libxml-rs 0.1.0-alpha.11

//! XML Reader API (§30, §85 Phase 7).
//!
//! Cursor-based streaming reader with node type, depth, attribute traversal,
//! namespace lookup, value retrieval, validation integration.
//!
//! Implements the `xmlTextReader` API from libxml2, which provides a
//! cursor-based streaming interface for reading XML documents. The reader
//! parses the entire document into a tree on the first `Read()` call, then
//! walks the tree in document order (depth-first traversal) generating
//! node events for elements, text, comments, PIs, etc.
//!
//! # UPSTREAM-PARITY
//!
//! The reader API is defined in `libxml/xmlreader.h` and `libxml/xmlreader.c`.
//! Key differences from upstream:
//!
//! - The reader parses the full document on first Read rather than using
//!   a true streaming/event-driven parser. This simplifies the implementation
//!   while preserving the observable API surface.
//! - Pattern-based reader operations (xmlTextReaderPreservePattern, etc.)
//!   are not yet implemented.

#![allow(
    missing_docs,
    non_snake_case,
    non_camel_case_types,
    non_upper_case_globals
)]

use core::ffi::c_void;
use core::ptr;
use std::os::raw::{c_char, c_int};

use crate::abi::allocator::xmlFree;
use crate::abi::callbacks::{xmlInputCloseCallback, xmlInputReadCallback};
use crate::abi::structs::{_xmlAttr, _xmlDoc, _xmlNode, _xmlParserCtxt, _xmlParserInputBuffer};

use crate::abi::types::xmlElementType::*;
use crate::abi::types::*;
use crate::xml::parser::helpers::{
    create_parser_ctxt, free_parser_ctxt, input_from_file, input_from_io, input_from_memory,
    parse_document, setup_parser_input,
};
use crate::xml::parser::input::InputBuffer;
use crate::xml::string::{bytes_to_xmlstr, xml_strdup, xmlstr_to_bytes, xmlstr_to_string};
use crate::xml::tree;

// ═══════════════════════════════════════════════════════════════════════════════
// Reader Types (xmlreader.h)
// ═══════════════════════════════════════════════════════════════════════════════

/// Reader node types (xmlReaderTypes enum).
///
/// # UPSTREAM-PARITY
///
/// ```c
/// typedef enum {
///     XML_TEXTREADER_NONE = 0,
///     XML_TEXTREADER_ELEMENT = 1,
///     XML_TEXTREADER_ATTRIBUTE = 2,
///     XML_TEXTREADER_TEXT = 3,
///     XML_TEXTREADER_CDATA = 4,
///     XML_TEXTREADER_ENTITY_REFERENCE = 5,
///     XML_TEXTREADER_ENTITY = 6,
///     XML_TEXTREADER_PROCESSING_INSTRUCTION = 7,
///     XML_TEXTREADER_COMMENT = 8,
///     XML_TEXTREADER_DOCUMENT = 9,
///     XML_TEXTREADER_DOCUMENT_TYPE = 10,
///     XML_TEXTREADER_DOCUMENT_FRAGMENT = 11,
///     XML_TEXTREADER_NOTATION = 12,
///     XML_TEXTREADER_WHITESPACE = 13,
///     XML_TEXTREADER_SIGNIFICANT_WHITESPACE = 14,
///     XML_TEXTREADER_END_ELEMENT = 15,
///     XML_TEXTREADER_END_ENTITY = 16,
///     XML_TEXTREADER_XML_DECLARATION = 17
/// } xmlReaderTypes;
/// ```
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(i32)]
pub(crate) enum ReaderNodeType {
    NONE = 0,
    ELEMENT = 1,
    ATTRIBUTE = 2,
    TEXT = 3,
    CDATA = 4,
    ENTITY_REFERENCE = 5,
    ENTITY = 6,
    PROCESSING_INSTRUCTION = 7,
    COMMENT = 8,
    DOCUMENT = 9,
    DOCUMENT_TYPE = 10,
    DOCUMENT_FRAGMENT = 11,
    NOTATION = 12,
    WHITESPACE = 13,
    SIGNIFICANT_WHITESPACE = 14,
    END_ELEMENT = 15,
    END_ENTITY = 16,
    XML_DECLARATION = 17,
}

/// Reader read state (xmlTextReaderReadState enum).
///
/// # UPSTREAM-PARITY
///
/// ```c
/// typedef enum {
///     XML_TEXTREADER_NOT_INITIALIZED = 0,
///     XML_TEXTREADER_INITIALIZED = 1,
///     XML_TEXTREADER_READING = 2,
///     XML_TEXTREADER_EOF = 3,
///     XML_TEXTREADER_CLOSED = 4,
///     XML_TEXTREADER_ERROR = 5
/// } xmlTextReaderReadState;
/// ```
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(i32)]
pub(crate) enum ReadState {
    NOT_INITIALIZED = 0,
    INITIALIZED = 1,
    READING = 2,
    EOF = 3,
    CLOSED = 4,
    ERROR = 5,
}

/// Parser properties for xmlTextReaderGetParserProp / SetParserProp.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// typedef enum {
///     XML_PARSER_LOADDTD = 1,
///     XML_PARSER_DEFAULTATTRS = 2,
///     XML_PARSER_VALIDATE = 3,
///     XML_PARSER_SUBST_ENTITIES = 4
/// } xmlParserProperties;
/// ```
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(i32)]
pub(crate) enum ParserProp {
    LOADDTD = 1,
    DEFAULTATTRS = 2,
    VALIDATE = 3,
    SUBST_ENTITIES = 4,
}

/// A traversal event in the document-order walk of the parsed tree.
///
/// Each event represents either entering a node (ELEMENT, TEXT, etc.) or
/// exiting an element (END_ELEMENT). The `depth` is the element nesting
/// depth at the time of the event.
#[derive(Debug, Clone)]
struct TraversalEvent {
    /// The node this event refers to.
    node: *mut _xmlNode,
    /// Whether this is an "exit" event (END_ELEMENT).
    is_end: bool,
    /// The depth at this event (number of ancestor elements).
    depth: i32,
}

/// Compute the element nesting depth of a node in the tree.
///
/// Counts the number of `XML_ELEMENT_NODE` ancestors.
///
/// # Safety
///
/// `node` must be a valid pointer to a node in a valid tree, or NULL.
unsafe fn compute_depth(node: *mut _xmlNode) -> i32 {
    if node.is_null() {
        return 0;
    }
    let mut depth: i32 = 0;
    // SAFETY: node is valid, and parent pointers form a tree.
    let mut cur = unsafe { (*node).parent };
    while !cur.is_null() {
        // SAFETY: cur is valid.
        if unsafe { (*cur).type_ } == XML_ELEMENT_NODE as c_int {
            depth += 1;
        }
        // SAFETY: cur's parent is valid.
        cur = unsafe { (*cur).parent };
    }
    depth
}

/// Convert an `xmlElementType` to the corresponding `ReaderNodeType`.
fn element_type_to_reader_type(etype: c_int) -> ReaderNodeType {
    match etype {
        x if x == XML_ELEMENT_NODE as c_int => ReaderNodeType::ELEMENT,
        x if x == XML_ATTRIBUTE_NODE as c_int => ReaderNodeType::ATTRIBUTE,
        x if x == XML_TEXT_NODE as c_int => ReaderNodeType::TEXT,
        x if x == XML_CDATA_SECTION_NODE as c_int => ReaderNodeType::CDATA,
        x if x == XML_ENTITY_REF_NODE as c_int => ReaderNodeType::ENTITY_REFERENCE,
        x if x == XML_ENTITY_NODE as c_int => ReaderNodeType::ENTITY,
        x if x == XML_PI_NODE as c_int => ReaderNodeType::PROCESSING_INSTRUCTION,
        x if x == XML_COMMENT_NODE as c_int => ReaderNodeType::COMMENT,
        x if x == XML_DOCUMENT_NODE as c_int => ReaderNodeType::DOCUMENT,
        x if x == XML_DOCUMENT_TYPE_NODE as c_int => ReaderNodeType::DOCUMENT_TYPE,
        x if x == XML_DOCUMENT_FRAG_NODE as c_int => ReaderNodeType::DOCUMENT_FRAGMENT,
        x if x == XML_NOTATION_NODE as c_int => ReaderNodeType::NOTATION,
        x if x == XML_DTD_NODE as c_int => ReaderNodeType::DOCUMENT_TYPE,
        x if x == XML_NAMESPACE_DECL as c_int => ReaderNodeType::NONE,
        _ => ReaderNodeType::NONE,
    }
}

/// Check whether a text node consists entirely of whitespace.
fn is_whitespace_only(text: &[u8]) -> bool {
    text.iter()
        .all(|&b| b == b' ' || b == b'\t' || b == b'\n' || b == b'\r')
}

// ═══════════════════════════════════════════════════════════════════════════════
// XmlTextReader — Internal Rust Type
// ═══════════════════════════════════════════════════════════════════════════════

/// The internal representation of an `xmlTextReader`.
///
/// This struct holds all state for the reader cursor: the parsed document,
/// the current position in the traversal, attribute navigation state, and
/// cached information about the current node.
pub(crate) struct XmlTextReader {
    /// The parsed XML document.
    doc: *mut _xmlDoc,
    /// The parser context used to parse the document (NULL after parsing).
    ctxt: *mut _xmlParserCtxt,
    /// The traversal events computed from the parsed tree.
    events: Vec<TraversalEvent>,
    /// Index into `events` for the current position.
    event_index: usize,
    /// Current read state.
    state: ReadState,
    /// The current node we're positioned on.
    cur_node: *mut _xmlNode,
    /// Current node type (reader node type).
    node_type: ReaderNodeType,
    /// Current depth.
    depth: i32,
    /// Cached name of the current node (xmlMalloc'd, NULL if none).
    name: *mut xmlChar,
    /// Cached value of the current node (xmlMalloc'd, NULL if none).
    value: *mut xmlChar,
    /// Number of attributes on the current element (-1 if not applicable).
    attribute_count: i32,
    /// Current attribute index (-1 = not on an attribute).
    cur_attribute: i32,
    /// Parser options bitmask.
    options: c_int,
    /// Document encoding string (xmlMalloc'd).
    encoding: *mut xmlChar,
    /// Document URL (xmlMalloc'd).
    URL: *mut xmlChar,
    /// Collected error messages.
    errors: Vec<String>,
    /// Whether the document has been parsed.
    parsed: bool,
}

impl XmlTextReader {
    /// Create a new reader with the given parser context and options.
    ///
    /// The reader takes ownership of the parser context. The document will be
    /// parsed on the first call to `Read()`.
    ///
    /// # Safety
    ///
    /// `ctxt` must be a valid parser context created by `create_parser_ctxt`
    /// and set up with input via `setup_parser_input`.
    unsafe fn new(ctxt: *mut _xmlParserCtxt, URL: Option<&[u8]>, encoding: Option<&[u8]>) -> Self {
        let url_ptr = URL
            .map(|u| unsafe { bytes_to_xmlstr(u) })
            .unwrap_or(ptr::null_mut());
        let enc_ptr = encoding
            .map(|e| unsafe { bytes_to_xmlstr(e) })
            .unwrap_or(ptr::null_mut());

        XmlTextReader {
            doc: ptr::null_mut(),
            ctxt,
            events: Vec::new(),
            event_index: 0,
            state: ReadState::INITIALIZED,
            cur_node: ptr::null_mut(),
            node_type: ReaderNodeType::NONE,
            depth: 0,
            name: ptr::null_mut(),
            value: ptr::null_mut(),
            attribute_count: -1,
            cur_attribute: -1,
            options: 0,
            encoding: enc_ptr,
            URL: url_ptr,
            errors: Vec::new(),
            parsed: false,
        }
    }

    /// Parse the document and build the event list.
    ///
    /// Returns 0 on success, -1 on error.
    ///
    /// # Safety
    ///
    /// `ctxt` must be a valid parser context with input set up.
    unsafe fn parse_and_build_events(&mut self) -> c_int {
        if self.ctxt.is_null() {
            self.state = ReadState::ERROR;
            self.errors.push("No parser context".to_string());
            return -1;
        }

        // Set options on the context.
        unsafe {
            (*self.ctxt).options = self.options;
        }

        // Parse the document.
        let result = unsafe { parse_document(self.ctxt) };

        // Get the parsed document.
        let doc = unsafe { (*self.ctxt).myDoc };
        self.doc = doc;

