#![allow(dead_code, unused_variables, unused_imports)]
//! Chaos engineering tests for adaptive network resilience
//!
//! This module implements chaos engineering principles to test the
//! adaptive network's resilience under various failure conditions.

use saorsa_core::adaptive::*;
use std::collections::HashMap;
use std::sync::Arc;
use std::time::Duration;
use tokio::sync::RwLock;
use tokio::time::{sleep, timeout};

#[tokio::test]
async fn test_node_failure_resilience() -> anyhow::Result<()> {
    println!("💥 Testing node failure resilience...");

    // Create a network of 5 nodes
    let mut nodes = Vec::new();
    for i in 0..5 {
        let node_id = NodeId {
            hash: [i as u8; 32],
        };
        let node = AdaptiveNode::new(node_id).await?;
        nodes.push(node);
    }

    // Establish connections
    for i in 0..5 {
        for j in 0..5 {
            if i != j {
                nodes[i].connect_to(&nodes[j]).await?;
            }
        }
    }

    // Verify initial connectivity
    for node in &nodes {
        let connections = node.get_connection_count().await?;
        assert_eq!(connections, 4, "Node should have 4 connections initially");
    }

    // Simulate node failures
    println!("🔥 Simulating node failures...");
    nodes[2].simulate_failure().await?;
    nodes[4].simulate_failure().await?;

    // Wait for system to adapt
    sleep(Duration::from_secs(2)).await;

    // Verify remaining nodes adapted
    for (i, node) in nodes.iter().enumerate() {
        if i == 2 || i == 4 {
            continue; // Skip failed nodes
        }

        let connections = node.get_connection_count().await?;
        assert!(
            connections >= 2,
            "Surviving node should maintain at least 2 connections"
        );
    }

    // Test that the system can still route messages
    let source = &nodes[0];
    let destination = &nodes[1];

    let success = timeout(
        Duration::from_secs(5),
        source.send_message(destination.get_id(), b"test message"),
    )
    .await
    .is_ok();

    assert!(
        success,
        "System should still be able to route messages after node failures"
    );

    println!("✅ Node failure resilience test passed");
    Ok(())
}

#[tokio::test]
async fn test_network_partition_recovery() -> anyhow::Result<()> {
    println!("🌐 Testing network partition recovery...");

    // Create two network partitions
    let mut partition_a = Vec::new();
    let mut partition_b = Vec::new();

    for i in 0..6 {
        let node_id = NodeId {
            hash: [i as u8; 32],
        };
        let node = AdaptiveNode::new(node_id).await?;

        if i < 3 {
            partition_a.push(node);
        } else {
            partition_b.push(node);
        }
    }

    // Connect nodes within partitions
    for node in &partition_a {
        for other in &partition_a {
            if node.get_id() != other.get_id() {
                node.connect_to(other).await?;
            }
        }
    }

    for node in &partition_b {
        for other in &partition_b {
            if node.get_id() != other.get_id() {
                node.connect_to(other).await?;
            }
        }
    }

    // Simulate network partition
    println!("🔌 Simulating network partition...");
    AdaptiveNode::simulate_partition(&partition_a, &partition_b).await?;

    // Wait for partition detection
    sleep(Duration::from_secs(3)).await;

    // Verify partition detection
    for node in &partition_a {
        let partition_detected = node.has_detected_partition().await?;
        assert!(partition_detected, "Node should detect network partition");
    }

    // Restore network connectivity
    println!("🔗 Restoring network connectivity...");
    AdaptiveNode::restore_connectivity(&partition_a, &partition_b).await?;

    // Wait for recovery
    sleep(Duration::from_secs(5)).await;

    // Verify recovery
    for node in &partition_a {
        let partition_resolved = !node.has_detected_partition().await?;
        assert!(partition_resolved, "Network partition should be resolved");
    }

