forge-runtime 0.0.2-alpha

use std::collections::VecDeque;
use std::sync::atomic::{AtomicU64, Ordering};
use std::sync::Arc;

use tokio::sync::{mpsc, RwLock};

use forge_core::observability::{LogEntry, Metric, Span};
use forge_core::LogLevel;

use super::config::{LogsConfig, MetricsConfig, TracesConfig};

/// Metrics collector for buffering and batching metrics.
pub struct MetricsCollector {
    config: MetricsConfig,
    buffer: Arc<RwLock<VecDeque<Metric>>>,
    sender: mpsc::Sender<Vec<Metric>>,
    #[allow(dead_code)]
    receiver: Arc<RwLock<mpsc::Receiver<Vec<Metric>>>>,
    counter: AtomicU64,
}

impl MetricsCollector {
    /// Create a new metrics collector.
    pub fn new(config: MetricsConfig) -> Self {
        let (sender, receiver) = mpsc::channel(1024);
        Self {
            config,
            buffer: Arc::new(RwLock::new(VecDeque::new())),
            sender,
            receiver: Arc::new(RwLock::new(receiver)),
            counter: AtomicU64::new(0),
        }
    }

    /// Record a metric.
    pub async fn record(&self, metric: Metric) {
        let mut buffer = self.buffer.write().await;
        buffer.push_back(metric);
        self.counter.fetch_add(1, Ordering::Relaxed);

        // Flush if buffer is full
        if buffer.len() >= self.config.buffer_size {
            let batch: Vec<Metric> = buffer.drain(..).collect();
            let _ = self.sender.send(batch).await;
        }
    }

    /// Record a counter increment.
    pub async fn increment_counter(&self, name: impl Into<String>, value: f64) {
        self.record(Metric::counter(name, value)).await;
    }

    /// Record a gauge value.
    pub async fn set_gauge(&self, name: impl Into<String>, value: f64) {
        self.record(Metric::gauge(name, value)).await;
    }

    /// Flush the buffer.
    pub async fn flush(&self) {
        let mut buffer = self.buffer.write().await;
        if !buffer.is_empty() {
            let batch: Vec<Metric> = buffer.drain(..).collect();
            let _ = self.sender.send(batch).await;
        }
    }

    /// Drain the buffer and return all metrics.
    ///
    /// This is used by the flush loop to get metrics for persistence.
    pub async fn drain(&self) -> Vec<Metric> {
        let mut buffer = self.buffer.write().await;
        buffer.drain(..).collect()
    }

    /// Get the flush receiver for consuming batches.
    pub fn subscribe(&self) -> mpsc::Receiver<Vec<Metric>> {
        let (_tx, rx) = mpsc::channel(1024);
        // Note: In a real implementation, this would clone the sender
        // For simplicity, we're creating a new channel here
        rx
    }

    /// Get collected metrics count.
    pub fn count(&self) -> u64 {
        self.counter.load(Ordering::Relaxed)
    }

    /// Get current buffer size.
    pub async fn buffer_size(&self) -> usize {
        self.buffer.read().await.len()
    }

    /// Run the flush loop.
    pub async fn run(&self) {
        let mut interval = tokio::time::interval(self.config.flush_interval);
        loop {
            interval.tick().await;
            self.flush().await;
        }
    }
}

/// Log collector for buffering and filtering logs.
pub struct LogCollector {
    config: LogsConfig,
    buffer: Arc<RwLock<VecDeque<LogEntry>>>,
    sender: mpsc::Sender<Vec<LogEntry>>,
    counter: AtomicU64,
}

impl LogCollector {
    /// Create a new log collector.
    pub fn new(config: LogsConfig) -> Self {
        let (sender, _receiver) = mpsc::channel(1024);
        Self {
            config,
            buffer: Arc::new(RwLock::new(VecDeque::new())),
            sender,
            counter: AtomicU64::new(0),
        }
    }

    /// Record a log entry.
    pub async fn record(&self, entry: LogEntry) {
        // Filter by log level
        if !entry.matches_level(self.config.level) {
            return;
        }

        let mut buffer = self.buffer.write().await;
        buffer.push_back(entry);
        self.counter.fetch_add(1, Ordering::Relaxed);

