aranet-core 0.2.0

//! Passive monitoring via BLE advertisements.
//!
//! This module provides functionality to monitor Aranet devices without
//! establishing a connection, using BLE advertisement data instead.
//!
//! # Benefits
//!
//! - **Lower power consumption**: No connection overhead
//! - **More devices**: Can monitor more than the BLE connection limit
//! - **Simpler**: No connection management needed
//!
//! # Requirements
//!
//! Smart Home integration must be enabled on each device:
//! - Go to device Settings > Smart Home > Enable
//!
//! # Example
//!
//! ```ignore
//! use aranet_core::passive::{PassiveMonitor, PassiveMonitorOptions};
//! use tokio_util::sync::CancellationToken;
//!
//! let monitor = PassiveMonitor::new(PassiveMonitorOptions::default());
//! let cancel = CancellationToken::new();
//!
//! // Start monitoring in background
//! let handle = monitor.start(cancel.clone());
//!
//! // Receive readings
//! let mut rx = monitor.subscribe();
//! while let Ok(reading) = rx.recv().await {
//!     println!("Device: {} CO2: {:?}", reading.device_name, reading.data.co2);
//! }
//! ```

use std::collections::HashMap;
use std::sync::Arc;
use std::time::Duration;

use btleplug::api::{Central, Peripheral as _, ScanFilter};
use tokio::sync::{RwLock, broadcast};
use tokio::time::sleep;
use tokio_util::sync::CancellationToken;
use tracing::{debug, info, warn};

use crate::advertisement::{AdvertisementData, parse_advertisement_with_name};
use crate::error::Result;
use crate::scan::get_adapter;
use crate::uuid::MANUFACTURER_ID;

/// Bitwise-exact comparison of two `Option<f32>` values (handles NaN correctly).
fn opt_f32_eq(a: Option<f32>, b: Option<f32>) -> bool {
    match (a, b) {
        (Some(x), Some(y)) => x.to_bits() == y.to_bits(),
        (None, None) => true,
        _ => false,
    }
}

/// A reading from passive advertisement monitoring.
#[derive(Debug, Clone)]
pub struct PassiveReading {
    /// Device identifier (MAC address or UUID).
    pub device_id: String,
    /// Device name if available.
    pub device_name: Option<String>,
    /// RSSI signal strength.
    pub rssi: Option<i16>,
    /// Parsed advertisement data.
    pub data: AdvertisementData,
    /// When this reading was received.
    pub received_at: std::time::Instant,
}

/// Options for passive monitoring.
#[derive(Debug, Clone)]
pub struct PassiveMonitorOptions {
    /// How long to scan between processing cycles.
    pub scan_duration: Duration,
    /// Delay between scan cycles.
    pub scan_interval: Duration,
    /// Channel capacity for readings.
    pub channel_capacity: usize,
    /// Only emit readings when values change (deduplicate).
    pub deduplicate: bool,
    /// Maximum age of cached readings before re-emitting (if deduplicate is true).
    pub max_reading_age: Duration,
    /// Filter to only these device IDs (empty = all Aranet devices).
    pub device_filter: Vec<String>,
}

impl Default for PassiveMonitorOptions {
    fn default() -> Self {
        Self {
            scan_duration: Duration::from_secs(5),
            scan_interval: Duration::from_secs(1),
            channel_capacity: 100,
            deduplicate: true,
            max_reading_age: Duration::from_secs(60),
            device_filter: Vec::new(),
        }
    }
}

impl PassiveMonitorOptions {
    /// Create new options with default settings.
    pub fn new() -> Self {
        Self::default()
    }

    /// Set the scan duration.
    pub fn scan_duration(mut self, duration: Duration) -> Self {
        self.scan_duration = duration;
        self
    }

    /// Set the interval between scan cycles.
    pub fn scan_interval(mut self, interval: Duration) -> Self {
        self.scan_interval = interval;
        self
    }

    /// Enable or disable deduplication.
    pub fn deduplicate(mut self, enable: bool) -> Self {
        self.deduplicate = enable;
        self
    }

    /// Filter to specific device IDs.
    pub fn filter_devices(mut self, device_ids: Vec<String>) -> Self {
        self.device_filter = device_ids;
        self
    }
}

