//! Integration Testing Framework for NAT Traversal
//!
//! This module provides comprehensive integration testing infrastructure for validating
//! NAT traversal functionality across various network configurations and scenarios.
//!
//! The framework includes:
//! - Mock NAT environments simulating different router configurations
//! - End-to-end workflow testing
//! - Performance benchmarking and stress testing
//! - Real-world network condition simulation
//! - Failure injection and chaos testing

use std::{
    collections::HashMap,
    net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr},
    sync::{Arc, Mutex},
    time::{Duration, Instant},
};

use tokio::sync::mpsc;
use tracing::{debug, info, warn};

use crate::{
    VarInt,
    connection::nat_traversal::{
        NatTraversalRole, CandidateSource, CandidateState,
    },
    nat_traversal_api::{
        NatTraversalConfig, NatTraversalEndpoint, NatTraversalEvent, EndpointRole, PeerId,
        BootstrapNode, CandidateAddress, NatTraversalStatistics,
    },
    quic_node::{QuicNodeConfig, QuicP2PNode, NodeStats},
};

pub mod mock_network;
pub mod nat_simulator;
pub mod performance_testing;
pub mod scenario_tests;
pub mod stress_tests;
pub mod validation_suite;

pub use mock_network::*;
pub use nat_simulator::*;
pub use performance_testing::*;
pub use scenario_tests::*;
pub use stress_tests::*;
pub use validation_suite::*;

/// Configuration for integration testing
#[derive(Debug, Clone)]
pub struct IntegrationTestConfig {
    /// Test duration for time-based tests
    pub test_duration: Duration,
    /// Number of test iterations
    pub iterations: u32,
    /// Enable performance monitoring
    pub enable_performance_monitoring: bool,
    /// Enable detailed logging
    pub enable_detailed_logging: bool,
    /// Test timeout for individual tests
    pub test_timeout: Duration,
    /// Number of concurrent test scenarios
    pub max_concurrent_tests: u32,
    /// Network simulation parameters
    pub network_config: NetworkSimulationConfig,
}

impl Default for IntegrationTestConfig {
    fn default() -> Self {
        Self {
            test_duration: Duration::from_secs(30),
            iterations: 10,
            enable_performance_monitoring: true,
            enable_detailed_logging: false,
            test_timeout: Duration::from_secs(60),
            max_concurrent_tests: 10,
            network_config: NetworkSimulationConfig::default(),
        }
    }
}

/// Network simulation configuration
#[derive(Debug, Clone)]
pub struct NetworkSimulationConfig {
    /// Packet loss percentage (0-100)
    pub packet_loss_percent: u8,
    /// Additional latency in milliseconds
    pub latency_ms: u32,
    /// Jitter in milliseconds
    pub jitter_ms: u32,
    /// Bandwidth limit in bytes per second
    pub bandwidth_limit_bps: Option<u64>,
    /// Enable NAT port prediction
    pub enable_nat_prediction: bool,
    /// Enable symmetric NAT behavior
    pub enable_symmetric_nat: bool,
}

impl Default for NetworkSimulationConfig {
    fn default() -> Self {
        Self {
            packet_loss_percent: 0,
            latency_ms: 50,
            jitter_ms: 10,
            bandwidth_limit_bps: None,
            enable_nat_prediction: true,
            enable_symmetric_nat: false,
        }
    }
}

/// Test result for integration testing
#[derive(Debug, Clone)]
pub struct IntegrationTestResult {
    /// Test name
    pub test_name: String,
    /// Test success status
    pub success: bool,
    /// Test duration
    pub duration: Duration,
    /// Performance metrics
    pub performance_metrics: PerformanceMetrics,
    /// Error message if test failed
    pub error_message: Option<String>,
    /// Additional test data
    pub test_data: HashMap<String, String>,
}

/// Performance metrics for integration tests
#[derive(Debug, Clone, Default)]
pub struct PerformanceMetrics {
    /// Total number of connection attempts
    pub connection_attempts: u64,
    /// Number of successful connections
    pub successful_connections: u64,
    /// Number of failed connections
    pub failed_connections: u64,
    /// Average connection establishment time
    pub avg_connection_time: Duration,
    /// Peak memory usage in bytes
    pub peak_memory_usage: u64,
    /// Average CPU usage percentage
    pub avg_cpu_usage: f32,
    /// Network bandwidth usage
    pub network_bandwidth_usage: u64,
    /// Number of packets sent
    pub packets_sent: u64,
    /// Number of packets received
    pub packets_received: u64,
    /// Packet loss rate
    pub packet_loss_rate: f32,
}

