oxirs-fuseki 0.2.4

//! Apache Kafka integration for event streaming

use async_trait::async_trait;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

use crate::{
    error::FusekiResult,
    streaming::{RDFEvent, StreamConsumer, StreamProducer},
};

/// Kafka-specific configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct KafkaConfig {
    /// Kafka broker addresses
    pub brokers: Vec<String>,
    /// Security protocol
    pub security_protocol: Option<String>,
    /// SASL mechanism
    pub sasl_mechanism: Option<String>,
    /// SASL username
    pub sasl_username: Option<String>,
    /// SASL password
    pub sasl_password: Option<String>,
    /// Additional Kafka properties
    pub properties: HashMap<String, String>,
}

impl Default for KafkaConfig {
    fn default() -> Self {
        Self {
            brokers: vec!["localhost:9092".to_string()],
            security_protocol: None,
            sasl_mechanism: None,
            sasl_username: None,
            sasl_password: None,
            properties: HashMap::new(),
        }
    }
}

impl From<crate::streaming::KafkaConfig> for KafkaConfig {
    fn from(config: crate::streaming::KafkaConfig) -> Self {
        Self {
            brokers: config.brokers,
            security_protocol: None,
            sasl_mechanism: None,
            sasl_username: None,
            sasl_password: None,
            properties: HashMap::new(),
        }
    }
}

/// Kafka producer implementation
pub struct KafkaProducer {
    config: KafkaConfig,
    // Future enhancement: Add actual Kafka producer (requires rdkafka/kafka-rust crate).
    // For v0.1.0: Stub implementation provides API surface for future Kafka integration.
}

impl KafkaProducer {
    /// Create a new Kafka producer
    pub async fn new(config: KafkaConfig) -> FusekiResult<Self> {
        tracing::info!("Creating Kafka producer with brokers: {:?}", config.brokers);

        // Future enhancement: Initialize rdkafka producer with config.
        // For v0.1.0: Stub allows testing of streaming pipeline without Kafka dependency.
        Ok(Self { config })
    }
}

#[async_trait]
impl StreamProducer for KafkaProducer {
    async fn send(&self, event: RDFEvent) -> FusekiResult<()> {
        tracing::debug!("Sending RDF event to Kafka");

        // Future enhancement: Implement rdkafka message sending.
        // For v0.1.0: Logs events for debugging. Full Kafka integration is optional.
        // For now, just log the event
        tracing::info!("Would send to Kafka: {:?}", event);

        Ok(())
    }

    async fn send_batch(&self, events: Vec<RDFEvent>) -> FusekiResult<()> {
        tracing::debug!("Sending batch of {} RDF events to Kafka", events.len());

        // Future enhancement: Implement rdkafka batch sending for better throughput.
        // For v0.1.0: Logs individual events. Batch optimization is future work.
        for event in events {
            self.send(event).await?;
        }

        Ok(())
    }

    async fn flush(&self) -> FusekiResult<()> {
        tracing::debug!("Flushing Kafka producer");
        // Future enhancement: Implement rdkafka flush for guaranteed delivery.
        // For v0.1.0: No-op. Full Kafka integration is optional.
        Ok(())
    }
}

/// Kafka consumer implementation
pub struct KafkaConsumer {
    config: KafkaConfig,
    // Future enhancement: Add actual Kafka consumer (requires rdkafka/kafka-rust crate).
    // For v0.1.0: Stub implementation provides API surface for future Kafka integration.
}

impl KafkaConsumer {
    /// Create a new Kafka consumer
    pub async fn new(config: KafkaConfig) -> FusekiResult<Self> {
        tracing::info!("Creating Kafka consumer with brokers: {:?}", config.brokers);

        // Future enhancement: Initialize rdkafka consumer with config.
        // For v0.1.0: Stub allows testing of streaming pipeline without Kafka dependency.
        Ok(Self { config })
    }
}

#[async_trait]
impl StreamConsumer for KafkaConsumer {
    async fn subscribe(
        &self,
        _handler: Box<dyn crate::streaming::EventHandler>,
    ) -> FusekiResult<()> {
        tracing::info!("Subscribing to Kafka events with handler");

        // Future enhancement: Implement rdkafka topic subscription.
        // For v0.1.0: No-op. Full Kafka integration is optional.
        // For now, just store the handler reference
        Ok(())
    }

    async fn unsubscribe(&self) -> FusekiResult<()> {
        tracing::info!("Unsubscribing from Kafka events");

        // Future enhancement: Implement rdkafka unsubscribe.
        // For v0.1.0: No-op. Full Kafka integration is optional.
        Ok(())
    }

    async fn commit(&self) -> FusekiResult<()> {
        tracing::debug!("Committing Kafka consumer offsets");
        // Future enhancement: Implement rdkafka offset commit.
        // For v0.1.0: No-op. Full Kafka integration is optional.
        Ok(())
    }
}