/// Cached reading for deduplication.
struct CachedReading {
    data: AdvertisementData,
    received_at: std::time::Instant,
}

/// Passive monitor for Aranet devices using BLE advertisements.
///
/// This allows monitoring multiple devices without establishing connections,
/// which is useful for scenarios where:
/// - You need to monitor more devices than the BLE connection limit
/// - Low power consumption is important
/// - Real-time data isn't critical (advertisement interval is typically 4+ seconds)
pub struct PassiveMonitor {
    options: PassiveMonitorOptions,
    /// Broadcast sender for readings.
    sender: broadcast::Sender<PassiveReading>,
    /// Cache of last readings for deduplication.
    cache: Arc<RwLock<HashMap<String, CachedReading>>>,
}

impl PassiveMonitor {
    /// Create a new passive monitor with the given options.
    pub fn new(options: PassiveMonitorOptions) -> Self {
        let (sender, _) = broadcast::channel(options.channel_capacity);
        Self {
            options,
            sender,
            cache: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    /// Subscribe to passive readings.
    ///
    /// Returns a receiver that will receive readings as they are detected.
    pub fn subscribe(&self) -> broadcast::Receiver<PassiveReading> {
        self.sender.subscribe()
    }

    /// Get the number of active subscribers.
    pub fn subscriber_count(&self) -> usize {
        self.sender.receiver_count()
    }

    /// Start the passive monitor.
    ///
    /// This spawns a background task that continuously scans for BLE
    /// advertisements and parses Aranet device data.
    ///
    /// The task runs until the cancellation token is triggered.
    pub fn start(self: &Arc<Self>, cancel_token: CancellationToken) -> tokio::task::JoinHandle<()> {
        let monitor = Arc::clone(self);

        tokio::spawn(async move {
            info!("Starting passive monitor");

            // Acquire the adapter once and reuse across scan cycles.
            // On persistent errors we re-acquire it in case the adapter
            // was reset or the D-Bus connection was lost.
            let mut adapter = loop {
                match get_adapter().await {
                    Ok(a) => break a,
                    Err(e) => {
                        warn!("Passive monitor failed to get adapter: {e} — retrying in 10s");
                        tokio::select! {
                            _ = cancel_token.cancelled() => {
                                info!("Passive monitor cancelled while waiting for adapter");
                                return;
                            }
                            _ = sleep(Duration::from_secs(10)) => {}
                        }
                    }
                }
            };
            let mut consecutive_errors: u32 = 0;

            loop {
                tokio::select! {
                    _ = cancel_token.cancelled() => {
                        info!("Passive monitor cancelled");
                        break;
                    }
                    result = monitor.scan_cycle_with_adapter(&adapter) => {
                        match result {
                            Ok(()) => {
                                consecutive_errors = 0;
                            }
                            Err(e) => {
                                consecutive_errors += 1;
                                warn!(
                                    "Passive monitor scan error ({consecutive_errors} consecutive): {e}"
                                );
                                // After several consecutive failures, try to
                                // re-acquire the adapter — it may have been
                                // reset or the D-Bus connection may have died.
                                if consecutive_errors >= 5 {
                                    warn!("Passive monitor: re-acquiring adapter after {} consecutive errors", consecutive_errors);
                                    match get_adapter().await {
                                        Ok(a) => {
                                            adapter = a;
                                            info!("Passive monitor: adapter re-acquired");
                                            consecutive_errors = 0;
                                        }
                                        Err(e2) => {
                                            // Adapter re-acquisition failed — back off
                                            // longer to avoid thrashing when the adapter
                                            // is permanently unavailable.
                                            warn!("Passive monitor: failed to re-acquire adapter: {}. Backing off.", e2);
                                            let backoff = std::cmp::min(
                                                monitor.options.scan_interval.saturating_mul(consecutive_errors),
                                                std::time::Duration::from_secs(300),
                                            );
                                            sleep(backoff).await;
                                        }
                                    }
                                }
                            }
                        }
                        // Wait before next scan cycle
                        sleep(monitor.options.scan_interval).await;
                    }
                }
            }
        })
    }