    // Test cross-partition communication
    let node_a = &partition_a[0];
    let node_b = &partition_b[0];

    let success = timeout(
        Duration::from_secs(5),
        node_a.send_message(node_b.get_id(), b"post-partition message"),
    )
    .await
    .is_ok();

    assert!(
        success,
        "Cross-partition communication should work after recovery"
    );

    println!("✅ Network partition recovery test passed");
    Ok(())
}

#[tokio::test]
async fn test_latency_spike_resilience() -> anyhow::Result<()> {
    println!("⚡ Testing latency spike resilience...");

    let node = AdaptiveNode::new(NodeId { hash: [0u8; 32] }).await?;

    // Establish baseline performance
    let mut baseline_latencies = Vec::new();
    for _ in 0..10 {
        let latency = node.measure_latency().await?;
        baseline_latencies.push(latency);
    }

    let baseline_avg =
        baseline_latencies.iter().sum::<Duration>() / baseline_latencies.len() as u32;

    // Inject latency spikes
    println!("📈 Injecting latency spikes...");
    node.inject_latency_spike(Duration::from_secs(2)).await?;

    // Measure performance during spike
    let mut spike_latencies = Vec::new();
    for _ in 0..10 {
        let latency = node.measure_latency().await?;
        spike_latencies.push(latency);
    }

    let spike_avg = spike_latencies.iter().sum::<Duration>() / spike_latencies.len() as u32;

    // Verify adaptive behavior
    assert!(
        spike_avg > baseline_avg,
        "Latency spike should be detectable"
    );

    // Wait for adaptation
    sleep(Duration::from_secs(3)).await;

    // Measure performance after adaptation
    let mut adapted_latencies = Vec::new();
    for _ in 0..10 {
        let latency = node.measure_latency().await?;
        adapted_latencies.push(latency);
    }

    let adapted_avg = adapted_latencies.iter().sum::<Duration>() / adapted_latencies.len() as u32;

    // Verify improvement
    assert!(
        adapted_avg < spike_avg,
        "System should adapt to reduce latency"
    );

    // The adapted performance should be better than the spike but may not reach baseline immediately
    let improvement_ratio = (spike_avg - adapted_avg).as_secs_f64() / spike_avg.as_secs_f64();
    assert!(
        improvement_ratio > 0.3,
        "Adaptation should provide at least 30% improvement"
    );

    println!(
        "✅ Latency spike resilience test passed with {:.1}% improvement",
        improvement_ratio * 100.0
    );
    Ok(())
}

#[tokio::test]
async fn test_resource_exhaustion_resilience() -> anyhow::Result<()> {
    println!("🪫 Testing resource exhaustion resilience...");

    let node = AdaptiveNode::new(NodeId { hash: [0u8; 32] }).await?;

    // Monitor initial resource usage
    let initial_memory = node.get_memory_usage().await?;
    let initial_connections = node.get_connection_count().await?;

    // Simulate resource exhaustion
    println!("💾 Simulating resource exhaustion...");
    node.simulate_resource_exhaustion().await?;

    // Wait for system to respond
    sleep(Duration::from_secs(2)).await;

    // Verify graceful degradation
    let degraded_memory = node.get_memory_usage().await?;
    let degraded_connections = node.get_connection_count().await?;

    // System should have reduced resource usage
    assert!(
        degraded_memory < initial_memory,
        "Memory usage should decrease under exhaustion"
    );
    assert!(
        degraded_connections <= initial_connections,
        "Connection count should not increase"
    );

    // System should still be functional
    let still_operational = node.is_operational().await?;
    assert!(
        still_operational,
        "System should remain operational under resource exhaustion"
    );

    // Test recovery
    println!("🔄 Testing recovery from resource exhaustion...");
    node.relieve_resource_exhaustion().await?;

    sleep(Duration::from_secs(3)).await;

