oxirs-vec 0.2.4

//! Advanced SPARQL Service Endpoint for Vector Operations
//!
//! This module implements SERVICE vec:endpoint functionality for federated vector search,
//! custom function registration, and advanced SPARQL integration features.

use crate::{
    sparql_integration::{
        CustomVectorFunction, PerformanceMonitor, VectorServiceArg, VectorServiceResult,
    },
    Vector,
};
use anyhow::{anyhow, Result};
use parking_lot::RwLock;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::sync::Arc;
use std::time::{Duration, Instant};

/// Federated vector service endpoint
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FederatedServiceEndpoint {
    pub endpoint_uri: String,
    pub service_type: ServiceType,
    pub capabilities: Vec<ServiceCapability>,
    pub authentication: Option<AuthenticationInfo>,
    pub retry_config: RetryConfiguration,
    pub timeout: Duration,
    pub health_status: ServiceHealthStatus,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ServiceType {
    VectorSearch,
    EmbeddingGeneration,
    SimilarityComputation,
    Hybrid, // Supports multiple capabilities
}

#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub enum ServiceCapability {
    KNNSearch,
    ThresholdSearch,
    TextEmbedding,
    ImageEmbedding,
    SimilarityCalculation,
    CustomFunction(String),
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AuthenticationInfo {
    pub auth_type: AuthenticationType,
    pub credentials: HashMap<String, String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum AuthenticationType {
    None,
    ApiKey,
    OAuth2,
    BasicAuth,
    Custom(String),
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RetryConfiguration {
    pub max_retries: usize,
    pub initial_delay: Duration,
    pub max_delay: Duration,
    pub backoff_multiplier: f32,
}

impl Default for RetryConfiguration {
    fn default() -> Self {
        Self {
            max_retries: 3,
            initial_delay: Duration::from_millis(100),
            max_delay: Duration::from_secs(10),
            backoff_multiplier: 2.0,
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ServiceHealthStatus {
    Healthy,
    Degraded,
    Unhealthy,
    Unknown,
}

/// SERVICE endpoint manager for federated vector operations
pub struct ServiceEndpointManager {
    endpoints: Arc<RwLock<HashMap<String, FederatedServiceEndpoint>>>,
    load_balancer: LoadBalancer,
    health_checker: HealthChecker,
    performance_monitor: PerformanceMonitor,
}

impl Default for ServiceEndpointManager {
    fn default() -> Self {
        Self::new()
    }
}

impl ServiceEndpointManager {
    pub fn new() -> Self {
        Self {
            endpoints: Arc::new(RwLock::new(HashMap::new())),
            load_balancer: LoadBalancer::new(),
            health_checker: HealthChecker::new(),
            performance_monitor: PerformanceMonitor::new(),
        }
    }

    /// Register a new service endpoint
    pub fn register_endpoint(&self, endpoint: FederatedServiceEndpoint) -> Result<()> {
        let mut endpoints = self.endpoints.write();
        endpoints.insert(endpoint.endpoint_uri.clone(), endpoint);
        Ok(())
    }

    /// Execute a federated vector search
    pub async fn execute_federated_search(
        &self,
        query: &FederatedVectorQuery,
    ) -> Result<FederatedSearchResult> {
        let start_time = Instant::now();

        // Select appropriate endpoints based on query requirements
        let selected_endpoints = self.select_endpoints(query)?;

        // Execute query on multiple endpoints in parallel
        let mut partial_results = Vec::new();
        for endpoint in selected_endpoints {
            match self.execute_on_endpoint(&endpoint, query).await {
                Ok(result) => partial_results.push(result),
                Err(e) => {
                    // Log error but continue with other endpoints
                    eprintln!(
                        "Error executing on endpoint {}: {}",
                        endpoint.endpoint_uri, e
                    );
                }
            }
        }

        // Merge results from all endpoints
        let merged_result = self.merge_federated_results(partial_results, query)?;

        let duration = start_time.elapsed();
        self.performance_monitor.record_query(duration, true);

