rumdl_lib/utils/

text_reflow.rs

//! Text reflow utilities for MD013
//!
//! This module implements text wrapping/reflow functionality that preserves
//! Markdown elements like links, emphasis, code spans, etc.

use crate::utils::is_definition_list_item;
use crate::utils::regex_cache::{
    DISPLAY_MATH_REGEX, EMOJI_SHORTCODE_REGEX, FOOTNOTE_REF_REGEX, HTML_ENTITY_REGEX, HTML_TAG_PATTERN,
    INLINE_IMAGE_FANCY_REGEX, INLINE_LINK_FANCY_REGEX, INLINE_MATH_REGEX, REF_IMAGE_REGEX, REF_LINK_REGEX,
    SHORTCUT_REF_REGEX, STRIKETHROUGH_FANCY_REGEX, WIKI_LINK_REGEX,
};
/// Options for reflowing text
#[derive(Clone)]
pub struct ReflowOptions {
    /// Target line length
    pub line_length: usize,
    /// Whether to break on sentence boundaries when possible
    pub break_on_sentences: bool,
    /// Whether to preserve existing line breaks in paragraphs
    pub preserve_breaks: bool,
    /// Whether to enforce one sentence per line
    pub sentence_per_line: bool,
}

impl Default for ReflowOptions {
    fn default() -> Self {
        Self {
            line_length: 80,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: false,
        }
    }
}

/// Detect if a character position is a sentence boundary
/// Based on the approach from github.com/JoshuaKGoldberg/sentences-per-line
fn is_sentence_boundary(text: &str, pos: usize) -> bool {
    let chars: Vec<char> = text.chars().collect();

    if pos + 1 >= chars.len() {
        return false;
    }

    // Check for sentence-ending punctuation
    let c = chars[pos];
    if c != '.' && c != '!' && c != '?' {
        return false;
    }

    // Must be followed by at least one space
    if chars[pos + 1] != ' ' {
        return false;
    }

    // Skip all whitespace after the punctuation to find the start of the next sentence
    let mut next_char_pos = pos + 2;
    while next_char_pos < chars.len() && chars[next_char_pos].is_whitespace() {
        next_char_pos += 1;
    }

    // Check if we reached the end of the string
    if next_char_pos >= chars.len() {
        return false;
    }

    // Next character after space(s) must be uppercase (new sentence indicator)
    if !chars[next_char_pos].is_uppercase() {
        return false;
    }

    // Look back to check for common abbreviations
    if pos > 0 {
        // Abbreviation list similar to sentences-per-line
        let prev_word = &text[..pos];
        let ignored_words = [
            "ie", "i.e", "eg", "e.g", "etc", "ex", "vs", "Mr", "Mrs", "Dr", "Ms", "Prof", "Sr", "Jr",
        ];
        for word in &ignored_words {
            if prev_word.to_lowercase().ends_with(&word.to_lowercase()) {
                return false;
            }
        }

        // Check for decimal numbers (e.g., "3.14")
        // Make sure to check if next_char_pos is within bounds
        if pos > 0 && chars[pos - 1].is_numeric() && next_char_pos < chars.len() && chars[next_char_pos].is_numeric() {
            return false;
        }
    }
    true
}

/// Split text into sentences
pub fn split_into_sentences(text: &str) -> Vec<String> {
    let mut sentences = Vec::new();
    let mut current_sentence = String::new();
    let mut chars = text.chars().peekable();
    let mut pos = 0;

    while let Some(c) = chars.next() {
        current_sentence.push(c);

        if is_sentence_boundary(text, pos) {
            // Include the space after sentence if it exists
            if chars.peek() == Some(&' ') {
                chars.next();
                pos += 1;
            }
            sentences.push(current_sentence.trim().to_string());
            current_sentence.clear();
        }

        pos += 1;
    }

    // Add any remaining text as the last sentence
    if !current_sentence.trim().is_empty() {
        sentences.push(current_sentence.trim().to_string());
    }
    sentences
}

/// Check if a line is a horizontal rule (---, ___, ***)
fn is_horizontal_rule(line: &str) -> bool {
    if line.len() < 3 {
        return false;
    }

