// Copyright (c) 2025 Saorsa Labs Limited
//
// This file is part of the Saorsa P2P network.
//
// Licensed under the AGPL-3.0 license:
// <https://www.gnu.org/licenses/agpl-3.0.html>

//! Storage orchestration system with audit and repair capabilities
//!
//! Implements the complete placement loop with EigenTrust feedback,
//! churn prediction integration, and automated shard repair.

use std::collections::{HashMap, HashSet};
use std::sync::Arc;
use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};

use serde::{Deserialize, Serialize};
use tokio::sync::{RwLock, Semaphore};
use tokio::time::interval;

use crate::adaptive::{
    NodeId, learning::ChurnPredictor, performance::PerformanceMonitor, trust::EigenTrustEngine,
};
use crate::dht::core_engine::DhtCoreEngine;
use crate::placement::{
    GeographicLocation,
    NetworkRegion,
    PlacementConfig,
    PlacementDecision,
    PlacementEngine,
    PlacementError,
    PlacementMetrics,
    //    DhtRecord, DataPointer,
    PlacementResult,
};

/// Main orchestrator for the placement and storage system
#[derive(Debug)]
pub struct PlacementOrchestrator {
    placement_engine: Arc<RwLock<PlacementEngine>>,
    storage_orchestrator: Arc<StorageOrchestrator>,
    audit_system: Arc<AuditSystem>,
    repair_system: Arc<RepairSystem>,
    metrics: Arc<RwLock<PlacementMetrics>>,
    #[allow(dead_code)]
    config: PlacementConfig,
}

impl PlacementOrchestrator {
    /// Create new placement orchestrator
    pub async fn new(
        config: PlacementConfig,
        dht_engine: Arc<DhtCoreEngine>,
        trust_system: Arc<EigenTrustEngine>,
        performance_monitor: Arc<PerformanceMonitor>,
        churn_predictor: Arc<ChurnPredictor>,
    ) -> PlacementResult<Self> {
        let placement_engine = Arc::new(RwLock::new(PlacementEngine::new(config.clone())));

        let storage_orchestrator = Arc::new(
            StorageOrchestrator::new(
                dht_engine.clone(),
                trust_system.clone(),
                performance_monitor.clone(),
            )
            .await?,
        );

        let audit_system = Arc::new(
            AuditSystem::new(
                dht_engine.clone(),
                trust_system.clone(),
                churn_predictor.clone(),
            )
            .await?,
        );

        let repair_system = Arc::new(
            RepairSystem::new(
                dht_engine.clone(),
                storage_orchestrator.clone(),
                audit_system.clone(),
            )
            .await?,
        );

        Ok(Self {
            placement_engine,
            storage_orchestrator,
            audit_system,
            repair_system,
            metrics: Arc::new(RwLock::new(PlacementMetrics::new())),
            config,
        })
    }

    /// Start the orchestration loop
    pub async fn start(&self) -> PlacementResult<()> {
        // Start audit system
        let audit_system = self.audit_system.clone();
        tokio::spawn(async move {
            if let Err(e) = audit_system.start_audit_loop().await {
                tracing::error!("Audit system failed: {}", e);
            }
        });

        // Start repair system
        let repair_system = self.repair_system.clone();
        tokio::spawn(async move {
            if let Err(e) = repair_system.start_repair_loop().await {
                tracing::error!("Repair system failed: {}", e);
            }
        });

        tracing::info!("Placement orchestrator started");
        Ok(())
    }

    /// Place data with optimal shard distribution
    pub async fn place_data(
        &self,
        data: Vec<u8>,
        replication_factor: u8,
        region_preference: Option<NetworkRegion>,
    ) -> PlacementResult<PlacementDecision> {
        let start_time = Instant::now();

        // Get available nodes (this would come from network discovery)
        let available_nodes = self.get_available_nodes(region_preference).await?;

        // Get node metadata
        let node_metadata = self.get_node_metadata(&available_nodes).await?;

        // Get trust and performance systems
        let trust_system = self.storage_orchestrator.trust_system.clone();
        let performance_monitor = self.storage_orchestrator.performance_monitor.clone();

        // Perform placement
        let mut placement_engine = self.placement_engine.write().await;
        let decision = placement_engine
            .select_nodes(
                &available_nodes,
                replication_factor,
                &trust_system,
                &performance_monitor,
                &node_metadata,
            )
            .await?;

        // Store data using the placement decision
        self.storage_orchestrator
            .store_shards(&data, &decision, &node_metadata)
            .await?;

