qssl 0.2.0

//! Stealth Mode - Maximum obfuscation against quantum analysis

use super::{QuantumFrame, FrameType};
use crate::QsslResult;
use rand::{Rng, RngCore};
use std::collections::VecDeque;
use std::time::{Duration, Instant};

/// Stealth mode controller for maximum traffic obfuscation
pub struct StealthController {
    /// Current stealth level (0-10)
    level: u8,

    /// Dummy traffic generator
    dummy_generator: DummyTrafficGenerator,

    /// Traffic shaper
    traffic_shaper: TrafficShaper,

    /// Pattern breaker
    pattern_breaker: PatternBreaker,
}

impl StealthController {
    /// Create new stealth controller
    pub fn new(level: u8) -> Self {
        Self {
            level: level.min(10),
            dummy_generator: DummyTrafficGenerator::new(level),
            traffic_shaper: TrafficShaper::new(level),
            pattern_breaker: PatternBreaker::new(),
        }
    }

    /// Process outgoing frame with stealth features
    pub async fn process_outgoing(
        &mut self,
        frame: QuantumFrame,
    ) -> QsslResult<Vec<QuantumFrame>> {
        let mut frames = Vec::new();

        // Add dummy frames based on stealth level
        let dummy_count = self.dummy_generator.get_dummy_count();
        for _ in 0..dummy_count {
            frames.push(self.dummy_generator.generate());
        }

        // Break patterns by inserting at random position
        let position = self.pattern_breaker.get_insertion_position(frames.len());
        frames.insert(position, frame);

        // Shape traffic timing
        self.traffic_shaper.shape_timing(&mut frames).await;

        Ok(frames)
    }

    /// Process incoming frames, filtering dummy traffic
    pub fn process_incoming(
        &mut self,
        frames: Vec<QuantumFrame>,
    ) -> Vec<QuantumFrame> {
        frames
            .into_iter()
            .filter(|f| f.header.frame_type != FrameType::Noise as u8)
            .collect()
    }

    /// Increase stealth level
    pub fn increase_stealth(&mut self) {
        if self.level < 10 {
            self.level += 1;
            self.dummy_generator.set_level(self.level);
            self.traffic_shaper.set_level(self.level);
        }
    }

    /// Decrease stealth level
    pub fn decrease_stealth(&mut self) {
        if self.level > 0 {
            self.level -= 1;
            self.dummy_generator.set_level(self.level);
            self.traffic_shaper.set_level(self.level);
        }
    }
}

/// Generate dummy traffic to hide real communication
struct DummyTrafficGenerator {
    level: u8,
    entropy_pool: Vec<u8>,
    pool_index: usize,
}

impl DummyTrafficGenerator {
    fn new(level: u8) -> Self {
        let mut entropy_pool = vec![0u8; 4096];
        rand::thread_rng().fill_bytes(&mut entropy_pool);

        Self {
            level,
            entropy_pool,
            pool_index: 0,
        }
    }

    fn set_level(&mut self, level: u8) {
        self.level = level;
    }

    /// Get number of dummy frames to generate
    fn get_dummy_count(&self) -> usize {
        match self.level {
            0 => 0,
            1..=3 => rand::thread_rng().gen_range(0..2),
            4..=6 => rand::thread_rng().gen_range(1..4),
            7..=9 => rand::thread_rng().gen_range(2..6),
            10 => rand::thread_rng().gen_range(3..8),
            _ => 0,
        }
    }

    /// Generate a dummy frame
    fn generate(&mut self) -> QuantumFrame {
        let mut frame = QuantumFrame {
            header: super::EncryptedHeader {
                sequence: rand::random(),
                timestamp: self.get_fake_timestamp(),
                frame_type: FrameType::Noise as u8,
            },
            payload: [0; 719],
            mac: [0; 32],
        };

        // Fill with entropy pool data (faster than RNG)
        for chunk in frame.payload.chunks_mut(32) {
            let start = self.pool_index;
            let end = (start + chunk.len()).min(self.entropy_pool.len());
            chunk.copy_from_slice(&self.entropy_pool[start..end]);
            self.pool_index = (self.pool_index + chunk.len()) % self.entropy_pool.len();
        }

        // Regenerate pool occasionally
        if self.pool_index == 0 {
            rand::thread_rng().fill_bytes(&mut self.entropy_pool);
        }

        frame
    }

    /// Generate fake timestamp with jitter
    fn get_fake_timestamp(&self) -> [u8; 8] {
        use std::time::{SystemTime, UNIX_EPOCH};

        let mut timestamp = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap_or_default()
            .as_micros() as u64;

        // Add jitter based on level
        let jitter = rand::thread_rng().gen_range(0..1000 * self.level as u64);
        timestamp = timestamp.wrapping_add(jitter);

        timestamp.to_be_bytes()
    }
}

/// Shape traffic to hide patterns
struct TrafficShaper {
    level: u8,
    last_send: Instant,
    target_rate: Duration,
    burst_buffer: VecDeque<QuantumFrame>,
}

impl TrafficShaper {
    fn new(level: u8) -> Self {
        Self {
            level,
            last_send: Instant::now(),
            target_rate: Self::calculate_rate(level),
            burst_buffer: VecDeque::new(),
        }
    }

    fn set_level(&mut self, level: u8) {
        self.level = level;
        self.target_rate = Self::calculate_rate(level);
    }

    /// Calculate target rate based on stealth level
    fn calculate_rate(level: u8) -> Duration {
        match level {
            0 => Duration::from_micros(100),    // 10,000 fps max
            1..=3 => Duration::from_micros(500), // 2,000 fps
            4..=6 => Duration::from_millis(1),   // 1,000 fps
            7..=9 => Duration::from_millis(5),   // 200 fps
            10 => Duration::from_millis(10),     // 100 fps (constant rate)
            _ => Duration::from_millis(1),
        }
    }