        // Free the parser context - we no longer need it.
        if !self.ctxt.is_null() {
            unsafe { free_parser_ctxt(self.ctxt) };
        }
        self.ctxt = ptr::null_mut();

        if result != 0 || doc.is_null() {
            self.state = ReadState::ERROR;
            self.errors.push("Failed to parse document".to_string());
            return -1;
        }

        // Set the encoding from the document if not already set.
        if self.encoding.is_null() && !doc.is_null() {
            // SAFETY: doc is valid.
            let doc_enc = unsafe { (*doc).encoding };
            if !doc_enc.is_null() {
                self.encoding = unsafe { xml_strdup(doc_enc as *const xmlChar) };
            }
        }

        // Build traversal events from the tree.
        self.build_events();

        self.parsed = true;
        0
    }

    /// Walk the tree in document order and build traversal events.
    ///
    /// Generates events for all nodes (ELEMENT, TEXT, COMMENT, PI, etc.)
    /// and END_ELEMENT events for elements.
    fn build_events(&mut self) {
        self.events.clear();

        if self.doc.is_null() {
            return;
        }

        // SAFETY: doc is valid.
        let root = unsafe { (*self.doc).children };
        if root.is_null() {
            return;
        }

        // Walk all top-level children (PIs, comments, the root element, etc.)
        // SAFETY: The tree is valid and all pointers are valid.
        unsafe {
            let mut n = root;
            while !n.is_null() {
                self.walk_tree(n, 0);
                n = (*n).next;
            }
        }
    }

    /// Recursively walk a subtree and generate events.
    ///
    /// # Safety
    ///
    /// `node` must be a valid pointer to a node in the parsed tree.
    unsafe fn walk_tree(&mut self, node: *mut _xmlNode, depth: i32) {
        if node.is_null() {
            return;
        }

        // SAFETY: node is valid.
        let node_type = unsafe { (*node).type_ };

        // For elements, generate an enter event and then recursively visit children,
        // then generate an exit (END_ELEMENT) event.
        if node_type == XML_ELEMENT_NODE as c_int {
            self.events.push(TraversalEvent {
                node,
                is_end: false,
                depth,
            });

            // Walk children.
            // SAFETY: node's children are valid.
            let mut child = unsafe { (*node).children };
            while !child.is_null() {
                let child_depth = depth + 1;
                self.walk_tree(child, child_depth);
                // SAFETY: child's next pointer is valid.
                child = unsafe { (*child).next };
            }

            // Generate END_ELEMENT.
            self.events.push(TraversalEvent {
                node,
                is_end: true,
                depth,
            });
        } else if node_type == XML_TEXT_NODE as c_int
            || node_type == XML_CDATA_SECTION_NODE as c_int
            || node_type == XML_COMMENT_NODE as c_int
            || node_type == XML_PI_NODE as c_int
            || node_type == XML_ENTITY_REF_NODE as c_int
        {
            // Leaf nodes: text, CDATA, comment, PI, entity reference.
            // Skip whitespace-only text nodes (libxml2 reader default behavior).
            if node_type == XML_TEXT_NODE as c_int || node_type == XML_CDATA_SECTION_NODE as c_int {
                let content = unsafe { (*node).content };
                if !content.is_null() {
                    let len = crate::xml::tree::xml_strlen(content);
                    let slice = unsafe { core::slice::from_raw_parts(content, len as usize) };
                    if slice
                        .iter()
                        .all(|&b| b == b' ' || b == b'\t' || b == b'\n' || b == b'\r')
                    {
                        // Skip whitespace-only text node
                        return;
                    }
                }
            }
            self.events.push(TraversalEvent {
                node,
                is_end: false,
                depth,
            });
        } else {
            // Other node types (ENTITY, NOTATION, DTD, etc.) — skip or just enter.
            self.events.push(TraversalEvent {
                node,
                is_end: false,
                depth,
            });
        }
    }

    /// Position the reader on the event at the given index.
    ///
    /// Updates all cached fields (name, value, depth, node_type, etc.).
    fn position_at(&mut self, index: usize) {
        if index >= self.events.len() {
            self.state = ReadState::EOF;
            self.cur_node = ptr::null_mut();
            self.node_type = ReaderNodeType::NONE;
            self.depth = 0;
            self.clear_cached_name();
            self.clear_cached_value();
            self.attribute_count = -1;
            self.cur_attribute = -1;
            return;
        }

        // Copy event data before any mutable self access to avoid borrow conflicts.
        let ev_node: *mut _xmlNode;
        let ev_is_end: bool;
        let ev_depth: i32;
        {
            let event = &self.events[index];
            ev_node = event.node;
            ev_is_end = event.is_end;
            ev_depth = event.depth;
        }

        self.event_index = index;
        self.cur_node = ev_node;
        self.depth = ev_depth;

        // SAFETY: node is valid.
        let etype = unsafe { (*ev_node).type_ };

        if ev_is_end {
            self.node_type = ReaderNodeType::END_ELEMENT;
        } else {
            self.node_type = element_type_to_reader_type(etype);
        }

        // Cache name and value.
        // SAFETY: ev_node is a valid node pointer.
        unsafe { self.cache_name_and_value(ev_node, ev_is_end) };

        // Count attributes if this is an element.
        if etype == XML_ELEMENT_NODE as c_int && !ev_is_end {
            // SAFETY: ev_node is a valid element node.
            self.attribute_count = unsafe { self.count_attributes(ev_node) };
        } else {
            self.attribute_count = -1;
        }

        // Reset attribute cursor.
        self.cur_attribute = -1;
    }

    /// Cache the name of the current node.
    ///
    /// # Safety
    ///
    /// `node` must be a valid node pointer or NULL.
    unsafe fn cache_name_and_value(&mut self, node: *mut _xmlNode, is_end: bool) {
        self.clear_cached_name();
        self.clear_cached_value();

        if node.is_null() {
            return;
        }

        // SAFETY: node is valid.
        let etype = unsafe { (*node).type_ };

        // Determine name.
        let name: *mut xmlChar = if is_end {
            // For END_ELEMENT, the name is the element name.
            // SAFETY: node is valid.
            unsafe { (*node).name as *mut xmlChar }
        } else {
            if etype == XML_ELEMENT_NODE as c_int
                || etype == XML_PI_NODE as c_int
                || etype == XML_ENTITY_REF_NODE as c_int
                || etype == XML_ENTITY_NODE as c_int
                || etype == XML_DOCUMENT_TYPE_NODE as c_int
                || etype == XML_NOTATION_NODE as c_int
            {
                // SAFETY: node is valid.
                unsafe { (*node).name as *mut xmlChar }
            } else if etype == XML_ATTRIBUTE_NODE as c_int {
                // For attribute nodes accessed via MoveToAttribute.
                ptr::null_mut()
            } else {
                ptr::null_mut()
            }
        };

        if !name.is_null() {
            // SAFETY: name is a valid null-terminated xmlChar string.
            self.name = unsafe { xml_strdup(name as *const xmlChar) };
        }

        // Determine value.
        let value: *mut xmlChar = if etype == XML_TEXT_NODE as c_int
            || etype == XML_CDATA_SECTION_NODE as c_int
            || etype == XML_COMMENT_NODE as c_int
        {
            // SAFETY: node is valid.
            unsafe { (*node).content }
        } else if etype == XML_PI_NODE as c_int {
            // PI nodes store content as the PI value (after the target).
            // SAFETY: node is valid.
            unsafe { (*node).content }
        } else if etype == XML_ENTITY_REF_NODE as c_int {
            // Entity references may have content.
            // SAFETY: node is valid.
            unsafe { (*node).content }
        } else {
            ptr::null_mut()
        };

        if !value.is_null() {
            // SAFETY: value is a valid null-terminated xmlChar string.
            self.value = unsafe { xml_strdup(value as *const xmlChar) };
        }
    }

    /// Count the number of attributes on an element node.
    ///
    /// # Safety
    ///
    /// `node` must be a valid element node pointer.
    unsafe fn count_attributes(&self, node: *mut _xmlNode) -> i32 {
        let mut count: i32 = 0;
        // SAFETY: node is a valid element.
        let mut prop = unsafe { (*node).properties };
        while !prop.is_null() {
            count += 1;
            // SAFETY: prop is valid.
            prop = unsafe { (*prop).next };
        }
        count
    }

    /// Free the cached name.
    fn clear_cached_name(&mut self) {
        if !self.name.is_null() {
            // SAFETY: name was allocated by xmlMalloc (via xml_strdup).
            unsafe { xmlFree(self.name as *mut c_void) };
            self.name = ptr::null_mut();
        }
    }

    /// Free the cached value.
    fn clear_cached_value(&mut self) {
        if !self.value.is_null() {
            // SAFETY: value was allocated by xmlMalloc (via xml_strdup).
            unsafe { xmlFree(self.value as *mut c_void) };
            self.value = ptr::null_mut();
        }
    }

    // ─────────────────────────────────────────────────────────────────────────
    // Navigation methods
    // ─────────────────────────────────────────────────────────────────────────

    /// Read the next node in document order.
    ///
    /// Returns 1 if a node was read, 0 if no more nodes (EOF), -1 on error.
    pub unsafe fn Read(&mut self) -> c_int {
        if self.state == ReadState::ERROR || self.state == ReadState::CLOSED {
            return -1;
        }

        // On first call, parse the document and build events.
        if !self.parsed {
            if self.parse_and_build_events() != 0 {
                self.state = ReadState::ERROR;
                return -1;
            }
            self.state = ReadState::READING;
        }

        if self.state == ReadState::EOF {
            return 0;
        }

        // If we're positioned on an attribute, return to the element first.
        if self.cur_attribute >= 0 {
            self.cur_attribute = -1;
            // Re-cache the element info.
            if !self.cur_node.is_null() {
                // SAFETY: cur_node is valid.
                unsafe { self.cache_name_and_value(self.cur_node, false) };
            }
        }

        // Advance to the next event.
        // If no events, we're at EOF.
        if self.events.is_empty() {
            self.state = ReadState::EOF;
            return 0;
        }

        // Determine the next event index to position on.
        // If cur_node is NULL, this is the first Read() after parsing —
        // position at event 0. On subsequent calls, advance to the next event.
        // We use cur_node.is_null() rather than event_index checks because
        // after position_at(0), event_index == 0 and state == READING, which
        // is indistinguishable from the pre-read state.
        let next_index = if self.cur_node.is_null() {
            // First Read() after parsing — position at event 0.
            0
        } else {
            self.event_index + 1
        };

        if next_index < self.events.len() {
            self.position_at(next_index);
            1
        } else {
            self.state = ReadState::EOF;
            self.cur_node = ptr::null_mut();
            self.node_type = ReaderNodeType::NONE;
            self.depth = 0;
            self.clear_cached_name();
            self.clear_cached_value();
            self.attribute_count = -1;
            self.cur_attribute = -1;
            0
        }
    }

    /// Skip to the next sibling of the current node.
    ///
    /// Returns 1 on success, 0 if no more siblings, -1 on error.
    pub unsafe fn Next(&mut self) -> c_int {
        if self.state != ReadState::READING || self.cur_node.is_null() {
            return -1;
        }

        // Find the next sibling by scanning forward through events.
        // We need to find the next event at depth <= current_depth that is not
        // an END_ELEMENT. This skips:
        // - All events in the current subtree (depth > current_depth)
        // - END_ELEMENT events (which close the current element)
        let current_depth = self.depth;
        let mut i = self.event_index + 1;

        while i < self.events.len() {
            let event = &self.events[i];
            if event.depth <= current_depth && !event.is_end {
                self.position_at(i);
                return 1;
            }
            i += 1;
        }

        0
    }

    /// Move to the parent element (if currently on an attribute).
    ///
    /// Returns 1 on success, 0 if not on an attribute, -1 on error.
    pub unsafe fn MoveToElement(&mut self) -> c_int {
        if self.cur_attribute < 0 {
            return 0;
        }
        self.cur_attribute = -1;
        if !self.cur_node.is_null() {
            // SAFETY: cur_node is valid.
            unsafe { self.cache_name_and_value(self.cur_node, false) };
            self.node_type = ReaderNodeType::ELEMENT;
        }
        1
    }

    /// Move to an attribute by name.
    ///
    /// Returns 1 on success, 0 if attribute not found, -1 on error.
    pub unsafe fn MoveToAttribute(&mut self, name: *const xmlChar) -> c_int {
        if self.cur_node.is_null() {
            return -1;
        }