        // Record metrics
        let region = region_preference.unwrap_or(NetworkRegion::Unknown);
        let mut metrics = self.metrics.write().await;
        metrics.record_success(&decision, region);

        tracing::info!(
            "Data placed successfully: {} nodes, {:.2}s",
            decision.selected_nodes.len(),
            start_time.elapsed().as_secs_f64()
        );

        Ok(decision)
    }

    /// Get placement metrics
    pub async fn get_metrics(&self) -> PlacementMetrics {
        self.metrics.read().await.clone()
    }

    /// Mock method for getting available nodes
    async fn get_available_nodes(
        &self,
        _region: Option<NetworkRegion>,
    ) -> PlacementResult<HashSet<NodeId>> {
        // In a real implementation, this would query the DHT or network discovery
        let mut nodes = HashSet::new();
        for i in 0..20 {
            let mut hash = [0u8; 32];
            hash[0] = i;
            let user_id = crate::peer_record::UserId { hash };
            nodes.insert(user_id);
        }
        Ok(nodes)
    }

    /// Mock method for getting node metadata
    async fn get_node_metadata(
        &self,
        nodes: &HashSet<NodeId>,
    ) -> PlacementResult<HashMap<NodeId, (GeographicLocation, u32, NetworkRegion)>> {
        let mut metadata = HashMap::new();

        for (i, node_id) in nodes.iter().enumerate() {
            // Generate diverse geographic locations
            let lat = 40.0 + (i as f64 * 0.1) % 90.0;
            let lon = -74.0 + (i as f64 * 0.2) % 180.0;
            let location = GeographicLocation::new(lat, lon).map_err(|_| {
                PlacementError::InvalidConfiguration {
                    field: "location".to_string(),
                    reason: "Invalid coordinates".to_string(),
                }
            })?;

            let asn = 12345 + (i as u32 % 1000);
            let region = NetworkRegion::from_coordinates(&location);

            metadata.insert(node_id.clone(), (location, asn, region));
        }

        Ok(metadata)
    }
}

/// Storage orchestrator for shard management
#[derive(Debug)]
pub struct StorageOrchestrator {
    #[allow(dead_code)]
    dht_engine: Arc<DhtCoreEngine>,
    trust_system: Arc<EigenTrustEngine>,
    performance_monitor: Arc<PerformanceMonitor>,
    shard_store: Arc<RwLock<HashMap<String, ShardInfo>>>,
}

impl StorageOrchestrator {
    /// Create new storage orchestrator
    pub async fn new(
        dht_engine: Arc<DhtCoreEngine>,
        trust_system: Arc<EigenTrustEngine>,
        performance_monitor: Arc<PerformanceMonitor>,
    ) -> PlacementResult<Self> {
        Ok(Self {
            dht_engine,
            trust_system,
            performance_monitor,
            shard_store: Arc::new(RwLock::new(HashMap::new())),
        })
    }

    /// Store shards according to placement decision
    pub async fn store_shards(
        &self,
        data: &[u8],
        decision: &PlacementDecision,
        _node_metadata: &HashMap<NodeId, (GeographicLocation, u32, NetworkRegion)>,
    ) -> PlacementResult<Vec<String>> {
        // For now, simulate shard storage
        let mut shard_ids = Vec::new();

        for (i, node_id) in decision.selected_nodes.iter().enumerate() {
            let shard_id = format!("shard_{}_{}", hex::encode(&data[..8.min(data.len())]), i);

            let shard_info = ShardInfo {
                shard_id: shard_id.clone(),
                node_id: node_id.clone(),
                data_size: data.len() / decision.selected_nodes.len(),
                created_at: SystemTime::now()
                    .duration_since(UNIX_EPOCH)
                    .unwrap_or_default()
                    .as_secs(),
                last_verified: 0,
                verification_count: 0,
                repair_count: 0,
            };

            let mut store = self.shard_store.write().await;
            store.insert(shard_id.clone(), shard_info);

            shard_ids.push(shard_id);
        }

        tracing::debug!(
            "Stored {} shards across {} nodes",
            shard_ids.len(),
            decision.selected_nodes.len()
        );

        Ok(shard_ids)
    }

    /// Retrieve shards for reconstruction
    pub async fn retrieve_shards(&self, shard_ids: &[String]) -> PlacementResult<Vec<Vec<u8>>> {
        // Mock shard retrieval
        let mut shards = Vec::new();

        for _shard_id in shard_ids {
            // Simulate retrieving shard data
            let shard_data = vec![0u8; 1024]; // Mock data
            shards.push(shard_data);
        }

        Ok(shards)
    }

    /// Get shard information
    pub async fn get_shard_info(&self, shard_id: &str) -> Option<ShardInfo> {
        self.shard_store.read().await.get(shard_id).cloned()
    }

