rumdl_lib/utils/

element_cache.rs

use fancy_regex::Regex as FancyRegex;
use regex::Regex;
use std::hash::{Hash, Hasher};
use std::sync::LazyLock;
use std::sync::{Arc, Mutex};

// Efficient regex patterns
static CODE_BLOCK_START_REGEX: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"^(\s*)(```|~~~)(.*)$").unwrap());
static INDENTED_CODE_BLOCK_REGEX: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"^(\s{4,})(.+)$").unwrap());

// List detection patterns
static UNORDERED_LIST_REGEX: LazyLock<FancyRegex> = LazyLock::new(|| {
    FancyRegex::new(r"^(?P<indent>[ \t]*)(?P<marker>[*+-])(?P<after>[ \t]*)(?P<content>.*)$").unwrap()
});
static ORDERED_LIST_REGEX: LazyLock<FancyRegex> = LazyLock::new(|| {
    FancyRegex::new(r"^(?P<indent>[ \t]*)(?P<marker>\d+\.)(?P<after>[ \t]*)(?P<content>.*)$").unwrap()
});

// Inline code span pattern
static CODE_SPAN_REGEX: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"`+").unwrap());

/// Represents a range in the document with start and end positions
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Range {
    pub start: usize,
    pub end: usize,
}

/// Represents the type of code block
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum CodeBlockType {
    Fenced,
    Indented,
}

/// Represents a code block in the document
#[derive(Debug, Clone)]
pub struct CodeBlock {
    pub range: Range,
    pub block_type: CodeBlockType,
    pub start_line: usize,
    pub end_line: usize,
    pub language: Option<String>,
}

/// Represents the type of list marker
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ListMarkerType {
    Asterisk,
    Plus,
    Minus,
    Ordered,
}

/// Represents a list item in the document
#[derive(Debug, Clone)]
pub struct ListItem {
    pub line_number: usize, // 1-indexed
    pub indentation: usize,
    pub indent_str: String, // Actual leading whitespace
    pub marker_type: ListMarkerType,
    pub marker: String,
    pub content: String,
    pub spaces_after_marker: usize,
    pub nesting_level: usize,
    pub parent_line_number: Option<usize>,
    pub blockquote_depth: usize,   // Number of leading blockquote markers
    pub blockquote_prefix: String, // The actual prefix (e.g., "> > ")
}

/// Cache for Markdown document structural elements
/// This allows sharing computed data across multiple rule checks
#[derive(Debug, Default, Clone)]
pub struct ElementCache {
    // Document content hash for cache validation (avoids storing full content)
    content_hash: u64,

    // Code blocks
    code_blocks: Vec<CodeBlock>,
    code_block_line_map: Vec<bool>, // Line index -> is in code block

    // Code spans (inline code)
    code_spans: Vec<Range>,

    // Lists
    list_items: Vec<ListItem>,
    list_line_map: Vec<bool>, // Line index -> is list item
}

impl ElementCache {
    /// Compute a hash of the content for cache validation
    fn compute_content_hash(content: &str) -> u64 {
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        content.hash(&mut hasher);
        hasher.finish()
    }

    /// Create a new cache from document content
    pub fn new(content: &str) -> Self {
        let content_hash = Self::compute_content_hash(content);
        let line_count = content.lines().count();

        let mut cache = ElementCache {
            content_hash,
            code_blocks: Vec::new(),
            code_block_line_map: vec![false; line_count],
            code_spans: Vec::new(),
            list_items: Vec::new(),
            list_line_map: vec![false; line_count],
        };

        // Populate the cache - pass content directly to avoid storing it
        cache.populate_code_blocks(content);
        cache.populate_code_spans(content);
        cache.populate_list_items(content);

        cache
    }

    /// Check if this cache is valid for the given content
    pub fn is_valid_for(&self, content: &str) -> bool {
        Self::compute_content_hash(content) == self.content_hash
    }