        Ok(merged_result)
    }

    /// Select appropriate endpoints for a query
    fn select_endpoints(
        &self,
        query: &FederatedVectorQuery,
    ) -> Result<Vec<FederatedServiceEndpoint>> {
        let endpoints = self.endpoints.read();
        let mut suitable_endpoints = Vec::new();

        for endpoint in endpoints.values() {
            if self.endpoint_supports_query(endpoint, query) {
                suitable_endpoints.push(endpoint.clone());
            }
        }

        if suitable_endpoints.is_empty() {
            return Err(anyhow!("No suitable endpoints found for query"));
        }

        // Apply load balancing
        Ok(self.load_balancer.balance_endpoints(suitable_endpoints))
    }

    /// Check if endpoint supports the given query
    fn endpoint_supports_query(
        &self,
        endpoint: &FederatedServiceEndpoint,
        query: &FederatedVectorQuery,
    ) -> bool {
        match &query.operation {
            FederatedOperation::KNNSearch { .. } => endpoint
                .capabilities
                .contains(&ServiceCapability::KNNSearch),
            FederatedOperation::ThresholdSearch { .. } => endpoint
                .capabilities
                .contains(&ServiceCapability::ThresholdSearch),
            FederatedOperation::SimilarityCalculation { .. } => endpoint
                .capabilities
                .contains(&ServiceCapability::SimilarityCalculation),
            FederatedOperation::CustomFunction { function_name, .. } => endpoint
                .capabilities
                .contains(&ServiceCapability::CustomFunction(function_name.clone())),
        }
    }

    /// Execute query on a specific endpoint
    async fn execute_on_endpoint(
        &self,
        endpoint: &FederatedServiceEndpoint,
        query: &FederatedVectorQuery,
    ) -> Result<PartialSearchResult> {
        // Implementation would depend on the actual service protocol
        // For now, we'll simulate the execution

        let start_time = Instant::now();

        // Simulate network request with retry logic
        let result = self.execute_with_retry(endpoint, query).await?;

        let duration = start_time.elapsed();
        self.performance_monitor
            .record_operation(&format!("endpoint_{}", endpoint.endpoint_uri), duration);

        Ok(result)
    }

    /// Execute with retry logic
    async fn execute_with_retry(
        &self,
        endpoint: &FederatedServiceEndpoint,
        query: &FederatedVectorQuery,
    ) -> Result<PartialSearchResult> {
        let mut attempt = 0;
        let mut delay = endpoint.retry_config.initial_delay;

        loop {
            match self.try_execute(endpoint, query).await {
                Ok(result) => return Ok(result),
                Err(_e) if attempt < endpoint.retry_config.max_retries => {
                    attempt += 1;

                    // Wait before retry
                    tokio::time::sleep(delay).await;

                    // Increase delay for next attempt
                    delay = std::cmp::min(
                        Duration::from_millis(
                            (delay.as_millis() as f32 * endpoint.retry_config.backoff_multiplier)
                                as u64,
                        ),
                        endpoint.retry_config.max_delay,
                    );
                }
                Err(e) => return Err(e),
            }
        }
    }

    /// Try to execute on endpoint (single attempt)
    async fn try_execute(
        &self,
        endpoint: &FederatedServiceEndpoint,
        query: &FederatedVectorQuery,
    ) -> Result<PartialSearchResult> {
        // Simulate the actual service call
        // In a real implementation, this would make HTTP requests to the endpoint

        match &query.operation {
            FederatedOperation::KNNSearch { .. } => {
                // Simulate KNN search result
                Ok(PartialSearchResult {
                    endpoint_uri: endpoint.endpoint_uri.clone(),
                    results: vec![
                        ("http://example.org/doc1".to_string(), 0.95),
                        ("http://example.org/doc2".to_string(), 0.87),
                    ],
                    metadata: HashMap::new(),
                })
            }
            _ => {
                // Placeholder for other operations
                Ok(PartialSearchResult {
                    endpoint_uri: endpoint.endpoint_uri.clone(),
                    results: Vec::new(),
                    metadata: HashMap::new(),
                })
            }
        }
    }

    /// Merge results from multiple endpoints
    fn merge_federated_results(
        &self,
        partial_results: Vec<PartialSearchResult>,
        query: &FederatedVectorQuery,
    ) -> Result<FederatedSearchResult> {
        let mut all_results = Vec::new();
        let mut source_endpoints = Vec::new();
        let merged_count = partial_results.len();

        for partial in partial_results {
            source_endpoints.push(partial.endpoint_uri.clone());
            all_results.extend(partial.results);
        }

