// Copyright 2024 Saorsa Labs Limited
//
// This software is dual-licensed under:
// - GNU Affero General Public License v3.0 or later (AGPL-3.0-or-later)
// - Commercial License
//
// For AGPL-3.0 license, see LICENSE-AGPL-3.0
// For commercial licensing, contact: david@saorsalabs.com
//
// Unless required by applicable law or agreed to in writing, software
// distributed under these licenses is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

//! Standalone test for enhanced DHT storage components
//! 
//! This test file allows us to test our enhanced storage implementation
//! independently of the rest of the codebase compilation issues.

use std::time::{Duration, SystemTime};
use std::collections::{HashMap, HashSet, VecDeque, BinaryHeap};
use serde::{Serialize, Deserialize};

// Minimal PeerId for testing
pub type PeerId = String;

// Minimal Key implementation for testing
#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub struct Key {
    hash: [u8; 32],
}

impl Key {
    pub fn from(data: Vec<u8>) -> Self {
        let mut hash = [0u8; 32];
        hash[..data.len().min(32)].copy_from_slice(&data[..data.len().min(32)]);
        Self { hash }
    }
}

/// Configuration for the K=8 replication system
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ReplicationConfig {
    /// Number of replicas to maintain (K=8 for production)
    pub replication_factor: usize,
    /// Minimum acceptable replicas before triggering emergency repair
    pub min_replication_factor: usize,
    /// XOR distance preference factor (0.0 = pure distance, 1.0 = pure random)
    pub preferred_distance_factor: f64,
    /// Whether to consider geographic distribution in peer selection
    pub geographic_awareness: bool,
    /// Trigger repair when replicas fall below this threshold
    pub repair_threshold: usize,
    /// How often to check for needed repairs
    pub repair_interval: Duration,
    /// Maximum concurrent repair operations
    pub max_repair_concurrent: usize,
}

impl Default for ReplicationConfig {
    fn default() -> Self {
        Self {
            replication_factor: 8,
            min_replication_factor: 3,
            preferred_distance_factor: 0.3,
            geographic_awareness: true,
            repair_threshold: 5,
            repair_interval: Duration::from_secs(300), // 5 minutes
            max_repair_concurrent: 3,
        }
    }
}

/// Result of a replication operation
#[derive(Debug, Clone)]
pub struct ReplicationResult {
    pub key: Key,
    pub successful_replicas: usize,
    pub failed_replicas: usize,
    pub target_replicas: usize,
    pub successful_peers: Vec<PeerId>,
    pub failed_peers: Vec<(PeerId, String)>, // Simplified error representation
    pub is_sufficient: bool,
}

impl ReplicationResult {
    /// Check if replication meets minimum requirements
    pub fn is_healthy(&self, min_replicas: usize) -> bool {
        self.successful_replicas >= min_replicas
    }
    
    /// Calculate replication success rate
    pub fn success_rate(&self) -> f64 {
        if self.target_replicas == 0 {
            0.0
        } else {
            self.successful_replicas as f64 / self.target_replicas as f64
        }
    }
    
    /// Get a summary of the replication attempt
    pub fn summary(&self) -> String {
        format!(
            "Replication: {}/{} successful ({}% success rate), {} failed",
            self.successful_replicas,
            self.target_replicas,
            (self.success_rate() * 100.0) as u32,
            self.failed_replicas
        )
    }
}

/// Errors that can occur during replication
#[derive(Debug, thiserror::Error)]
pub enum ReplicationError {
    #[error("Insufficient peers available: required {required}, available {available}")]
    InsufficientPeers { required: usize, available: usize },
    
    #[error("No peers available for replication")]
    NoPeersAvailable,
    
    #[error("Network error during replication: {0}")]
    NetworkError(String),
    
    #[error("DHT operation failed: {0}")]
    DhtError(String),
    
    #[error("Geographic information unavailable")]
    GeographicInfoUnavailable,
    
    #[error("Timeout during replication operation")]
    Timeout,
    
    #[error("Invalid configuration: {0}")]
    InvalidConfiguration(String),
    
    #[error("Repair operation failed: {0}")]
    RepairFailed(String),
}

/// Health information for individual peers
#[derive(Debug, Clone)]
pub struct PeerHealthInfo {
    pub success_rate: f64,
    pub last_successful_store: SystemTime,
    pub last_failed_store: Option<SystemTime>,
    pub total_attempts: u64,
    pub successful_attempts: u64,
}

impl Default for PeerHealthInfo {
    fn default() -> Self {
        Self {
            success_rate: 1.0,
            last_successful_store: SystemTime::now(),
            last_failed_store: None,
            total_attempts: 0,
            successful_attempts: 0,
        }
    }
}