        // Flush if buffer is full
        if buffer.len() >= self.config.buffer_size {
            let batch: Vec<LogEntry> = buffer.drain(..).collect();
            let _ = self.sender.send(batch).await;
        }
    }

    /// Log at trace level.
    pub async fn trace(&self, message: impl Into<String>) {
        self.record(LogEntry::trace(message)).await;
    }

    /// Log at debug level.
    pub async fn debug(&self, message: impl Into<String>) {
        self.record(LogEntry::debug(message)).await;
    }

    /// Log at info level.
    pub async fn info(&self, message: impl Into<String>) {
        self.record(LogEntry::info(message)).await;
    }

    /// Log at warn level.
    pub async fn warn(&self, message: impl Into<String>) {
        self.record(LogEntry::warn(message)).await;
    }

    /// Log at error level.
    pub async fn error(&self, message: impl Into<String>) {
        self.record(LogEntry::error(message)).await;
    }

    /// Flush the buffer.
    pub async fn flush(&self) {
        let mut buffer = self.buffer.write().await;
        if !buffer.is_empty() {
            let batch: Vec<LogEntry> = buffer.drain(..).collect();
            let _ = self.sender.send(batch).await;
        }
    }

    /// Drain the buffer and return all logs.
    ///
    /// This is used by the flush loop to get logs for persistence.
    pub async fn drain(&self) -> Vec<LogEntry> {
        let mut buffer = self.buffer.write().await;
        buffer.drain(..).collect()
    }

    /// Get collected log count.
    pub fn count(&self) -> u64 {
        self.counter.load(Ordering::Relaxed)
    }

    /// Get current buffer size.
    pub async fn buffer_size(&self) -> usize {
        self.buffer.read().await.len()
    }

    /// Get the minimum log level.
    pub fn min_level(&self) -> LogLevel {
        self.config.level
    }
}

/// Trace collector for sampling and batching traces.
pub struct TraceCollector {
    config: TracesConfig,
    buffer: Arc<RwLock<VecDeque<Span>>>,
    sender: mpsc::Sender<Vec<Span>>,
    counter: AtomicU64,
    sampled_counter: AtomicU64,
}

impl TraceCollector {
    /// Create a new trace collector.
    pub fn new(config: TracesConfig) -> Self {
        let (sender, _receiver) = mpsc::channel(1024);
        Self {
            config,
            buffer: Arc::new(RwLock::new(VecDeque::new())),
            sender,
            counter: AtomicU64::new(0),
            sampled_counter: AtomicU64::new(0),
        }
    }

    /// Record a span.
    pub async fn record(&self, span: Span) {
        self.counter.fetch_add(1, Ordering::Relaxed);

        // Sample decision
        let should_sample = self.should_sample(&span);
        if !should_sample {
            return;
        }

        self.sampled_counter.fetch_add(1, Ordering::Relaxed);

        let mut buffer = self.buffer.write().await;
        buffer.push_back(span);
    }

    /// Check if a span should be sampled.
    fn should_sample(&self, span: &Span) -> bool {
        // Always sample errors if configured
        if self.config.always_trace_errors && span.status == forge_core::SpanStatus::Error {
            return true;
        }

        // Check if context is sampled
        if !span.context.is_sampled() {
            return false;
        }

        // Apply sample rate
        if self.config.sample_rate >= 1.0 {
            return true;
        }

        // Simple probabilistic sampling
        let hash = span
            .context
            .trace_id
            .as_str()
            .as_bytes()
            .iter()
            .fold(0u64, |acc, b| acc.wrapping_mul(31).wrapping_add(*b as u64));
        let threshold = (self.config.sample_rate * u64::MAX as f64) as u64;
        hash < threshold
    }

    /// Flush the buffer.
    pub async fn flush(&self) {
        let mut buffer = self.buffer.write().await;
        if !buffer.is_empty() {
            let batch: Vec<Span> = buffer.drain(..).collect();
            let _ = self.sender.send(batch).await;
        }
    }

    /// Drain the buffer and return all spans.
    ///
    /// This is used by the flush loop to get spans for persistence.
    pub async fn drain(&self) -> Vec<Span> {
        let mut buffer = self.buffer.write().await;
        buffer.drain(..).collect()
    }

    /// Get total span count.
    pub fn count(&self) -> u64 {
        self.counter.load(Ordering::Relaxed)
    }

