monitor: ResourceMonitor) {
        self.resource_monitors.push(monitor);
    }
}

/// Result from stress test execution
#[derive(Debug)]
struct StressTestExecutionResult {
    /// Maximum load achieved
    pub max_load_achieved: f64,
    /// Breaking point (problem size)
    pub breaking_point: Option<usize>,
    /// Success rate
    pub success_rate: f64,
    /// Average throughput
    pub throughput: f64,
    /// Scalability metrics
    pub scalability_metrics: ScalabilityMetrics,
    /// Resource utilization
    pub resource_utilization: HashMap<ResourceType, f64>,
}

/// Result from individual stress test instance
#[derive(Debug)]
struct StressTestInstanceResult {
    /// Problem size
    pub size: usize,
    /// Load level
    pub load: f64,
    /// Execution time
    pub execution_time: Duration,
    /// Success status
    pub success: bool,
    /// Throughput achieved
    pub throughput: f64,
    /// Error message (if failed)
    pub error: Option<String>,
}