/// Priority levels for repair operations
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
pub enum RepairPriority {
    Low,      // Replicas above threshold but below target
    Medium,   // Replicas at threshold
    High,     // Replicas below threshold
    Critical, // Very few replicas remaining
}

/// A repair task for maintaining replication levels
#[derive(Debug, Clone)]
pub struct RepairTask {
    pub key: Key,
    pub current_replicas: Vec<PeerId>,
    pub required_replicas: usize,
    pub priority: RepairPriority,
    pub scheduled_at: SystemTime,
}

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

    #[test]
    fn test_replication_config_default() {
        let config = ReplicationConfig::default();
        assert_eq!(config.replication_factor, 8);
        assert_eq!(config.min_replication_factor, 3);
        assert_eq!(config.repair_threshold, 5);
        assert!(config.geographic_awareness);
    }

    #[test]
    fn test_replication_config_custom() {
        let config = ReplicationConfig {
            replication_factor: 12,
            min_replication_factor: 4,
            preferred_distance_factor: 0.5,
            geographic_awareness: false,
            repair_threshold: 8,
            repair_interval: Duration::from_secs(600),
            max_repair_concurrent: 5,
        };
        
        assert_eq!(config.replication_factor, 12);
        assert_eq!(config.min_replication_factor, 4);
        assert_eq!(config.preferred_distance_factor, 0.5);
        assert!(!config.geographic_awareness);
        assert_eq!(config.repair_threshold, 8);
        assert_eq!(config.repair_interval, Duration::from_secs(600));
        assert_eq!(config.max_repair_concurrent, 5);
    }

    #[test]
    fn test_replication_result_health_check() {
        let result = ReplicationResult {
            key: Key::from(vec![1, 2, 3]),
            successful_replicas: 6,
            failed_replicas: 2,
            target_replicas: 8,
            successful_peers: vec!["peer1".to_string(), "peer2".to_string()],
            failed_peers: vec![("peer3".to_string(), "network error".to_string())],
            is_sufficient: true,
        };

        assert!(result.is_healthy(3));
        assert!(result.is_healthy(5));
        assert!(result.is_healthy(6));
        assert!(!result.is_healthy(7));
        assert!(!result.is_healthy(8));
    }

    #[test]
    fn test_replication_result_success_rate() {
        let result = ReplicationResult {
            key: Key::from(vec![1, 2, 3]),
            successful_replicas: 6,
            failed_replicas: 2,
            target_replicas: 8,
            successful_peers: vec![],
            failed_peers: vec![],
            is_sufficient: true,
        };

        assert_eq!(result.success_rate(), 0.75);
        assert_eq!(result.summary(), "Replication: 6/8 successful (75% success rate), 2 failed");
    }

    #[test]
    fn test_replication_result_edge_cases() {
        // Test zero target replicas
        let result = ReplicationResult {
            key: Key::from(vec![1, 2, 3]),
            successful_replicas: 0,
            failed_replicas: 0,
            target_replicas: 0,
            successful_peers: vec![],
            failed_peers: vec![],
            is_sufficient: false,
        };

        assert_eq!(result.success_rate(), 0.0);
        assert!(!result.is_healthy(1));
        
        // Test perfect replication
        let perfect_result = ReplicationResult {
            key: Key::from(vec![4, 5, 6]),
            successful_replicas: 8,
            failed_replicas: 0,
            target_replicas: 8,
            successful_peers: (0..8).map(|i| format!("peer{}", i).into()).collect(),
            failed_peers: vec![],
            is_sufficient: true,
        };

        assert_eq!(perfect_result.success_rate(), 1.0);
        assert!(perfect_result.is_healthy(8));
        assert_eq!(perfect_result.summary(), "Replication: 8/8 successful (100% success rate), 0 failed");
    }

    #[test]
    fn test_peer_health_info_default() {
        let health = PeerHealthInfo::default();
        assert_eq!(health.success_rate, 1.0);
        assert_eq!(health.total_attempts, 0);
        assert_eq!(health.successful_attempts, 0);
        assert!(health.last_failed_store.is_none());
    }

    #[test]
    fn test_peer_health_info_updates() {
        let mut health = PeerHealthInfo::default();
        
        // Simulate some operations
        health.total_attempts = 10;
        health.successful_attempts = 8;
        health.success_rate = health.successful_attempts as f64 / health.total_attempts as f64;
        
        assert_eq!(health.success_rate, 0.8);
        assert_eq!(health.total_attempts, 10);
        assert_eq!(health.successful_attempts, 8);
    }

    #[test]
    fn test_repair_priority_ordering() {
        assert!(RepairPriority::Critical > RepairPriority::High);
        assert!(RepairPriority::High > RepairPriority::Medium);
        assert!(RepairPriority::Medium > RepairPriority::Low);
        