    /// Perform a single scan cycle using a pre-existing adapter.
    async fn scan_cycle_with_adapter(&self, adapter: &btleplug::platform::Adapter) -> Result<()> {
        // Start scanning
        adapter.start_scan(ScanFilter::default()).await?;
        sleep(self.options.scan_duration).await;
        adapter.stop_scan().await?;

        // Process discovered peripherals
        let peripherals = adapter.peripherals().await?;

        for peripheral in peripherals {
            if let Ok(Some(props)) = peripheral.properties().await {
                // Check if this is an Aranet device by manufacturer data
                if let Some(data) = props.manufacturer_data.get(&MANUFACTURER_ID) {
                    let device_id = crate::util::create_identifier(
                        &props.address.to_string(),
                        &peripheral.id(),
                    );

                    // Check device filter
                    if !self.options.device_filter.is_empty()
                        && !self.options.device_filter.contains(&device_id)
                    {
                        continue;
                    }

                    // Try to parse the advertisement
                    match parse_advertisement_with_name(data, props.local_name.as_deref()) {
                        Ok(adv_data) => {
                            // Check for deduplication
                            let should_emit = if self.options.deduplicate {
                                self.should_emit(&device_id, &adv_data).await
                            } else {
                                true
                            };

                            if should_emit {
                                let reading = PassiveReading {
                                    device_id: device_id.clone(),
                                    device_name: props.local_name.clone(),
                                    rssi: props.rssi,
                                    data: adv_data.clone(),
                                    received_at: std::time::Instant::now(),
                                };

                                // Update cache
                                self.cache.write().await.insert(
                                    device_id,
                                    CachedReading {
                                        data: adv_data,
                                        received_at: std::time::Instant::now(),
                                    },
                                );

                                // Send to subscribers (ignore if no receivers)
                                let _ = self.sender.send(reading);
                            }
                        }
                        Err(e) => {
                            debug!("Failed to parse advertisement from {}: {}", device_id, e);
                        }
                    }
                }
            }
        }

        Ok(())
    }

    /// Check if a reading should be emitted (for deduplication).
    async fn should_emit(&self, device_id: &str, data: &AdvertisementData) -> bool {
        let cache = self.cache.read().await;

        if let Some(cached) = cache.get(device_id) {
            // Check if reading is too old
            if cached.received_at.elapsed() > self.options.max_reading_age {
                return true;
            }

            // Check if values have changed (use total_cmp for floats to handle NaN correctly)
            if cached.data.co2 != data.co2
                || !opt_f32_eq(cached.data.temperature, data.temperature)
                || cached.data.humidity != data.humidity
                || !opt_f32_eq(cached.data.pressure, data.pressure)
                || cached.data.radon != data.radon
                || !opt_f32_eq(cached.data.radiation_dose_rate, data.radiation_dose_rate)
                || cached.data.battery != data.battery
            {
                return true;
            }

            // Check if counter changed (new measurement)
            if cached.data.counter != data.counter {
                return true;
            }

            false
        } else {
            // Not in cache, emit
            true
        }
    }

    /// Get the last known reading for a device.
    pub async fn get_last_reading(&self, device_id: &str) -> Option<AdvertisementData> {
        let cache = self.cache.read().await;
        cache.get(device_id).map(|c| c.data.clone())
    }

    /// Get all known device IDs.
    pub async fn known_devices(&self) -> Vec<String> {
        let cache = self.cache.read().await;
        cache.keys().cloned().collect()
    }

    /// Clear the reading cache.
    pub async fn clear_cache(&self) {
        self.cache.write().await.clear();
    }
}

impl Default for PassiveMonitor {
    fn default() -> Self {
        Self::new(PassiveMonitorOptions::default())
    }
}

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

    #[test]
    fn test_passive_monitor_options_default() {
        let opts = PassiveMonitorOptions::default();
        assert_eq!(opts.scan_duration, Duration::from_secs(5));
        assert!(opts.deduplicate);
        assert!(opts.device_filter.is_empty());
    }

    #[test]
    fn test_passive_monitor_options_builder() {
        let opts = PassiveMonitorOptions::new()
            .scan_duration(Duration::from_secs(10))
            .deduplicate(false)
            .filter_devices(vec!["device1".to_string()]);

        assert_eq!(opts.scan_duration, Duration::from_secs(10));
        assert!(!opts.deduplicate);
        assert_eq!(opts.device_filter, vec!["device1"]);
    }

