synapse 1.1.0

//! Email Transport implementation conforming to the unified Transport trait

use crate::{
    types::{SecureMessage, EmailConfig, synapse::blockchain::serialization::{DateTimeWrapper, UuidWrapper}},,
    error::{Result, SynapseError},
    circuit_breaker::{CircuitBreaker, CircuitBreakerConfig, RequestOutcome},
};
use super::abstraction::*;
use async_trait::async_trait;
use tokio::{
    sync::{RwLock, Mutex},
    time::timeout,
};
use std::{
    time::{Duration, Instant},
    collections::HashMap,
    sync::Arc,
};
use tracing::{info, debug, warn, error};
use serde_json;

/// Email Transport implementation for unified abstraction
pub struct EmailTransportImpl {
    /// Email configuration
    config: EmailConfig,
    /// Connection timeout
    connection_timeout: Duration,
    /// Received messages queue
    received_messages: Arc<Mutex<Vec<IncomingMessage>>>,
    /// Current status
    status: Arc<RwLock<TransportStatus>>,
    /// Performance metrics
    metrics: Arc<RwLock<TransportMetrics>>,
    /// Circuit breaker for reliability
    circuit_breaker: Arc<CircuitBreaker>,
    /// Maximum message size for email
    max_message_size: usize,
}

impl EmailTransportImpl {
    /// Create a new Email transport instance
    pub async fn new(config: &HashMap<String, String>) -> Result<Self> {
        let smtp_server = config.get("smtp_server")
            .cloned()
            .unwrap_or_else(|| "localhost".to_string());
        
        let smtp_port = config.get("smtp_port")
            .and_then(|p| p.parse().ok())
            .unwrap_or(587);
            
        let imap_server = config.get("imap_server")
            .cloned()
            .unwrap_or_else(|| "localhost".to_string());
            
        let imap_port = config.get("imap_port")
            .and_then(|p| p.parse().ok())
            .unwrap_or(993);
            
        let username = config.get("username")
            .cloned()
            .unwrap_or_else(|| "synapse@localhost".to_string());
            
        let password = config.get("password")
            .cloned()
            .unwrap_or_else(|| "password".to_string());
            
        let connection_timeout = config.get("connection_timeout_ms")
            .and_then(|t| t.parse().ok())
            .map(Duration::from_millis)
            .unwrap_or(Duration::from_secs(30));
            
        let max_message_size = config.get("max_message_size")
            .and_then(|s| s.parse().ok())
            .unwrap_or(25 * 1024 * 1024); // 25MB default
        
        let email_config = EmailConfig {
            smtp: crate::types::SmtpConfig {
                host: smtp_server,
                port: smtp_port,
                username: username.clone(),
                password: password.clone(),
                use_tls: true,
                use_ssl: false,
            },
            imap: crate::types::ImapConfig {
                host: imap_server,
                port: imap_port,
                username,
                password,
                use_ssl: true,
            },
        };
        
        let circuit_breaker_config = CircuitBreakerConfig {
            failure_threshold: 5,
            minimum_requests: 2,
            failure_window: Duration::from_secs(60),
            recovery_timeout: Duration::from_secs(60),
            half_open_max_calls: 1,
            success_threshold: 0.7,
        };
        
        let mut metrics = TransportMetrics::default();
        metrics.transport_type = TransportType::Email;
        
        Ok(Self {
            config: email_config,
            connection_timeout,
            received_messages: Arc::new(Mutex::new(Vec::new())),
            status: Arc::new(RwLock::new(TransportStatus::Stopped)),
            metrics: Arc::new(RwLock::new(metrics)),
            circuit_breaker: Arc::new(CircuitBreaker::new(circuit_breaker_config)),
            max_message_size,
        })
    }
    
    /// Send email message using SMTP
    async fn send_smtp_message(&self, to_address: &str, message: &SecureMessage) -> Result<()> {
        let start_time = Instant::now();
        
        // Simulate SMTP send - in real implementation, use lettre or similar crate
        info!("Sending email message to {} via SMTP", to_address);
        
        // Basic email format validation
        if !to_address.contains('@') {
            return Err(crate::error::SynapseError::TransportError(
                "Invalid email address format".to_string()
            ));
        }
        
        // Serialize message for email body
        let message_json = serde_json::to_string(message)
            .map_err(|e| crate::error::SynapseError::SerializationError(
                format!("Failed to serialize email message: {}", e)
            ))?;
        
