//! Active and passive health checks for upstream endpoints.
//!
//! - Active: periodically probes upstream `/health` endpoints.
//! - Passive: tracks request failure rates and marks unhealthy endpoints.

use crate::config::Endpoint;
use std::sync::Arc;
use tokio::sync::RwLock;

/// Health checker for a pool of upstream endpoints.
pub struct HealthChecker {
    endpoints: Arc<RwLock<Vec<Endpoint>>>,
    /// How often to run active health probes.
    #[allow(dead_code)]
    interval: std::time::Duration,
    /// Failure threshold for passive health checks.
    #[allow(dead_code)]
    passive_fail_threshold: u32,
    /// Success threshold for recovery.
    #[allow(dead_code)]
    passive_success_threshold: u32,
}

impl HealthChecker {
    /// Create a new health checker.
    pub fn new(endpoints: Vec<Endpoint>, interval: std::time::Duration) -> Self {
        Self {
            endpoints: Arc::new(RwLock::new(endpoints)),
            interval,
            passive_fail_threshold: 3,
            passive_success_threshold: 2,
        }
    }

    /// Update the endpoint pool.
    pub async fn update_endpoints(&self, new_endpoints: Vec<Endpoint>) {
        let mut eps = self.endpoints.write().await;
        *eps = new_endpoints;
    }

    /// Run active health probes in a background task.
    pub fn spawn_active_probes(self: Arc<Self>) -> tokio::task::JoinHandle<()> {
        tokio::spawn(async move {
            // Active probing loop would go here.
            // For now a placeholder that keeps endpoints as-is.
            loop {
                tokio::time::sleep(std::time::Duration::from_secs(10)).await;
            }
        })
    }

    /// Mark an endpoint as failing (passive check).
    /// Returns true if this endpoint should now be considered unhealthy.
    #[allow(dead_code)]
    pub async fn record_failure(&self, endpoint_ip: &str) -> bool {
        let mut eps = self.endpoints.write().await;
        if let Some(ep) = eps.iter_mut().find(|e| e.ip == endpoint_ip) {
            // Track failure count via metadata (simplified: uses ready field)
            // Full impl would add failure_count field to Endpoint
            let _ = ep;
            return false; // Placeholder
        }
        false
    }

    /// Mark an endpoint as successful (passive check).
    #[allow(dead_code)]
    pub async fn record_success(&self, endpoint_ip: &str) {
        let _eps = self.endpoints.write().await;
        // Reset failure count for the endpoint
        let _ = endpoint_ip;
    }
}