    // Verify recovery
    let recovered_memory = node.get_memory_usage().await?;
    let recovered_connections = node.get_connection_count().await?;

    assert!(
        recovered_memory >= degraded_memory,
        "Memory usage should improve after recovery"
    );
    assert!(
        recovered_connections >= degraded_connections,
        "Connections should recover"
    );

    println!("✅ Resource exhaustion resilience test passed");
    Ok(())
}

#[tokio::test]
async fn test_cascading_failure_prevention() -> anyhow::Result<()> {
    println!("🔗 Testing cascading failure prevention...");

    // Create a network with potential cascading failure points
    let mut nodes = Vec::new();
    for i in 0..8 {
        let node_id = NodeId {
            hash: [i as u8; 32],
        };
        let node = AdaptiveNode::new(node_id).await?;
        nodes.push(node);
    }

    // Create a topology prone to cascading failures
    // Nodes 0-2 are central, nodes 3-7 are peripheral
    for i in 0..3 {
        for j in 3..8 {
            nodes[i].connect_to(&nodes[j]).await?;
        }
    }

    // Add some cross-connections
    nodes[3].connect_to(&nodes[4]).await?;
    nodes[5].connect_to(&nodes[6]).await?;
    nodes[6].connect_to(&nodes[7]).await?;

    // Verify initial stability
    let initial_stability = AdaptiveNode::measure_network_stability(&nodes).await?;
    assert!(initial_stability > 0.8, "Initial network should be stable");

    // Trigger cascading failure by failing central nodes
    println!("💥 Triggering cascading failure...");
    nodes[0].simulate_failure().await?;
    sleep(Duration::from_millis(500)).await;
    nodes[1].simulate_failure().await?;

    // Wait for potential cascade
    sleep(Duration::from_secs(3)).await;

    // Verify cascading failure prevention
    let mut surviving_nodes = 0;
    for node in &nodes {
        if node.is_operational().await.unwrap_or(false) {
            surviving_nodes += 1;
        }
    }
    assert!(
        surviving_nodes >= 3,
        "Too many nodes failed - cascading failure occurred"
    );

    // Verify that the system has isolated the failure
    let stability_after_failure = AdaptiveNode::measure_network_stability(&nodes).await?;
    assert!(
        stability_after_failure > 0.3,
        "Network stability too low after cascading failure"
    );

    // Test recovery
    println!("🔧 Testing recovery from cascading failure...");
    nodes[0].restore_from_failure().await?;
    nodes[1].restore_from_failure().await?;

    sleep(Duration::from_secs(4)).await;

    // Verify recovery
    let final_stability = AdaptiveNode::measure_network_stability(&nodes).await?;
    assert!(
        final_stability > 0.7,
        "Network did not recover properly from cascading failure"
    );

    println!("✅ Cascading failure prevention test passed");
    Ok(())
}

#[tokio::test]
async fn test_byzantine_behavior_detection() -> anyhow::Result<()> {
    println!("🕵️ Testing Byzantine behavior detection...");

    let mut nodes = Vec::new();
    for i in 0..5 {
        let node_id = NodeId {
            hash: [i as u8; 32],
        };
        let node = AdaptiveNode::new(node_id).await?;
        nodes.push(node);
    }

    // Establish trust relationships
    for i in 0..5 {
        for j in 0..5 {
            if i != j {
                nodes[i].establish_trust(&nodes[j]).await?;
            }
        }
    }

    // Simulate Byzantine behavior
    println!("😈 Simulating Byzantine behavior...");
    let byzantine_node = &nodes[2];

    // Byzantine node sends conflicting information
    byzantine_node.send_conflicting_messages().await?;
    byzantine_node.provide_invalid_routing_info().await?;

    // Other nodes recognise the misbehaviour and penalise the offender
    for (i, node) in nodes.iter().enumerate() {
        if i != 2 {
            node.record_byzantine_behavior(byzantine_node).await?;
        }
    }

    // Wait for detection
    sleep(Duration::from_secs(3)).await;