        // Check message size
        if message_json.len() > self.max_message_size {
            return Err(crate::error::SynapseError::TransportError(
                format!("Message too large: {} bytes", message_json.len())
            ));
        }
        
        // Simulate email sending delay (real implementation would use SMTP client)
        tokio::time::sleep(Duration::from_millis(100)).await;
        
        debug!("Email sent to {}", to_address);
        
        Ok(())
    }
    
    /// Check for incoming messages via IMAP
    async fn check_imap_messages(&self) -> Result<Vec<IncomingMessage>> {
        // Simulate IMAP message checking - in real implementation, use imap crate
        debug!("Checking for incoming email messages via IMAP");
        
        // In a real implementation, this would:
        // 1. Connect to IMAP server
        // 2. Search for new messages
        // 3. Parse message content 
        // 4. Deserialize SecureMessage from email body
        // 5. Return as IncomingMessage instances
        
        Ok(Vec::new()) // No messages for simulation
    }
    
    /// Update transport metrics
    async fn update_metrics(&self, operation: &str, duration: Duration, success: bool) {
        let mut metrics = self.metrics.write().await;
        
        if success {
            if operation == "send" {
                metrics.messages_sent += 1;
                metrics.bytes_sent += 1024; // Estimate
            } else if operation == "receive" {
                metrics.messages_received += 1;
                metrics.bytes_received += 1024; // Estimate
            }
            
            // Update average latency
            let current_avg = metrics.average_latency_ms;
            let new_latency = duration.as_millis() as u64;
            metrics.average_latency_ms = if current_avg == 0 {
                new_latency
            } else {
                (current_avg + new_latency) / 2
            };
            
            // Update reliability (moving average)
            metrics.reliability_score = (metrics.reliability_score * 0.9) + 0.1;
        } else {
            if operation == "send" {
                metrics.send_failures += 1;
            } else if operation == "receive" {
                metrics.receive_failures += 1;
            }
            
            // Decrease reliability
            metrics.reliability_score = (metrics.reliability_score * 0.9);
        }
        
        metrics.last_updated_timestamp = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .unwrap_or_default()
            .as_secs();
    }
}

#[async_trait]
impl Transport for EmailTransportImpl {
    fn transport_type(&self) -> TransportType {
        TransportType::Email
    }
    
    fn capabilities(&self) -> TransportCapabilities {
        TransportCapabilities {
            max_message_size: self.max_message_size,
            reliable: true, // Email is store-and-forward, highly reliable
            real_time: false, // Email is not real-time
            broadcast: false, // No native broadcast (though can send to multiple recipients)
            bidirectional: true, // Can send and receive
            encrypted: true, // Can use TLS/SSL
            network_spanning: true, // Works across networks/internet
            supported_urgencies: vec![
                MessageUrgency::Background,
                MessageUrgency::Batch,
                MessageUrgency::Interactive, // Though with higher latency
            ],
            features: vec![
                "smtp".to_string(),
                "imap".to_string(),
                "store_and_forward".to_string(),
                "authentication".to_string(),
                "tls_encryption".to_string(),
            ],
        }
    }
    
    async fn can_reach(&self, target: &TransportTarget) -> bool {
        // Check if target identifier looks like an email address
        if let Some(address) = &target.address {
            address.contains('@')
        } else {
            target.identifier.contains('@')
        }
    }
    
    async fn estimate_metrics(&self, target: &TransportTarget) -> Result<TransportEstimate> {
        let _can_reach = self.can_reach(target).await;
        
        Ok(TransportEstimate {
            latency: Duration::from_secs(30), // Email typically has higher latency
            reliability: 0.95, // Email is very reliable due to store-and-forward
            bandwidth: 1024 * 1024, // 1MB/s effective throughput
            cost: 1.0, // Low cost
            available: true, // Assume available if configured
            confidence: 0.8, // Medium confidence in estimates
        })
    }
    
    async fn send_message(&self, target: &TransportTarget, message: &SecureMessage) -> Result<DeliveryReceipt> {
        let email_address = target.address.as_ref()
            .unwrap_or(&target.identifier);
        
        // Check circuit breaker before proceeding
        if !self.circuit_breaker.can_proceed().await {
            return Err(SynapseError::TransportError("Circuit breaker is open".to_string()));
        }

        let start_time = Instant::now();
        
