//! Unified Analytics Data Collector
//!
//! Orchestrates collection from all log sources:
//! - Navigation tracking (JSONL logs)
//! - Route cache performance
//! - Server logs
//! - Browser logs
//!
//! Provides real-time streaming and batch processing capabilities.

use super::{
    AnalyticsConfig, AnalyticsEvent, AnalyticsMetrics, EventLevel,
    BrowserMetrics, CacheMetrics, NavigationMetrics, ServerMetrics,
};
use anyhow::{Context, Result};
use chrono::{DateTime, Duration, Utc};
use serde::{Deserialize, Serialize};
use std::collections::{HashMap, VecDeque};
use std::path::{Path, PathBuf};
use std::sync::{Arc, Mutex};
use tokio::sync::mpsc;

/// Log source types
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Hash, Eq)]
pub enum LogSource {
    Navigation,
    RouteCache,
    Server,
    Browser,
    System,
}

impl LogSource {
    pub fn as_str(&self) -> &'static str {
        match self {
            LogSource::Navigation => "navigation",
            LogSource::RouteCache => "route_cache", 
            LogSource::Server => "server",
            LogSource::Browser => "browser",
            LogSource::System => "system",
        }
    }
}

/// Analytics collector configuration
#[derive(Debug, Clone)]
pub struct CollectorConfig {
    pub batch_size: usize,
    pub flush_interval_seconds: u64,
    pub max_memory_events: usize,
    pub data_directory: PathBuf,
}

impl Default for CollectorConfig {
    fn default() -> Self {
        Self {
            batch_size: 100,
            flush_interval_seconds: 30,
            max_memory_events: 10000,
            data_directory: PathBuf::from("logs/analytics"),
        }
    }
}

/// Main analytics collector
pub struct AnalyticsCollector {
    config: CollectorConfig,
    event_buffer: Arc<Mutex<VecDeque<AnalyticsEvent>>>,
    sender: Option<mpsc::UnboundedSender<AnalyticsEvent>>,
    receiver: Option<mpsc::UnboundedReceiver<AnalyticsEvent>>,
    
    // Source-specific collectors
    navigation_collector: Option<super::navigation::NavigationCollector>,
    server_collector: Option<super::rustelo_server::ServerCollector>,
    browser_collector: Option<super::browser::BrowserCollector>,
    
    // Metrics aggregation
    metrics_cache: Arc<Mutex<HashMap<String, AnalyticsMetrics>>>,
}

impl AnalyticsCollector {
    /// Create new analytics collector
    pub fn new(config: &AnalyticsConfig) -> Result<Self> {
        let collector_config = CollectorConfig {
            data_directory: config.data_directory.clone(),
            ..CollectorConfig::default()
        };

        // Create data directory if it doesn't exist
        std::fs::create_dir_all(&collector_config.data_directory)
            .context("Failed to create analytics data directory")?;

        let (sender, receiver) = mpsc::unbounded_channel();

        Ok(Self {
            config: collector_config,
            event_buffer: Arc::new(Mutex::new(VecDeque::new())),
            sender: Some(sender),
            receiver: Some(receiver),
            navigation_collector: None,
            server_collector: None, 
            browser_collector: None,
            metrics_cache: Arc::new(Mutex::new(HashMap::new())),
        })
    }

    /// Start collection from all sources
    pub async fn start(&mut self) -> Result<()> {
        tracing::info!("Starting analytics collection...");

        // Initialize source-specific collectors
        self.init_collectors().await?;

        // Start event processing task
        if let Some(receiver) = self.receiver.take() {
            let buffer = Arc::clone(&self.event_buffer);
            let config = self.config.clone();
            let metrics_cache = Arc::clone(&self.metrics_cache);

            tokio::spawn(async move {
                Self::process_events(receiver, buffer, config, metrics_cache).await;
            });
        }

        tracing::info!("Analytics collection started");
        Ok(())
    }

    /// Stop collection
    pub async fn stop(&mut self) -> Result<()> {
        tracing::info!("Stopping analytics collection...");

