use anyhow::Result;
use gethostname::gethostname;
use std::time::{Duration, Instant};
use tokio::time::interval;
use tracing::{debug, error, info};

use crate::communication::ZmqHandler;
use crate::config::AgentConfig;
use crate::collectors::{
    Collector,
    backup::BackupCollector,
    cpu::CpuCollector,
    disk::DiskCollector,
    memory::MemoryCollector,
    network::NetworkCollector,
    nixos::NixOSCollector,
    systemd::SystemdCollector,
};
use crate::notifications::NotificationManager;
use cm_dashboard_shared::AgentData;

/// Wrapper for collectors with timing information
struct TimedCollector {
    collector: Box<dyn Collector>,
    interval: Duration,
    last_collection: Option<Instant>,
    name: String,
}

pub struct Agent {
    hostname: String,
    config: AgentConfig,
    zmq_handler: ZmqHandler,
    collectors: Vec<TimedCollector>,
    notification_manager: NotificationManager,
    previous_status: Option<SystemStatus>,
}

/// Track system component status for change detection
#[derive(Debug, Clone)]
struct SystemStatus {
    cpu_load_status: cm_dashboard_shared::Status,
    cpu_temperature_status: cm_dashboard_shared::Status,
    memory_usage_status: cm_dashboard_shared::Status,
    // Add more as needed
}

impl Agent {
    pub async fn new(config_path: Option<String>) -> Result<Self> {
        let hostname = gethostname().to_string_lossy().to_string();
        info!("Initializing agent for host: {}", hostname);

        // Load configuration (now required)
        let config_path = config_path.ok_or_else(|| anyhow::anyhow!("Configuration file path is required"))?;
        let config = AgentConfig::from_file(&config_path)?;

        info!("Agent configuration loaded");

        // Initialize ZMQ communication
        let zmq_handler = ZmqHandler::new(&config.zmq).await?;
        info!(
            "ZMQ communication initialized on port {}",
            config.zmq.publisher_port
        );

        // Initialize collectors with timing information
        let mut collectors: Vec<TimedCollector> = Vec::new();

        // Add enabled collectors
        if config.collectors.cpu.enabled {
            collectors.push(TimedCollector {
                collector: Box::new(CpuCollector::new(config.collectors.cpu.clone())),
                interval: Duration::from_secs(config.collectors.cpu.interval_seconds),
                last_collection: None,
                name: "CPU".to_string(),
            });
            info!("CPU collector initialized with {}s interval", config.collectors.cpu.interval_seconds);
        }

        if config.collectors.memory.enabled {
            collectors.push(TimedCollector {
                collector: Box::new(MemoryCollector::new(config.collectors.memory.clone())),
                interval: Duration::from_secs(config.collectors.memory.interval_seconds),
                last_collection: None,
                name: "Memory".to_string(),
            });
            info!("Memory collector initialized with {}s interval", config.collectors.memory.interval_seconds);
        }

        if config.collectors.disk.enabled {
            collectors.push(TimedCollector {
                collector: Box::new(DiskCollector::new(config.collectors.disk.clone())),
                interval: Duration::from_secs(config.collectors.disk.interval_seconds),
                last_collection: None,
                name: "Disk".to_string(),
            });
            info!("Disk collector initialized with {}s interval", config.collectors.disk.interval_seconds);
        }

        if config.collectors.systemd.enabled {
            collectors.push(TimedCollector {
                collector: Box::new(SystemdCollector::new(config.collectors.systemd.clone())),
                interval: Duration::from_secs(config.collectors.systemd.interval_seconds),
                last_collection: None,
                name: "Systemd".to_string(),
            });
            info!("Systemd collector initialized with {}s interval", config.collectors.systemd.interval_seconds);
        }

        if config.collectors.backup.enabled {
            collectors.push(TimedCollector {
                collector: Box::new(BackupCollector::new()),
                interval: Duration::from_secs(config.collectors.backup.interval_seconds),
                last_collection: None,
                name: "Backup".to_string(),
            });
            info!("Backup collector initialized with {}s interval", config.collectors.backup.interval_seconds);
        }

        if config.collectors.network.enabled {
            collectors.push(TimedCollector {
                collector: Box::new(NetworkCollector::new(config.collectors.network.clone())),
                interval: Duration::from_secs(config.collectors.network.interval_seconds),
                last_collection: None,
                name: "Network".to_string(),
            });
            info!("Network collector initialized with {}s interval", config.collectors.network.interval_seconds);
        }

        if config.collectors.nixos.enabled {
            collectors.push(TimedCollector {
                collector: Box::new(NixOSCollector::new(config.collectors.nixos.clone())),
                interval: Duration::from_secs(config.collectors.nixos.interval_seconds),
                last_collection: None,
                name: "NixOS".to_string(),
            });
            info!("NixOS collector initialized with {}s interval", config.collectors.nixos.interval_seconds);
        }

        info!("Initialized {} collectors", collectors.len());

        // Initialize notification manager
        let notification_manager = NotificationManager::new(&config.notifications, &hostname)?;
        info!("Notification manager initialized");

        Ok(Self {
            hostname,
            config,
            zmq_handler,
            collectors,
            notification_manager,
            previous_status: None,
        })
    }

    /// Main agent loop with structured data collection
    pub async fn run(&mut self, mut shutdown_rx: tokio::sync::oneshot::Receiver<()>) -> Result<()> {
        info!("Starting agent main loop");