        // Attempt to send the email
        let send_result = timeout(self.connection_timeout, self.send_smtp_message(email_address, message)).await
            .map_err(|_| SynapseError::TransportError("Timeout sending email".to_string()))?;
        
        let duration = start_time.elapsed();
        
        match send_result {
            Ok(()) => {
                // Record success
                self.circuit_breaker.record_outcome(RequestOutcome::Success).await;
                self.update_metrics("send", duration, true).await;
                
                Ok(DeliveryReceipt {
                    message_id: message.message_id.clone(),
                    transport_used: TransportType::Email,
                    delivery_time: duration,
                    target_reached: email_address.clone(),
                    confirmation: DeliveryConfirmation::Sent, // Email only confirms sending, not delivery
                    metadata: {
                        let mut map = HashMap::new();
                        map.insert("email_address".to_string(), email_address.clone());
                        map.insert("smtp_server".to_string(), self.config.smtp.host.clone());
                        map
                    },
                })
            }
            Err(e) => {
                // Record failure
                self.circuit_breaker.record_outcome(RequestOutcome::Failure(e.to_string())).await;
                self.update_metrics("send", Duration::from_secs(0), false).await;
                Err(e)
            }
        }
    }
    
    async fn receive_messages(&self) -> Result<Vec<IncomingMessage>> {
        // Check circuit breaker before proceeding
        if !self.circuit_breaker.can_proceed().await {
            return Err(SynapseError::TransportError("Circuit breaker is open".to_string()));
        }

        let start_time = Instant::now();
        
        // Attempt to check for new messages
        let check_result = timeout(self.connection_timeout, self.check_imap_messages()).await
            .map_err(|_| SynapseError::TransportError("Timeout checking email".to_string()))?;
        
        match check_result {
            Ok(messages) => {
                // Record success
                self.circuit_breaker.record_outcome(RequestOutcome::Success).await;
                self.update_metrics("receive", start_time.elapsed(), true).await;
                
                // Add messages to internal queue
                let mut received = self.received_messages.lock().await;
                received.extend(messages.clone());
                
                Ok(messages)
            }
            Err(e) => {
                // Record failure
                self.circuit_breaker.record_outcome(RequestOutcome::Failure(e.to_string())).await;
                self.update_metrics("receive", Duration::from_secs(0), false).await;
                Err(e)
            }
        }
    }
    
    async fn test_connectivity(&self, target: &TransportTarget) -> Result<ConnectivityResult> {
        let email_address = target.address.as_ref()
            .unwrap_or(&target.identifier);
        
        let start_time = Instant::now();
        
        // Basic connectivity test - check if we can reach SMTP server
        // In real implementation, this would establish SMTP connection
        tokio::time::sleep(Duration::from_millis(50)).await;
        
        let rtt = start_time.elapsed();
        
        Ok(ConnectivityResult {
            connected: email_address.contains('@'), // Simple validation
            rtt: Some(rtt),
            error: None,
            quality: 0.8, // Good quality for email
            details: {
                let mut map = HashMap::new();
                map.insert("smtp_server".to_string(), self.config.smtp.server.clone());
                map.insert("imap_server".to_string(), self.config.imap.server.clone());
                map.insert("target_email".to_string(), email_address.clone());
                map
            },
        })
    }
    
    async fn start(&self) -> Result<()> {
        info!("Starting Email transport");
        
        {
            let mut status = self.status.write().await;
            *status = TransportStatus::Starting;
        }
        
        // In real implementation, establish SMTP/IMAP connections here
        
        {
            let mut status = self.status.write().await;
            *status = TransportStatus::Running;
        }
        
        info!("Email transport started successfully");
        Ok(())
    }
    
    async fn stop(&self) -> Result<()> {
        info!("Stopping Email transport");
        
        {
            let mut status = self.status.write().await;
            *status = TransportStatus::Stopping;
        }
        
        // In real implementation, close SMTP/IMAP connections here
        
        {
            let mut status = self.status.write().await;
            *status = TransportStatus::Stopped;
        }
        
        info!("Email transport stopped");
        Ok(())
    }
    
    async fn status(&self) -> TransportStatus {
        *self.status.read().await
    }
    
    async fn metrics(&self) -> TransportMetrics {
        self.metrics.read().await.clone()
    }
}