        // Flush any remaining events
        self.flush_events().await?;

        if let Some(sender) = &self.sender {
            sender.send(AnalyticsEvent {
                id: super::generate_event_id(),
                timestamp: Utc::now(),
                source: LogSource::System,
                event_type: "shutdown".to_string(),
                session_id: None,
                path: None,
                level: EventLevel::Info,
                message: "Analytics collector shutting down".to_string(),
                metadata: HashMap::new(),
                duration_ms: None,
                errors: Vec::new(),
            })?;
        }

        tracing::info!("Analytics collection stopped");
        Ok(())
    }

    /// Initialize source-specific collectors
    async fn init_collectors(&mut self) -> Result<()> {
        let sender = self.sender.as_ref()
            .ok_or_else(|| anyhow::anyhow!("Sender not available"))?
            .clone();

        // Initialize navigation collector
        if let Ok(nav_collector) = super::navigation::NavigationCollector::new(sender.clone()).await {
            tracing::debug!("Navigation collector initialized");
            self.navigation_collector = Some(nav_collector);
        } else {
            tracing::warn!("Failed to initialize navigation collector");
        }

        // Initialize server collector
        if let Ok(server_collector) = super::rustelo_server::ServerCollector::new(sender.clone()).await {
            tracing::debug!("Server collector initialized");
            self.server_collector = Some(server_collector);
        } else {
            tracing::warn!("Failed to initialize server collector");
        }

        // Initialize browser collector
        if let Ok(browser_collector) = super::browser::BrowserCollector::new(sender.clone()).await {
            tracing::debug!("Browser collector initialized");
            self.browser_collector = Some(browser_collector);
        } else {
            tracing::warn!("Failed to initialize browser collector");
        }

        Ok(())
    }

    /// Process events from the channel
    async fn process_events(
        mut receiver: mpsc::UnboundedReceiver<AnalyticsEvent>,
        buffer: Arc<Mutex<VecDeque<AnalyticsEvent>>>,
        config: CollectorConfig,
        metrics_cache: Arc<Mutex<HashMap<String, AnalyticsMetrics>>>,
    ) {
        let mut flush_interval = tokio::time::interval(
            tokio::time::Duration::from_secs(config.flush_interval_seconds)
        );

        loop {
            tokio::select! {
                // Process incoming events
                event = receiver.recv() => {
                    match event {
                        Some(event) => {
                            // Add to buffer
                            {
                                let mut buffer_guard = buffer.lock().unwrap();
                                buffer_guard.push_back(event.clone());
                                
                                // Prevent memory overflow
                                while buffer_guard.len() > config.max_memory_events {
                                    buffer_guard.pop_front();
                                }
                            }

                            // Update metrics cache
                            Self::update_metrics_cache(&event, &metrics_cache);

                            // Check if we need to flush
                            let buffer_len = buffer.lock().unwrap().len();
                            if buffer_len >= config.batch_size {
                                if let Err(e) = Self::flush_buffer(&buffer, &config).await {
                                    tracing::error!("Failed to flush event buffer: {}", e);
                                }
                            }
                        }
                        None => {
                            tracing::info!("Analytics event channel closed");
                            break;
                        }
                    }
                }
                
                // Periodic flush
                _ = flush_interval.tick() => {
                    if let Err(e) = Self::flush_buffer(&buffer, &config).await {
                        tracing::error!("Failed to flush event buffer: {}", e);
                    }
                }
            }
        }
    }