        // SAFETY: cur_node is valid.
        let etype = unsafe { (*self.cur_node).type_ };
        if etype != XML_ELEMENT_NODE as c_int {
            return -1;
        }

        // SAFETY: cur_node is an element.
        let mut prop = unsafe { (*self.cur_node).properties };
        let mut index: i32 = 0;
        while !prop.is_null() {
            // SAFETY: prop is a valid attribute.
            let prop_name = unsafe { (*prop).name };
            if !prop_name.is_null() {
                // Compare names.
                // SAFETY: Both strings are null-terminated.
                if unsafe { crate::xml::string::xml_strcmp(prop_name as *const xmlChar, name) == 0 }
                {
                    self.cur_attribute = index;
                    // Cache attribute info.
                    self.cache_attribute_info(prop);
                    return 1;
                }
            }
            index += 1;
            // SAFETY: prop's next pointer is valid.
            prop = unsafe { (*prop).next };
        }

        0
    }

    /// Move to an attribute by index.
    ///
    /// Returns 1 on success, 0 if index out of range, -1 on error.
    pub unsafe fn MoveToAttributeNo(&mut self, index: c_int) -> c_int {
        if self.cur_node.is_null() || index < 0 {
            return -1;
        }

        // SAFETY: cur_node is valid.
        let etype = unsafe { (*self.cur_node).type_ };
        if etype != XML_ELEMENT_NODE as c_int {
            return -1;
        }

        // SAFETY: cur_node is an element.
        let mut prop = unsafe { (*self.cur_node).properties };
        let mut i: i32 = 0;
        while !prop.is_null() {
            if i == index {
                self.cur_attribute = index;
                // Cache attribute info.
                self.cache_attribute_info(prop);
                return 1;
            }
            i += 1;
            // SAFETY: prop's next pointer is valid.
            prop = unsafe { (*prop).next };
        }

        0
    }

    /// Move to the first attribute of the current element.
    ///
    /// Returns 1 on success, 0 if no attributes, -1 on error.
    pub unsafe fn MoveToFirstAttribute(&mut self) -> c_int {
        if self.cur_node.is_null() {
            return -1;
        }

        // SAFETY: cur_node is valid.
        let etype = unsafe { (*self.cur_node).type_ };
        if etype != XML_ELEMENT_NODE as c_int {
            return -1;
        }

        // SAFETY: cur_node is an element.
        let first_prop = unsafe { (*self.cur_node).properties };
        if first_prop.is_null() {
            return 0;
        }

        self.cur_attribute = 0;
        // Cache attribute info.
        self.cache_attribute_info(first_prop);
        1
    }

    /// Move to the next attribute.
    ///
    /// Returns 1 on success, 0 if no more attributes, -1 on error.
    pub unsafe fn MoveToNextAttribute(&mut self) -> c_int {
        if self.cur_attribute < 0 || self.cur_node.is_null() {
            return -1;
        }

        // SAFETY: cur_node is valid.
        let etype = unsafe { (*self.cur_node).type_ };
        if etype != XML_ELEMENT_NODE as c_int {
            return -1;
        }

        // Find the attribute at cur_attribute index.
        // SAFETY: cur_node is an element.
        let mut prop = unsafe { (*self.cur_node).properties };
        let mut i: i32 = 0;
        while !prop.is_null() && i <= self.cur_attribute {
            if i == self.cur_attribute {
                // Move to the next attribute.
                // SAFETY: prop is a valid attribute.
                let next_prop = unsafe { (*prop).next };
                if next_prop.is_null() {
                    return 0;
                }
                self.cur_attribute += 1;
                self.cache_attribute_info(next_prop);
                return 1;
            }
            i += 1;
            // SAFETY: prop's next pointer is valid.
            prop = unsafe { (*prop).next };
        }

        0
    }

    /// Cache the current position info for an attribute.
    ///
    /// # Safety
    ///
    /// `prop` must be a valid `_xmlAttr` pointer.
    unsafe fn cache_attribute_info(&mut self, prop: *mut _xmlAttr) {
        self.node_type = ReaderNodeType::ATTRIBUTE;
        self.clear_cached_name();
        self.clear_cached_value();

        // SAFETY: prop is valid.
        let attr = unsafe { &*prop };

        // Name.
        if !attr.name.is_null() {
            // SAFETY: attr.name is null-terminated.
            self.name = unsafe { xml_strdup(attr.name as *const xmlChar) };
        }

        // Value — the attribute's text content is in its child text node.
        if !attr.children.is_null() {
            // SAFETY: attr.children is a text node.
            let val = unsafe { (*attr.children).content };
            if !val.is_null() {
                // SAFETY: val is null-terminated.
                self.value = unsafe { xml_strdup(val as *const xmlChar) };
            }
        }
    }

    /// Move to the previous sibling.
    ///
    /// Returns 1 on success, 0 if no previous sibling, -1 on error.
    pub unsafe fn Prev(&mut self) -> c_int {
        if self.state != ReadState::READING || self.cur_node.is_null() {
            return -1;
        }

        // Scan backward through events to find the previous sibling.
        let current_depth = self.depth;
        let mut i = if self.event_index > 0 {
            self.event_index - 1
        } else {
            return 0;
        };

        loop {
            let event = &self.events[i];
            if event.depth == current_depth && !event.is_end {
                self.position_at(i);
                return 1;
            }
            if i == 0 {
                break;
            }
            i -= 1;
        }

        0
    }

    // ─────────────────────────────────────────────────────────────────────────
    // Information methods
    // ─────────────────────────────────────────────────────────────────────────

    /// Get the depth of the current node.
    pub fn Depth(&self) -> c_int {
        self.depth
    }

    /// Get the node type of the current node.
    pub fn NodeType(&self) -> ReaderNodeType {
        self.node_type
    }

    /// Get the name of the current node.
    ///
    /// Returns a pointer to a newly allocated string (caller must free with `xmlFree`),
    /// or NULL if there is no name.
    pub unsafe fn Name(&self) -> *mut xmlChar {
        if self.name.is_null() {
            return ptr::null_mut();
        }
        // SAFETY: name is a valid null-terminated xmlChar string.
        unsafe { xml_strdup(self.name as *const xmlChar) }
    }

    /// Get the value of the current node.
    ///
    /// Returns a pointer to a newly allocated string (caller must free with `xmlFree`),
    /// or NULL if there is no value.
    pub unsafe fn Value(&self) -> *mut xmlChar {
        if self.value.is_null() {
            return ptr::null_mut();
        }
        // SAFETY: value is a valid null-terminated xmlChar string.
        unsafe { xml_strdup(self.value as *const xmlChar) }
    }

    /// Get a constant pointer to the name (no copy).
    ///
    /// The returned pointer is valid only while the reader is alive and positioned
    /// on the same node.
    pub fn ConstName(&self) -> *const xmlChar {
        self.name as *const xmlChar
    }

    /// Get a constant pointer to the value (no copy).
    ///
    /// The returned pointer is valid only while the reader is alive and positioned
    /// on the same node.
    pub fn ConstValue(&self) -> *const xmlChar {
        self.value as *const xmlChar
    }

    /// Check if the current node has a value.
    pub fn HasValue(&self) -> c_int {
        if self.value.is_null() {
            0
        } else {
            1
        }
    }

    /// Check if the current node has attributes.
    pub fn HasAttributes(&self) -> c_int {
        if self.cur_node.is_null() {
            return 0;
        }
        // SAFETY: cur_node is valid.
        let etype = unsafe { (*self.cur_node).type_ };
        if etype != XML_ELEMENT_NODE as c_int {
            return 0;
        }
        // SAFETY: cur_node is an element.
        let props = unsafe { (*self.cur_node).properties };
        if props.is_null() {
            0
        } else {
            1
        }
    }

    /// Check if the current element is an empty element (no children).
    pub fn IsEmptyElement(&self) -> c_int {
        if self.cur_node.is_null() {
            return 0;
        }
        // SAFETY: cur_node is valid.
        let etype = unsafe { (*self.cur_node).type_ };
        if etype != XML_ELEMENT_NODE as c_int {
            return 0;
        }
        // SAFETY: cur_node is an element.
        let children = unsafe { (*self.cur_node).children };
        if children.is_null() {
            1
        } else {
            0
        }
    }

    /// Get the base URI of the current node.
    ///
    /// Returns a newly allocated string (caller must free with `xmlFree`),
    /// or NULL if not available.
    pub unsafe fn BaseUri(&self) -> *mut xmlChar {
        // The base URI is typically the document URL.
        if self.doc.is_null() {
            return ptr::null_mut();
        }
        // SAFETY: doc is valid.
        let url = unsafe { (*self.doc).URL };
        if url.is_null() {
            return ptr::null_mut();
        }
        // SAFETY: url is null-terminated.
        unsafe { xml_strdup(url as *const xmlChar) }
    }

    /// Get the local name of the current node.
    ///
    /// For namespaced names, this strips the prefix.
    /// Returns a newly allocated string, or NULL.
    pub unsafe fn LocalName(&self) -> *mut xmlChar {
        if self.name.is_null() {
            return ptr::null_mut();
        }

        // SAFETY: name is a valid null-terminated string.
        let name_bytes = unsafe { xmlstr_to_bytes(self.name as *const xmlChar) };

        // Find the colon separator.
        if let Some(pos) = name_bytes.iter().position(|&b| b == b':') {
            // Return everything after the colon.
            let local = &name_bytes[pos + 1..];
            if local.is_empty() {
                return ptr::null_mut();
            }
            // SAFETY: bytes_to_xmlstr allocates via xmlMalloc.
            unsafe { bytes_to_xmlstr(local) }
        } else {
            // No prefix, return the name as-is.
            // SAFETY: xml_strdup allocates via xmlMalloc.
            unsafe { xml_strdup(self.name as *const xmlChar) }
        }
    }

    /// Get the namespace URI of the current node.
    ///
    /// Returns a newly allocated string, or NULL.
    pub unsafe fn NamespaceUri(&self) -> *mut xmlChar {
        if self.cur_node.is_null() {
            return ptr::null_mut();
        }

        // SAFETY: cur_node is valid.
        let ns = unsafe { (*self.cur_node).ns };
        if ns.is_null() {
            return ptr::null_mut();
        }

        // SAFETY: ns is valid.
        let href = unsafe { (*ns).href };
        if href.is_null() {
            return ptr::null_mut();
        }

        // SAFETY: href is null-terminated.
        unsafe { xml_strdup(href as *const xmlChar) }
    }

    /// Get the prefix of the current node.
    ///
    /// Returns a newly allocated string, or NULL.
    pub unsafe fn Prefix(&self) -> *mut xmlChar {
        if self.cur_node.is_null() {
            return ptr::null_mut();
        }

        // SAFETY: cur_node is valid.
        let ns = unsafe { (*self.cur_node).ns };
        if ns.is_null() {
            return ptr::null_mut();
        }

        // SAFETY: ns is valid.
        let prefix = unsafe { (*ns).prefix };
        if prefix.is_null() {
            return ptr::null_mut();
        }

        // SAFETY: prefix is null-terminated.
        unsafe { xml_strdup(prefix as *const xmlChar) }
    }

    /// Get the attribute count of the current element.
    pub fn AttributeCount(&self) -> c_int {
        self.attribute_count
    }

    /// Get the read state.
    pub fn ReadState(&self) -> ReadState {
        self.state
    }

    /// Get an attribute value by name.
    ///
    /// Returns a newly allocated string, or NULL.
    pub unsafe fn GetAttribute(&self, name: *const xmlChar) -> *mut xmlChar {
        if self.cur_node.is_null() {
            return ptr::null_mut();
        }

        // SAFETY: cur_node is valid.
        let etype = unsafe { (*self.cur_node).type_ };
        if etype != XML_ELEMENT_NODE as c_int {
            return ptr::null_mut();
        }

        // SAFETY: cur_node is an element.
        let mut prop = unsafe { (*self.cur_node).properties };
        while !prop.is_null() {
            // SAFETY: prop is valid.
            let prop_name = unsafe { (*prop).name };
            if !prop_name.is_null() {
                // SAFETY: Both strings are null-terminated.
                if unsafe { crate::xml::string::xml_strcmp(prop_name as *const xmlChar, name) == 0 }
                {
                    // Get the attribute value from its child text node.
                    // SAFETY: prop's children is valid.
                    let val = unsafe { (*prop).children };
                    if !val.is_null() {
                        // SAFETY: val's content is null-terminated.
                        let content = unsafe { (*val).content };
                        if !content.is_null() {
                            // SAFETY: content is null-terminated.
                            return unsafe { xml_strdup(content as *const xmlChar) };
                        }
                    }
                    return ptr::null_mut();
                }
            }
            // SAFETY: prop's next is valid.
            prop = unsafe { (*prop).next };
        }

        ptr::null_mut()
    }

    /// Get an attribute value by index.
    ///
    /// Returns a newly allocated string, or NULL.
    pub unsafe fn GetAttributeNo(&self, index: c_int) -> *mut xmlChar {
        if self.cur_node.is_null() || index < 0 {
            return ptr::null_mut();
        }