        // Test that we can collect and sort priorities
        let mut priorities = vec![
            RepairPriority::Low,
            RepairPriority::Critical,
            RepairPriority::Medium,
            RepairPriority::High,
        ];
        
        priorities.sort();
        
        assert_eq!(priorities, vec![
            RepairPriority::Low,
            RepairPriority::Medium,
            RepairPriority::High,
            RepairPriority::Critical,
        ]);
    }

    #[test]
    fn test_repair_task_creation() {
        let key = Key::from(vec![7, 8, 9]);
        let peers = vec!["peer1".to_string(), "peer2".to_string(), "peer3".to_string()];
        
        let task = RepairTask {
            key: key.clone(),
            current_replicas: peers.clone(),
            required_replicas: 5,
            priority: RepairPriority::High,
            scheduled_at: SystemTime::now(),
        };
        
        assert_eq!(task.key, key);
        assert_eq!(task.current_replicas, peers);
        assert_eq!(task.required_replicas, 5);
        assert_eq!(task.priority, RepairPriority::High);
    }

    #[test]
    fn test_replication_error_types() {
        let insufficient_error = ReplicationError::InsufficientPeers {
            required: 8,
            available: 3,
        };
        
        assert_eq!(
            insufficient_error.to_string(),
            "Insufficient peers available: required 8, available 3"
        );
        
        let network_error = ReplicationError::NetworkError("Connection timeout".to_string());
        assert_eq!(
            network_error.to_string(),
            "Network error during replication: Connection timeout"
        );
        
        let no_peers_error = ReplicationError::NoPeersAvailable;
        assert_eq!(
            no_peers_error.to_string(),
            "No peers available for replication"
        );
    }

    #[test]
    fn test_key_creation() {
        let key1 = Key::from(vec![1, 2, 3, 4, 5]);
        let key2 = Key::from(vec![1, 2, 3, 4, 5]);
        let key3 = Key::from(vec![6, 7, 8, 9, 10]);
        
        assert_eq!(key1, key2);
        assert_ne!(key1, key3);
        
        // Test that keys can be used in hash maps
        let mut key_map = HashMap::new();
        key_map.insert(key1.clone(), "value1");
        key_map.insert(key3.clone(), "value3");
        
        assert_eq!(key_map.get(&key2), Some(&"value1"));
        assert_eq!(key_map.len(), 2);
    }

    #[test]
    fn test_serialization() {
        let config = ReplicationConfig::default();
        
        // Test that config can be serialized and deserialized
        let serialized = serde_json::to_string(&config).expect("Failed to serialize config");
        let deserialized: ReplicationConfig = serde_json::from_str(&serialized)
            .expect("Failed to deserialize config");
        
        assert_eq!(config.replication_factor, deserialized.replication_factor);
        assert_eq!(config.min_replication_factor, deserialized.min_replication_factor);
        assert_eq!(config.geographic_awareness, deserialized.geographic_awareness);
    }

    #[test] 
    fn test_comprehensive_replication_scenario() {
        // Simulate a comprehensive replication scenario
        let config = ReplicationConfig {
            replication_factor: 5,
            min_replication_factor: 2,
            preferred_distance_factor: 0.3,
            geographic_awareness: true,
            repair_threshold: 3,
            repair_interval: Duration::from_secs(300),
            max_repair_concurrent: 2,
        };
        
        let key = Key::from(vec![10, 20, 30]);
        
        // Simulate partial replication success
        let result = ReplicationResult {
            key: key.clone(),
            successful_replicas: 3,
            failed_replicas: 2,
            target_replicas: config.replication_factor,
            successful_peers: vec![
                "peer_a".to_string(),
                "peer_b".to_string(),
                "peer_c".to_string(),
            ],
            failed_peers: vec![
                ("peer_d".to_string(), "timeout".to_string()),
                ("peer_e".to_string(), "connection refused".to_string()),
            ],
            is_sufficient: true,
        };
        
        // Verify the result meets minimum requirements
        assert!(result.is_healthy(config.min_replication_factor));
        assert!(!result.is_healthy(config.replication_factor));
        
        // Check if repair should be triggered
        let needs_repair = result.successful_replicas < config.repair_threshold;
        assert!(!needs_repair); // 3 >= 3, so no repair needed
        
        // Test success rate calculation
        assert_eq!(result.success_rate(), 0.6); // 3/5
        
        // Verify summary format
        let summary = result.summary();
        assert!(summary.contains("3/5 successful"));
        assert!(summary.contains("60% success rate"));
        assert!(summary.contains("2 failed"));
        
        println!("Replication scenario test passed: {}", summary);
    }
}