/// Integration test runner
pub struct IntegrationTestRunner {
    /// Test configuration
    config: IntegrationTestConfig,
    /// Test results
    results: Vec<IntegrationTestResult>,
    /// Performance monitor
    performance_monitor: Arc<Mutex<PerformanceMonitor>>,
    /// Network simulator
    network_simulator: Arc<Mutex<NetworkSimulator>>,
}

impl IntegrationTestRunner {
    /// Create a new integration test runner
    pub fn new(config: IntegrationTestConfig) -> Self {
        let performance_monitor = Arc::new(Mutex::new(PerformanceMonitor::new()));
        let network_simulator = Arc::new(Mutex::new(NetworkSimulator::new(config.network_config.clone())));
        
        Self {
            config,
            results: Vec::new(),
            performance_monitor,
            network_simulator,
        }
    }

    /// Run all integration tests
    pub async fn run_all_tests(&mut self) -> Vec<IntegrationTestResult> {
        info!("Starting integration test suite with {} iterations", self.config.iterations);
        
        // Initialize test environment
        self.initialize_test_environment().await;
        
        // Run test scenarios
        self.run_basic_connectivity_tests().await;
        self.run_nat_traversal_scenarios().await;
        self.run_multi_peer_scenarios().await;
        self.run_failure_scenarios().await;
        self.run_performance_tests().await;
        self.run_stress_tests().await;
        
        // Generate summary report
        self.generate_test_report().await;
        
        self.results.clone()
    }

    /// Initialize test environment
    async fn initialize_test_environment(&mut self) {
        info!("Initializing integration test environment");
        
        // Start performance monitoring
        if self.config.enable_performance_monitoring {
            self.performance_monitor.lock().unwrap().start_monitoring();
        }
        
        // Initialize network simulator
        self.network_simulator.lock().unwrap().initialize();
        
        // Set up logging
        if self.config.enable_detailed_logging {
            self.setup_detailed_logging();
        }
    }

    /// Run basic connectivity tests
    async fn run_basic_connectivity_tests(&mut self) {
        info!("Running basic connectivity tests");
        
        let test_scenarios = vec![
            ("basic_client_server", TestScenario::BasicClientServer),
            ("client_with_bootstrap", TestScenario::ClientWithBootstrap),
            ("server_coordination", TestScenario::ServerCoordination),
            ("bootstrap_node_functionality", TestScenario::BootstrapNodeFunctionality),
        ];
        
        for (test_name, scenario) in test_scenarios {
            let result = self.run_test_scenario(test_name, scenario).await;
            self.results.push(result);
        }
    }

    /// Run NAT traversal scenarios
    async fn run_nat_traversal_scenarios(&mut self) {
        info!("Running NAT traversal scenarios");
        
        let nat_scenarios = vec![
            ("full_cone_to_full_cone", NatScenario::FullConeToFullCone),
            ("full_cone_to_restricted", NatScenario::FullConeToRestricted),
            ("restricted_to_port_restricted", NatScenario::RestrictedToPortRestricted),
            ("port_restricted_to_symmetric", NatScenario::PortRestrictedToSymmetric),
            ("symmetric_to_symmetric", NatScenario::SymmetricToSymmetric),
            ("cgnat_scenario", NatScenario::CgnatScenario),
            ("double_nat_scenario", NatScenario::DoubleNatScenario),
        ];
        
        for (test_name, scenario) in nat_scenarios {
            let result = self.run_nat_scenario(test_name, scenario).await;
            self.results.push(result);
        }
    }

    /// Run multi-peer scenarios
    async fn run_multi_peer_scenarios(&mut self) {
        info!("Running multi-peer scenarios");
        
        let multi_peer_scenarios = vec![
            ("three_peer_mesh", MultiPeerScenario::ThreePeerMesh),
            ("five_peer_star", MultiPeerScenario::FivePeerStar),
            ("ten_peer_random", MultiPeerScenario::TenPeerRandom),
            ("bootstrap_coordination", MultiPeerScenario::BootstrapCoordination),
        ];
        
        for (test_name, scenario) in multi_peer_scenarios {
            let result = self.run_multi_peer_scenario(test_name, scenario).await;
            self.results.push(result);
        }
    }