    /// Calculate the visual indentation width of a string, expanding tabs to spaces.
    ///
    /// Per CommonMark, tabs expand to the next tab stop (columns 4, 8, 12, ...).
    /// This means:
    /// - " \t" (1 space + tab) → 4 columns
    /// - "  \t" (2 spaces + tab) → 4 columns
    /// - "   \t" (3 spaces + tab) → 4 columns
    /// - "\t" (just tab) → 4 columns
    /// - "    " (4 spaces) → 4 columns
    pub fn calculate_indentation_width(indent_str: &str, tab_width: usize) -> usize {
        let mut width = 0;
        for ch in indent_str.chars() {
            if ch == '\t' {
                // Round up to next tab stop
                width = ((width / tab_width) + 1) * tab_width;
            } else if ch == ' ' {
                width += 1;
            } else {
                // Non-whitespace character, stop counting
                break;
            }
        }
        width
    }

    /// Calculate the visual indentation width using default tab width of 4
    pub fn calculate_indentation_width_default(indent_str: &str) -> usize {
        Self::calculate_indentation_width(indent_str, 4)
    }

    /// Check if a line is within a code block
    pub fn is_in_code_block(&self, line_num: usize) -> bool {
        if line_num == 0 || line_num > self.code_block_line_map.len() {
            return false;
        }
        self.code_block_line_map[line_num - 1] // Convert 1-indexed to 0-indexed
    }

    /// Check if a position is within a code span
    pub fn is_in_code_span(&self, position: usize) -> bool {
        self.code_spans
            .iter()
            .any(|span| position >= span.start && position < span.end)
    }

    /// Check if a line is a list item
    pub fn is_list_item(&self, line_num: usize) -> bool {
        if line_num == 0 || line_num > self.list_line_map.len() {
            return false;
        }
        self.list_line_map[line_num - 1] // Convert 1-indexed to 0-indexed
    }

    /// Get list item at line
    pub fn get_list_item(&self, line_num: usize) -> Option<&ListItem> {
        self.list_items.iter().find(|item| item.line_number == line_num)
    }

    /// Get all list items
    pub fn get_list_items(&self) -> &[ListItem] {
        &self.list_items
    }

    /// Get all code blocks
    pub fn get_code_blocks(&self) -> &[CodeBlock] {
        &self.code_blocks
    }

    /// Get all code spans
    pub fn get_code_spans(&self) -> &[Range] {
        &self.code_spans
    }

    /// Detect and populate code blocks
    fn populate_code_blocks(&mut self, content: &str) {
        let lines: Vec<&str> = content.lines().collect();
        let mut in_fenced_block = false;
        let mut fence_marker = String::new();
        let mut block_start_line = 0;
        let mut block_language = String::new();

        for (i, line) in lines.iter().enumerate() {
            if in_fenced_block {
                // Already in a fenced code block, look for the end
                self.code_block_line_map[i] = true;

                if line.trim().starts_with(&fence_marker) {
                    // End of code block
                    let start_pos =
                        lines[0..block_start_line].join("\n").len() + if block_start_line > 0 { 1 } else { 0 };
                    let end_pos = lines[0..=i].join("\n").len();

                    self.code_blocks.push(CodeBlock {
                        range: Range {
                            start: start_pos,
                            end: end_pos,
                        },
                        block_type: CodeBlockType::Fenced,
                        start_line: block_start_line + 1, // 1-indexed
                        end_line: i + 1,                  // 1-indexed
                        language: if !block_language.is_empty() {
                            Some(block_language.clone())
                        } else {
                            None
                        },
                    });

                    in_fenced_block = false;
                    fence_marker.clear();
                    block_language.clear();
                }
            } else if let Some(caps) = CODE_BLOCK_START_REGEX.captures(line) {
                // Start of a new code block
                fence_marker = caps.get(2).map_or("```", |m| m.as_str()).to_string();
                in_fenced_block = true;
                block_start_line = i;
                block_language = caps.get(3).map_or("", |m| m.as_str().trim()).to_string();
                self.code_block_line_map[i] = true;
            } else if INDENTED_CODE_BLOCK_REGEX.is_match(line) {
                // Only mark as indented code block if not a list item
                let is_unordered_list = UNORDERED_LIST_REGEX.is_match(line).unwrap_or(false);
                let is_ordered_list = ORDERED_LIST_REGEX.is_match(line).unwrap_or(false);
                if !is_unordered_list && !is_ordered_list {
                    // Indented code block
                    self.code_block_line_map[i] = true;
                    // For indented code blocks, we handle them as individual lines
                    // We don't track them as blocks with start/end because they can be
                    // interrupted by blank lines, etc.
                    let start_pos = lines[0..i].join("\n").len() + if i > 0 { 1 } else { 0 };
                    let end_pos = start_pos + line.len();
                    self.code_blocks.push(CodeBlock {
                        range: Range {
                            start: start_pos,
                            end: end_pos,
                        },
                        block_type: CodeBlockType::Indented,
                        start_line: i + 1, // 1-indexed
                        end_line: i + 1,   // 1-indexed
                        language: None,
                    });
                }
            }
        }

