//! Simplified security tests for QUIC Address Discovery
//!
//! These tests validate security properties of the address discovery implementation

#![allow(clippy::unwrap_used, clippy::expect_used)]

use std::{
    net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr},
    time::Duration,
};

/// Test timing attack resistance in address processing
#[tokio::test]
async fn test_constant_time_operations() {
    let _ = tracing_subscriber::fmt::try_init();

    // Test that address type detection is constant time
    let ipv4_addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(192, 168, 1, 1)), 50000);

    let ipv6_addr = SocketAddr::new(
        IpAddr::V6(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 1)),
        50000,
    );

    // Measure processing time for different address types
    let mut ipv4_times = Vec::new();
    let mut ipv6_times = Vec::new();

    for _ in 0..100 {
        let start = std::time::Instant::now();
        let _is_ipv4 = matches!(ipv4_addr, SocketAddr::V4(_));
        ipv4_times.push(start.elapsed());

        let start = std::time::Instant::now();
        let _is_ipv6 = matches!(ipv6_addr, SocketAddr::V6(_));
        ipv6_times.push(start.elapsed());
    }

    // Calculate average times
    let avg_ipv4: Duration = ipv4_times.iter().sum::<Duration>() / ipv4_times.len() as u32;
    let avg_ipv6: Duration = ipv6_times.iter().sum::<Duration>() / ipv6_times.len() as u32;

    // Times should be similar (within 100ns)
    let time_diff = avg_ipv4.abs_diff(avg_ipv6);

    assert!(
        time_diff < Duration::from_nanos(100),
        "Address type detection should be constant time: diff={time_diff:?}"
    );
}

/// Test private address detection security
#[test]
fn test_private_address_detection() {
    // Test that private address detection doesn't leak information
    let test_cases = vec![
        ([10, 0, 0, 1], true),        // 10.0.0.0/8
        ([10, 255, 255, 255], true),  // 10.0.0.0/8
        ([172, 16, 0, 1], true),      // 172.16.0.0/12
        ([172, 31, 255, 255], true),  // 172.16.0.0/12
        ([172, 32, 0, 1], false),     // Outside range
        ([192, 168, 0, 1], true),     // 192.168.0.0/16
        ([192, 168, 255, 255], true), // 192.168.0.0/16
        ([8, 8, 8, 8], false),        // Public
        ([1, 1, 1, 1], false),        // Public
    ];

    for (octets, expected_private) in test_cases {
        // Bitwise operations for constant-time checking
        let is_10 = octets[0] == 10;
        let is_172_16 = octets[0] == 172 && (octets[1] & 0xf0) == 16;
        let is_192_168 = octets[0] == 192 && octets[1] == 168;
        let is_private = is_10 | is_172_16 | is_192_168;

        assert_eq!(
            is_private, expected_private,
            "Private address detection failed for {octets:?}"
        );
    }
}

/// Test frame size limits for amplification protection
#[test]
fn test_frame_size_limits() {
    // OBSERVED_ADDRESS frame structure analysis
    // Frame type: 1 byte (0x43)
    // Sequence number: 1-8 bytes (varint)
    // Address type: 1 byte
    // Address: 4 bytes (IPv4) or 16 bytes (IPv6)
    // Port: 2 bytes

    let _min_ipv4_frame_size = 1 + 1 + 1 + 4 + 2; // 9 bytes
    let max_ipv4_frame_size = 1 + 8 + 1 + 4 + 2; // 16 bytes

    let _min_ipv6_frame_size = 1 + 1 + 1 + 16 + 2; // 21 bytes
    let max_ipv6_frame_size = 1 + 8 + 1 + 16 + 2; // 28 bytes

    // Verify frames are small enough to prevent amplification
    assert!(max_ipv4_frame_size < 50, "IPv4 frame must be small");
    assert!(max_ipv6_frame_size < 50, "IPv6 frame must be small");