    /// Update shard verification status
    pub async fn update_shard_verification(&self, shard_id: &str) -> PlacementResult<()> {
        let mut store = self.shard_store.write().await;
        if let Some(shard_info) = store.get_mut(shard_id) {
            shard_info.last_verified = SystemTime::now()
                .duration_since(UNIX_EPOCH)
                .unwrap_or_default()
                .as_secs();
            shard_info.verification_count += 1;
        }
        Ok(())
    }
}

/// Audit system for continuous shard verification
#[derive(Debug)]
pub struct AuditSystem {
    #[allow(dead_code)]
    dht_engine: Arc<DhtCoreEngine>,
    trust_system: Arc<EigenTrustEngine>,
    churn_predictor: Arc<ChurnPredictor>,
    audit_interval: Duration,
    max_concurrent_audits: usize,
}

impl AuditSystem {
    /// Create new audit system
    pub async fn new(
        dht_engine: Arc<DhtCoreEngine>,
        trust_system: Arc<EigenTrustEngine>,
        churn_predictor: Arc<ChurnPredictor>,
    ) -> PlacementResult<Self> {
        Ok(Self {
            dht_engine,
            trust_system,
            churn_predictor,
            audit_interval: Duration::from_secs(300), // 5 minutes
            max_concurrent_audits: 10,
        })
    }

    /// Start the audit loop
    pub async fn start_audit_loop(&self) -> PlacementResult<()> {
        let mut interval = interval(self.audit_interval);
        let semaphore = Arc::new(Semaphore::new(self.max_concurrent_audits));

        tracing::info!(
            "Starting audit loop with interval {:?}",
            self.audit_interval
        );

        loop {
            interval.tick().await;

            // Get shards to audit
            let shards_to_audit = self.select_shards_for_audit().await?;

            for shard_id in shards_to_audit {
                let permit = semaphore
                    .clone()
                    .acquire_owned()
                    .await
                    .map_err(|e| PlacementError::AuditSystem(e.to_string()))?;

                let trust_system = self.trust_system.clone();
                let churn_predictor = self.churn_predictor.clone();

                tokio::spawn(async move {
                    let _permit = permit; // Keep permit until task completes

                    if let Err(e) = Self::audit_shard(shard_id, trust_system, churn_predictor).await
                    {
                        tracing::warn!("Shard audit failed: {}", e);
                    }
                });
            }
        }
    }

    /// Select shards that need auditing
    async fn select_shards_for_audit(&self) -> PlacementResult<Vec<String>> {
        // Mock implementation - select random shards
        Ok(vec![
            "shard_1".to_string(),
            "shard_2".to_string(),
            "shard_3".to_string(),
        ])
    }

    /// Audit a specific shard
    async fn audit_shard(
        shard_id: String,
        _trust_system: Arc<EigenTrustEngine>,
        _churn_predictor: Arc<ChurnPredictor>,
    ) -> PlacementResult<AuditResult> {
        // Mock audit implementation
        let audit_result = AuditResult {
            shard_id: shard_id.clone(),
            status: AuditStatus::Healthy,
            node_responses: HashMap::new(),
            integrity_verified: true,
            availability_score: 0.95,
            performance_metrics: HashMap::new(),
        };

        // Update trust scores based on audit results
        // This would be implemented based on actual node responses

        tracing::debug!("Audited shard {}: {:?}", shard_id, audit_result.status);
        Ok(audit_result)
    }
}

/// Repair system with hysteresis to prevent repair storms
#[derive(Debug)]
pub struct RepairSystem {
    #[allow(dead_code)]
    dht_engine: Arc<DhtCoreEngine>,
    storage_orchestrator: Arc<StorageOrchestrator>,
    #[allow(dead_code)]
    audit_system: Arc<AuditSystem>,
    repair_threshold: f64,
    repair_hysteresis: f64,
    repair_cooldown: Duration,
    active_repairs: Arc<RwLock<HashMap<String, Instant>>>,
}

impl RepairSystem {
    /// Create new repair system
    pub async fn new(
        dht_engine: Arc<DhtCoreEngine>,
        storage_orchestrator: Arc<StorageOrchestrator>,
        audit_system: Arc<AuditSystem>,
    ) -> PlacementResult<Self> {
        Ok(Self {
            dht_engine,
            storage_orchestrator,
            audit_system,
            repair_threshold: 0.7,  // Start repair when availability < 70%
            repair_hysteresis: 0.1, // 10% hysteresis band
            repair_cooldown: Duration::from_secs(3600), // 1 hour cooldown
            active_repairs: Arc::new(RwLock::new(HashMap::new())),
        })
    }