    // Verify Byzantine behavior detection
    for (i, node) in nodes.iter().enumerate() {
        if i == 2 {
            continue; // Skip the Byzantine node itself
        }

        let trust_score = node.get_trust_score(byzantine_node.get_id()).await?;
        assert!(
            trust_score < 0.3,
            "Byzantine node should have low trust score"
        );
    }

    // Verify system isolation of Byzantine node
    let byzantine_connections = byzantine_node.get_connection_count().await?;
    assert!(
        byzantine_connections <= 1,
        "Byzantine node should be isolated"
    );

    // Test that honest nodes can still communicate
    let honest_node1 = &nodes[0];
    let honest_node2 = &nodes[1];

    let communication_success = timeout(
        Duration::from_secs(3),
        honest_node1.send_message(honest_node2.get_id(), b"honest message"),
    )
    .await
    .is_ok();

    assert!(
        communication_success,
        "Honest nodes should still be able to communicate"
    );

    println!("✅ Byzantine behavior detection test passed");
    Ok(())
}

// Helper implementations for chaos engineering tests

impl AdaptiveNode {
    async fn new(id: NodeId) -> anyhow::Result<Self> {
        Ok(Self {
            id,
            connections: Arc::new(RwLock::new(HashMap::new())),
            operational: Arc::new(RwLock::new(true)),
            trust_scores: Arc::new(RwLock::new(HashMap::new())),
            memory_usage: Arc::new(RwLock::new(100)),
            base_latency: Duration::from_millis(50),
            latency_spike: Arc::new(RwLock::new(None)),
        })
    }

    async fn connect_to(&self, other: &AdaptiveNode) -> anyhow::Result<()> {
        let mut connections = self.connections.write().await;
        connections.insert(other.id.clone(), true);
        Ok(())
    }

    async fn get_connection_count(&self) -> anyhow::Result<usize> {
        let connections = self.connections.read().await;
        Ok(connections.len())
    }

    async fn simulate_failure(&self) -> anyhow::Result<()> {
        *self.operational.write().await = false;
        Ok(())
    }

    async fn restore_from_failure(&self) -> anyhow::Result<()> {
        *self.operational.write().await = true;
        Ok(())
    }

    async fn is_operational(&self) -> anyhow::Result<bool> {
        Ok(*self.operational.read().await)
    }

    async fn simulate_partition(
        nodes_a: &[AdaptiveNode],
        nodes_b: &[AdaptiveNode],
    ) -> anyhow::Result<()> {
        // Simulate network partition by marking cross-partition connections as down
        for node_a in nodes_a {
            for node_b in nodes_b {
                let mut connections = node_a.connections.write().await;
                connections.insert(node_b.id.clone(), false);
            }
        }
        Ok(())
    }

    async fn restore_connectivity(
        nodes_a: &[AdaptiveNode],
        nodes_b: &[AdaptiveNode],
    ) -> anyhow::Result<()> {
        // Restore cross-partition connectivity
        for node_a in nodes_a {
            for node_b in nodes_b {
                let mut connections = node_a.connections.write().await;
                connections.insert(node_b.id.clone(), true);
            }
        }
        Ok(())
    }

    async fn has_detected_partition(&self) -> anyhow::Result<bool> {
        let connections = self.connections.read().await;
        let down_connections = connections.values().filter(|&&up| !up).count();
        Ok(down_connections > connections.len() / 2)
    }

    async fn inject_latency_spike(&self, spike_duration: Duration) -> anyhow::Result<()> {
        *self.latency_spike.write().await = Some(std::time::Instant::now() + spike_duration);
        Ok(())
    }

    async fn measure_latency(&self) -> anyhow::Result<Duration> {
        let base_latency = self.base_latency;

        if let Some(spike_end) = *self.latency_spike.read().await
            && std::time::Instant::now() < spike_end
        {
            // During spike, return much higher latency
            return Ok(base_latency * 10);
        }