    // Amplification factor check
    let typical_request_size = 100; // Typical QUIC packet
    let amplification_factor = max_ipv6_frame_size as f32 / typical_request_size as f32;

    assert!(
        amplification_factor < 0.5,
        "No amplification possible: factor={amplification_factor}"
    );
}

/// Test memory bounds per connection
#[test]
fn test_memory_bounds() {
    // Calculate memory usage for address discovery state
    let address_size = std::mem::size_of::<SocketAddr>(); // 28 bytes
    let timestamp_size = std::mem::size_of::<std::time::Instant>(); // 16 bytes
    let entry_size = address_size + timestamp_size; // ~44 bytes

    const MAX_ADDRESSES_PER_CONNECTION: usize = 100;
    let max_memory = entry_size * MAX_ADDRESSES_PER_CONNECTION;

    assert!(
        max_memory < 10_000,
        "Memory per connection should be bounded: {max_memory} bytes"
    );

    // With overhead for HashMaps
    let hashmap_overhead = 2.0; // Typical HashMap overhead factor
    let total_memory = (max_memory as f64 * hashmap_overhead) as usize;

    assert!(
        total_memory < 20_000,
        "Total memory with overhead should be < 20KB: {total_memory} bytes"
    );
}

/// Test port randomization for symmetric NAT defense
#[test]
fn test_port_randomization() {
    use std::collections::HashSet;

    // Simulate port allocation
    let mut ports = HashSet::new();

    // Generate 100 "random" ports
    for i in 0..100u32 {
        // Simulate OS port allocation with some randomness
        let base = 49152; // Dynamic port range start
        let range = 16384; // Dynamic port range size

        // Simple hash-based pseudo-randomization for testing
        let hash = i.wrapping_mul(2654435761); // Knuth's multiplicative hash
        let port = base + (hash % range) as u16;

        ports.insert(port);
    }

    // Check for good distribution
    assert!(
        ports.len() > 90,
        "Port allocation should have good distribution"
    );

    // Check that ports aren't sequential
    let mut sorted_ports: Vec<_> = ports.iter().copied().collect();
    sorted_ports.sort();

    let mut sequential_count = 0;
    for window in sorted_ports.windows(2) {
        if window[1] == window[0] + 1 {
            sequential_count += 1;
        }
    }

    assert!(
        sequential_count < 10,
        "Ports should not be mostly sequential: {sequential_count} sequential pairs"
    );
}

/// Test rate limiting calculations
#[test]
fn test_rate_limiting_math() {
    // Token bucket algorithm verification
    struct TokenBucket {
        tokens: f64,
        max_tokens: f64,
        refill_rate: f64,
        last_update: std::time::Instant,
    }

    impl TokenBucket {
        fn new(rate: f64) -> Self {
            Self {
                tokens: rate,
                max_tokens: rate,
                refill_rate: rate,
                last_update: std::time::Instant::now(),
            }
        }

        fn try_consume(&mut self) -> bool {
            let now = std::time::Instant::now();
            let elapsed = now.duration_since(self.last_update).as_secs_f64();

            // Refill tokens
            self.tokens = (self.tokens + elapsed * self.refill_rate).min(self.max_tokens);
            self.last_update = now;

            // Try to consume
            if self.tokens >= 1.0 {
                self.tokens -= 1.0;
                true
            } else {
                false
            }
        }
    }

    let mut bucket = TokenBucket::new(10.0); // 10 per second

    // Should allow initial burst
    let mut allowed = 0;
    for _ in 0..15 {
        if bucket.try_consume() {
            allowed += 1;
        }
    }

    assert_eq!(allowed, 10, "Should allow initial burst of 10");

    // After 1 second, should allow more
    std::thread::sleep(Duration::from_secs(1));

    let mut allowed_after_wait = 0;
    for _ in 0..15 {
        if bucket.try_consume() {
            allowed_after_wait += 1;
        }
    }

    assert!(
        (9..=11).contains(&allowed_after_wait),
        "Should allow ~10 more after 1 second: {allowed_after_wait}"
    );
}