        // Sort by similarity score (descending)
        all_results.sort_by(|a, b| b.1.partial_cmp(&a.1).unwrap_or(std::cmp::Ordering::Equal));

        // Apply global limit if specified
        if let Some(limit) = query.global_limit {
            all_results.truncate(limit);
        }

        Ok(FederatedSearchResult {
            results: all_results,
            source_endpoints,
            execution_time: Duration::from_millis(0), // Would be calculated properly
            merged_count,
        })
    }

    /// Get endpoint health status
    pub async fn check_endpoint_health(&self, endpoint_uri: &str) -> Result<ServiceHealthStatus> {
        self.health_checker.check_health(endpoint_uri).await
    }

    /// Update endpoint health status
    pub fn update_endpoint_health(&self, endpoint_uri: &str, status: ServiceHealthStatus) {
        let mut endpoints = self.endpoints.write();
        if let Some(endpoint) = endpoints.get_mut(endpoint_uri) {
            endpoint.health_status = status;
        }
    }
}

/// Load balancer for distributing queries across endpoints
pub struct LoadBalancer {
    strategy: LoadBalancingStrategy,
}

#[derive(Debug, Clone)]
pub enum LoadBalancingStrategy {
    RoundRobin,
    LeastConnections,
    WeightedRandom,
    HealthBased,
}

impl LoadBalancer {
    pub fn new() -> Self {
        Self {
            strategy: LoadBalancingStrategy::HealthBased,
        }
    }

    pub fn balance_endpoints(
        &self,
        endpoints: Vec<FederatedServiceEndpoint>,
    ) -> Vec<FederatedServiceEndpoint> {
        match self.strategy {
            LoadBalancingStrategy::HealthBased => {
                let mut healthy_endpoints: Vec<_> = endpoints
                    .iter()
                    .filter(|e| matches!(e.health_status, ServiceHealthStatus::Healthy))
                    .cloned()
                    .collect();

                if healthy_endpoints.is_empty() {
                    // Fall back to degraded endpoints if no healthy ones
                    healthy_endpoints = endpoints
                        .iter()
                        .filter(|e| matches!(e.health_status, ServiceHealthStatus::Degraded))
                        .cloned()
                        .collect();
                }

                healthy_endpoints
            }
            _ => endpoints, // Other strategies would be implemented here
        }
    }
}

impl Default for LoadBalancer {
    fn default() -> Self {
        Self::new()
    }
}

/// Health checker for monitoring endpoint availability
pub struct HealthChecker {
    check_interval: Duration,
}

impl HealthChecker {
    pub fn new() -> Self {
        Self {
            check_interval: Duration::from_secs(30),
        }
    }

    pub async fn check_health(&self, endpoint_uri: &str) -> Result<ServiceHealthStatus> {
        // Simulate health check
        // In a real implementation, this would make a health check request

        if endpoint_uri.contains("unhealthy") {
            Ok(ServiceHealthStatus::Unhealthy)
        } else if endpoint_uri.contains("degraded") {
            Ok(ServiceHealthStatus::Degraded)
        } else {
            Ok(ServiceHealthStatus::Healthy)
        }
    }
}

impl Default for HealthChecker {
    fn default() -> Self {
        Self::new()
    }
}

/// Custom function registry for user-defined vector operations
pub struct CustomFunctionRegistry {
    functions: Arc<RwLock<HashMap<String, Box<dyn CustomVectorFunction>>>>,
    metadata: Arc<RwLock<HashMap<String, FunctionMetadata>>>,
}

#[derive(Debug, Clone)]
pub struct FunctionMetadata {
    pub name: String,
    pub description: String,
    pub parameters: Vec<ParameterInfo>,
    pub return_type: ReturnType,
    pub examples: Vec<String>,
}

#[derive(Debug, Clone)]
pub struct ParameterInfo {
    pub name: String,
    pub param_type: ParameterType,
    pub required: bool,
    pub description: String,
    pub default_value: Option<String>,
}

#[derive(Debug, Clone)]
pub enum ParameterType {
    Vector,
    String,
    Number,
    Boolean,
    URI,
}