    // Check if line consists only of -, _, or * characters (at least 3)
    let chars: Vec<char> = line.chars().collect();
    if chars.is_empty() {
        return false;
    }

    let first_char = chars[0];
    if first_char != '-' && first_char != '_' && first_char != '*' {
        return false;
    }

    // All characters should be the same (allowing spaces between)
    for c in &chars {
        if *c != first_char && *c != ' ' {
            return false;
        }
    }

    // Count non-space characters
    let non_space_count = chars.iter().filter(|c| **c != ' ').count();
    non_space_count >= 3
}

/// Check if a line is a numbered list item (e.g., "1. ", "10. ")
fn is_numbered_list_item(line: &str) -> bool {
    let mut chars = line.chars();

    // Must start with a digit
    if !chars.next().is_some_and(|c| c.is_numeric()) {
        return false;
    }

    // Can have more digits
    while let Some(c) = chars.next() {
        if c == '.' {
            // After period, must have a space or be end of line
            return chars.next().is_none_or(|c| c == ' ');
        }
        if !c.is_numeric() {
            return false;
        }
    }

    false
}

/// Check if a line ends with a hard break (either two spaces or backslash)
///
/// CommonMark supports two formats for hard line breaks:
/// 1. Two or more trailing spaces
/// 2. A backslash at the end of the line
fn has_hard_break(line: &str) -> bool {
    let line = line.strip_suffix('\r').unwrap_or(line);
    line.ends_with("  ") || line.ends_with('\\')
}

/// Trim trailing whitespace while preserving hard breaks (two trailing spaces or backslash)
///
/// Hard breaks in Markdown can be indicated by:
/// 1. Two trailing spaces before a newline (traditional)
/// 2. A backslash at the end of the line (mdformat style)
fn trim_preserving_hard_break(s: &str) -> String {
    // Strip trailing \r from CRLF line endings first to handle Windows files
    let s = s.strip_suffix('\r').unwrap_or(s);

    // Check for backslash hard break (mdformat style)
    if s.ends_with('\\') {
        // Preserve the backslash exactly as-is
        return s.to_string();
    }

    // Check if there are at least 2 trailing spaces (traditional hard break)
    if s.ends_with("  ") {
        // Find the position where non-space content ends
        let content_end = s.trim_end().len();
        if content_end == 0 {
            // String is all whitespace
            return String::new();
        }
        // Preserve exactly 2 trailing spaces for hard break
        format!("{}  ", &s[..content_end])
    } else {
        // No hard break, just trim all trailing whitespace
        s.trim_end().to_string()
    }
}

pub fn reflow_line(line: &str, options: &ReflowOptions) -> Vec<String> {
    // For sentence-per-line mode, always process regardless of length
    if options.sentence_per_line {
        let elements = parse_markdown_elements(line);
        return reflow_elements_sentence_per_line(&elements);
    }

    // Quick check: if line is already short enough, return as-is
    if line.chars().count() <= options.line_length {
        return vec![line.to_string()];
    }

    // Parse the markdown to identify elements
    let elements = parse_markdown_elements(line);

    // Reflow the elements into lines
    reflow_elements(&elements, options)
}

/// Represents a piece of content in the markdown
#[derive(Debug, Clone)]
enum Element {
    /// Plain text that can be wrapped
    Text(String),
    /// A complete markdown inline link [text](url)
    Link { text: String, url: String },
    /// A complete markdown reference link [text][ref]
    ReferenceLink { text: String, reference: String },
    /// A complete markdown empty reference link [text][]
    EmptyReferenceLink { text: String },
    /// A complete markdown shortcut reference link [ref]
    ShortcutReference { reference: String },
    /// A complete markdown inline image ![alt](url)
    InlineImage { alt: String, url: String },
    /// A complete markdown reference image ![alt][ref]
    ReferenceImage { alt: String, reference: String },
    /// A complete markdown empty reference image ![alt][]
    EmptyReferenceImage { alt: String },
    /// Footnote reference [^note]
    FootnoteReference { note: String },
    /// Strikethrough text ~~text~~
    Strikethrough(String),
    /// Wiki-style link [[wiki]] or [[wiki|text]]
    WikiLink(String),
    /// Inline math $math$
    InlineMath(String),
    /// Display math $$math$$
    DisplayMath(String),
    /// Emoji shortcode :emoji:
    EmojiShortcode(String),
    /// HTML tag <tag> or </tag> or <tag/>
    HtmlTag(String),
    /// HTML entity &nbsp; or &#123;
    HtmlEntity(String),
    /// Inline code `code`
    Code(String),
    /// Bold text **text**
    Bold(String),
    /// Italic text *text*
    Italic(String),
}