        // SAFETY: cur_node is valid.
        let etype = unsafe { (*self.cur_node).type_ };
        if etype != XML_ELEMENT_NODE as c_int {
            return ptr::null_mut();
        }

        // SAFETY: cur_node is an element.
        let mut prop = unsafe { (*self.cur_node).properties };
        let mut i: i32 = 0;
        while !prop.is_null() {
            if i == index {
                // SAFETY: prop is valid.
                let val = unsafe { (*prop).children };
                if !val.is_null() {
                    // SAFETY: val's content is null-terminated.
                    let content = unsafe { (*val).content };
                    if !content.is_null() {
                        // SAFETY: content is null-terminated.
                        return unsafe { xml_strdup(content as *const xmlChar) };
                    }
                }
                return ptr::null_mut();
            }
            i += 1;
            // SAFETY: prop's next is valid.
            prop = unsafe { (*prop).next };
        }

        ptr::null_mut()
    }

    /// Get an attribute value by local name and namespace URI.
    ///
    /// Returns a newly allocated string, or NULL.
    pub unsafe fn GetAttributeNs(
        &self,
        localName: *const xmlChar,
        namespaceURI: *const xmlChar,
    ) -> *mut xmlChar {
        if self.cur_node.is_null() {
            return ptr::null_mut();
        }

        // SAFETY: cur_node is valid.
        let etype = unsafe { (*self.cur_node).type_ };
        if etype != XML_ELEMENT_NODE as c_int {
            return ptr::null_mut();
        }

        // SAFETY: cur_node is an element.
        let mut prop = unsafe { (*self.cur_node).properties };
        while !prop.is_null() {
            // SAFETY: prop is valid.
            let prop_local = unsafe { (*prop).name };
            let prop_ns = unsafe { (*prop).ns };

            // Check local name match.
            if prop_local.is_null() {
                // SAFETY: prop's next is valid.
                prop = unsafe { (*prop).next };
                continue;
            }

            // SAFETY: prop_local is null-terminated.
            let name_match = unsafe {
                crate::xml::string::xml_strcmp(prop_local as *const xmlChar, localName) == 0
            };

            if name_match {
                // Check namespace URI match.
                let ns_match = if namespaceURI.is_null() {
                    prop_ns.is_null()
                } else if prop_ns.is_null() {
                    false
                } else {
                    // SAFETY: Both hrefs are null-terminated.
                    unsafe {
                        crate::xml::string::xml_strcmp(
                            (*prop_ns).href as *const xmlChar,
                            namespaceURI,
                        ) == 0
                    }
                };

                if ns_match {
                    // SAFETY: prop is valid.
                    let val = unsafe { (*prop).children };
                    if !val.is_null() {
                        // SAFETY: val's content is null-terminated.
                        let content = unsafe { (*val).content };
                        if !content.is_null() {
                            // SAFETY: content is null-terminated.
                            return unsafe { xml_strdup(content as *const xmlChar) };
                        }
                    }
                    return ptr::null_mut();
                }
            }

            // SAFETY: prop's next is valid.
            prop = unsafe { (*prop).next };
        }

        ptr::null_mut()
    }

    /// Look up a namespace by prefix.
    ///
    /// Returns a newly allocated string with the namespace URI, or NULL.
    pub unsafe fn LookupNamespace(&self, prefix: *const xmlChar) -> *mut xmlChar {
        if self.cur_node.is_null() {
            return ptr::null_mut();
        }

        // Walk up the tree looking for a namespace declaration matching the prefix.
        // SAFETY: cur_node is valid.
        let mut cur = self.cur_node;
        while !cur.is_null() {
            // SAFETY: cur is valid.
            let mut ns_def = unsafe { (*cur).nsDef };
            while !ns_def.is_null() {
                // SAFETY: ns_def is valid.
                let ns_prefix = unsafe { (*ns_def).prefix };

                let match_prefix = if prefix.is_null() || *prefix == 0 {
                    // Looking for default namespace.
                    ns_prefix.is_null()
                } else if ns_prefix.is_null() {
                    false
                } else {
                    // SAFETY: Both are null-terminated.
                    unsafe {
                        crate::xml::string::xml_strcmp(ns_prefix as *const xmlChar, prefix) == 0
                    }
                };

                if match_prefix {
                    // SAFETY: ns_def is valid.
                    let href = unsafe { (*ns_def).href };
                    if !href.is_null() {
                        // SAFETY: href is null-terminated.
                        return unsafe { xml_strdup(href as *const xmlChar) };
                    }
                    return ptr::null_mut();
                }

                // SAFETY: ns_def's next is valid.
                ns_def = unsafe { (*ns_def).next };
            }

            // SAFETY: cur's parent is valid.
            cur = unsafe { (*cur).parent };
        }

        ptr::null_mut()
    }

    /// Get a parser property.
    pub fn GetParserProp(&self, prop: c_int) -> c_int {
        match prop {
            1 /* XML_PARSER_LOADDTD */ => {
                if (self.options & XML_PARSE_DTDLOAD) != 0 { 1 } else { 0 }
            }
            2 /* XML_PARSER_DEFAULTATTRS */ => {
                if (self.options & XML_PARSE_DTDATTR) != 0 { 1 } else { 0 }
            }
            3 /* XML_PARSER_VALIDATE */ => {
                if (self.options & XML_PARSE_DTDVALID) != 0 { 1 } else { 0 }
            }
            4 /* XML_PARSER_SUBST_ENTITIES */ => {
                if (self.options & XML_PARSE_NOENT) != 0 { 1 } else { 0 }
            }
            _ => -1,
        }
    }

    /// Set a parser property.
    pub fn SetParserProp(&mut self, prop: c_int, value: c_int) -> c_int {
        match prop {
            1 /* XML_PARSER_LOADDTD */ => {
                if value != 0 {
                    self.options |= XML_PARSE_DTDLOAD;
                } else {
                    self.options &= !XML_PARSE_DTDLOAD;
                }
                0
            }
            2 /* XML_PARSER_DEFAULTATTRS */ => {
                if value != 0 {
                    self.options |= XML_PARSE_DTDATTR;
                } else {
                    self.options &= !XML_PARSE_DTDATTR;
                }
                0
            }
            3 /* XML_PARSER_VALIDATE */ => {
                if value != 0 {
                    self.options |= XML_PARSE_DTDVALID;
                } else {
                    self.options &= !XML_PARSE_DTDVALID;
                }
                0
            }
            4 /* XML_PARSER_SUBST_ENTITIES */ => {
                if value != 0 {
                    self.options |= XML_PARSE_NOENT;
                } else {
                    self.options &= !XML_PARSE_NOENT;
                }
                0
            }
            _ => -1,
        }
    }

    /// Get the current document.
    pub fn CurrentDoc(&self) -> *mut _xmlDoc {
        self.doc
    }
}

impl Drop for XmlTextReader {
    fn drop(&mut self) {
        // Free cached strings.
        self.clear_cached_name();
        self.clear_cached_value();

        // Free encoding and URL.
        if !self.encoding.is_null() {
            // SAFETY: encoding was allocated by xmlMalloc.
            unsafe { xmlFree(self.encoding as *mut c_void) };
            self.encoding = ptr::null_mut();
        }
        if !self.URL.is_null() {
            // SAFETY: URL was allocated by xmlMalloc.
            unsafe { xmlFree(self.URL as *mut c_void) };
            self.URL = ptr::null_mut();
        }

        // Free the document if we own it.
        if !self.doc.is_null() {
            // SAFETY: doc was created by the parser, which allocates via xmlMalloc.
            // We own the doc since we created it.
            unsafe { tree::free_doc(self.doc) };
            self.doc = ptr::null_mut();
        }

        // Free the parser context if still alive.
        if !self.ctxt.is_null() {
            // SAFETY: ctxt was created by create_parser_ctxt.
            unsafe { free_parser_ctxt(self.ctxt) };
            self.ctxt = ptr::null_mut();
        }
    }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Reader construction helpers
// ═══════════════════════════════════════════════════════════════════════════════

/// Create a reader from a parser input buffer.
///
/// # Safety
///
/// `input` must be a valid `_xmlParserInputBuffer` pointer.
unsafe fn reader_from_input(
    input: *mut _xmlParserInputBuffer,
    URL: *const c_char,
    encoding: *const c_char,
    options: c_int,
) -> *mut XmlTextReader {
    if input.is_null() {
        return ptr::null_mut();
    }

    // Create a parser context.
    let ctxt = create_parser_ctxt();
    if ctxt.is_null() {
        return ptr::null_mut();
    }

    // Read all data from the input buffer using the read callback.
    let mut data = Vec::new();
    let mut tmp = [0u8; 4096];

    // SAFETY: input is valid.
    let read_cb = unsafe { (*input).readcallback };
    let ioctx = unsafe { (*input).context };

    if let Some(read) = read_cb {
        loop {
            // SAFETY: The read callback must be valid and ioctx must be a valid context.
            let n = unsafe { read(ioctx, tmp.as_mut_ptr() as *mut c_char, tmp.len() as c_int) };
            if n <= 0 {
                break;
            }
            data.extend_from_slice(&tmp[..n as usize]);
        }
    }

    // Close the input if there's a close callback.
    // SAFETY: input is valid.
    let close_cb = unsafe { (*input).closecallback };
    if let Some(close) = close_cb {
        // SAFETY: The close callback must be valid.
        unsafe { close(ioctx) };
    }

    // Create an InputBuffer from the data.
    let input_buf = InputBuffer::from_memory(&data, None);

    // Set up the parser context with the input.
    setup_parser_input(ctxt, input_buf);

    // Set options.
    unsafe {
        (*ctxt).options = options;
    }

    // Build URL and encoding strings.
    let url_bytes = if URL.is_null() {
        None
    } else {
        // SAFETY: URL is a valid C string.
        unsafe {
            let cstr = std::ffi::CStr::from_ptr(URL);
            Some(cstr.to_bytes().to_vec())
        }
    };

    let enc_bytes = if encoding.is_null() {
        None
    } else {
        // SAFETY: encoding is a valid C string.
        unsafe {
            let cstr = std::ffi::CStr::from_ptr(encoding);
            Some(cstr.to_bytes().to_vec())
        }
    };

    // Create the reader.
    let mut reader = XmlTextReader::new(ctxt, url_bytes.as_deref(), enc_bytes.as_deref());
    reader.options = options;

    // Box and leak the reader to return a raw pointer.
    Box::into_raw(Box::new(reader))
}

// ═══════════════════════════════════════════════════════════════════════════════
// Public API functions
// ═══════════════════════════════════════════════════════════════════════════════

/// Create a new text reader from an input buffer.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlTextReaderPtr xmlNewTextReader(xmlParserInputBufferPtr input, const char *URI);
/// ```
///
/// # Safety
///
/// - `input` must be a valid `_xmlParserInputBuffer` pointer or NULL.
/// - `URI` must be a valid C string or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlNewTextReader(
    input: *mut _xmlParserInputBuffer,
    URI: *const c_char,
) -> *mut XmlTextReader {
    // SAFETY: Forward to the helper.
    unsafe { reader_from_input(input, URI, ptr::null(), 0) }
}

/// Create a text reader for a file.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlTextReaderPtr xmlReaderForFile(const char *filename, const char *encoding, int options);
/// ```
///
/// # Safety
///
/// - `filename` must be a valid C string or NULL.
/// - `encoding` must be a valid C string or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlReaderForFile(
    filename: *const c_char,
    encoding: *const c_char,
    options: c_int,
) -> *mut XmlTextReader {
    if filename.is_null() {
        return ptr::null_mut();
    }

    // SAFETY: create_parser_ctxt returns a valid context or NULL.
    let ctxt = unsafe { create_parser_ctxt() };
    if ctxt.is_null() {
        return ptr::null_mut();
    }