    /// Get sampled span count.
    pub fn sampled_count(&self) -> u64 {
        self.sampled_counter.load(Ordering::Relaxed)
    }

    /// Get current buffer size.
    pub async fn buffer_size(&self) -> usize {
        self.buffer.read().await.len()
    }

    /// Get the sample rate.
    pub fn sample_rate(&self) -> f64 {
        self.config.sample_rate
    }
}

/// System metrics collector for CPU, memory, disk, and network stats.
///
/// This collector periodically samples system metrics and records them
/// to a MetricsCollector.
pub struct SystemMetricsCollector {
    system: RwLock<sysinfo::System>,
    shutdown: Arc<RwLock<bool>>,
}

impl SystemMetricsCollector {
    /// Create a new system metrics collector.
    pub fn new() -> Self {
        Self {
            system: RwLock::new(sysinfo::System::new_all()),
            shutdown: Arc::new(RwLock::new(false)),
        }
    }

    /// Start collecting system metrics.
    ///
    /// This spawns a background task that periodically collects system metrics
    /// and records them to the provided MetricsCollector.
    pub fn start(
        &self,
        metrics: Arc<MetricsCollector>,
        interval: std::time::Duration,
    ) -> tokio::task::JoinHandle<()> {
        let shutdown = self.shutdown.clone();
        let system = RwLock::new(sysinfo::System::new_all());

        tokio::spawn(async move {
            let mut ticker = tokio::time::interval(interval);
            loop {
                ticker.tick().await;

                if *shutdown.read().await {
                    break;
                }

                // Refresh system info
                {
                    let mut sys = system.write().await;
                    sys.refresh_all();

                    // CPU usage (overall)
                    let cpu_usage = sys.global_cpu_usage();
                    metrics
                        .set_gauge("forge_system_cpu_usage_percent", cpu_usage as f64)
                        .await;

                    // Memory
                    let total_memory = sys.total_memory();
                    let used_memory = sys.used_memory();
                    let memory_usage_percent = if total_memory > 0 {
                        (used_memory as f64 / total_memory as f64) * 100.0
                    } else {
                        0.0
                    };
                    metrics
                        .set_gauge("forge_system_memory_total_bytes", total_memory as f64)
                        .await;
                    metrics
                        .set_gauge("forge_system_memory_used_bytes", used_memory as f64)
                        .await;
                    metrics
                        .set_gauge("forge_system_memory_usage_percent", memory_usage_percent)
                        .await;

                    // Swap
                    let total_swap = sys.total_swap();
                    let used_swap = sys.used_swap();
                    metrics
                        .set_gauge("forge_system_swap_total_bytes", total_swap as f64)
                        .await;
                    metrics
                        .set_gauge("forge_system_swap_used_bytes", used_swap as f64)
                        .await;

                    // Per-CPU usage
                    for (i, cpu) in sys.cpus().iter().enumerate() {
                        let label = format!("cpu{}", i);
                        let mut metric = Metric::gauge(
                            "forge_system_cpu_core_usage_percent",
                            cpu.cpu_usage() as f64,
                        );
                        metric.labels.insert("core".to_string(), label);
                        metrics.record(metric).await;
                    }
                }

                // Disk usage
                let disks = sysinfo::Disks::new_with_refreshed_list();
                for disk in disks.list() {
                    let mount = disk.mount_point().to_string_lossy().to_string();
                    let total = disk.total_space();
                    let available = disk.available_space();
                    let used = total.saturating_sub(available);
                    let usage_percent = if total > 0 {
                        (used as f64 / total as f64) * 100.0
                    } else {
                        0.0
                    };

                    let mut metric = Metric::gauge("forge_system_disk_total_bytes", total as f64);
                    metric.labels.insert("mount".to_string(), mount.clone());
                    metrics.record(metric).await;

                    let mut metric = Metric::gauge("forge_system_disk_used_bytes", used as f64);
                    metric.labels.insert("mount".to_string(), mount.clone());
                    metrics.record(metric).await;

                    let mut metric =
                        Metric::gauge("forge_system_disk_usage_percent", usage_percent);
                    metric.labels.insert("mount".to_string(), mount);
                    metrics.record(metric).await;
                }

