oxirs-core 0.2.4

//! Simplified streaming RDF/XML parser to fix compilation issues
//!
//! This module provides streaming capabilities for RDF/XML processing
//! without building a DOM tree, using SAX-style parsing.

use crate::{
    rdfxml::{RdfXmlParseError, RdfXmlSyntaxError},
    model::{Triple, NamedNode, BlankNode, Literal, Term, Subject, Predicate, Object},
};
use std::{
    collections::{HashMap, VecDeque},
    sync::{Arc, atomic::{AtomicUsize, Ordering}, Mutex, RwLock},
    time::{Duration, Instant},
};
use quick_xml::{
    events::{Event, BytesStart, BytesEnd, BytesText, attributes::Attributes},
    Reader as XmlReader,
};
use bumpalo::Bump;

/// Ultra-high performance DOM-free streaming RDF/XML parser
pub struct DomFreeStreamingRdfXmlParser {
    config: RdfXmlStreamingConfig,
    namespace_stack: Vec<NamespaceContext>,
    element_stack: Vec<ElementContext>,
    performance_monitor: Arc<RdfXmlPerformanceMonitor>,
    arena: Bump,
    buffer_pool: Arc<RdfXmlBufferPool>,
}

/// Configuration for streaming RDF/XML processing
#[derive(Debug, Clone)]
pub struct RdfXmlStreamingConfig {
    pub xml_buffer_size: usize,
    pub max_namespace_depth: usize,
    pub max_element_depth: usize,
    pub enable_zero_copy: bool,
    pub enable_parallel_processing: bool,
    pub triple_batch_size: usize,
    pub arena_size: usize,
    pub memory_pressure_threshold: usize,
}

/// Namespace context for RDF/XML processing
#[derive(Debug, Clone)]
pub struct NamespaceContext {
    pub prefixes: HashMap<String, String>,
    pub default_namespace: Option<String>,
    pub base_uri: Option<String>,
}

/// Element context for streaming parsing
#[derive(Debug, Clone)]
pub struct ElementContext {
    pub element_type: ElementType,
    pub subject: Option<Subject>,
    pub predicate: Option<Predicate>,
    pub object: Option<Object>,
    pub datatype: Option<NamedNode>,
    pub language: Option<String>,
    pub attributes: HashMap<String, String>,
}

/// Type of RDF/XML element
#[derive(Debug, Clone, PartialEq)]
pub enum ElementType {
    RdfRoot,
    Description,
    Property,
    Collection,
    ParseType(ParseType),
    Unknown,
}

/// RDF/XML parse types
#[derive(Debug, Clone, PartialEq)]
pub enum ParseType {
    Resource,
    Collection,
    Literal,
}

/// Performance monitoring for RDF/XML streaming
pub struct RdfXmlPerformanceMonitor {
    elements_processed: AtomicUsize,
    triples_generated: AtomicUsize,
    namespace_lookups: AtomicUsize,
    zero_copy_operations: AtomicUsize,
    memory_allocations: AtomicUsize,
    parse_errors: AtomicUsize,
    start_time: Instant,
    processing_times: Arc<Mutex<VecDeque<Duration>>>,
}

/// Buffer pool for RDF/XML processing
pub struct RdfXmlBufferPool {
    xml_buffers: Arc<Mutex<Vec<Vec<u8>>>>,
    string_buffers: Arc<Mutex<Vec<String>>>,
    max_buffers: usize,
    buffer_size: usize,
}

/// High-performance streaming sink for RDF/XML output
pub trait RdfXmlStreamingSink: Send + Sync {
    type Error: Send + Sync + std::error::Error;
    
    fn process_triple_stream(&mut self, triples: Vec<Triple>) -> Result<(), Self::Error>;
    fn process_namespace_declaration(&mut self, prefix: &str, namespace: &str) -> Result<(), Self::Error>;
    fn flush_output(&mut self) -> Result<(), Self::Error>;
    fn get_statistics(&self) -> RdfXmlSinkStatistics;
}

/// Statistics for RDF/XML sink performance
#[derive(Debug, Clone)]
pub struct RdfXmlSinkStatistics {
    pub triples_processed: usize,
    pub namespaces_declared: usize,
    pub processing_rate_tps: f64,
    pub memory_usage_bytes: usize,
    pub compression_ratio: f64,
}