    // SAFETY: input_from_file reads the file; filename is a valid C string.
    let input = match unsafe { input_from_file(filename) } {
        Ok(input) => input,
        Err(_) => {
            // SAFETY: ctxt is valid.
            unsafe { free_parser_ctxt(ctxt) };
            return ptr::null_mut();
        }
    };

    // SAFETY: ctxt and input are valid.
    unsafe { setup_parser_input(ctxt, input) };
    unsafe {
        (*ctxt).options = options;
    }

    let enc_bytes = if encoding.is_null() {
        None
    } else {
        // SAFETY: encoding is a valid C string.
        unsafe {
            let cstr = std::ffi::CStr::from_ptr(encoding);
            Some(cstr.to_bytes().to_vec())
        }
    };

    let mut reader = XmlTextReader::new(ctxt, None, enc_bytes.as_deref());
    reader.options = options;
    Box::into_raw(Box::new(reader))
}

/// Create a text reader from memory.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlTextReaderPtr xmlReaderForMemory(const char *buffer, int size,
///                                     const char *URL, const char *encoding, int options);
/// ```
///
/// # Safety
///
/// - `buffer` must be a valid pointer with at least `size` readable bytes.
/// - `URL` and `encoding` must be valid C strings or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlReaderForMemory(
    buffer: *const c_char,
    size: c_int,
    URL: *const c_char,
    encoding: *const c_char,
    options: c_int,
) -> *mut XmlTextReader {
    if buffer.is_null() || size <= 0 {
        return ptr::null_mut();
    }

    // SAFETY: create_parser_ctxt returns a valid context or NULL.
    let ctxt = unsafe { create_parser_ctxt() };
    if ctxt.is_null() {
        return ptr::null_mut();
    }

    // SAFETY: input_from_memory copies the data; buffer and size are valid.
    let input = unsafe { input_from_memory(buffer, size) };

    // SAFETY: ctxt and input are valid.
    unsafe { setup_parser_input(ctxt, input) };
    unsafe {
        (*ctxt).options = options;
    }

    let url_bytes = if URL.is_null() {
        None
    } else {
        // SAFETY: URL is a valid C string.
        unsafe {
            let cstr = std::ffi::CStr::from_ptr(URL);
            Some(cstr.to_bytes().to_vec())
        }
    };

    let enc_bytes = if encoding.is_null() {
        None
    } else {
        // SAFETY: encoding is a valid C string.
        unsafe {
            let cstr = std::ffi::CStr::from_ptr(encoding);
            Some(cstr.to_bytes().to_vec())
        }
    };

    let mut reader = XmlTextReader::new(ctxt, url_bytes.as_deref(), enc_bytes.as_deref());
    reader.options = options;
    Box::into_raw(Box::new(reader))
}

/// Create a text reader from a file descriptor.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlTextReaderPtr xmlReaderForFd(int fd, const char *URL,
///                                 const char *encoding, int options);
/// ```
///
/// # Safety
///
/// - `fd` must be a valid open file descriptor.
/// - `URL` and `encoding` must be valid C strings or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlReaderForFd(
    fd: c_int,
    URL: *const c_char,
    encoding: *const c_char,
    options: c_int,
) -> *mut XmlTextReader {
    // SAFETY: create_parser_ctxt returns a valid context or NULL.
    let ctxt = unsafe { create_parser_ctxt() };
    if ctxt.is_null() {
        return ptr::null_mut();
    }

    // Read all data from the fd.
    let mut buf = Vec::new();
    let mut tmp = [0u8; 4096];
    loop {
        // SAFETY: fd must be a valid open file descriptor.
        let n = unsafe { libc::read(fd, tmp.as_mut_ptr() as *mut c_void, tmp.len()) };
        if n <= 0 {
            break;
        }
        buf.extend_from_slice(&tmp[..n as usize]);
    }

    // SAFETY: input_from_memory copies the buffer contents.
    let input = unsafe { input_from_memory(buf.as_ptr() as *const c_char, buf.len() as c_int) };

    // SAFETY: ctxt and input are valid.
    unsafe { setup_parser_input(ctxt, input) };
    unsafe {
        (*ctxt).options = options;
    }

    let url_bytes = if URL.is_null() {
        None
    } else {
        // SAFETY: URL is a valid C string.
        unsafe {
            let cstr = std::ffi::CStr::from_ptr(URL);
            Some(cstr.to_bytes().to_vec())
        }
    };

    let enc_bytes = if encoding.is_null() {
        None
    } else {
        // SAFETY: encoding is a valid C string.
        unsafe {
            let cstr = std::ffi::CStr::from_ptr(encoding);
            Some(cstr.to_bytes().to_vec())
        }
    };

    let mut reader = XmlTextReader::new(ctxt, url_bytes.as_deref(), enc_bytes.as_deref());
    reader.options = options;
    Box::into_raw(Box::new(reader))
}

/// Create a text reader from I/O callbacks.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlTextReaderPtr xmlReaderForIO(xmlInputReadCallback ioread, xmlInputCloseCallback ioclose,
///                                 void *ioctx, const char *URL,
///                                 const char *encoding, int options);
/// ```
///
/// # Safety
///
/// - `ioread` and `ioclose` must be valid function pointers or None.
/// - `ioctx` must be a valid context pointer for the callbacks.
/// - `URL` and `encoding` must be valid C strings or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlReaderForIO(
    ioread: Option<xmlInputReadCallback>,
    ioclose: Option<xmlInputCloseCallback>,
    ioctx: *mut c_void,
    URL: *const c_char,
    encoding: *const c_char,
    options: c_int,
) -> *mut XmlTextReader {
    // SAFETY: create_parser_ctxt returns a valid context or NULL.
    let ctxt = unsafe { create_parser_ctxt() };
    if ctxt.is_null() {
        return ptr::null_mut();
    }

    // SAFETY: input_from_io reads all data via callbacks.
    let input = unsafe { input_from_io(ioread, ioclose, ioctx) };

    // SAFETY: ctxt and input are valid.
    unsafe { setup_parser_input(ctxt, input) };
    unsafe {
        (*ctxt).options = options;
    }

    let url_bytes = if URL.is_null() {
        None
    } else {
        // SAFETY: URL is a valid C string.
        unsafe {
            let cstr = std::ffi::CStr::from_ptr(URL);
            Some(cstr.to_bytes().to_vec())
        }
    };

    let enc_bytes = if encoding.is_null() {
        None
    } else {
        // SAFETY: encoding is a valid C string.
        unsafe {
            let cstr = std::ffi::CStr::from_ptr(encoding);
            Some(cstr.to_bytes().to_vec())
        }
    };

    let mut reader = XmlTextReader::new(ctxt, url_bytes.as_deref(), enc_bytes.as_deref());
    reader.options = options;
    Box::into_raw(Box::new(reader))
}

// ─────────────────────────────────────────────────────────────────────────────
// Navigation functions
// ─────────────────────────────────────────────────────────────────────────────

/// Advance the reader to the next node in document order.
///
/// Returns 1 on success, 0 if EOF, -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderRead(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer returned by `xmlNewTextReader` or one of the
/// `xmlReaderFor*` functions, or NULL (in which case -1 is returned).
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderRead(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).Read() }
}

/// Skip to the next sibling of the current node.
///
/// Returns 1 on success, 0 if no more siblings, -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderNext(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderNext(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).Next() }
}

/// Skip to the next sibling (same as xmlTextReaderNext).
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderNextSibling(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderNextSibling(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).Next() }
}

/// Skip to the previous sibling of the current node.
///
/// Returns 1 on success, 0 if no previous sibling, -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderPrev(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderPrev(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).Prev() }
}

/// Move the reader back to the parent element (from an attribute).
///
/// Returns 1 on success, 0 if not on an attribute, -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderMoveToElement(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderMoveToElement(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).MoveToElement() }
}

/// Move to an attribute by name.
///
/// Returns 1 on success, 0 if not found, -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderMoveToAttribute(xmlTextReaderPtr reader, const xmlChar *name);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL. `name` must be a valid C string or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderMoveToAttribute(
    reader: *mut XmlTextReader,
    name: *const xmlChar,
) -> c_int {
    if reader.is_null() || name.is_null() {
        return -1;
    }
    // SAFETY: reader and name are valid.
    unsafe { (*reader).MoveToAttribute(name) }
}

/// Move to an attribute by index.
///
/// Returns 1 on success, 0 if not found, -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderMoveToAttributeNo(xmlTextReaderPtr reader, int index);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderMoveToAttributeNo(
    reader: *mut XmlTextReader,
    index: c_int,
) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).MoveToAttributeNo(index) }
}

/// Move to the first attribute of the current element.
///
/// Returns 1 on success, 0 if no attributes, -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderMoveToFirstAttribute(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderMoveToFirstAttribute(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).MoveToFirstAttribute() }
}

/// Move to the next attribute.
///
/// Returns 1 on success, 0 if no more attributes, -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderMoveToNextAttribute(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderMoveToNextAttribute(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).MoveToNextAttribute() }
}

// ─────────────────────────────────────────────────────────────────────────────
// Information methods
// ─────────────────────────────────────────────────────────────────────────────

/// Get the attribute count of the current element.
///
/// Returns the number of attributes, or -1 if not on an element.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderAttributeCount(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderAttributeCount(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).AttributeCount() }
}

/// Get the depth of the current node.
///
/// Returns the depth (0 for root element), or -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderDepth(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderDepth(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).Depth() }
}

/// Get the node type of the current node.
///
/// Returns one of the `xmlReaderTypes` constants, or -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderNodeType(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderNodeType(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).NodeType() as c_int }
}

/// Get the name of the current node.
///
/// Returns a newly allocated string (caller must free with `xmlFree`),
/// or NULL if there is no name.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlChar *xmlTextReaderName(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderName(reader: *mut XmlTextReader) -> *mut xmlChar {
    if reader.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).Name() }
}

/// Get the value of the current node.
///
/// Returns a newly allocated string (caller must free with `xmlFree`),
/// or NULL if there is no value.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlChar *xmlTextReaderValue(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderValue(reader: *mut XmlTextReader) -> *mut xmlChar {
    if reader.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).Value() }
}

/// Get a constant pointer to the name (no copy).
///
/// The returned pointer is valid only while the reader is alive and positioned
/// on the same node.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// const xmlChar *xmlTextReaderConstName(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderConstName(reader: *mut XmlTextReader) -> *const xmlChar {
    if reader.is_null() {
        return ptr::null();
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).ConstName() }
}

/// Get a constant pointer to the value (no copy).
///
/// The returned pointer is valid only while the reader is alive and positioned
/// on the same node.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// const xmlChar *xmlTextReaderConstValue(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderConstValue(reader: *mut XmlTextReader) -> *const xmlChar {
    if reader.is_null() {
        return ptr::null();
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).ConstValue() }
}

/// Get the base URI of the current node.
///
/// Returns a newly allocated string (caller must free with `xmlFree`),
/// or NULL if not available.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlChar *xmlTextReaderBaseUri(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderBaseUri(reader: *mut XmlTextReader) -> *mut xmlChar {
    if reader.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).BaseUri() }
}

/// Get the local name of the current node.
///
/// Returns a newly allocated string, or NULL.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlChar *xmlTextReaderLocalName(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderLocalName(reader: *mut XmlTextReader) -> *mut xmlChar {
    if reader.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).LocalName() }
}

/// Get the namespace URI of the current node.
///
/// Returns a newly allocated string, or NULL.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlChar *xmlTextReaderNamespaceUri(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderNamespaceUri(reader: *mut XmlTextReader) -> *mut xmlChar {
    if reader.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).NamespaceUri() }
}

/// Get the prefix of the current node.
///
/// Returns a newly allocated string, or NULL.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlChar *xmlTextReaderPrefix(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderPrefix(reader: *mut XmlTextReader) -> *mut xmlChar {
    if reader.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).Prefix() }
}

/// Check if the current node has a value.
///
/// Returns 1 if the node has a value, 0 otherwise.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderHasValue(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderHasValue(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return 0;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).HasValue() }
}

/// Check if the current node has attributes.
///
/// Returns 1 if the node has attributes, 0 otherwise.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderHasAttributes(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderHasAttributes(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return 0;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).HasAttributes() }
}

/// Check if the current element is an empty element (no children).
///
/// Returns 1 if empty, 0 otherwise.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderIsEmptyElement(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderIsEmptyElement(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return 0;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).IsEmptyElement() }
}