#[derive(Debug, Clone)]
pub enum ReturnType {
    Vector,
    Number,
    String,
    Boolean,
    Array(Box<ReturnType>),
}

impl CustomFunctionRegistry {
    pub fn new() -> Self {
        Self {
            functions: Arc::new(RwLock::new(HashMap::new())),
            metadata: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    /// Register a custom function
    pub fn register_function(
        &self,
        name: String,
        function: Box<dyn CustomVectorFunction>,
        metadata: FunctionMetadata,
    ) -> Result<()> {
        let mut functions = self.functions.write();
        let mut meta = self.metadata.write();

        if functions.contains_key(&name) {
            return Err(anyhow!("Function '{}' is already registered", name));
        }

        functions.insert(name.clone(), function);
        meta.insert(name, metadata);

        Ok(())
    }

    /// Execute a custom function
    pub fn execute_function(
        &self,
        name: &str,
        args: &[VectorServiceArg],
    ) -> Result<VectorServiceResult> {
        let functions = self.functions.read();

        if let Some(function) = functions.get(name) {
            function.execute(args)
        } else {
            Err(anyhow!("Function '{}' not found", name))
        }
    }

    /// Get function metadata
    pub fn get_metadata(&self, name: &str) -> Option<FunctionMetadata> {
        let metadata = self.metadata.read();
        metadata.get(name).cloned()
    }

    /// List all registered functions
    pub fn list_functions(&self) -> Vec<String> {
        let functions = self.functions.read();
        functions.keys().cloned().collect()
    }

    /// Unregister a function
    pub fn unregister_function(&self, name: &str) -> Result<()> {
        let mut functions = self.functions.write();
        let mut metadata = self.metadata.write();

        functions.remove(name);
        metadata.remove(name);

        Ok(())
    }
}

impl Default for CustomFunctionRegistry {
    fn default() -> Self {
        Self::new()
    }
}

/// Query types for federated vector operations
#[derive(Debug, Clone)]
pub struct FederatedVectorQuery {
    pub operation: FederatedOperation,
    pub scope: QueryScope,
    pub global_limit: Option<usize>,
    pub timeout: Option<Duration>,
    pub explain: bool,
}

#[derive(Debug, Clone)]
pub enum FederatedOperation {
    KNNSearch {
        vector: Vector,
        k: usize,
        threshold: Option<f32>,
    },
    ThresholdSearch {
        vector: Vector,
        threshold: f32,
    },
    SimilarityCalculation {
        vector1: Vector,
        vector2: Vector,
    },
    CustomFunction {
        function_name: String,
        arguments: Vec<VectorServiceArg>,
    },
}

#[derive(Debug, Clone)]
pub enum QueryScope {
    All,
    Endpoints(Vec<String>),
    GraphScope(String),
}

/// Results from federated search operations
#[derive(Debug, Clone)]
pub struct FederatedSearchResult {
    pub results: Vec<(String, f32)>,
    pub source_endpoints: Vec<String>,
    pub execution_time: Duration,
    pub merged_count: usize,
}

#[derive(Debug, Clone)]
pub struct PartialSearchResult {
    pub endpoint_uri: String,
    pub results: Vec<(String, f32)>,
    pub metadata: HashMap<String, String>,
}

/// Example custom functions
pub struct CosineSimilarityFunction;

impl CustomVectorFunction for CosineSimilarityFunction {
    fn execute(&self, args: &[VectorServiceArg]) -> Result<VectorServiceResult> {
        if args.len() != 2 {
            return Err(anyhow!(
                "CosineSimilarity requires exactly 2 vector arguments"
            ));
        }

        let vector1 = match &args[0] {
            VectorServiceArg::Vector(v) => v,
            _ => return Err(anyhow!("First argument must be a vector")),
        };

        let vector2 = match &args[1] {
            VectorServiceArg::Vector(v) => v,
            _ => return Err(anyhow!("Second argument must be a vector")),
        };

        let similarity = vector1.cosine_similarity(vector2)?;
        Ok(VectorServiceResult::Number(similarity))
    }

    fn arity(&self) -> usize {
        2
    }

    fn description(&self) -> String {
        "Calculate cosine similarity between two vectors".to_string()
    }
}

pub struct VectorMagnitudeFunction;