        // Handle unclosed code block
        if in_fenced_block {
            let start_pos = lines[0..block_start_line].join("\n").len() + if block_start_line > 0 { 1 } else { 0 };
            let end_pos = content.len();

            self.code_blocks.push(CodeBlock {
                range: Range {
                    start: start_pos,
                    end: end_pos,
                },
                block_type: CodeBlockType::Fenced,
                start_line: block_start_line + 1, // 1-indexed
                end_line: lines.len(),            // 1-indexed
                language: if !block_language.is_empty() {
                    Some(block_language)
                } else {
                    None
                },
            });
        }
    }

    /// Detect and populate code spans
    fn populate_code_spans(&mut self, content: &str) {
        // Find inline code spans using regex for backticks
        let mut i = 0;
        while i < content.len() {
            if let Some(m) = CODE_SPAN_REGEX.find_at(content, i) {
                let backtick_length = m.end() - m.start();
                let start = m.start();

                // Find matching closing backticks
                if let Some(end_pos) = content[m.end()..].find(&"`".repeat(backtick_length)) {
                    let end = m.end() + end_pos + backtick_length;
                    self.code_spans.push(Range { start, end });
                    i = end;
                } else {
                    i = m.end();
                }
            } else {
                break;
            }
        }
    }

    /// Detect and populate list items
    fn populate_list_items(&mut self, content: &str) {
        let lines: Vec<&str> = content.lines().collect();
        let mut prev_items: Vec<(usize, usize, usize)> = Vec::new(); // (blockquote_depth, nesting_level, line_number)
        for (i, line) in lines.iter().enumerate() {
            // Skip blank lines but don't reset nesting context
            if line.trim().is_empty() {
                continue;
            }
            // Parse and strip blockquote prefix
            let (blockquote_depth, blockquote_prefix, rest) = Self::parse_blockquote_prefix(line);
            // Always call parse_list_item and always push if Some
            if let Some(item) = self.parse_list_item(
                rest,
                i + 1,
                &mut prev_items,
                blockquote_depth,
                blockquote_prefix.clone(),
            ) {
                self.list_items.push(item);
                self.list_line_map[i] = true;
            }
        }
    }

    /// Parse and strip all leading blockquote markers, returning (depth, prefix, rest_of_line)
    fn parse_blockquote_prefix(line: &str) -> (usize, String, &str) {
        let mut rest = line;
        let mut prefix = String::new();
        let mut depth = 0;
        loop {
            let trimmed = rest.trim_start();
            if let Some(after) = trimmed.strip_prefix('>') {
                // Find the '>' and a single optional space
                let mut chars = after.chars();
                let mut space_count = 0;
                if let Some(' ') = chars.next() {
                    space_count = 1;
                }
                let (spaces, after_marker) = after.split_at(space_count);
                prefix.push('>');
                prefix.push_str(spaces);
                rest = after_marker;
                depth += 1;
            } else {
                break;
            }
        }
        (depth, prefix, rest)
    }

    /// Calculate the nesting level for a list item, considering blockquote depth
    fn calculate_nesting_level(
        &self,
        indent: usize,
        blockquote_depth: usize,
        prev_items: &mut Vec<(usize, usize, usize)>,
    ) -> usize {
        let mut nesting_level = 0;

        // Only consider previous items with the same blockquote depth
        if let Some(&(_last_bq, last_indent, last_level)) =
            prev_items.iter().rev().find(|(bq, _, _)| *bq == blockquote_depth)
        {
            use std::cmp::Ordering;
            match indent.cmp(&last_indent) {
                Ordering::Greater => {
                    // More indented - increase nesting level
                    nesting_level = last_level + 1;
                }
                Ordering::Equal => {
                    // Same indentation - same level
                    nesting_level = last_level;
                }
                Ordering::Less => {
                    // Less indented - find the appropriate level
                    let mut found_level = None;