/// Get the read state.
///
/// Returns one of the `xmlTextReaderReadState` constants.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderReadState(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderReadState(reader: *mut XmlTextReader) -> c_int {
    if reader.is_null() {
        return ReadState::ERROR as c_int;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).ReadState() as c_int }
}

// ─────────────────────────────────────────────────────────────────────────────
// Attribute access
// ─────────────────────────────────────────────────────────────────────────────

/// Get an attribute value by name.
///
/// Returns a newly allocated string, or NULL.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlChar *xmlTextReaderGetAttribute(xmlTextReaderPtr reader, const xmlChar *name);
/// ```
///
/// # Safety
///
/// `reader` and `name` must be valid pointers or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderGetAttribute(
    reader: *mut XmlTextReader,
    name: *const xmlChar,
) -> *mut xmlChar {
    if reader.is_null() || name.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader and name are valid.
    unsafe { (*reader).GetAttribute(name) }
}

/// Get an attribute value by index.
///
/// Returns a newly allocated string, or NULL.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlChar *xmlTextReaderGetAttributeNo(xmlTextReaderPtr reader, int index);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderGetAttributeNo(
    reader: *mut XmlTextReader,
    index: c_int,
) -> *mut xmlChar {
    if reader.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).GetAttributeNo(index) }
}

/// Get an attribute value by local name and namespace URI.
///
/// Returns a newly allocated string, or NULL.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlChar *xmlTextReaderGetAttributeNs(xmlTextReaderPtr reader,
///                                      const xmlChar *localName,
///                                      const xmlChar *namespaceURI);
/// ```
///
/// # Safety
///
/// `reader`, `localName`, and `namespaceURI` must be valid pointers or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderGetAttributeNs(
    reader: *mut XmlTextReader,
    localName: *const xmlChar,
    namespaceURI: *const xmlChar,
) -> *mut xmlChar {
    if reader.is_null() || localName.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader, localName, and namespaceURI are valid.
    unsafe { (*reader).GetAttributeNs(localName, namespaceURI) }
}

/// Look up a namespace by prefix.
///
/// Returns a newly allocated string with the namespace URI, or NULL.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlChar *xmlTextReaderLookupNamespace(xmlTextReaderPtr reader, const xmlChar *prefix);
/// ```
///
/// # Safety
///
/// `reader` and `prefix` must be valid pointers or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderLookupNamespace(
    reader: *mut XmlTextReader,
    prefix: *const xmlChar,
) -> *mut xmlChar {
    if reader.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader and prefix are valid.
    unsafe { (*reader).LookupNamespace(prefix) }
}

// ─────────────────────────────────────────────────────────────────────────────
// Parser properties
// ─────────────────────────────────────────────────────────────────────────────

/// Get a parser property.
///
/// Returns the property value (0 or 1), or -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderGetParserProp(xmlTextReaderPtr reader, int prop);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderGetParserProp(
    reader: *mut XmlTextReader,
    prop: c_int,
) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).GetParserProp(prop) }
}

/// Set a parser property.
///
/// Returns 0 on success, -1 on error.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderSetParserProp(xmlTextReaderPtr reader, int prop, int value);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderSetParserProp(
    reader: *mut XmlTextReader,
    prop: c_int,
    value: c_int,
) -> c_int {
    if reader.is_null() {
        return -1;
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).SetParserProp(prop, value) }
}

// ─────────────────────────────────────────────────────────────────────────────
// Lifecycle
// ─────────────────────────────────────────────────────────────────────────────

/// Free a text reader.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// void xmlFreeTextReader(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer returned by `xmlNewTextReader` or one of the
/// `xmlReaderFor*` functions, or NULL (in which case this is a no-op).
#[no_mangle]
pub unsafe extern "C" fn xmlFreeTextReader(reader: *mut XmlTextReader) {
    if reader.is_null() {
        return;
    }
    // SAFETY: reader was created via Box::into_raw, so we reconstruct the Box
    // and let it drop, which calls the Drop impl.
    unsafe {
        let _ = Box::from_raw(reader);
    }
}

/// Setup/reinitialize a reader with new input.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// int xmlTextReaderSetup(xmlTextReaderPtr reader,
///                        xmlParserInputBufferPtr input,
///                        const char *URL, const char *encoding, int options);
/// ```
///
/// # Safety
///
/// - `reader` must be a valid pointer or NULL.
/// - `input` must be a valid `_xmlParserInputBuffer` pointer or NULL.
/// - `URL` and `encoding` must be valid C strings or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderSetup(
    reader: *mut XmlTextReader,
    input: *mut _xmlParserInputBuffer,
    URL: *const c_char,
    encoding: *const c_char,
    options: c_int,
) -> c_int {
    if reader.is_null() {
        return -1;
    }

    // SAFETY: reader is valid.
    let r = unsafe { &mut *reader };

    // Reset the reader state.
    r.clear_cached_name();
    r.clear_cached_value();

    // Free the old document.
    if !r.doc.is_null() {
        // SAFETY: doc was allocated by the parser.
        unsafe { tree::free_doc(r.doc) };
        r.doc = ptr::null_mut();
    }

    // Free old parser context.
    if !r.ctxt.is_null() {
        // SAFETY: ctxt was created by create_parser_ctxt.
        unsafe { free_parser_ctxt(r.ctxt) };
        r.ctxt = ptr::null_mut();
    }

    r.events.clear();
    r.event_index = 0;
    r.state = ReadState::INITIALIZED;
    r.cur_node = ptr::null_mut();
    r.node_type = ReaderNodeType::NONE;
    r.depth = 0;
    r.attribute_count = -1;
    r.cur_attribute = -1;
    r.options = options;
    r.parsed = false;
    r.errors.clear();

    // Update URL.
    if !r.URL.is_null() {
        // SAFETY: URL was allocated by xmlMalloc.
        unsafe { xmlFree(r.URL as *mut c_void) };
        r.URL = ptr::null_mut();
    }
    if !URL.is_null() {
        // SAFETY: URL is a valid C string.
        let url_str = unsafe { std::ffi::CStr::from_ptr(URL) };
        // SAFETY: bytes_to_xmlstr allocates via xmlMalloc.
        r.URL = unsafe { bytes_to_xmlstr(url_str.to_bytes()) };
    }

    // Update encoding.
    if !r.encoding.is_null() {
        // SAFETY: encoding was allocated by xmlMalloc.
        unsafe { xmlFree(r.encoding as *mut c_void) };
        r.encoding = ptr::null_mut();
    }
    if !encoding.is_null() {
        // SAFETY: encoding is a valid C string.
        let enc_str = unsafe { std::ffi::CStr::from_ptr(encoding) };
        // SAFETY: bytes_to_xmlstr allocates via xmlMalloc.
        r.encoding = unsafe { bytes_to_xmlstr(enc_str.to_bytes()) };
    }

    // Create new parser context and set up input.
    if !input.is_null() {
        // SAFETY: create_parser_ctxt returns a valid context or NULL.
        let ctxt = unsafe { create_parser_ctxt() };
        if ctxt.is_null() {
            return -1;
        }

        // Read all data from the input buffer.
        let mut data = Vec::new();
        let mut tmp = [0u8; 4096];

        // SAFETY: input is valid.
        let read_cb = unsafe { (*input).readcallback };
        let ioctx = unsafe { (*input).context };

        if let Some(read) = read_cb {
            loop {
                // SAFETY: callbacks are valid.
                let n = unsafe { read(ioctx, tmp.as_mut_ptr() as *mut c_char, tmp.len() as c_int) };
                if n <= 0 {
                    break;
                }
                data.extend_from_slice(&tmp[..n as usize]);
            }
        }

        // Close the input.
        let close_cb = unsafe { (*input).closecallback };
        if let Some(close) = close_cb {
            // SAFETY: close callback is valid.
            unsafe { close(ioctx) };
        }

        let input_buf = InputBuffer::from_memory(&data, None);

        // SAFETY: ctxt and input_buf are valid.
        unsafe { setup_parser_input(ctxt, input_buf) };
        unsafe {
            (*ctxt).options = options;
        }

        r.ctxt = ctxt;
    }

    0
}

/// Get the current document from the reader.
///
/// Returns a pointer to the `_xmlDoc` or NULL.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlDocPtr xmlTextReaderCurrentDoc(xmlTextReaderPtr reader);
/// ```
///
/// # Safety
///
/// `reader` must be a valid pointer or NULL.
#[no_mangle]
pub unsafe extern "C" fn xmlTextReaderCurrentDoc(reader: *mut XmlTextReader) -> *mut _xmlDoc {
    if reader.is_null() {
        return ptr::null_mut();
    }
    // SAFETY: reader is valid.
    unsafe { (*reader).CurrentDoc() }
}

// ═══════════════════════════════════════════════════════════════════════════════
// Tests
// ═══════════════════════════════════════════════════════════════════════════════

#[cfg(test)]
mod tests {
    use super::*;
    use crate::abi::allocator::xmlFree;
    use core::ffi::c_void;
    use std::os::raw::c_char;

    /// Helper: create a reader from a string.
    unsafe fn create_reader(xml: &str) -> *mut XmlTextReader {
        let bytes = xml.as_bytes();
        xmlReaderForMemory(
            bytes.as_ptr() as *const c_char,
            bytes.len() as c_int,
            ptr::null(),
            ptr::null(),
            0,
        )
    }

    /// Helper: free a reader.
    unsafe fn free_reader(reader: *mut XmlTextReader) {
        if !reader.is_null() {
            xmlFreeTextReader(reader);
        }
    }

    /// Helper: read through all nodes and collect their types and names.
    unsafe fn collect_nodes(reader: *mut XmlTextReader) -> Vec<(ReaderNodeType, String, i32)> {
        let mut result = Vec::new();
        loop {
            let ret = xmlTextReaderRead(reader);
            if ret <= 0 {
                break;
            }
            // SAFETY: reader is valid.
            let r = &*reader;
            let ntype = r.NodeType();
            let name = if r.name.is_null() {
                String::new()
            } else {
                xmlstr_to_string(r.name as *const xmlChar)
            };
            let depth = r.Depth();
            result.push((ntype, name, depth));
        }
        result
    }

    // ─── Basic tests ───────────────────────────────────────────────────────

    #[test]
    fn test_create_reader_from_memory() {
        unsafe {
            let reader = create_reader("<root/>");
            assert!(!reader.is_null());
            assert_eq!((*reader).ReadState(), ReadState::INITIALIZED);
            free_reader(reader);
        }
    }

    #[test]
    fn test_read_simple_document() {
        unsafe {
            let reader = create_reader("<root><child>text</child></root>");
            assert!(!reader.is_null());

            let nodes = collect_nodes(reader);
            // Expected sequence:
            // ELEMENT root (depth=0)
            // ELEMENT child (depth=1)
            // TEXT text (depth=2)
            // END_ELEMENT child (depth=1)
            // END_ELEMENT root (depth=0)

            assert_eq!(nodes.len(), 5);
            assert_eq!(nodes[0], (ReaderNodeType::ELEMENT, "root".to_string(), 0));
            assert_eq!(nodes[1], (ReaderNodeType::ELEMENT, "child".to_string(), 1));
            assert_eq!(nodes[2], (ReaderNodeType::TEXT, "".to_string(), 2));
            assert_eq!(
                nodes[3],
                (ReaderNodeType::END_ELEMENT, "child".to_string(), 1)
            );
            assert_eq!(
                nodes[4],
                (ReaderNodeType::END_ELEMENT, "root".to_string(), 0)
            );

            assert_eq!((*reader).ReadState(), ReadState::EOF);
            free_reader(reader);
        }
    }

    #[test]
    fn test_read_state_transitions() {
        unsafe {
            let reader = create_reader("<root/>");
            assert!(!reader.is_null());
            assert_eq!((*reader).ReadState(), ReadState::INITIALIZED);

            // First read.
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).ReadState(), ReadState::READING);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);
            assert_eq!((*reader).Depth(), 0);

            // Second read — should be END_ELEMENT.
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::END_ELEMENT);

            // Third read — EOF.
            assert_eq!(xmlTextReaderRead(reader), 0);
            assert_eq!((*reader).ReadState(), ReadState::EOF);

            free_reader(reader);
        }
    }

    #[test]
    fn test_null_reader_returns_error() {
        unsafe {
            assert_eq!(xmlTextReaderRead(ptr::null_mut()), -1);
            assert_eq!(xmlTextReaderDepth(ptr::null_mut()), -1);
            assert_eq!(xmlTextReaderNodeType(ptr::null_mut()), -1);
            assert!(xmlTextReaderName(ptr::null_mut()).is_null());
            assert!(xmlTextReaderValue(ptr::null_mut()).is_null());
            assert_eq!(xmlTextReaderHasValue(ptr::null_mut()), 0);
            assert_eq!(xmlTextReaderIsEmptyElement(ptr::null_mut()), 0);
            assert_eq!(
                xmlTextReaderReadState(ptr::null_mut()),
                ReadState::ERROR as c_int
            );
        }
    }