        // Initial collection
        if let Err(e) = self.collect_and_broadcast().await {
            error!("Initial metric collection failed: {}", e);
        }

        // Set up intervals
        let mut transmission_interval = interval(Duration::from_secs(
            self.config.zmq.transmission_interval_seconds,
        ));
        let mut notification_interval = interval(Duration::from_secs(30)); // Check notifications every 30s

        // Skip initial ticks to avoid immediate execution
        transmission_interval.tick().await;
        notification_interval.tick().await;

        loop {
            tokio::select! {
                _ = transmission_interval.tick() => {
                    if let Err(e) = self.collect_and_broadcast().await {
                        error!("Failed to collect and broadcast metrics: {}", e);
                    }
                }
                _ = notification_interval.tick() => {
                    // Process any pending notifications
                    // NOTE: With structured data, we might need to implement status tracking differently
                    // For now, we skip this until status evaluation is migrated
                }
                _ = &mut shutdown_rx => {
                    info!("Shutdown signal received, stopping agent loop");
                    break;
                }
            }
        }

        info!("Agent main loop stopped");
        Ok(())
    }

    /// Collect structured data from all collectors and broadcast via ZMQ
    async fn collect_and_broadcast(&mut self) -> Result<()> {
        debug!("Starting structured data collection");

        // Initialize empty AgentData
        let mut agent_data = AgentData::new(self.hostname.clone(), env!("CARGO_PKG_VERSION").to_string());

        // Collect data from collectors whose intervals have elapsed
        let now = Instant::now();
        for timed_collector in &mut self.collectors {
            let should_collect = match timed_collector.last_collection {
                None => true, // First collection
                Some(last_time) => now.duration_since(last_time) >= timed_collector.interval,
            };

            if should_collect {
                if let Err(e) = timed_collector.collector.collect_structured(&mut agent_data).await {
                    error!("Collector {} failed: {}", timed_collector.name, e);
                    // Update last_collection time even on failure to prevent immediate retries
                    timed_collector.last_collection = Some(now);
                } else {
                    timed_collector.last_collection = Some(now);
                    debug!(
                        "Collected from {} ({}s interval)",
                        timed_collector.name,
                        timed_collector.interval.as_secs()
                    );
                }
            }
        }

        // Check for status changes and send notifications
        if let Err(e) = self.check_status_changes_and_notify(&agent_data).await {
            error!("Failed to check status changes: {}", e);
        }

        // Broadcast the structured data via ZMQ
        if let Err(e) = self.zmq_handler.publish_agent_data(&agent_data).await {
            error!("Failed to broadcast agent data: {}", e);
        } else {
            debug!("Successfully broadcast structured agent data");
        }

        Ok(())
    }

    /// Check for status changes and send notifications
    async fn check_status_changes_and_notify(&mut self, agent_data: &AgentData) -> Result<()> {
        // Extract current status
        let current_status = SystemStatus {
            cpu_load_status: agent_data.system.cpu.load_status.clone(),
            cpu_temperature_status: agent_data.system.cpu.temperature_status.clone(),
            memory_usage_status: agent_data.system.memory.usage_status.clone(),
        };

        // Check for status changes
        if let Some(previous) = self.previous_status.clone() {
            self.check_and_notify_status_change(
                "CPU Load",
                &previous.cpu_load_status,
                &current_status.cpu_load_status,
                format!("CPU load: {:.1}", agent_data.system.cpu.load_1min)
            ).await?;

            self.check_and_notify_status_change(
                "CPU Temperature", 
                &previous.cpu_temperature_status,
                &current_status.cpu_temperature_status,
                format!("CPU temperature: {}°C", 
                    agent_data.system.cpu.temperature_celsius.unwrap_or(0.0) as i32)
            ).await?;

            self.check_and_notify_status_change(
                "Memory Usage",
                &previous.memory_usage_status, 
                &current_status.memory_usage_status,
                format!("Memory usage: {:.1}%", agent_data.system.memory.usage_percent)
            ).await?;
        }

        // Store current status for next comparison
        self.previous_status = Some(current_status);
        Ok(())
    }

    /// Check individual status change and send notification if degraded
    async fn check_and_notify_status_change(
        &mut self,
        component: &str,
        previous: &cm_dashboard_shared::Status,
        current: &cm_dashboard_shared::Status,
        details: String
    ) -> Result<()> {
        use cm_dashboard_shared::Status;

        // Only notify on status degradation (OK → Warning/Critical, Warning → Critical)
        let should_notify = match (previous, current) {
            (Status::Ok, Status::Warning) => true,
            (Status::Ok, Status::Critical) => true,
            (Status::Warning, Status::Critical) => true,
            _ => false,
        };

        if should_notify {
            let subject = format!("{} {} Alert", self.hostname, component);
            let body = format!(
                "Alert: {} status changed from {:?} to {:?}\n\nDetails: {}\n\nTime: {}",
                component,
                previous,
                current, 
                details,
                chrono::Utc::now().format("%Y-%m-%d %H:%M:%S UTC")
            );

            info!("Sending notification: {} - {:?} → {:?}", component, previous, current);
            
            if let Err(e) = self.notification_manager.send_direct_email(&subject, &body).await {
                error!("Failed to send notification for {}: {}", component, e);
            }
        }

        Ok(())
    }

}