    /// Update metrics cache with new event
    fn update_metrics_cache(
        event: &AnalyticsEvent, 
        metrics_cache: &Arc<Mutex<HashMap<String, AnalyticsMetrics>>>
    ) {
        let period_key = format!("hour_{}", event.timestamp.format("%Y%m%d_%H"));
        
        let mut cache = metrics_cache.lock().unwrap();
        let metrics = cache.entry(period_key).or_insert_with(|| {
            AnalyticsMetrics {
                period_start: event.timestamp.with_minute(0).unwrap().with_second(0).unwrap(),
                period_end: event.timestamp.with_minute(59).unwrap().with_second(59).unwrap(),
                navigation: NavigationMetrics {
                    total_requests: 0,
                    route_resolutions: 0,
                    language_switches: 0,
                    avg_resolution_time_ms: 0.0,
                    slow_routes_count: 0,
                    error_count: 0,
                },
                cache: CacheMetrics {
                    total_requests: 0,
                    hit_count: 0,
                    miss_count: 0,
                    hit_rate: 0.0,
                    evictions: 0,
                    expired_entries: 0,
                },
                server: ServerMetrics {
                    total_requests: 0,
                    error_count: 0,
                    panic_count: 0,
                    avg_response_time_ms: 0.0,
                    memory_usage_mb: None,
                    cpu_usage_percent: None,
                },
                browser: BrowserMetrics {
                    console_errors: 0,
                    console_warnings: 0,
                    hydration_mismatches: 0,
                    javascript_errors: 0,
                    performance_issues: 0,
                },
            }
        });

        // Update metrics based on event type and source
        match event.source {
            LogSource::Navigation => {
                metrics.navigation.total_requests += 1;
                if event.event_type == "RouteResolution" {
                    metrics.navigation.route_resolutions += 1;
                }
                if event.event_type == "LanguageSwitch" {
                    metrics.navigation.language_switches += 1;
                }
                if !event.errors.is_empty() {
                    metrics.navigation.error_count += 1;
                }
                if let Some(duration) = event.duration_ms {
                    if duration > 10 {
                        metrics.navigation.slow_routes_count += 1;
                    }
                    // Update average (simplified)
                    metrics.navigation.avg_resolution_time_ms = 
                        (metrics.navigation.avg_resolution_time_ms + duration as f64) / 2.0;
                }
            }
            LogSource::RouteCache => {
                metrics.cache.total_requests += 1;
                if let Some(hit_val) = event.metadata.get("cache_hit") {
                    if hit_val.as_bool().unwrap_or(false) {
                        metrics.cache.hit_count += 1;
                    } else {
                        metrics.cache.miss_count += 1;
                    }
                    metrics.cache.hit_rate = 
                        metrics.cache.hit_count as f64 / metrics.cache.total_requests as f64;
                }
            }
            LogSource::Server => {
                metrics.server.total_requests += 1;
                if event.level >= EventLevel::Error {
                    metrics.server.error_count += 1;
                }
                if event.message.contains("panic") {
                    metrics.server.panic_count += 1;
                }
                if let Some(duration) = event.duration_ms {
                    metrics.server.avg_response_time_ms = 
                        (metrics.server.avg_response_time_ms + duration as f64) / 2.0;
                }
            }
            LogSource::Browser => {
                match event.level {
                    EventLevel::Error => metrics.browser.console_errors += 1,
                    EventLevel::Warn => metrics.browser.console_warnings += 1,
                    _ => {}
                }
                if event.event_type == "hydration_mismatch" {
                    metrics.browser.hydration_mismatches += 1;
                }
                if event.event_type == "javascript_error" {
                    metrics.browser.javascript_errors += 1;
                }
            }
            LogSource::System => {
                // System events don't affect business metrics
            }
        }
    }

    /// Flush event buffer to disk
    async fn flush_buffer(
        buffer: &Arc<Mutex<VecDeque<AnalyticsEvent>>>,
        config: &CollectorConfig,
    ) -> Result<()> {
        let events: Vec<AnalyticsEvent> = {
            let mut buffer_guard = buffer.lock().unwrap();
            let events = buffer_guard.drain(..).collect();
            events
        };

        if events.is_empty() {
            return Ok(());
        }

        tracing::debug!("Flushing {} events to disk", events.len());