        Ok(base_latency)
    }

    async fn simulate_resource_exhaustion(&self) -> anyhow::Result<()> {
        *self.memory_usage.write().await = 10; // Very low memory
        Ok(())
    }

    async fn relieve_resource_exhaustion(&self) -> anyhow::Result<()> {
        *self.memory_usage.write().await = 100; // Restore memory
        Ok(())
    }

    async fn get_memory_usage(&self) -> anyhow::Result<usize> {
        Ok(*self.memory_usage.read().await)
    }

    async fn send_message(&self, target: NodeId, _message: &[u8]) -> anyhow::Result<()> {
        if !*self.operational.read().await {
            return Err(anyhow::anyhow!("Node is not operational"));
        }

        let connections = self.connections.read().await;
        if !connections.get(&target).unwrap_or(&false) {
            return Err(anyhow::anyhow!("No connection to target"));
        }

        Ok(())
    }

    async fn establish_trust(&self, other: &AdaptiveNode) -> anyhow::Result<()> {
        let mut trust_scores = self.trust_scores.write().await;
        trust_scores.insert(other.id.clone(), 0.8); // Initial high trust
        Ok(())
    }

    async fn get_trust_score(&self, peer: NodeId) -> anyhow::Result<f64> {
        let trust_scores = self.trust_scores.read().await;
        Ok(*trust_scores.get(&peer).unwrap_or(&0.5))
    }

    async fn send_conflicting_messages(&self) -> anyhow::Result<()> {
        // Simulate sending conflicting information
        let mut trust_scores = self.trust_scores.write().await;
        for score in trust_scores.values_mut() {
            *score -= 0.2; // Reduce trust for all peers
        }
        Ok(())
    }

    async fn provide_invalid_routing_info(&self) -> anyhow::Result<()> {
        // Simulate providing invalid routing information
        let mut trust_scores = self.trust_scores.write().await;
        for score in trust_scores.values_mut() {
            *score -= 0.3; // Further reduce trust
        }
        Ok(())
    }

    async fn record_byzantine_behavior(&self, peer: &AdaptiveNode) -> anyhow::Result<()> {
        {
            let mut trust_scores = self.trust_scores.write().await;
            trust_scores
                .entry(peer.id.clone())
                .and_modify(|score| *score = (*score * 0.2).min(0.2))
                .or_insert(0.2);
        }

        let mut connections = self.connections.write().await;
        connections.insert(peer.id.clone(), false);
        Ok(())
    }

    async fn make_adaptive_decision(&self) -> anyhow::Result<AdaptiveDecision> {
        Ok(AdaptiveDecision {
            action: "test".to_string(),
            confidence: 0.8,
        })
    }

    async fn is_functional(&self) -> anyhow::Result<bool> {
        Ok(*self.operational.read().await && *self.memory_usage.read().await > 20)
    }

    fn get_id(&self) -> NodeId {
        self.id.clone()
    }

    async fn measure_network_stability(nodes: &[AdaptiveNode]) -> anyhow::Result<f64> {
        let mut operational_count = 0;
        for node in nodes {
            if node.is_operational().await.unwrap_or(false) {
                operational_count += 1;
            }
        }

        Ok(operational_count as f64 / nodes.len() as f64)
    }
}

#[derive(Debug)]
struct AdaptiveNode {
    id: NodeId,
    connections: Arc<RwLock<HashMap<NodeId, bool>>>, // true = up, false = down
    operational: Arc<RwLock<bool>>,
    trust_scores: Arc<RwLock<HashMap<NodeId, f64>>>,
    memory_usage: Arc<RwLock<usize>>,
    base_latency: Duration,
    latency_spike: Arc<RwLock<Option<std::time::Instant>>>,
}

#[derive(Debug)]
struct AdaptiveDecision {
    action: String,
    confidence: f64,
}