    /// Run failure scenarios
    async fn run_failure_scenarios(&mut self) {
        info!("Running failure scenarios");
        
        let failure_scenarios = vec![
            ("bootstrap_node_failure", FailureScenario::BootstrapNodeFailure),
            ("network_partition", FailureScenario::NetworkPartition),
            ("high_packet_loss", FailureScenario::HighPacketLoss),
            ("random_failures", FailureScenario::RandomFailures),
            ("resource_exhaustion", FailureScenario::ResourceExhaustion),
        ];
        
        for (test_name, scenario) in failure_scenarios {
            let result = self.run_failure_scenario(test_name, scenario).await;
            self.results.push(result);
        }
    }

    /// Run performance tests
    async fn run_performance_tests(&mut self) {
        info!("Running performance tests");
        
        let performance_tests = vec![
            ("connection_establishment_latency", PerformanceTest::ConnectionEstablishmentLatency),
            ("throughput_measurement", PerformanceTest::ThroughputMeasurement),
            ("memory_usage_analysis", PerformanceTest::MemoryUsageAnalysis),
            ("cpu_usage_monitoring", PerformanceTest::CpuUsageMonitoring),
            ("scalability_testing", PerformanceTest::ScalabilityTesting),
        ];
        
        for (test_name, test_type) in performance_tests {
            let result = self.run_performance_test(test_name, test_type).await;
            self.results.push(result);
        }
    }

    /// Run stress tests
    async fn run_stress_tests(&mut self) {
        info!("Running stress tests");
        
        let stress_tests = vec![
            ("concurrent_connections", StressTest::ConcurrentConnections),
            ("connection_churn", StressTest::ConnectionChurn),
            ("memory_pressure", StressTest::MemoryPressure),
            ("extended_duration", StressTest::ExtendedDuration),
        ];
        
        for (test_name, test_type) in stress_tests {
            let result = self.run_stress_test(test_name, test_type).await;
            self.results.push(result);
        }
    }

    /// Run a single test scenario
    pub async fn run_test_scenario(&mut self, test_name: &str, scenario: TestScenario) -> IntegrationTestResult {
        info!("Running test scenario: {}", test_name);
        let start_time = Instant::now();
        
        // Start performance monitoring for this test
        self.performance_monitor.lock().unwrap().start_test_monitoring(test_name);
        
        let result = match scenario {
            TestScenario::BasicClientServer => {
                self.test_basic_client_server().await
            }
            TestScenario::ClientWithBootstrap => {
                self.test_client_with_bootstrap().await
            }
            TestScenario::ServerCoordination => {
                self.test_server_coordination().await
            }
            TestScenario::BootstrapNodeFunctionality => {
                self.test_bootstrap_node_functionality().await
            }
        };
        
        let duration = start_time.elapsed();
        let performance_metrics = self.performance_monitor.lock().unwrap().get_test_metrics(test_name);
        
        IntegrationTestResult {
            test_name: test_name.to_string(),
            success: result.is_ok(),
            duration,
            performance_metrics,
            error_message: result.err().map(|e| e.to_string()),
            test_data: HashMap::new(),
        }
    }

    /// Run a NAT scenario test
    pub async fn run_nat_scenario(&mut self, test_name: &str, scenario: NatScenario) -> IntegrationTestResult {
        info!("Running NAT scenario: {}", test_name);
        let start_time = Instant::now();
        
        // Configure network simulator for this NAT scenario
        self.network_simulator.lock().unwrap().configure_nat_scenario(scenario.clone());
        
        let result = self.execute_nat_traversal_test(scenario).await;
        
        let duration = start_time.elapsed();
        let performance_metrics = self.performance_monitor.lock().unwrap().get_test_metrics(test_name);
        
        IntegrationTestResult {
            test_name: test_name.to_string(),
            success: result.is_ok(),
            duration,
            performance_metrics,
            error_message: result.err().map(|e| e.to_string()),
            test_data: HashMap::new(),
        }
    }