                    // First look for exact match
                    for &(prev_bq, prev_indent, prev_level) in prev_items.iter().rev() {
                        if prev_bq == blockquote_depth && prev_indent == indent {
                            found_level = Some(prev_level);
                            break;
                        }
                    }

                    // If no exact match, check if this is a case where we should treat similar indentations as same level
                    // This handles mixed tab/space scenarios where 4 and 6 spaces should be at the same level
                    if found_level.is_none() && indent > 0 && last_indent > 0 {
                        // Only apply similar indentation logic if the difference is small and we're dealing with small indentations
                        let diff = (indent as i32 - last_indent as i32).abs();
                        if diff <= 2 && indent <= 8 && last_indent <= 8 {
                            // Check if there's a recent item at a lower indentation level
                            let has_lower_indent = prev_items.iter().rev().take(3).any(|(bq, prev_indent, _)| {
                                *bq == blockquote_depth && *prev_indent < indent.min(last_indent)
                            });
                            if has_lower_indent {
                                found_level = Some(last_level);
                            }
                        }
                    }

                    // If still no match, look for the most recent less indented item
                    if found_level.is_none() {
                        for &(prev_bq, prev_indent, prev_level) in prev_items.iter().rev() {
                            if prev_bq == blockquote_depth && prev_indent < indent {
                                found_level = Some(prev_level);
                                break;
                            }
                        }
                    }

                    nesting_level = found_level.unwrap_or(0);
                }
            }
        }

        // Remove stack entries with indent >= current indent and same blockquote depth
        while let Some(&(prev_bq, prev_indent, _)) = prev_items.last() {
            if prev_bq != blockquote_depth || prev_indent < indent {
                break;
            }
            prev_items.pop();
        }
        prev_items.push((blockquote_depth, indent, nesting_level));
        nesting_level
    }

    /// Parse a line as a list item and determine its nesting level
    fn parse_list_item(
        &self,
        line: &str,
        line_num: usize,
        prev_items: &mut Vec<(usize, usize, usize)>,
        blockquote_depth: usize,
        blockquote_prefix: String,
    ) -> Option<ListItem> {
        match UNORDERED_LIST_REGEX.captures(line) {
            Ok(Some(captures)) => {
                let indent_str = captures.name("indent").map_or("", |m| m.as_str()).to_string();
                let indentation = Self::calculate_indentation_width_default(&indent_str);
                let marker = captures.name("marker").unwrap().as_str();
                let after = captures.name("after").map_or("", |m| m.as_str());
                let spaces = after.len();
                let raw_content = captures.name("content").map_or("", |m| m.as_str());
                let content = raw_content.trim_start().to_string();
                let marker_type = match marker {
                    "*" => ListMarkerType::Asterisk,
                    "+" => ListMarkerType::Plus,
                    "-" => ListMarkerType::Minus,
                    other => {
                        // This should never happen due to regex validation,
                        // but default to dash if it does
                        eprintln!("Warning: Unexpected list marker '{other}', defaulting to dash");
                        ListMarkerType::Minus
                    }
                };
                let nesting_level = self.calculate_nesting_level(indentation, blockquote_depth, prev_items);
                // Find parent: most recent previous item with lower nesting_level and same blockquote depth
                let parent_line_number = prev_items
                    .iter()
                    .rev()
                    .find(|(bq, _, level)| *bq == blockquote_depth && *level < nesting_level)
                    .map(|(_, _, line_num)| *line_num);
                return Some(ListItem {
                    line_number: line_num,
                    indentation,
                    indent_str,
                    marker_type,
                    marker: marker.to_string(),
                    content,
                    spaces_after_marker: spaces,
                    nesting_level,
                    parent_line_number,
                    blockquote_depth,
                    blockquote_prefix,
                });
            }
            Ok(None) => {
                // No debug output
            }
            Err(_) => {}
        }
        match ORDERED_LIST_REGEX.captures(line) {
            Ok(Some(captures)) => {
                let indent_str = captures.name("indent").map_or("", |m| m.as_str()).to_string();
                let indentation = Self::calculate_indentation_width_default(&indent_str);
                let marker = captures.name("marker").unwrap().as_str();
                let spaces = captures.name("after").map_or(0, |m| m.as_str().len());
                let content = captures
                    .name("content")
                    .map_or("", |m| m.as_str())
                    .trim_start()
                    .to_string();
                let nesting_level = self.calculate_nesting_level(indentation, blockquote_depth, prev_items);
                // Find parent: most recent previous item with lower nesting_level and same blockquote depth
                let parent_line_number = prev_items
                    .iter()
                    .rev()
                    .find(|(bq, _, level)| *bq == blockquote_depth && *level < nesting_level)
                    .map(|(_, _, line_num)| *line_num);
                return Some(ListItem {
                    line_number: line_num,
                    indentation,
                    indent_str,
                    marker_type: ListMarkerType::Ordered,
                    marker: marker.to_string(),
                    content,
                    spaces_after_marker: spaces,
                    nesting_level,
                    parent_line_number,
                    blockquote_depth,
                    blockquote_prefix,
                });
            }
            Ok(None) => {}
            Err(_) => {}
        }
        None
    }
}