impl std::fmt::Display for Element {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Element::Text(s) => write!(f, "{s}"),
            Element::Link { text, url } => write!(f, "[{text}]({url})"),
            Element::ReferenceLink { text, reference } => write!(f, "[{text}][{reference}]"),
            Element::EmptyReferenceLink { text } => write!(f, "[{text}][]"),
            Element::ShortcutReference { reference } => write!(f, "[{reference}]"),
            Element::InlineImage { alt, url } => write!(f, "![{alt}]({url})"),
            Element::ReferenceImage { alt, reference } => write!(f, "![{alt}][{reference}]"),
            Element::EmptyReferenceImage { alt } => write!(f, "![{alt}][]"),
            Element::FootnoteReference { note } => write!(f, "[^{note}]"),
            Element::Strikethrough(s) => write!(f, "~~{s}~~"),
            Element::WikiLink(s) => write!(f, "[[{s}]]"),
            Element::InlineMath(s) => write!(f, "${s}$"),
            Element::DisplayMath(s) => write!(f, "$${s}$$"),
            Element::EmojiShortcode(s) => write!(f, ":{s}:"),
            Element::HtmlTag(s) => write!(f, "{s}"),
            Element::HtmlEntity(s) => write!(f, "{s}"),
            Element::Code(s) => write!(f, "`{s}`"),
            Element::Bold(s) => write!(f, "**{s}**"),
            Element::Italic(s) => write!(f, "*{s}*"),
        }
    }
}

impl Element {
    fn len(&self) -> usize {
        match self {
            Element::Text(s) => s.chars().count(),
            Element::Link { text, url } => text.chars().count() + url.chars().count() + 4, // [text](url)
            Element::ReferenceLink { text, reference } => text.chars().count() + reference.chars().count() + 4, // [text][ref]
            Element::EmptyReferenceLink { text } => text.chars().count() + 4, // [text][]
            Element::ShortcutReference { reference } => reference.chars().count() + 2, // [ref]
            Element::InlineImage { alt, url } => alt.chars().count() + url.chars().count() + 5, // ![alt](url)
            Element::ReferenceImage { alt, reference } => alt.chars().count() + reference.chars().count() + 5, // ![alt][ref]
            Element::EmptyReferenceImage { alt } => alt.chars().count() + 5, // ![alt][]
            Element::FootnoteReference { note } => note.chars().count() + 3, // [^note]
            Element::Strikethrough(s) => s.chars().count() + 4,              // ~~text~~
            Element::WikiLink(s) => s.chars().count() + 4,                   // [[wiki]]
            Element::InlineMath(s) => s.chars().count() + 2,                 // $math$
            Element::DisplayMath(s) => s.chars().count() + 4,                // $$math$$
            Element::EmojiShortcode(s) => s.chars().count() + 2,             // :emoji:
            Element::HtmlTag(s) => s.chars().count(),                        // <tag> - already includes brackets
            Element::HtmlEntity(s) => s.chars().count(),                     // &nbsp; - already complete
            Element::Code(s) => s.chars().count() + 2,                       // `code`
            Element::Bold(s) => s.chars().count() + 4,                       // **text**
            Element::Italic(s) => s.chars().count() + 2,                     // *text*
        }
    }
}

/// Parse markdown elements from text preserving the raw syntax
///
/// Detection order is critical:
/// 1. Inline links [text](url) - must be detected first to avoid conflicts
/// 2. Reference links [text][ref] - detected before shortcut references
/// 3. Empty reference links [text][] - a special case of reference links
/// 4. Shortcut reference links [ref] - detected last to avoid false positives
/// 5. Other elements (code, bold, italic) - processed normally
fn parse_markdown_elements(text: &str) -> Vec<Element> {
    let mut elements = Vec::new();
    let mut remaining = text;

    while !remaining.is_empty() {
        // Find the earliest occurrence of any markdown pattern
        let mut earliest_match: Option<(usize, &str, fancy_regex::Match)> = None;