impl CustomVectorFunction for VectorMagnitudeFunction {
    fn execute(&self, args: &[VectorServiceArg]) -> Result<VectorServiceResult> {
        if args.len() != 1 {
            return Err(anyhow!(
                "VectorMagnitude requires exactly 1 vector argument"
            ));
        }

        let vector = match &args[0] {
            VectorServiceArg::Vector(v) => v,
            _ => return Err(anyhow!("Argument must be a vector")),
        };

        let magnitude = vector.magnitude();
        Ok(VectorServiceResult::Number(magnitude))
    }

    fn arity(&self) -> usize {
        1
    }

    fn description(&self) -> String {
        "Calculate the magnitude (L2 norm) of a vector".to_string()
    }
}

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

    #[test]
    fn test_endpoint_registration() {
        let manager = ServiceEndpointManager::new();

        let endpoint = FederatedServiceEndpoint {
            endpoint_uri: "http://example.org/vector-service".to_string(),
            service_type: ServiceType::VectorSearch,
            capabilities: vec![
                ServiceCapability::KNNSearch,
                ServiceCapability::ThresholdSearch,
            ],
            authentication: None,
            retry_config: RetryConfiguration::default(),
            timeout: Duration::from_secs(30),
            health_status: ServiceHealthStatus::Healthy,
        };

        assert!(manager.register_endpoint(endpoint).is_ok());
    }

    #[test]
    fn test_custom_function_registry() {
        let registry = CustomFunctionRegistry::new();

        let metadata = FunctionMetadata {
            name: "cosine_similarity".to_string(),
            description: "Calculate cosine similarity".to_string(),
            parameters: vec![
                ParameterInfo {
                    name: "vector1".to_string(),
                    param_type: ParameterType::Vector,
                    required: true,
                    description: "First vector".to_string(),
                    default_value: None,
                },
                ParameterInfo {
                    name: "vector2".to_string(),
                    param_type: ParameterType::Vector,
                    required: true,
                    description: "Second vector".to_string(),
                    default_value: None,
                },
            ],
            return_type: ReturnType::Number,
            examples: vec!["cosine_similarity(?v1, ?v2)".to_string()],
        };

        let function = Box::new(CosineSimilarityFunction);

        assert!(registry
            .register_function("cosine_similarity".to_string(), function, metadata,)
            .is_ok());

        let functions = registry.list_functions();
        assert!(functions.contains(&"cosine_similarity".to_string()));
    }

    #[test]
    fn test_cosine_similarity_function() -> Result<()> {
        let function = CosineSimilarityFunction;

        let v1 = Vector::new(vec![1.0, 0.0, 0.0]);
        let v2 = Vector::new(vec![1.0, 0.0, 0.0]);

        let args = vec![VectorServiceArg::Vector(v1), VectorServiceArg::Vector(v2)];

        let result = function.execute(&args)?;

        match result {
            VectorServiceResult::Number(similarity) => {
                assert!((similarity - 1.0).abs() < 0.001); // Should be 1.0 for identical vectors
            }
            _ => panic!("Expected number result"),
        }
        Ok(())
    }

    #[test]
    fn test_load_balancer() {
        let balancer = LoadBalancer::new();

        let endpoints = vec![
            FederatedServiceEndpoint {
                endpoint_uri: "http://healthy.example.org".to_string(),
                service_type: ServiceType::VectorSearch,
                capabilities: vec![ServiceCapability::KNNSearch],
                authentication: None,
                retry_config: RetryConfiguration::default(),
                timeout: Duration::from_secs(30),
                health_status: ServiceHealthStatus::Healthy,
            },
            FederatedServiceEndpoint {
                endpoint_uri: "http://unhealthy.example.org".to_string(),
                service_type: ServiceType::VectorSearch,
                capabilities: vec![ServiceCapability::KNNSearch],
                authentication: None,
                retry_config: RetryConfiguration::default(),
                timeout: Duration::from_secs(30),
                health_status: ServiceHealthStatus::Unhealthy,
            },
        ];

        let balanced = balancer.balance_endpoints(endpoints);

        // Should only return healthy endpoints
        assert_eq!(balanced.len(), 1);
        assert_eq!(balanced[0].endpoint_uri, "http://healthy.example.org");
    }
}