// Global cache for sharing across threads
static ELEMENT_CACHE: LazyLock<Arc<Mutex<Option<ElementCache>>>> = LazyLock::new(|| Arc::new(Mutex::new(None)));

/// Get or create element cache for document content
///
/// If the mutex is poisoned, creates a fresh cache without storing it globally.
/// This ensures the library never panics due to mutex poisoning.
pub fn get_element_cache(content: &str) -> ElementCache {
    // Try to get existing cache
    if let Ok(cache_guard) = ELEMENT_CACHE.lock() {
        // If cache exists and content matches (by hash), return it
        if let Some(existing_cache) = &*cache_guard
            && existing_cache.is_valid_for(content)
        {
            return existing_cache.clone();
        }
    }

    // Content doesn't match or mutex poisoned, create new cache
    let new_cache = ElementCache::new(content);

    // Store in global cache (ignore if mutex is poisoned)
    if let Ok(mut cache_guard) = ELEMENT_CACHE.lock() {
        *cache_guard = Some(new_cache.clone());
    }

    new_cache
}

/// Reset the element cache
///
/// If the mutex is poisoned, this is a no-op.
pub fn reset_element_cache() {
    if let Ok(mut cache_guard) = ELEMENT_CACHE.lock() {
        *cache_guard = None;
    }
}

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

    #[test]
    fn test_code_block_detection() {
        let content = "Regular text\n\n```rust\nfn main() {\n    println!(\"Hello\");\n}\n```\n\nMore text";
        let cache = ElementCache::new(content);

        assert_eq!(cache.code_blocks.len(), 1);
        assert_eq!(cache.code_blocks[0].start_line, 3);
        assert_eq!(cache.code_blocks[0].end_line, 7);
        assert_eq!(cache.code_blocks[0].block_type, CodeBlockType::Fenced);
        assert_eq!(cache.code_blocks[0].language, Some("rust".to_string()));

        assert!(!cache.is_in_code_block(1));
        assert!(!cache.is_in_code_block(2));
        assert!(cache.is_in_code_block(3));
        assert!(cache.is_in_code_block(4));
        assert!(cache.is_in_code_block(5));
        assert!(cache.is_in_code_block(6));
        assert!(cache.is_in_code_block(7));
        assert!(!cache.is_in_code_block(8));
        assert!(!cache.is_in_code_block(9));
    }

    #[test]
    fn test_list_item_detection_simple() {
        let content =
            "# Heading\n\n- First item\n  - Nested item\n- Second item\n\n1. Ordered item\n   1. Nested ordered\n";
        let cache = ElementCache::new(content);
        assert_eq!(cache.list_items.len(), 5);
        // Check the first item
        assert_eq!(cache.list_items[0].line_number, 3);
        assert_eq!(cache.list_items[0].marker, "-");
        assert_eq!(cache.list_items[0].nesting_level, 0);
        // Check the nested item
        assert_eq!(cache.list_items[1].line_number, 4);
        assert_eq!(cache.list_items[1].marker, "-");
        assert_eq!(cache.list_items[1].nesting_level, 1);
        // Check the second list item
        assert_eq!(cache.list_items[2].line_number, 5);
        assert_eq!(cache.list_items[2].marker, "-");
        assert_eq!(cache.list_items[2].nesting_level, 0);
        // Check ordered list item
        assert_eq!(cache.list_items[3].line_number, 7);
        assert_eq!(cache.list_items[3].marker, "1.");
        assert_eq!(cache.list_items[3].nesting_level, 0);
        // Check nested ordered list item
        assert_eq!(cache.list_items[4].line_number, 8);
        assert_eq!(cache.list_items[4].marker, "1.");
        assert_eq!(cache.list_items[4].nesting_level, 1);
    }