/// Streaming statistics for RDF/XML processing
#[derive(Debug, Clone)]
pub struct RdfXmlStreamingStatistics {
    pub elements_processed: usize,
    pub triples_generated: usize,
    pub namespace_lookups: usize,
    pub zero_copy_operations: usize,
    pub parse_errors: usize,
    pub processing_time: Duration,
    pub memory_usage_bytes: usize,
    pub throughput_elements_per_second: f64,
}

impl Default for RdfXmlStreamingConfig {
    fn default() -> Self {
        Self {
            xml_buffer_size: 64 * 1024,
            max_namespace_depth: 100,
            max_element_depth: 1000,
            enable_zero_copy: true,
            enable_parallel_processing: true,
            triple_batch_size: 1000,
            arena_size: 1024 * 1024,
            memory_pressure_threshold: 512 * 1024 * 1024,
        }
    }
}

impl Default for NamespaceContext {
    fn default() -> Self {
        let mut prefixes = HashMap::new();
        prefixes.insert("rdf".to_string(), "http://www.w3.org/1999/02/22-rdf-syntax-ns#".to_string());
        prefixes.insert("rdfs".to_string(), "http://www.w3.org/2000/01/rdf-schema#".to_string());
        prefixes.insert("xsd".to_string(), "http://www.w3.org/2001/XMLSchema#".to_string());
        
        Self {
            prefixes,
            default_namespace: None,
            base_uri: None,
        }
    }
}

impl ElementContext {
    fn new() -> Self {
        Self {
            element_type: ElementType::Unknown,
            subject: None,
            predicate: None,
            object: None,
            datatype: None,
            language: None,
            attributes: HashMap::new(),
        }
    }
}

impl DomFreeStreamingRdfXmlParser {
    pub fn new(config: RdfXmlStreamingConfig) -> Self {
        Self {
            namespace_stack: vec![NamespaceContext::default()],
            element_stack: Vec::with_capacity(config.max_element_depth),
            performance_monitor: Arc::new(RdfXmlPerformanceMonitor::new()),
            arena: Bump::with_capacity(config.arena_size),
            buffer_pool: Arc::new(RdfXmlBufferPool::new(config.xml_buffer_size, 50)),
            config,
        }
    }
}

impl RdfXmlPerformanceMonitor {
    fn new() -> Self {
        Self {
            elements_processed: AtomicUsize::new(0),
            triples_generated: AtomicUsize::new(0),
            namespace_lookups: AtomicUsize::new(0),
            zero_copy_operations: AtomicUsize::new(0),
            memory_allocations: AtomicUsize::new(0),
            parse_errors: AtomicUsize::new(0),
            start_time: Instant::now(),
            processing_times: Arc::new(Mutex::new(VecDeque::with_capacity(1000))),
        }
    }
}

impl RdfXmlBufferPool {
    fn new(buffer_size: usize, max_buffers: usize) -> Self {
        Self {
            xml_buffers: Arc::new(Mutex::new(Vec::with_capacity(max_buffers))),
            string_buffers: Arc::new(Mutex::new(Vec::with_capacity(max_buffers))),
            max_buffers,
            buffer_size,
        }
    }
}

/// Memory-efficient sink for RDF/XML streaming output
pub struct MemoryRdfXmlSink {
    triples: Arc<RwLock<Vec<Triple>>>,
    namespaces: Arc<RwLock<HashMap<String, String>>>,
    statistics: Arc<RwLock<RdfXmlSinkStatistics>>,
}

impl MemoryRdfXmlSink {
    pub fn new() -> Self {
        Self {
            triples: Arc::new(RwLock::new(Vec::new())),
            namespaces: Arc::new(RwLock::new(HashMap::new())),
            statistics: Arc::new(RwLock::new(RdfXmlSinkStatistics {
                triples_processed: 0,
                namespaces_declared: 0,
                processing_rate_tps: 0.0,
                memory_usage_bytes: 0,
                compression_ratio: 1.0,
            })),
        }
    }
}

/// Simple error wrapper for streaming sink
#[derive(Debug)]
pub struct StreamingSinkError(String);

impl std::fmt::Display for StreamingSinkError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "Streaming sink error: {}", self.0)
    }
}

impl std::error::Error for StreamingSinkError {}

impl StreamingSinkError {
    pub fn new(message: String) -> Self {
        Self(message)
    }
}

impl RdfXmlStreamingSink for MemoryRdfXmlSink {
    type Error = StreamingSinkError;

    fn process_triple_stream(&mut self, triples: Vec<Triple>) -> Result<(), Self::Error> {
        let count = triples.len();
        let mut triples_guard = self.triples.write().expect("lock should not be poisoned");
        triples_guard.extend(triples);
        
        let mut stats_guard = self.statistics.write().expect("lock should not be poisoned");
        stats_guard.triples_processed += count;
        Ok(())
    }

    fn process_namespace_declaration(&mut self, prefix: &str, namespace: &str) -> Result<(), Self::Error> {
        let mut namespaces_guard = self.namespaces.write().expect("lock should not be poisoned");
        namespaces_guard.insert(prefix.to_string(), namespace.to_string());
        
        let mut stats_guard = self.statistics.write().expect("lock should not be poisoned");
        stats_guard.namespaces_declared += 1;
        Ok(())
    }

    fn flush_output(&mut self) -> Result<(), Self::Error> {
        // Memory sink doesn't need explicit flushing
        Ok(())
    }

    fn get_statistics(&self) -> RdfXmlSinkStatistics {
        self.statistics.read().expect("lock should not be poisoned").clone()
    }
}