use anyhow::Result;
use cm_dashboard_shared::{Metric, StatusTracker};
use std::time::{Duration, Instant};
use tracing::{debug, error, info};

use crate::collectors::{
    backup::BackupCollector, cpu::CpuCollector, disk::DiskCollector, memory::MemoryCollector,
    nixos::NixOSCollector, systemd::SystemdCollector, Collector,
};
use crate::config::{AgentConfig, CollectorConfig};

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

/// Manages all metric collectors with individual intervals
pub struct MetricCollectionManager {
    collectors: Vec<TimedCollector>,
    status_tracker: StatusTracker,
    cached_metrics: Vec<Metric>,
}

impl MetricCollectionManager {
    pub async fn new(config: &CollectorConfig, _agent_config: &AgentConfig) -> Result<Self> {
        let mut collectors: Vec<TimedCollector> = Vec::new();

        // Benchmark mode - only enable specific collector based on env var
        let benchmark_mode = std::env::var("BENCHMARK_COLLECTOR").ok();

        match benchmark_mode.as_deref() {
            Some("cpu") => {
                // CPU collector only
                if config.cpu.enabled {
                    let cpu_collector = CpuCollector::new(config.cpu.clone());
                    collectors.push(TimedCollector {
                        collector: Box::new(cpu_collector),
                        interval: Duration::from_secs(config.cpu.interval_seconds),
                        last_collection: None,
                        name: "CPU".to_string(),
                    });
                    info!("BENCHMARK: CPU collector only");
                }
            }
            Some("memory") => {
                // Memory collector only
                if config.memory.enabled {
                    let memory_collector = MemoryCollector::new(config.memory.clone());
                    collectors.push(TimedCollector {
                        collector: Box::new(memory_collector),
                        interval: Duration::from_secs(config.memory.interval_seconds),
                        last_collection: None,
                        name: "Memory".to_string(),
                    });
                    info!("BENCHMARK: Memory collector only");
                }
            }
            Some("disk") => {
                // Disk collector only
                let disk_collector = DiskCollector::new(config.disk.clone());
                collectors.push(TimedCollector {
                    collector: Box::new(disk_collector),
                    interval: Duration::from_secs(config.disk.interval_seconds),
                    last_collection: None,
                    name: "Disk".to_string(),
                });
                info!("BENCHMARK: Disk collector only");
            }
            Some("systemd") => {
                // Systemd collector only
                let systemd_collector = SystemdCollector::new(config.systemd.clone());
                collectors.push(TimedCollector {
                    collector: Box::new(systemd_collector),
                    interval: Duration::from_secs(config.systemd.interval_seconds),
                    last_collection: None,
                    name: "Systemd".to_string(),
                });
                info!("BENCHMARK: Systemd collector only");
            }
            Some("backup") => {
                // Backup collector only
                if config.backup.enabled {
                    let backup_collector = BackupCollector::new(
                        config.backup.backup_paths.first().cloned(),
                        config.backup.max_age_hours,
                    );
                    collectors.push(TimedCollector {
                        collector: Box::new(backup_collector),
                        interval: Duration::from_secs(config.backup.interval_seconds),
                        last_collection: None,
                        name: "Backup".to_string(),
                    });
                    info!("BENCHMARK: Backup collector only");
                }
            }
            Some("none") => {
                // No collectors - test agent loop only
                info!("BENCHMARK: No collectors enabled");
            }
            _ => {
                // Normal mode - all collectors
                if config.cpu.enabled {
                    let cpu_collector = CpuCollector::new(config.cpu.clone());
                    collectors.push(TimedCollector {
                        collector: Box::new(cpu_collector),
                        interval: Duration::from_secs(config.cpu.interval_seconds),
                        last_collection: None,
                        name: "CPU".to_string(),
                    });
                    info!("CPU collector initialized with {}s interval", config.cpu.interval_seconds);
                }

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

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

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

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

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

            }
        }

        info!(
            "Metric collection manager initialized with {} collectors",
            collectors.len()
        );

        Ok(Self {
            collectors,
            status_tracker: StatusTracker::new(),
            cached_metrics: Vec::new(),
        })
    }

    /// Force collection from ALL collectors immediately (used at startup)
    pub async fn collect_all_metrics_force(&mut self) -> Result<Vec<Metric>> {
        let mut all_metrics = Vec::new();
        let now = Instant::now();

        for timed_collector in &mut self.collectors {
            match timed_collector.collector.collect(&mut self.status_tracker).await {
                Ok(metrics) => {
                    let metric_count = metrics.len();
                    all_metrics.extend(metrics);
                    timed_collector.last_collection = Some(now);
                    debug!("Force collected {} metrics from {}", metric_count, timed_collector.name);
                }
                Err(e) => {
                    error!("Collector {} failed: {}", timed_collector.name, e);
                }
            }
        }
        
        // Cache the collected metrics
        self.cached_metrics = all_metrics.clone();
        Ok(all_metrics)
    }

    /// Collect metrics from collectors whose intervals have elapsed
    pub async fn collect_metrics_timed(&mut self) -> Result<Vec<Metric>> {
        let mut all_metrics = Vec::new();
        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 {
                match timed_collector.collector.collect(&mut self.status_tracker).await {
                    Ok(metrics) => {
                        let metric_count = metrics.len();
                        all_metrics.extend(metrics);
                        timed_collector.last_collection = Some(now);
                        debug!(
                            "Collected {} metrics from {} ({}s interval)",
                            metric_count,
                            timed_collector.name,
                            timed_collector.interval.as_secs()
                        );
                    }
                    Err(e) => {
                        error!("Collector {} failed: {}", timed_collector.name, e);
                    }
                }
            }
        }
        
        // Update cache with newly collected metrics
        if !all_metrics.is_empty() {
            // Merge new metrics with cached metrics (replace by name)
            for new_metric in &all_metrics {
                // Remove any existing metric with the same name
                self.cached_metrics.retain(|cached| cached.name != new_metric.name);
                // Add the new metric
                self.cached_metrics.push(new_metric.clone());
            }
        }
        
        Ok(all_metrics)
    }

    /// Collect metrics from all collectors (legacy method for compatibility)
    pub async fn collect_all_metrics(&mut self) -> Result<Vec<Metric>> {
        self.collect_metrics_timed().await
    }
    
    /// Get cached metrics without triggering fresh collection
    pub fn get_cached_metrics(&self) -> Vec<Metric> {
        self.cached_metrics.clone()
    }

}