                // Load average (Unix only)
                #[cfg(unix)]
                {
                    let load_avg = sysinfo::System::load_average();
                    metrics
                        .set_gauge("forge_system_load_1m", load_avg.one)
                        .await;
                    metrics
                        .set_gauge("forge_system_load_5m", load_avg.five)
                        .await;
                    metrics
                        .set_gauge("forge_system_load_15m", load_avg.fifteen)
                        .await;
                }
            }

            tracing::info!("System metrics collector stopped");
        })
    }

    /// Stop the collector.
    pub async fn stop(&self) {
        let mut shutdown = self.shutdown.write().await;
        *shutdown = true;
    }

    /// Get current system metrics snapshot.
    pub async fn snapshot(&self) -> SystemMetricsSnapshot {
        let mut sys = self.system.write().await;
        sys.refresh_all();

        let total_memory = sys.total_memory();
        let used_memory = sys.used_memory();

        SystemMetricsSnapshot {
            cpu_usage_percent: sys.global_cpu_usage() as f64,
            memory_total_bytes: total_memory,
            memory_used_bytes: used_memory,
            memory_usage_percent: if total_memory > 0 {
                (used_memory as f64 / total_memory as f64) * 100.0
            } else {
                0.0
            },
            swap_total_bytes: sys.total_swap(),
            swap_used_bytes: sys.used_swap(),
        }
    }
}

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

/// Snapshot of system metrics.
#[derive(Debug, Clone)]
pub struct SystemMetricsSnapshot {
    /// CPU usage percentage (0-100).
    pub cpu_usage_percent: f64,
    /// Total memory in bytes.
    pub memory_total_bytes: u64,
    /// Used memory in bytes.
    pub memory_used_bytes: u64,
    /// Memory usage percentage (0-100).
    pub memory_usage_percent: f64,
    /// Total swap in bytes.
    pub swap_total_bytes: u64,
    /// Used swap in bytes.
    pub swap_used_bytes: u64,
}

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

    #[tokio::test]
    async fn test_metrics_collector_record() {
        let collector = MetricsCollector::new(MetricsConfig::default());

        collector.increment_counter("test_counter", 1.0).await;
        collector.set_gauge("test_gauge", 42.0).await;

        assert_eq!(collector.count(), 2);
        assert_eq!(collector.buffer_size().await, 2);
    }

    #[tokio::test]
    async fn test_metrics_collector_flush() {
        let config = MetricsConfig {
            buffer_size: 2,
            ..Default::default()
        };
        let collector = MetricsCollector::new(config);

        collector.increment_counter("test1", 1.0).await;
        collector.increment_counter("test2", 2.0).await;
        // Buffer should auto-flush at 2

        assert_eq!(collector.count(), 2);
    }

    #[tokio::test]
    async fn test_log_collector_level_filter() {
        let config = LogsConfig {
            level: LogLevel::Warn,
            ..Default::default()
        };
        let collector = LogCollector::new(config);

        collector.debug("Debug message").await;
        collector.info("Info message").await;
        collector.warn("Warn message").await;
        collector.error("Error message").await;

        // Only warn and error should be collected
        assert_eq!(collector.count(), 2);
    }

    #[tokio::test]
    async fn test_log_collector_record() {
        let collector = LogCollector::new(LogsConfig::default());

        collector.info("Test message").await;
        assert_eq!(collector.count(), 1);
        assert_eq!(collector.buffer_size().await, 1);
    }

    #[tokio::test]
    async fn test_trace_collector_sampling() {
        let config = TracesConfig {
            sample_rate: 1.0, // 100% sampling
            ..Default::default()
        };
        let collector = TraceCollector::new(config);

        let span = Span::new("test_span");
        collector.record(span).await;

        assert_eq!(collector.count(), 1);
        assert_eq!(collector.sampled_count(), 1);
    }

    #[tokio::test]
    async fn test_trace_collector_always_trace_errors() {
        let config = TracesConfig {
            sample_rate: 0.0, // No sampling
            always_trace_errors: true,
            ..Default::default()
        };
        let collector = TraceCollector::new(config);

        let mut span = Span::new("error_span");
        span.end_error("Test error");
        collector.record(span).await;

        // Error should still be recorded
        assert_eq!(collector.sampled_count(), 1);
    }
}