        // Check for images first (they start with ! so should be detected before links)
        // Inline images - ![alt](url)
        if let Ok(Some(m)) = INLINE_IMAGE_FANCY_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "inline_image", m));
        }

        // Reference images - ![alt][ref]
        if let Ok(Some(m)) = REF_IMAGE_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "ref_image", m));
        }

        // Check for footnote references - [^note]
        if let Ok(Some(m)) = FOOTNOTE_REF_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "footnote_ref", m));
        }

        // Check for inline links - [text](url)
        if let Ok(Some(m)) = INLINE_LINK_FANCY_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "inline_link", m));
        }

        // Check for reference links - [text][ref]
        if let Ok(Some(m)) = REF_LINK_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "ref_link", m));
        }

        // Check for shortcut reference links - [ref]
        // Only check if we haven't found an earlier pattern that would conflict
        if let Ok(Some(m)) = SHORTCUT_REF_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "shortcut_ref", m));
        }

        // Check for wiki-style links - [[wiki]]
        if let Ok(Some(m)) = WIKI_LINK_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "wiki_link", m));
        }

        // Check for display math first (before inline) - $$math$$
        if let Ok(Some(m)) = DISPLAY_MATH_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "display_math", m));
        }

        // Check for inline math - $math$
        if let Ok(Some(m)) = INLINE_MATH_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "inline_math", m));
        }

        // Check for strikethrough - ~~text~~
        if let Ok(Some(m)) = STRIKETHROUGH_FANCY_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "strikethrough", m));
        }

        // Check for emoji shortcodes - :emoji:
        if let Ok(Some(m)) = EMOJI_SHORTCODE_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "emoji", m));
        }

        // Check for HTML entities - &nbsp; etc
        if let Ok(Some(m)) = HTML_ENTITY_REGEX.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            earliest_match = Some((m.start(), "html_entity", m));
        }

        // Check for HTML tags - <tag> </tag> <tag/>
        // But exclude autolinks like <https://...> or <mailto:...>
        if let Ok(Some(m)) = HTML_TAG_PATTERN.find(remaining)
            && earliest_match.as_ref().is_none_or(|(start, _, _)| m.start() < *start)
        {
            // Check if this is an autolink (starts with protocol or mailto:)
            let matched_text = &remaining[m.start()..m.end()];
            let is_autolink = matched_text.starts_with("<http://")
                || matched_text.starts_with("<https://")
                || matched_text.starts_with("<mailto:")
                || matched_text.starts_with("<ftp://")
                || matched_text.starts_with("<ftps://");

            if !is_autolink {
                earliest_match = Some((m.start(), "html_tag", m));
            }
        }

        // Find earliest non-link special characters
        let mut next_special = remaining.len();
        let mut special_type = "";

        if let Some(pos) = remaining.find('`')
            && pos < next_special
        {
            next_special = pos;
            special_type = "code";
        }
        if let Some(pos) = remaining.find("**")
            && pos < next_special
        {
            next_special = pos;
            special_type = "bold";
        }
        if let Some(pos) = remaining.find('*')
            && pos < next_special
            && !remaining[pos..].starts_with("**")
        {
            next_special = pos;
            special_type = "italic";
        }

        // Determine which pattern to process first
        let should_process_markdown_link = if let Some((pos, _, _)) = earliest_match {
            pos < next_special
        } else {
            false
        };

        if should_process_markdown_link {
            let (pos, pattern_type, match_obj) = earliest_match.unwrap();

            // Add any text before the match
            if pos > 0 {
                elements.push(Element::Text(remaining[..pos].to_string()));
            }