    #[test]
    fn test_xmlFreeTextReader_null() {
        unsafe {
            // Should not crash.
            xmlFreeTextReader(ptr::null_mut());
        }
    }

    #[test]
    fn test_reader_name_and_value() {
        unsafe {
            let reader = create_reader("<root>hello</root>");
            assert!(!reader.is_null());

            // Read root element.
            assert_eq!(xmlTextReaderRead(reader), 1);
            let name = xmlTextReaderName(reader);
            assert!(!name.is_null());
            assert_eq!(xmlstr_to_string(name), "root");
            xmlFree(name as *mut c_void);

            assert_eq!(xmlTextReaderHasValue(reader), 0);

            // Read text node.
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::TEXT);
            assert_eq!((*reader).HasValue(), 1);

            let val = xmlTextReaderValue(reader);
            assert!(!val.is_null());
            assert_eq!(xmlstr_to_string(val), "hello");
            xmlFree(val as *mut c_void);

            free_reader(reader);
        }
    }

    #[test]
    fn test_empty_element() {
        unsafe {
            let reader = create_reader("<empty/>");
            assert!(!reader.is_null());

            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);
            assert_eq!((*reader).IsEmptyElement(), 1);
            assert_eq!((*reader).HasAttributes(), 0);
            assert_eq!((*reader).AttributeCount(), 0);

            // END_ELEMENT.
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::END_ELEMENT);

            free_reader(reader);
        }
    }

    #[test]
    fn test_element_with_attributes() {
        unsafe {
            let reader = create_reader(r#"<root a="1" b="2"/>"#);
            assert!(!reader.is_null());

            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);
            assert_eq!((*reader).HasAttributes(), 1);

            // We know the attribute count if we've built the events properly.
            // The count_attributes checks the element's properties list.
            let attrs = xmlTextReaderAttributeCount(reader);
            assert_eq!(attrs, 2);

            free_reader(reader);
        }
    }

    #[test]
    fn test_attribute_navigation() {
        unsafe {
            let reader = create_reader(r#"<root a="1" b="2"></root>"#);
            assert!(!reader.is_null());

            // Position on root element.
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);

            // Move to first attribute.
            assert_eq!(xmlTextReaderMoveToFirstAttribute(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ATTRIBUTE);

            let name = xmlTextReaderConstName(reader);
            assert!(!name.is_null());
            assert_eq!(xmlstr_to_bytes(name), b"a");

            let val = xmlTextReaderConstValue(reader);
            assert!(!val.is_null());
            assert_eq!(xmlstr_to_bytes(val), b"1");

            // Move to next attribute.
            assert_eq!(xmlTextReaderMoveToNextAttribute(reader), 1);
            let name = xmlTextReaderConstName(reader);
            assert!(!name.is_null());
            assert_eq!(xmlstr_to_bytes(name), b"b");
            let val = xmlTextReaderConstValue(reader);
            assert!(!val.is_null());
            assert_eq!(xmlstr_to_bytes(val), b"2");

            // No more attributes.
            assert_eq!(xmlTextReaderMoveToNextAttribute(reader), 0);

            // Move back to element.
            assert_eq!(xmlTextReaderMoveToElement(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);

            // Move to attribute by name.
            assert_eq!(
                xmlTextReaderMoveToAttribute(reader, b"a\0" as *const u8 as *const xmlChar),
                1
            );
            assert_eq!((*reader).NodeType(), ReaderNodeType::ATTRIBUTE);

            // Move to attribute by index.
            assert_eq!(xmlTextReaderMoveToElement(reader), 1);
            assert_eq!(xmlTextReaderMoveToAttributeNo(reader, 1), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ATTRIBUTE);

            free_reader(reader);
        }
    }

    #[test]
    fn test_get_attribute() {
        unsafe {
            let reader = create_reader(r#"<root a="hello" b="world"/>"#);
            assert!(!reader.is_null());

            assert_eq!(xmlTextReaderRead(reader), 1);

            // Get attribute by name.
            let val = xmlTextReaderGetAttribute(reader, b"a\0" as *const u8 as *const xmlChar);
            assert!(!val.is_null());
            assert_eq!(xmlstr_to_bytes(val), b"hello");
            xmlFree(val as *mut c_void);

            let val = xmlTextReaderGetAttribute(reader, b"b\0" as *const u8 as *const xmlChar);
            assert!(!val.is_null());
            assert_eq!(xmlstr_to_bytes(val), b"world");
            xmlFree(val as *mut c_void);

            // Non-existent attribute.
            let val = xmlTextReaderGetAttribute(reader, b"c\0" as *const u8 as *const xmlChar);
            assert!(val.is_null());

            // Get attribute by index.
            let val = xmlTextReaderGetAttributeNo(reader, 0);
            assert!(!val.is_null());
            assert_eq!(xmlstr_to_bytes(val), b"hello");
            xmlFree(val as *mut c_void);

            let val = xmlTextReaderGetAttributeNo(reader, 1);
            assert!(!val.is_null());
            assert_eq!(xmlstr_to_bytes(val), b"world");
            xmlFree(val as *mut c_void);

            let val = xmlTextReaderGetAttributeNo(reader, 2);
            assert!(val.is_null());

            free_reader(reader);
        }
    }

    #[test]
    fn test_depth_tracking() {
        unsafe {
            let reader = create_reader("<a><b><c/></b></a>");
            assert!(!reader.is_null());

            let nodes = collect_nodes(reader);
            // ELEMENT a (0), ELEMENT b (1), ELEMENT c (2),
            // END_ELEMENT c (2), END_ELEMENT b (1), END_ELEMENT a (0)
            assert_eq!(nodes.len(), 6);
            assert_eq!(nodes[0].2, 0); // a depth 0
            assert_eq!(nodes[1].2, 1); // b depth 1
            assert_eq!(nodes[2].2, 2); // c depth 2
            assert_eq!(nodes[3].2, 2); // END c depth 2
            assert_eq!(nodes[4].2, 1); // END b depth 1
            assert_eq!(nodes[5].2, 0); // END a depth 0

            free_reader(reader);
        }
    }

    #[test]
    fn test_multiple_siblings() {
        unsafe {
            let reader = create_reader("<root><a>A</a><b>B</b><c>C</c></root>");
            assert!(!reader.is_null());

            let nodes = collect_nodes(reader);
            // ELEMENT root(0), ELEMENT a(1), TEXT(2), END a(1),
            // ELEMENT b(1), TEXT(2), END b(1),
            // ELEMENT c(1), TEXT(2), END c(1),
            // END root(0)
            assert_eq!(nodes.len(), 11);

            // Check the sibling elements.
            assert_eq!(nodes[1], (ReaderNodeType::ELEMENT, "a".to_string(), 1));
            assert_eq!(nodes[4], (ReaderNodeType::ELEMENT, "b".to_string(), 1));
            assert_eq!(nodes[7], (ReaderNodeType::ELEMENT, "c".to_string(), 1));

            free_reader(reader);
        }
    }

    #[test]
    fn test_next_skip_to_sibling() {
        unsafe {
            let reader = create_reader("<root><a>A</a><b>B</b><c>C</c></root>");
            assert!(!reader.is_null());

            // Read to first node (root element).
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);

            // Read to a.
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);
            assert_eq!(xmlstr_to_string((*reader).name as *const xmlChar), "a");

            // Read to text of a.
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::TEXT);

            // Skip to next sibling — should skip END a and go to ELEMENT b.
            assert_eq!(xmlTextReaderNext(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);
            assert_eq!(xmlstr_to_string((*reader).name as *const xmlChar), "b");

            // Next again — should go to c.
            assert_eq!(xmlTextReaderNext(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);
            assert_eq!(xmlstr_to_string((*reader).name as *const xmlChar), "c");

            // Next again — no more siblings.
            assert_eq!(xmlTextReaderNext(reader), 0);

            free_reader(reader);
        }
    }

    #[test]
    fn test_comment_and_pi_nodes() {
        unsafe {
            let xml = b"<?pi target?><root><!-- comment -->text</root>\0";
            let reader = xmlReaderForMemory(
                xml.as_ptr() as *const c_char,
                (xml.len() - 1) as c_int,
                ptr::null(),
                ptr::null(),
                0,
            );
            assert!(!reader.is_null());

            let nodes = collect_nodes(reader);
            // PI, ELEMENT root, COMMENT, TEXT, END_ELEMENT root
            // Note: PI appears as PROCESSING_INSTRUCTION node.
            assert!(!nodes.is_empty(), "no nodes collected: {:?}", nodes);

            // Check PI.
            assert_eq!(
                nodes[0].0,
                ReaderNodeType::PROCESSING_INSTRUCTION,
                "expected PI at nodes[0], got {:?} name={}",
                nodes[0].0,
                nodes[0].1
            );
            assert_eq!(
                nodes[0].0,
                ReaderNodeType::PROCESSING_INSTRUCTION,
                "expected PI at nodes[0], got {:?} name={}",
                nodes[0].0,
                nodes[0].1
            );

            // Check root element.
            let root_idx = nodes
                .iter()
                .position(|(t, n, _)| *t == ReaderNodeType::ELEMENT && n == "root");
            assert!(
                root_idx.is_some(),
                "no ELEMENT root found in nodes: {:?}",
                nodes
                    .iter()
                    .map(|(t, n, _)| format!("{:?}:{}", t, n))
                    .collect::<Vec<_>>()
            );

            // Check comment.
            let comment_idx = nodes
                .iter()
                .position(|(t, _, _)| *t == ReaderNodeType::COMMENT);
            assert!(comment_idx.is_some(), "no COMMENT found");

            // Check text.
            let text_idx = nodes
                .iter()
                .position(|(t, _, _)| *t == ReaderNodeType::TEXT);
            assert!(text_idx.is_some(), "no TEXT found");

            free_reader(reader);
        }
    }

    #[test]
    fn test_local_name() {
        unsafe {
            // We need a namespace-aware element. For now, test without namespace.
            let reader = create_reader("<root/>");
            assert!(!reader.is_null());

            assert_eq!(xmlTextReaderRead(reader), 1);
            let local = xmlTextReaderLocalName(reader);
            assert!(!local.is_null());
            assert_eq!(xmlstr_to_bytes(local), b"root");
            xmlFree(local as *mut c_void);

            free_reader(reader);
        }
    }

    #[test]
    fn test_base_uri() {
        unsafe {
            let reader = create_reader("<root/>");
            assert!(!reader.is_null());

            assert_eq!(xmlTextReaderRead(reader), 1);
            // Base URI should be NULL for memory-created readers.
            let uri = xmlTextReaderBaseUri(reader);
            assert!(uri.is_null());

            free_reader(reader);
        }
    }

    #[test]
    fn test_lookup_namespace() {
        unsafe {
            let reader = create_reader(r#"<root xmlns:ns="http://example.com"><ns:child/></root>"#);
            assert!(!reader.is_null());

            // Read to root.
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);

            // Read to child (ns:child).
            assert_eq!(xmlTextReaderRead(reader), 1);

            // Lookup the "ns" prefix.
            let uri = xmlTextReaderLookupNamespace(reader, b"ns\0" as *const u8 as *const xmlChar);
            assert!(!uri.is_null());
            assert_eq!(xmlstr_to_bytes(uri), b"http://example.com");
            xmlFree(uri as *mut c_void);

            // Lookup default namespace (NULL prefix).
            let uri = xmlTextReaderLookupNamespace(reader, ptr::null());
            assert!(uri.is_null());

            // Lookup non-existent prefix.
            let uri = xmlTextReaderLookupNamespace(
                reader,
                b"nonexistent\0" as *const u8 as *const xmlChar,
            );
            assert!(uri.is_null());

            free_reader(reader);
        }
    }

    #[test]
    fn test_parser_properties() {
        unsafe {
            let reader = create_reader("<root/>");
            assert!(!reader.is_null());