    #[test]
    fn test_list_item_detection_complex() {
        let complex = "  * Level 1 item 1\n    - Level 2 item 1\n      + Level 3 item 1\n    - Level 2 item 2\n  * Level 1 item 2\n\n* Top\n  + Nested\n    - Deep\n      * Deeper\n        + Deepest\n";
        let cache = ElementCache::new(complex);

        // Should detect all 10 list items
        assert_eq!(cache.list_items.len(), 10);
        // Check markers and nesting levels
        assert_eq!(cache.list_items[0].marker, "*");
        assert_eq!(cache.list_items[0].nesting_level, 0);
        assert_eq!(cache.list_items[1].marker, "-");
        assert_eq!(cache.list_items[1].nesting_level, 1);
        assert_eq!(cache.list_items[2].marker, "+");
        assert_eq!(cache.list_items[2].nesting_level, 2);
        assert_eq!(cache.list_items[3].marker, "-");
        assert_eq!(cache.list_items[3].nesting_level, 1);
        assert_eq!(cache.list_items[4].marker, "*");
        assert_eq!(cache.list_items[4].nesting_level, 0);
        assert_eq!(cache.list_items[5].marker, "*");
        assert_eq!(cache.list_items[5].nesting_level, 0);
        assert_eq!(cache.list_items[6].marker, "+");
        assert_eq!(cache.list_items[6].nesting_level, 1);
        assert_eq!(cache.list_items[7].marker, "-");
        assert_eq!(cache.list_items[7].nesting_level, 2);
        assert_eq!(cache.list_items[8].marker, "*");
        assert_eq!(cache.list_items[8].nesting_level, 3);
        assert_eq!(cache.list_items[9].marker, "+");
        assert_eq!(cache.list_items[9].nesting_level, 4);
        let expected_nesting = vec![0, 1, 2, 1, 0, 0, 1, 2, 3, 4];
        let actual_nesting: Vec<_> = cache.list_items.iter().map(|item| item.nesting_level).collect();
        assert_eq!(
            actual_nesting, expected_nesting,
            "Nesting levels should match expected values"
        );
    }

    #[test]
    fn test_list_item_detection_edge() {
        let edge = "* Item 1\n\n    - Nested 1\n  + Nested 2\n\n* Item 2\n";
        let cache = ElementCache::new(edge);
        assert_eq!(cache.list_items.len(), 4);

        // Check correct nesting levels according to CommonMark:
        // * Item 1 (indent=0) -> level 0
        // - Nested 1 (indent=4) -> level 1 (nested under Item 1)
        // + Nested 2 (indent=2) -> level 1 (nested under Item 1)
        // * Item 2 (indent=0) -> level 0
        let expected_nesting = vec![0, 1, 1, 0];
        let actual_nesting: Vec<_> = cache.list_items.iter().map(|item| item.nesting_level).collect();
        assert_eq!(
            actual_nesting, expected_nesting,
            "Nesting levels should be calculated based on indentation, not reset by blank lines"
        );
    }

    #[test]
    fn test_code_span_detection() {
        let content = "Here is some `inline code` and here are ``nested `code` spans``";
        let cache = ElementCache::new(content);

        // Should have two code spans
        assert_eq!(cache.code_spans.len(), 2);

        // Check spans
        let span1_content = &content[cache.code_spans[0].start..cache.code_spans[0].end];
        assert_eq!(span1_content, "`inline code`");

        let span2_content = &content[cache.code_spans[1].start..cache.code_spans[1].end];
        assert_eq!(span2_content, "``nested `code` spans``");
    }

    #[test]
    fn test_get_element_cache() {
        let content1 = "Test content";
        let content2 = "Different content";

