//! Enhanced reconnection and error recovery utilities for brokers

use std::sync::Arc;
use std::sync::atomic::{AtomicU64, AtomicBool, Ordering};
use std::time::Duration;
use tokio::time::Instant;
use tracing::{error, info, warn};

use crate::brokers::error::{BrokerError, Result};

/// Enhanced reconnection manager with exponential backoff
#[derive(Debug)]
/// ReconnectionManager
/// 
/// Auto-generated documentation placeholder - enhance with specifics
pub struct ReconnectionManager {
    attempts: Arc<AtomicU64>,
    auto_reconnect: Arc<AtomicBool>,
    max_attempts: u64,
    last_attempt: Arc<tokio::sync::RwLock<Option<Instant>>>,
}

impl ReconnectionManager {
    pub fn new(max_attempts: u64) -> Self {
        Self {
            attempts: Arc::new(AtomicU64::new(0)),
            auto_reconnect: Arc::new(AtomicBool::new(true)),
            max_attempts,
            last_attempt: Arc::new(tokio::sync::RwLock::new(None)),
        }
    }
    
    /// Attempt reconnection with exponential backoff
    pub async fn attempt_reconnect<F, Fut>(&self, reconnect_fn: F) -> Result<()>
    where
        F: Fn() -> Fut,
        Fut: std::future::Future<Output = Result<()>>,
    {
        let attempt_count = self.attempts.fetch_add(1, Ordering::Relaxed);
        
        if attempt_count >= self.max_attempts {
            error!("Maximum reconnection attempts ({}) exceeded", self.max_attempts);
            return Err(BrokerError::ConnectionFailed("Max reconnect attempts exceeded".to_string()));
        }
        
        // Exponential backoff: 1s, 2s, 4s, 8s, 16s, max 60s
        let delay_secs = std::cmp::min(2_u64.pow(attempt_count as u32), 60);
        warn!("Reconnection attempt {} in {} seconds", attempt_count + 1, delay_secs);
        
        tokio::time::sleep(Duration::from_secs(delay_secs)).await;
        *self.last_attempt.write().await = Some(Instant::now());
        
        match reconnect_fn().await {
            Ok(()) => {
                info!("Reconnection successful on attempt {}", attempt_count + 1);
                self.attempts.store(0, Ordering::Relaxed); // Reset counter on success
                Ok(())
            }
            Err(e) => {
                error!("Reconnection attempt {} failed: {}", attempt_count + 1, e);
    // Err variant
                Err(e)
            }
        }
    }
    
    /// Enable/disable automatic reconnection
    pub fn set_auto_reconnect(&self, enabled: bool) {
        self.auto_reconnect.store(enabled, Ordering::Relaxed);
        info!("Auto-reconnect {}", if enabled { "enabled" } else { "disabled" });
    }
    
    /// Check if auto-reconnect is enabled
    pub fn is_auto_reconnect_enabled(&self) -> bool {
        self.auto_reconnect.load(Ordering::Relaxed)
    }
    
    /// Get current attempt count
    pub fn get_attempt_count(&self) -> u64 {
        self.attempts.load(Ordering::Relaxed)
    }
    
    /// Reset attempt counter
    pub fn reset_attempts(&self) {
        self.attempts.store(0, Ordering::Relaxed);
    }
}

/// Circuit breaker for broker connections
#[derive(Debug)]
/// CircuitBreaker
/// 
/// Auto-generated documentation placeholder - enhance with specifics
pub struct CircuitBreaker {
    failure_count: Arc<AtomicU64>,
    failure_threshold: u64,
    recovery_timeout: Duration,
    last_failure: Arc<tokio::sync::RwLock<Option<Instant>>>,
    state: Arc<tokio::sync::RwLock<CircuitBreakerState>>,
}

#[derive(Debug, Clone, PartialEq)]
/// CircuitBreakerState
/// 
/// Auto-generated documentation placeholder - enhance with specifics
pub enum CircuitBreakerState {
    Closed,  // Normal operation
    Open,    // Failing fast
    HalfOpen, // Testing recovery
}

impl CircuitBreaker {
    pub fn new(failure_threshold: u64, recovery_timeout: Duration) -> Self {
        Self {
            failure_count: Arc::new(AtomicU64::new(0)),
            failure_threshold,
            recovery_timeout,
            last_failure: Arc::new(tokio::sync::RwLock::new(None)),
            state: Arc::new(tokio::sync::RwLock::new(CircuitBreakerState::Closed)),
        }
    }
    
    /// Execute operation through circuit breaker
    pub async fn execute<F, Fut, T>(&self, operation: F) -> Result<T>
    where
        F: Fn() -> Fut,
        Fut: std::future::Future<Output = Result<T>>,
    {
        // Check if circuit breaker should transition to half-open
        self.check_recovery_timeout().await;
        
        let state = *self.state.read().await;
        match state {
            CircuitBreakerState::Open => {
                Err(BrokerError::ConnectionFailed("Circuit breaker is open".to_string()))
            }
            CircuitBreakerState::Closed | CircuitBreakerState::HalfOpen => {
                match operation().await {
                    Ok(result) => {
                        self.on_success().await;
    // Ok variant
                        Ok(result)
                    }
                    Err(e) => {
                        self.on_failure().await;
    // Err variant
                        Err(e)
                    }
                }
            }
        }
    }
    
    /// Handle successful operation
    async fn on_success(&self) {
        self.failure_count.store(0, Ordering::Relaxed);
        *self.state.write().await = CircuitBreakerState::Closed;
    }
    
    /// Handle failed operation
    async fn on_failure(&self) {
        let failures = self.failure_count.fetch_add(1, Ordering::Relaxed) + 1;
        *self.last_failure.write().await = Some(Instant::now());
        
        if failures >= self.failure_threshold {
            *self.state.write().await = CircuitBreakerState::Open;
            warn!("Circuit breaker opened after {} failures", failures);
        }
    }
    
    /// Check if enough time has passed to attempt recovery
    async fn check_recovery_timeout(&self) {
        let state = *self.state.read().await;
        if state == CircuitBreakerState::Open {
            if let Some(last_failure) = *self.last_failure.read().await {
                if last_failure.elapsed() >= self.recovery_timeout {
                    *self.state.write().await = CircuitBreakerState::HalfOpen;
                    info!("Circuit breaker transitioning to half-open for recovery test");
                }
            }
        }
    }
    
    /// Get current circuit breaker state
    pub async fn get_state(&self) -> CircuitBreakerState {
        *self.state.read().await
    }
}