    /// Run a multi-peer scenario test
    pub async fn run_multi_peer_scenario(&mut self, test_name: &str, scenario: MultiPeerScenario) -> IntegrationTestResult {
        info!("Running multi-peer scenario: {}", test_name);
        let start_time = Instant::now();
        
        let result = self.execute_multi_peer_test(scenario).await;
        
        let duration = start_time.elapsed();
        let performance_metrics = self.performance_monitor.lock().unwrap().get_test_metrics(test_name);
        
        IntegrationTestResult {
            test_name: test_name.to_string(),
            success: result.is_ok(),
            duration,
            performance_metrics,
            error_message: result.err().map(|e| e.to_string()),
            test_data: HashMap::new(),
        }
    }

    /// Run a failure scenario test
    pub async fn run_failure_scenario(&mut self, test_name: &str, scenario: FailureScenario) -> IntegrationTestResult {
        info!("Running failure scenario: {}", test_name);
        let start_time = Instant::now();
        
        let result = self.execute_failure_test(scenario).await;
        
        let duration = start_time.elapsed();
        let performance_metrics = self.performance_monitor.lock().unwrap().get_test_metrics(test_name);
        
        IntegrationTestResult {
            test_name: test_name.to_string(),
            success: result.is_ok(),
            duration,
            performance_metrics,
            error_message: result.err().map(|e| e.to_string()),
            test_data: HashMap::new(),
        }
    }

    /// Run a performance test
    pub async fn run_performance_test(&mut self, test_name: &str, test_type: PerformanceTest) -> IntegrationTestResult {
        info!("Running performance test: {}", test_name);
        let start_time = Instant::now();
        
        let result = self.execute_performance_test(test_type).await;
        
        let duration = start_time.elapsed();
        let performance_metrics = self.performance_monitor.lock().unwrap().get_test_metrics(test_name);
        
        IntegrationTestResult {
            test_name: test_name.to_string(),
            success: result.is_ok(),
            duration,
            performance_metrics,
            error_message: result.err().map(|e| e.to_string()),
            test_data: HashMap::new(),
        }
    }

    /// Run a stress test
    pub async fn run_stress_test(&mut self, test_name: &str, test_type: StressTest) -> IntegrationTestResult {
        info!("Running stress test: {}", test_name);
        let start_time = Instant::now();
        
        let result = self.execute_stress_test(test_type).await;
        
        let duration = start_time.elapsed();
        let performance_metrics = self.performance_monitor.lock().unwrap().get_test_metrics(test_name);
        
        IntegrationTestResult {
            test_name: test_name.to_string(),
            success: result.is_ok(),
            duration,
            performance_metrics,
            error_message: result.err().map(|e| e.to_string()),
            test_data: HashMap::new(),
        }
    }

    /// Setup detailed logging for tests
    fn setup_detailed_logging(&self) {
        // Configure tracing for detailed test logging
        use tracing_subscriber::{EnvFilter, FmtSubscriber};
        
        let subscriber = FmtSubscriber::builder()
            .with_env_filter(EnvFilter::from_default_env())
            .with_test_writer()
            .finish();
            
        tracing::subscriber::set_global_default(subscriber)
            .expect("setting default subscriber failed");
    }

    /// Generate comprehensive test report
    async fn generate_test_report(&self) {
        let successful_tests = self.results.iter().filter(|r| r.success).count();
        let total_tests = self.results.len();
        let success_rate = (successful_tests as f32 / total_tests as f32) * 100.0;
        
        info!("=== Integration Test Report ===");
        info!("Total tests: {}", total_tests);
        info!("Successful tests: {}", successful_tests);
        info!("Failed tests: {}", total_tests - successful_tests);
        info!("Success rate: {:.1}%", success_rate);
        
        // Print detailed results for failed tests
        for result in &self.results {
            if !result.success {
                warn!("FAILED: {} - {}", result.test_name, 
                      result.error_message.as_deref().unwrap_or("Unknown error"));
            }
        }
        
        // Print performance summary
        let total_connection_attempts: u64 = self.results.iter()
            .map(|r| r.performance_metrics.connection_attempts)
            .sum();
        let total_successful_connections: u64 = self.results.iter()
            .map(|r| r.performance_metrics.successful_connections)
            .sum();
        
        if total_connection_attempts > 0 {
            let overall_success_rate = (total_successful_connections as f32 / total_connection_attempts as f32) * 100.0;
            info!("Overall connection success rate: {:.1}%", overall_success_rate);
        }
    }