        // First call should create a new cache
        let cache1 = get_element_cache(content1);

        // Second call with same content should return the same cache
        let cache2 = get_element_cache(content1);

        // Third call with different content should create new cache
        let cache3 = get_element_cache(content2);

        // Verify caches are valid for their respective content
        assert!(cache1.is_valid_for(content1));
        assert!(cache2.is_valid_for(content1));
        assert!(cache3.is_valid_for(content2));

        // Verify caches are NOT valid for different content
        assert!(!cache1.is_valid_for(content2));
        assert!(!cache3.is_valid_for(content1));
    }

    #[test]
    fn test_list_item_detection_deep_nesting_and_edge_cases() {
        // Deeply nested unordered lists, mixed markers, excessive indentation, tabs, and blank lines
        let content = "\
* Level 1
  - Level 2
    + Level 3
      * Level 4
        - Level 5
          + Level 6
* Sibling 1
    * Sibling 2
\n    - After blank line, not nested\n\n\t* Tab indented\n        * 8 spaces indented\n* After excessive indent\n";
        let cache = ElementCache::new(content);
        // Should detect all lines that start with a valid unordered list marker
        let _expected_markers = ["*", "-", "+", "*", "-", "+", "*", "*", "-", "*", "*", "*"];
        let _expected_indents = [0, 4, 8, 0, 4, 8, 0, 4, 8, 12, 16, 20];
        let expected_content = vec![
            "Level 1",
            "Level 2",
            "Level 3",
            "Level 4",
            "Level 5",
            "Level 6",
            "Sibling 1",
            "Sibling 2",
            "After blank line, not nested",
            "Tab indented",      // Content after marker
            "8 spaces indented", // Content after marker
            "After excessive indent",
        ];
        let actual_content: Vec<_> = cache.list_items.iter().map(|item| item.content.clone()).collect();
        assert_eq!(
            actual_content, expected_content,
            "List item contents should match expected values"
        );
        // Updated expected nesting levels based on correct CommonMark behavior:
        // Blank lines should NOT reset nesting context
        let expected_nesting = vec![0, 1, 2, 3, 4, 5, 0, 1, 1, 1, 2, 0];
        let actual_nesting: Vec<_> = cache.list_items.iter().map(|item| item.nesting_level).collect();
        assert_eq!(
            actual_nesting, expected_nesting,
            "Nesting levels should match expected values"
        );
        // Check that tab-indented and 8-space-indented items are detected
        assert!(
            cache
                .list_items
                .iter()
                .any(|item| item.marker == "*" && item.indentation >= 1),
            "Tab or 8-space indented item not detected"
        );
        // Check that after blank lines, items maintain correct nesting based on indentation
        let after_blank = cache
            .list_items
            .iter()
            .find(|item| item.content.contains("After blank line"));
        assert!(after_blank.is_some());
        assert_eq!(
            after_blank.unwrap().nesting_level,
            1,
            "Item after blank line should maintain nesting based on indentation"
        );
    }

    #[test]
    fn test_tab_indentation_calculation() {
        // Test that tabs are properly converted to spaces for indentation calculation
        let content = "* Level 0\n\t* Tab indented (should be level 1)\n\t\t* Double tab (should be level 2)\n    * 4 spaces (should be level 1)\n        * 8 spaces (should be level 2)\n";
        let cache = ElementCache::new(content);

        assert_eq!(cache.list_items.len(), 5);

        // Check indentation values (tabs should be converted to spaces)
        assert_eq!(cache.list_items[0].indentation, 0); // "* Level 0"
        assert_eq!(cache.list_items[1].indentation, 4); // "\t* Tab indented" (tab = 4 spaces)
        assert_eq!(cache.list_items[2].indentation, 8); // "\t\t* Double tab" (2 tabs = 8 spaces)
        assert_eq!(cache.list_items[3].indentation, 4); // "    * 4 spaces"
        assert_eq!(cache.list_items[4].indentation, 8); // "        * 8 spaces"

        // Check nesting levels
        assert_eq!(cache.list_items[0].nesting_level, 0);
        assert_eq!(cache.list_items[1].nesting_level, 1);
        assert_eq!(cache.list_items[2].nesting_level, 2);
        assert_eq!(cache.list_items[3].nesting_level, 1);
        assert_eq!(cache.list_items[4].nesting_level, 2);
    }