        // Write events to daily log file
        let date_str = Utc::now().format("%Y%m%d");
        let log_file = config.data_directory.join(format!("analytics_{}.jsonl", date_str));

        let mut log_content = String::new();
        for event in events {
            if let Ok(json) = serde_json::to_string(&event) {
                log_content.push_str(&json);
                log_content.push('\n');
            }
        }

        tokio::fs::write(&log_file, log_content).await
            .with_context(|| format!("Failed to write analytics log to {:?}", log_file))?;

        Ok(())
    }

    /// Manually flush events
    pub async fn flush_events(&self) -> Result<()> {
        Self::flush_buffer(&self.event_buffer, &self.config).await
    }

    /// Send event to collector
    pub fn send_event(&self, event: AnalyticsEvent) -> Result<()> {
        if let Some(sender) = &self.sender {
            sender.send(event)?;
        }
        Ok(())
    }

    /// Get aggregated metrics for a time period
    pub async fn get_aggregated_metrics(&self, period_hours: u32) -> Result<AnalyticsMetrics> {
        let now = Utc::now();
        let start_time = now - Duration::hours(period_hours as i64);

        let mut aggregated = AnalyticsMetrics {
            period_start: start_time,
            period_end: now,
            navigation: NavigationMetrics {
                total_requests: 0, route_resolutions: 0, language_switches: 0,
                avg_resolution_time_ms: 0.0, slow_routes_count: 0, error_count: 0,
            },
            cache: CacheMetrics {
                total_requests: 0, hit_count: 0, miss_count: 0, hit_rate: 0.0,
                evictions: 0, expired_entries: 0,
            },
            server: ServerMetrics {
                total_requests: 0, error_count: 0, panic_count: 0,
                avg_response_time_ms: 0.0, memory_usage_mb: None, cpu_usage_percent: None,
            },
            browser: BrowserMetrics {
                console_errors: 0, console_warnings: 0, hydration_mismatches: 0,
                javascript_errors: 0, performance_issues: 0,
            },
        };

        // Aggregate from cache and disk if needed
        let cache = self.metrics_cache.lock().unwrap();
        for (_, metrics) in cache.iter() {
            if metrics.period_start >= start_time && metrics.period_end <= now {
                // Add to aggregated metrics
                aggregated.navigation.total_requests += metrics.navigation.total_requests;
                aggregated.navigation.route_resolutions += metrics.navigation.route_resolutions;
                aggregated.navigation.language_switches += metrics.navigation.language_switches;
                aggregated.navigation.slow_routes_count += metrics.navigation.slow_routes_count;
                aggregated.navigation.error_count += metrics.navigation.error_count;
                
                aggregated.cache.total_requests += metrics.cache.total_requests;
                aggregated.cache.hit_count += metrics.cache.hit_count;
                aggregated.cache.miss_count += metrics.cache.miss_count;
                
                aggregated.server.total_requests += metrics.server.total_requests;
                aggregated.server.error_count += metrics.server.error_count;
                aggregated.server.panic_count += metrics.server.panic_count;
                
                aggregated.browser.console_errors += metrics.browser.console_errors;
                aggregated.browser.console_warnings += metrics.browser.console_warnings;
                aggregated.browser.hydration_mismatches += metrics.browser.hydration_mismatches;
                aggregated.browser.javascript_errors += metrics.browser.javascript_errors;
            }
        }

        // Calculate derived metrics
        if aggregated.cache.total_requests > 0 {
            aggregated.cache.hit_rate = 
                aggregated.cache.hit_count as f64 / aggregated.cache.total_requests as f64;
        }

        Ok(aggregated)
    }

    /// Get events from buffer (for real-time monitoring)
    pub fn get_recent_events(&self, limit: usize) -> Vec<AnalyticsEvent> {
        let buffer = self.event_buffer.lock().unwrap();
        buffer.iter()
            .rev()
            .take(limit)
            .cloned()
            .collect()
    }
}