    // Test implementation methods will be implemented in separate modules
    async fn test_basic_client_server(&self) -> Result<(), Box<dyn std::error::Error>> {
        // Implementation will be in scenario_tests.rs
        Ok(())
    }

    async fn test_client_with_bootstrap(&self) -> Result<(), Box<dyn std::error::Error>> {
        // Implementation will be in scenario_tests.rs
        Ok(())
    }

    async fn test_server_coordination(&self) -> Result<(), Box<dyn std::error::Error>> {
        // Implementation will be in scenario_tests.rs
        Ok(())
    }

    async fn test_bootstrap_node_functionality(&self) -> Result<(), Box<dyn std::error::Error>> {
        // Implementation will be in scenario_tests.rs
        Ok(())
    }

    async fn execute_nat_traversal_test(&self, _scenario: NatScenario) -> Result<(), Box<dyn std::error::Error>> {
        // Implementation will be in nat_simulator.rs
        Ok(())
    }

    async fn execute_multi_peer_test(&self, _scenario: MultiPeerScenario) -> Result<(), Box<dyn std::error::Error>> {
        // Implementation will be in scenario_tests.rs
        Ok(())
    }

    async fn execute_failure_test(&self, _scenario: FailureScenario) -> Result<(), Box<dyn std::error::Error>> {
        // Implementation will be in scenario_tests.rs
        Ok(())
    }

    async fn execute_performance_test(&self, _test_type: PerformanceTest) -> Result<(), Box<dyn std::error::Error>> {
        // Implementation will be in performance_testing.rs
        Ok(())
    }

    async fn execute_stress_test(&self, _test_type: StressTest) -> Result<(), Box<dyn std::error::Error>> {
        // Implementation will be in stress_tests.rs
        Ok(())
    }
}

/// Test scenario types
#[derive(Debug, Clone)]
pub enum TestScenario {
    BasicClientServer,
    ClientWithBootstrap,
    ServerCoordination,
    BootstrapNodeFunctionality,
}

/// NAT scenario types
#[derive(Debug, Clone)]
pub enum NatScenario {
    FullConeToFullCone,
    FullConeToRestricted,
    RestrictedToPortRestricted,
    PortRestrictedToSymmetric,
    SymmetricToSymmetric,
    CgnatScenario,
    DoubleNatScenario,
}

/// Multi-peer scenario types
#[derive(Debug, Clone)]
pub enum MultiPeerScenario {
    ThreePeerMesh,
    FivePeerStar,
    TenPeerRandom,
    BootstrapCoordination,
}

/// Failure scenario types
#[derive(Debug, Clone)]
pub enum FailureScenario {
    BootstrapNodeFailure,
    NetworkPartition,
    HighPacketLoss,
    RandomFailures,
    ResourceExhaustion,
}

/// Performance test types
#[derive(Debug, Clone)]
pub enum PerformanceTest {
    ConnectionEstablishmentLatency,
    ThroughputMeasurement,
    MemoryUsageAnalysis,
    CpuUsageMonitoring,
    ScalabilityTesting,
}

/// Stress test types
#[derive(Debug, Clone)]
pub enum StressTest {
    ConcurrentConnections,
    ConnectionChurn,
    MemoryPressure,
    ExtendedDuration,
}

/// Performance monitoring component
pub struct PerformanceMonitor {
    /// Test metrics by test name
    test_metrics: HashMap<String, PerformanceMetrics>,
    /// Monitoring start time
    start_time: Option<Instant>,
}

impl PerformanceMonitor {
    /// Create a new performance monitor
    pub fn new() -> Self {
        Self {
            test_metrics: HashMap::new(),
            start_time: None,
        }
    }

    /// Start monitoring
    pub fn start_monitoring(&mut self) {
        self.start_time = Some(Instant::now());
    }

    /// Start monitoring for a specific test
    pub fn start_test_monitoring(&mut self, test_name: &str) {
        self.test_metrics.insert(test_name.to_string(), PerformanceMetrics::default());
    }

    /// Get metrics for a specific test
    pub fn get_test_metrics(&self, test_name: &str) -> PerformanceMetrics {
        self.test_metrics.get(test_name).cloned().unwrap_or_default()
    }

    /// Update metrics for a test
    pub fn update_test_metrics(&mut self, test_name: &str, metrics: PerformanceMetrics) {
        self.test_metrics.insert(test_name.to_string(), metrics);
    }
}