    #[test]
    fn test_mixed_tabs_and_spaces_indentation() {
        // Test mixed tabs and spaces
        let content = "* Level 0\n\t  * Tab + 2 spaces (should be level 1)\n  \t* 2 spaces + tab (should be level 1)\n\t\t  * 2 tabs + 2 spaces (should be level 2)\n";

        // Clear any cached data to ensure fresh parsing
        reset_element_cache();
        let cache = ElementCache::new(content);

        assert_eq!(cache.list_items.len(), 4);

        // Check indentation values
        assert_eq!(cache.list_items[0].indentation, 0); // "* Level 0"
        assert_eq!(cache.list_items[1].indentation, 6); // "\t  * Tab + 2 spaces" (tab to 4 + 2 spaces = 6)
        assert_eq!(cache.list_items[2].indentation, 4); // "  \t* 2 spaces + tab" (2 spaces, then tab to next stop = 4)
        assert_eq!(cache.list_items[3].indentation, 10); // "\t\t  * 2 tabs + 2 spaces" (2 tabs = 8 + 2 spaces = 10)

        // Check nesting levels
        assert_eq!(cache.list_items[0].nesting_level, 0);
        assert_eq!(cache.list_items[1].nesting_level, 1);
        assert_eq!(cache.list_items[2].nesting_level, 1);
        assert_eq!(cache.list_items[3].nesting_level, 2);
    }

    #[test]
    fn test_tab_width_configuration() {
        // Test with different tab widths (default should be 4)
        let content = "\t* Single tab\n\t\t* Double tab\n";
        let cache = ElementCache::new(content);

        assert_eq!(cache.list_items.len(), 2);

        // With default tab width of 4
        assert_eq!(cache.list_items[0].indentation, 4); // "\t*" = 4 spaces
        assert_eq!(cache.list_items[1].indentation, 8); // "\t\t*" = 8 spaces

        // Check nesting levels
        assert_eq!(cache.list_items[0].nesting_level, 0);
        assert_eq!(cache.list_items[1].nesting_level, 1);
    }

    #[test]
    fn test_tab_expansion_debug() {
        // Debug the tab expansion logic
        assert_eq!(ElementCache::calculate_indentation_width_default(""), 0);
        assert_eq!(ElementCache::calculate_indentation_width_default(" "), 1);
        assert_eq!(ElementCache::calculate_indentation_width_default("  "), 2);
        assert_eq!(ElementCache::calculate_indentation_width_default("    "), 4);
        assert_eq!(ElementCache::calculate_indentation_width_default("\t"), 4);
        assert_eq!(ElementCache::calculate_indentation_width_default("\t\t"), 8);
        assert_eq!(ElementCache::calculate_indentation_width_default("\t  "), 6); // tab to 4, then 2 spaces = 6
        assert_eq!(ElementCache::calculate_indentation_width_default("  \t"), 4); // 2 spaces, then tab to next stop (4)
        assert_eq!(ElementCache::calculate_indentation_width_default("\t\t  "), 10);
        // 2 tabs = 8, then 2 spaces = 10
    }

    #[test]
    fn test_mixed_tabs_debug() {
        // Debug the specific failing case
        let content = "* Level 0\n\t  * Tab + 2 spaces (should be level 1)\n  \t* 2 spaces + tab (should be level 1)\n\t\t  * 2 tabs + 2 spaces (should be level 2)\n";
        let cache = ElementCache::new(content);

        println!("Number of list items: {}", cache.list_items.len());
        for (i, item) in cache.list_items.iter().enumerate() {
            println!(
                "Item {}: indent_str={:?}, indentation={}, content={:?}",
                i, item.indent_str, item.indentation, item.content
            );
        }

        // Test the specific indentation strings
        assert_eq!(ElementCache::calculate_indentation_width_default("\t  "), 6); // tab + 2 spaces
        assert_eq!(ElementCache::calculate_indentation_width_default("  \t"), 4); // 2 spaces + tab
        assert_eq!(ElementCache::calculate_indentation_width_default("\t\t  "), 10);
        // 2 tabs + 2 spaces
    }
}