    /// Start the repair loop
    pub async fn start_repair_loop(&self) -> PlacementResult<()> {
        let mut interval = interval(Duration::from_secs(60)); // Check every minute

        tracing::info!("Starting repair loop");

        loop {
            interval.tick().await;

            if let Err(e) = self.check_and_repair_shards().await {
                tracing::error!("Repair check failed: {}", e);
            }
        }
    }

    /// Check shards and initiate repairs if needed
    async fn check_and_repair_shards(&self) -> PlacementResult<()> {
        let shards_needing_repair = self.identify_shards_needing_repair().await?;

        for shard_id in shards_needing_repair {
            if self.should_repair_shard(&shard_id).await?
                && let Err(e) = self.initiate_repair(&shard_id).await
            {
                tracing::error!("Failed to repair shard {}: {}", shard_id, e);
            }
        }

        Ok(())
    }

    /// Identify shards that need repair
    async fn identify_shards_needing_repair(&self) -> PlacementResult<Vec<String>> {
        // Mock implementation
        Ok(vec!["damaged_shard_1".to_string()])
    }

    /// Check if shard should be repaired (apply hysteresis)
    async fn should_repair_shard(&self, shard_id: &str) -> PlacementResult<bool> {
        // Check cooldown
        let active_repairs = self.active_repairs.read().await;
        if let Some(last_repair) = active_repairs.get(shard_id)
            && last_repair.elapsed() < self.repair_cooldown
        {
            return Ok(false);
        }

        // Mock availability check
        let availability = 0.6; // Simulated low availability

        // Apply hysteresis
        let threshold = if active_repairs.contains_key(shard_id) {
            self.repair_threshold + self.repair_hysteresis
        } else {
            self.repair_threshold
        };

        Ok(availability < threshold)
    }

    /// Initiate repair for a shard
    async fn initiate_repair(&self, shard_id: &str) -> PlacementResult<()> {
        // Mark as being repaired
        let mut active_repairs = self.active_repairs.write().await;
        active_repairs.insert(shard_id.to_string(), Instant::now());
        drop(active_repairs);

        tracing::info!("Initiating repair for shard {}", shard_id);

        // Mock repair process
        tokio::time::sleep(Duration::from_secs(1)).await;

        // Update shard store after repair
        if let Some(_shard_info) = self.storage_orchestrator.get_shard_info(shard_id).await {
            let mut store = self.storage_orchestrator.shard_store.write().await;
            if let Some(info) = store.get_mut(shard_id) {
                info.repair_count += 1;
            }
        }

        tracing::info!("Completed repair for shard {}", shard_id);
        Ok(())
    }
}

/// Information about stored shards
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ShardInfo {
    pub shard_id: String,
    pub node_id: NodeId,
    pub data_size: usize,
    pub created_at: u64,
    pub last_verified: u64,
    pub verification_count: u32,
    pub repair_count: u32,
}

/// Result of shard audit
#[derive(Debug, Clone)]
pub struct AuditResult {
    pub shard_id: String,
    pub status: AuditStatus,
    pub node_responses: HashMap<NodeId, bool>,
    pub integrity_verified: bool,
    pub availability_score: f64,
    pub performance_metrics: HashMap<String, f64>,
}

/// Status of shard audit
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum AuditStatus {
    Healthy,
    Degraded,
    Critical,
    Missing,
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::sync::Arc;

    // Mock implementations for testing
    #[allow(dead_code)]
    async fn create_mock_dht_engine() -> Arc<DhtCoreEngine> {
        // This would need proper mocking
        // For now, we'll skip this test since it requires complex setup
        unimplemented!("Mock DHT engine needed for tests")
    }

    #[tokio::test]
    #[ignore] // Ignore until we have proper mocks
    async fn test_placement_orchestrator_creation() {
        // Test would go here with proper mocks
    }

    #[test]
    fn test_shard_info() {
        let shard_info = ShardInfo {
            shard_id: "test_shard".to_string(),
            node_id: NodeId::from_bytes([1u8; 32]),
            data_size: 1024,
            created_at: 1234567890,
            last_verified: 0,
            verification_count: 0,
            repair_count: 0,
        };

        assert_eq!(shard_info.shard_id, "test_shard");
        assert_eq!(shard_info.data_size, 1024);
        assert_eq!(shard_info.verification_count, 0);
    }

    #[test]
    fn test_audit_status() {
        assert_eq!(AuditStatus::Healthy, AuditStatus::Healthy);
        assert_ne!(AuditStatus::Healthy, AuditStatus::Degraded);
    }
}