    #[test]
    fn test_passive_monitor_subscribe() {
        let monitor = Arc::new(PassiveMonitor::default());
        let _rx1 = monitor.subscribe();
        let _rx2 = monitor.subscribe();
        assert_eq!(monitor.subscriber_count(), 2);
    }

    /// Helper to create test advertisement data with sensible defaults.
    fn make_adv_data() -> AdvertisementData {
        AdvertisementData {
            device_type: aranet_types::DeviceType::Aranet4,
            co2: Some(800),
            temperature: Some(22.5),
            pressure: Some(1013.2),
            humidity: Some(45),
            battery: 85,
            status: aranet_types::Status::Green,
            interval: 300,
            age: 120,
            radon: None,
            radiation_dose_rate: None,
            counter: Some(5),
            flags: 0x22,
        }
    }

    #[tokio::test]
    async fn test_should_emit_first_reading() {
        let monitor = PassiveMonitor::default();
        let data = make_adv_data();

        // First reading for a device should always be emitted.
        assert!(monitor.should_emit("device-1", &data).await);
    }

    #[tokio::test]
    async fn test_should_emit_duplicate_suppressed() {
        let monitor = PassiveMonitor::default();
        let data = make_adv_data();

        // Populate the cache.
        monitor.cache.write().await.insert(
            "device-1".to_string(),
            CachedReading {
                data: data.clone(),
                received_at: std::time::Instant::now(),
            },
        );

        // Identical reading should be suppressed.
        assert!(!monitor.should_emit("device-1", &data).await);
    }

    #[tokio::test]
    async fn test_should_emit_on_value_change() {
        let monitor = PassiveMonitor::default();
        let data = make_adv_data();

        monitor.cache.write().await.insert(
            "device-1".to_string(),
            CachedReading {
                data: data.clone(),
                received_at: std::time::Instant::now(),
            },
        );

        // Changed CO2 should trigger emission.
        let mut changed = data.clone();
        changed.co2 = Some(900);
        assert!(monitor.should_emit("device-1", &changed).await);

        // Changed battery should trigger emission.
        let mut changed = data.clone();
        changed.battery = 50;
        assert!(monitor.should_emit("device-1", &changed).await);

        // Changed temperature should trigger emission.
        let mut changed = data;
        changed.temperature = Some(23.0);
        assert!(monitor.should_emit("device-1", &changed).await);
    }

    #[tokio::test]
    async fn test_should_emit_on_counter_change() {
        let monitor = PassiveMonitor::default();
        let data = make_adv_data();

        monitor.cache.write().await.insert(
            "device-1".to_string(),
            CachedReading {
                data: data.clone(),
                received_at: std::time::Instant::now(),
            },
        );

        // Counter increment means a new measurement was taken.
        let mut changed = data;
        changed.counter = Some(6);
        assert!(monitor.should_emit("device-1", &changed).await);
    }

    #[tokio::test]
    async fn test_should_emit_on_stale_cache() {
        let opts = PassiveMonitorOptions {
            max_reading_age: Duration::from_millis(10),
            ..Default::default()
        };
        let monitor = PassiveMonitor::new(opts);
        let data = make_adv_data();

        // Insert a reading that is already "old".
        monitor.cache.write().await.insert(
            "device-1".to_string(),
            CachedReading {
                data: data.clone(),
                received_at: std::time::Instant::now() - Duration::from_millis(50),
            },
        );

        // Identical data should still be emitted because the cache entry expired.
        assert!(monitor.should_emit("device-1", &data).await);
    }

    #[tokio::test]
    async fn test_should_emit_different_device() {
        let monitor = PassiveMonitor::default();
        let data = make_adv_data();

        // Cache a reading for device-1.
        monitor.cache.write().await.insert(
            "device-1".to_string(),
            CachedReading {
                data: data.clone(),
                received_at: std::time::Instant::now(),
            },
        );

        // device-2 has no cache entry, so it should emit even with identical data.
        assert!(monitor.should_emit("device-2", &data).await);
    }
}