            // Get default properties.
            assert_eq!(xmlTextReaderGetParserProp(reader, 1), 0); // LOADDTD
            assert_eq!(xmlTextReaderGetParserProp(reader, 2), 0); // DEFAULTATTRS
            assert_eq!(xmlTextReaderGetParserProp(reader, 3), 0); // VALIDATE
            assert_eq!(xmlTextReaderGetParserProp(reader, 4), 0); // SUBST_ENTITIES

            // Set and verify.
            assert_eq!(xmlTextReaderSetParserProp(reader, 1, 1), 0);
            assert_eq!(xmlTextReaderGetParserProp(reader, 1), 1);

            assert_eq!(xmlTextReaderSetParserProp(reader, 4, 1), 0);
            assert_eq!(xmlTextReaderGetParserProp(reader, 4), 1);

            // Invalid property.
            assert_eq!(xmlTextReaderGetParserProp(reader, 99), -1);
            assert_eq!(xmlTextReaderSetParserProp(reader, 99, 1), -1);

            free_reader(reader);
        }
    }

    #[test]
    fn test_current_doc() {
        unsafe {
            let reader = create_reader("<root/>");
            assert!(!reader.is_null());

            // Before reading, doc should be null.
            assert!((*reader).CurrentDoc().is_null());

            // After reading, doc should be available.
            assert_eq!(xmlTextReaderRead(reader), 1);
            let doc = xmlTextReaderCurrentDoc(reader);
            assert!(!doc.is_null());

            free_reader(reader);
        }
    }

    #[test]
    fn test_free_reader_after_read() {
        unsafe {
            let reader = create_reader("<root><child/></root>");
            assert!(!reader.is_null());

            // Read through the document.
            while xmlTextReaderRead(reader) > 0 {}
            assert_eq!((*reader).ReadState(), ReadState::EOF);

            // Free should not crash.
            free_reader(reader);
        }
    }

    #[test]
    fn test_reader_for_memory_null_buffer() {
        unsafe {
            let reader = xmlReaderForMemory(ptr::null(), 10, ptr::null(), ptr::null(), 0);
            assert!(reader.is_null());
        }
    }

    #[test]
    fn test_reader_for_memory_empty_size() {
        unsafe {
            let data = b"<root/>";
            let reader = xmlReaderForMemory(
                data.as_ptr() as *const c_char,
                0,
                ptr::null(),
                ptr::null(),
                0,
            );
            assert!(reader.is_null());
        }
    }

    #[test]
    fn test_reader_for_file_not_found() {
        unsafe {
            let filename = b"/nonexistent/file.xml\0" as *const u8 as *const c_char;
            let reader = xmlReaderForFile(filename, ptr::null(), 0);
            assert!(reader.is_null());
        }
    }

    #[test]
    fn test_const_name_and_value() {
        unsafe {
            let reader = create_reader("<root>text</root>");
            assert!(!reader.is_null());

            // Root element.
            assert_eq!(xmlTextReaderRead(reader), 1);
            let cname = xmlTextReaderConstName(reader);
            assert!(!cname.is_null());
            assert_eq!(xmlstr_to_bytes(cname), b"root");

            // Text node.
            assert_eq!(xmlTextReaderRead(reader), 1);
            let cval = xmlTextReaderConstValue(reader);
            assert!(!cval.is_null());
            assert_eq!(xmlstr_to_bytes(cval), b"text");

            free_reader(reader);
        }
    }

    #[test]
    fn test_complex_nested_document() {
        unsafe {
            let xml = r#"<?xml version="1.0"?>
<library>
  <book id="1">
    <title>XML Fundamentals</title>
    <author>John Doe</author>
  </book>
  <book id="2">
    <title>XSLT Recipes</title>
    <author>Jane Smith</author>
  </book>
</library>"#;

            let reader = create_reader(xml);
            assert!(!reader.is_null());

            let mut element_count = 0;
            let mut end_element_count = 0;
            let mut text_count = 0;
            let mut pi_count = 0;

            loop {
                let ret = xmlTextReaderRead(reader);
                if ret <= 0 {
                    break;
                }
                match (*reader).NodeType() {
                    ReaderNodeType::ELEMENT => element_count += 1,
                    ReaderNodeType::END_ELEMENT => end_element_count += 1,
                    ReaderNodeType::TEXT => text_count += 1,
                    ReaderNodeType::PROCESSING_INSTRUCTION => pi_count += 1,
                    _ => {}
                }
            }

            // Elements: library, book(2), title(2), author(2) = 7
            assert_eq!(element_count, 7);
            // End elements: same count as elements
            assert_eq!(end_element_count, 7);
            // Text nodes: one per title and author = 4
            assert_eq!(text_count, 4);
            // UPSTREAM-PARITY: XML declaration (<?xml ...?>) is NOT stored as
            // a PI node in the tree. It is consumed by the parser and stored
            // in the document's version/encoding fields. Only <?pi ...?> nodes
            // (processing instructions) appear as XML_PI_NODE in the tree.
            assert_eq!(pi_count, 0);

            free_reader(reader);
        }
    }

    #[test]
    fn test_setup_reinitialize() {
        unsafe {
            let reader = create_reader("<root/>");
            assert!(!reader.is_null());

            // Read through.
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).ReadState(), ReadState::READING);

            // Setup with new input (simulate re-initialization).
            // For this test, we just verify the setup function exists and
            // handles a NULL input gracefully (resetting the reader).
            assert_eq!(
                xmlTextReaderSetup(reader, ptr::null_mut(), ptr::null(), ptr::null(), 0),
                0
            );
            assert_eq!((*reader).ReadState(), ReadState::INITIALIZED);

            free_reader(reader);
        }
    }

    #[test]
    fn test_has_attributes_on_non_element() {
        unsafe {
            let reader = create_reader("<root>text</root>");
            assert!(!reader.is_null());

            // Position on text node.
            assert_eq!(xmlTextReaderRead(reader), 1); // root element
            assert_eq!((*reader).HasAttributes(), 0); // 0 attributes on root
            assert_eq!(xmlTextReaderRead(reader), 1); // text
            assert_eq!((*reader).HasAttributes(), 0);

            free_reader(reader);
        }
    }

    #[test]
    fn test_prev_sibling() {
        unsafe {
            let reader = create_reader("<root><a/><b/><c/></root>");
            assert!(!reader.is_null());

            // Read through the document.
            while xmlTextReaderRead(reader) > 0 {
                // Skip to END_ELEMENT root or beyond.
            }

            // Can't go prev after EOF.
            assert_eq!(xmlTextReaderPrev(reader), -1);

            free_reader(reader);
        }
    }

    #[test]
    fn test_move_to_attribute_no_not_on_element() {
        unsafe {
            let reader = create_reader("<root>text</root>");
            assert!(!reader.is_null());

            assert_eq!(xmlTextReaderRead(reader), 1); // root
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);

            // Move to non-existent attribute index.
            assert_eq!(xmlTextReaderMoveToAttributeNo(reader, 0), 0);

            free_reader(reader);
        }
    }

    #[test]
    fn test_get_attribute_ns() {
        unsafe {
            let reader = create_reader(r#"<root a="1" b="2"/>"#);
            assert!(!reader.is_null());

            assert_eq!(xmlTextReaderRead(reader), 1);

            // Get attribute by local name only (namespaceURI is NULL).
            let val = xmlTextReaderGetAttributeNs(
                reader,
                b"a\0" as *const u8 as *const xmlChar,
                ptr::null(),
            );
            assert!(!val.is_null());
            assert_eq!(xmlstr_to_bytes(val), b"1");
            xmlFree(val as *mut c_void);

            free_reader(reader);
        }
    }

    #[test]
    fn test_mixed_content() {
        unsafe {
            let reader = create_reader("<root>before<child/>after</root>");
            assert!(!reader.is_null());

            let nodes = collect_nodes(reader);
            // ELEMENT root(0), TEXT "before"(1), ELEMENT child(1),
            // END_ELEMENT child(1), TEXT "after"(1), END_ELEMENT root(0)
            assert_eq!(nodes.len(), 6);
            assert_eq!(nodes[0], (ReaderNodeType::ELEMENT, "root".to_string(), 0));
            assert_eq!(nodes[1].0, ReaderNodeType::TEXT);
            assert_eq!(nodes[2], (ReaderNodeType::ELEMENT, "child".to_string(), 1));
            assert_eq!(nodes[4].0, ReaderNodeType::TEXT);

            free_reader(reader);
        }
    }

    #[test]
    fn test_error_handling_invalid_xml() {
        unsafe {
            // Malformed XML.
            let data = b"<root><\0" as *const u8 as *const c_char;
            let reader = xmlReaderForMemory(data, 7, ptr::null(), ptr::null(), 0);
            assert!(!reader.is_null());

            // Reading should fail.
            let ret = xmlTextReaderRead(reader);
            assert!(ret == -1 || ret == 0);

            free_reader(reader);
        }
    }

    #[test]
    fn test_reader_with_options() {
        unsafe {
            let data = b"<root/>\0" as *const u8 as *const c_char;
            let reader = xmlReaderForMemory(
                data,
                7,
                ptr::null(),
                ptr::null(),
                XML_PARSE_NOENT | XML_PARSE_DTDLOAD,
            );
            assert!(!reader.is_null());

            // Verify options were set.
            assert_eq!((*reader).options & XML_PARSE_NOENT, XML_PARSE_NOENT);
            assert_eq!((*reader).options & XML_PARSE_DTDLOAD, XML_PARSE_DTDLOAD);

            assert_eq!(xmlTextReaderRead(reader), 1);
            free_reader(reader);
        }
    }

    #[test]
    fn test_reader_for_fd() {
        unsafe {
            // Create a temp file and test xmlReaderForFd.
            let tmp_path = "/tmp/libxml_rs_test_reader_fd.xml";
            let tmp_cstr = std::ffi::CString::new(tmp_path).unwrap();
            let content = b"<root><data/></root>";
            let fd = libc::open(
                tmp_cstr.as_ptr(),
                libc::O_WRONLY | libc::O_CREAT | libc::O_TRUNC,
                0o644,
            );
            assert!(fd >= 0);
            libc::write(fd, content.as_ptr() as *const c_void, content.len());
            libc::close(fd);

            // Open for reading.
            let fd = libc::open(tmp_cstr.as_ptr(), libc::O_RDONLY, 0);
            assert!(fd >= 0);

            let reader = xmlReaderForFd(fd, ptr::null(), ptr::null(), 0);
            assert!(!reader.is_null());

            let nodes = collect_nodes(reader);
            assert_eq!(nodes.len(), 4); // ELEMENT root, ELEMENT data, END data, END root

            free_reader(reader);
            libc::close(fd);
            std::fs::remove_file(tmp_path).ok();
        }
    }

    #[test]
    fn test_reader_for_io() {
        unsafe {
            extern "C" fn io_read(context: *mut c_void, buffer: *mut c_char, len: c_int) -> c_int {
                if context.is_null() || buffer.is_null() || len <= 0 {
                    return -1;
                }
                // SAFETY: context points to an IoCtx struct.
                let ctx = unsafe { &mut *(context as *mut IoCtx) };
                if ctx.pos >= ctx.data.len() {
                    return 0;
                }
                let remaining = ctx.data.len() - ctx.pos;
                let to_copy = if (remaining as c_int) < len {
                    remaining
                } else {
                    len as usize
                };
                // SAFETY: buffer has at least `len` bytes of space.
                unsafe {
                    std::ptr::copy_nonoverlapping(
                        ctx.data.as_ptr().add(ctx.pos),
                        buffer as *mut u8,
                        to_copy,
                    );
                }
                ctx.pos += to_copy;
                to_copy as c_int
            }

            extern "C" fn io_close(_context: *mut c_void) -> c_int {
                0
            }

            struct IoCtx {
                data: &'static [u8],
                pos: usize,
            }
            let mut ctx = IoCtx {
                data: b"<root/>",
                pos: 0,
            };

            let reader = xmlReaderForIO(
                Some(io_read),
                Some(io_close),
                &mut ctx as *mut IoCtx as *mut c_void,
                ptr::null(),
                ptr::null(),
                0,
            );
            assert!(!reader.is_null());

            // Read through the document.
            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::ELEMENT);
            let cname = xmlTextReaderConstName(reader);
            assert!(!cname.is_null());
            assert_eq!(xmlstr_to_bytes(cname), b"root");

            assert_eq!(xmlTextReaderRead(reader), 1);
            assert_eq!((*reader).NodeType(), ReaderNodeType::END_ELEMENT);

            assert_eq!(xmlTextReaderRead(reader), 0); // EOF

            free_reader(reader);
        }
    }
}