    /// Shape timing of frames
    async fn shape_timing(&mut self, frames: &mut Vec<QuantumFrame>) {
        if self.level == 0 {
            return; // No shaping at level 0
        }

        // Calculate delays to create constant rate
        let now = Instant::now();
        let elapsed = now.duration_since(self.last_send);

        if elapsed < self.target_rate {
            let delay = self.target_rate - elapsed;
            tokio::time::sleep(delay).await;
        }

        self.last_send = Instant::now();

        // At high stealth levels, buffer and release in bursts
        if self.level >= 7 {
            self.burst_mode(frames).await;
        }
    }

    /// Burst mode - collect frames and release in bursts
    async fn burst_mode(&mut self, frames: &mut Vec<QuantumFrame>) {
        // Add frames to buffer
        for frame in frames.drain(..) {
            self.burst_buffer.push_back(frame);
        }

        // Release burst if buffer is full or timeout
        if self.burst_buffer.len() >= 10 || self.last_send.elapsed() > Duration::from_millis(100) {
            frames.extend(self.burst_buffer.drain(..));
        }
    }
}

/// Break patterns in traffic to prevent analysis
struct PatternBreaker {
    history: Vec<usize>,
    counter: usize,
}

impl PatternBreaker {
    fn new() -> Self {
        Self {
            history: Vec::with_capacity(100),
            counter: 0,
        }
    }

    /// Get random insertion position to break patterns
    fn get_insertion_position(&mut self, max: usize) -> usize {
        if max == 0 {
            return 0;
        }

        // Avoid creating patterns in insertion positions
        let position = if self.counter % 7 == 0 {
            // Occasionally insert at beginning
            0
        } else if self.counter % 11 == 0 {
            // Occasionally insert at end
            max
        } else {
            // Random position, but avoid recent positions
            let mut pos = rand::thread_rng().gen_range(0..=max);

            // Check if we've used this position recently
            if self.history.len() > 10 {
                let recent = &self.history[self.history.len() - 10..];
                if recent.contains(&pos) {
                    // Choose different position
                    pos = (pos + max / 2) % (max + 1);
                }
            }

            pos
        };

        self.history.push(position);
        if self.history.len() > 100 {
            self.history.remove(0);
        }

        self.counter = self.counter.wrapping_add(1);
        position
    }
}

/// Quantum RNG integration for maximum entropy
pub struct QuantumRng {
    /// Source of quantum entropy
    source: QuantumEntropySource,
    /// Fallback to system RNG
    fallback: rand::rngs::ThreadRng,
}

#[derive(Debug)]
enum QuantumEntropySource {
    Hardware,    // Hardware QRNG
    Network,     // Network QRNG service
    Simulated,   // Simulated quantum noise
}

impl QuantumRng {
    /// Create new quantum RNG
    pub fn new() -> Self {
        // Try to detect quantum hardware
        let source = Self::detect_quantum_source();

        Self {
            source,
            fallback: rand::thread_rng(),
        }
    }

    /// Detect available quantum entropy source
    fn detect_quantum_source() -> QuantumEntropySource {
        // Check for hardware QRNG
        if std::path::Path::new("/dev/qrng").exists() {
            return QuantumEntropySource::Hardware;
        }

        // Check for network QRNG
        if std::env::var("QRNG_ENDPOINT").is_ok() {
            return QuantumEntropySource::Network;
        }

        // Fallback to simulated
        QuantumEntropySource::Simulated
    }

    /// Get quantum random bytes
    pub fn get_bytes(&mut self, buffer: &mut [u8]) {
        match self.source {
            QuantumEntropySource::Hardware => {
                // Read from hardware QRNG
                if let Ok(mut file) = std::fs::File::open("/dev/qrng") {
                    use std::io::Read;
                    let _ = file.read_exact(buffer);
                } else {
                    self.fallback.fill_bytes(buffer);
                }
            }
            QuantumEntropySource::Network => {
                // Fetch from network QRNG service
                // For now, use fallback
                self.fallback.fill_bytes(buffer);
            }
            QuantumEntropySource::Simulated => {
                // Simulate quantum noise patterns
                self.fallback.fill_bytes(buffer);
                // Add quantum-like noise
                for byte in buffer.iter_mut() {
                    *byte ^= (*byte).rotate_left(3);
                }
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_stealth_controller() {
        let mut controller = StealthController::new(5);

        let frame = QuantumFrame {
            header: super::super::EncryptedHeader {
                sequence: [0; 8],
                timestamp: [0; 8],
                frame_type: FrameType::Data as u8,
            },
            payload: [0; 719],
            mac: [0; 32],
        };

        let frames = controller.process_outgoing(frame).await.unwrap();
        assert!(!frames.is_empty());
    }

    #[test]
    fn test_dummy_generator() {
        let mut generator = DummyTrafficGenerator::new(5);

        let count = generator.get_dummy_count();
        assert!(count > 0);

        let frame = generator.generate();
        assert_eq!(frame.header.frame_type, FrameType::Noise as u8);
    }

    #[test]
    fn test_pattern_breaker() {
        let mut breaker = PatternBreaker::new();

        let positions: Vec<usize> = (0..20)
            .map(|_| breaker.get_insertion_position(10))
            .collect();

        // Should have variety in positions
        let unique_count = positions.iter().collect::<std::collections::HashSet<_>>().len();
        assert!(unique_count > 1);
    }
}