            // Process the matched pattern
            match pattern_type {
                "inline_image" => {
                    if let Ok(Some(caps)) = INLINE_IMAGE_FANCY_REGEX.captures(remaining) {
                        let alt = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        let url = caps.get(2).map(|m| m.as_str()).unwrap_or("");
                        elements.push(Element::InlineImage {
                            alt: alt.to_string(),
                            url: url.to_string(),
                        });
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        elements.push(Element::Text("!".to_string()));
                        remaining = &remaining[1..];
                    }
                }
                "ref_image" => {
                    if let Ok(Some(caps)) = REF_IMAGE_REGEX.captures(remaining) {
                        let alt = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        let reference = caps.get(2).map(|m| m.as_str()).unwrap_or("");

                        if reference.is_empty() {
                            elements.push(Element::EmptyReferenceImage { alt: alt.to_string() });
                        } else {
                            elements.push(Element::ReferenceImage {
                                alt: alt.to_string(),
                                reference: reference.to_string(),
                            });
                        }
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        elements.push(Element::Text("!".to_string()));
                        remaining = &remaining[1..];
                    }
                }
                "footnote_ref" => {
                    if let Ok(Some(caps)) = FOOTNOTE_REF_REGEX.captures(remaining) {
                        let note = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        elements.push(Element::FootnoteReference { note: note.to_string() });
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        elements.push(Element::Text("[".to_string()));
                        remaining = &remaining[1..];
                    }
                }
                "inline_link" => {
                    if let Ok(Some(caps)) = INLINE_LINK_FANCY_REGEX.captures(remaining) {
                        let text = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        let url = caps.get(2).map(|m| m.as_str()).unwrap_or("");
                        elements.push(Element::Link {
                            text: text.to_string(),
                            url: url.to_string(),
                        });
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        // Fallback - shouldn't happen
                        elements.push(Element::Text("[".to_string()));
                        remaining = &remaining[1..];
                    }
                }
                "ref_link" => {
                    if let Ok(Some(caps)) = REF_LINK_REGEX.captures(remaining) {
                        let text = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        let reference = caps.get(2).map(|m| m.as_str()).unwrap_or("");

                        if reference.is_empty() {
                            // Empty reference link [text][]
                            elements.push(Element::EmptyReferenceLink { text: text.to_string() });
                        } else {
                            // Regular reference link [text][ref]
                            elements.push(Element::ReferenceLink {
                                text: text.to_string(),
                                reference: reference.to_string(),
                            });
                        }
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        // Fallback - shouldn't happen
                        elements.push(Element::Text("[".to_string()));
                        remaining = &remaining[1..];
                    }
                }
                "shortcut_ref" => {
                    if let Ok(Some(caps)) = SHORTCUT_REF_REGEX.captures(remaining) {
                        let reference = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        elements.push(Element::ShortcutReference {
                            reference: reference.to_string(),
                        });
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        // Fallback - shouldn't happen
                        elements.push(Element::Text("[".to_string()));
                        remaining = &remaining[1..];
                    }
                }
                "wiki_link" => {
                    if let Ok(Some(caps)) = WIKI_LINK_REGEX.captures(remaining) {
                        let content = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        elements.push(Element::WikiLink(content.to_string()));
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        elements.push(Element::Text("[[".to_string()));
                        remaining = &remaining[2..];
                    }
                }
                "display_math" => {
                    if let Ok(Some(caps)) = DISPLAY_MATH_REGEX.captures(remaining) {
                        let math = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        elements.push(Element::DisplayMath(math.to_string()));
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        elements.push(Element::Text("$$".to_string()));
                        remaining = &remaining[2..];
                    }
                }
                "inline_math" => {
                    if let Ok(Some(caps)) = INLINE_MATH_REGEX.captures(remaining) {
                        let math = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        elements.push(Element::InlineMath(math.to_string()));
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        elements.push(Element::Text("$".to_string()));
                        remaining = &remaining[1..];
                    }
                }
                "strikethrough" => {
                    if let Ok(Some(caps)) = STRIKETHROUGH_FANCY_REGEX.captures(remaining) {
                        let text = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        elements.push(Element::Strikethrough(text.to_string()));
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        elements.push(Element::Text("~~".to_string()));
                        remaining = &remaining[2..];
                    }
                }
                "emoji" => {
                    if let Ok(Some(caps)) = EMOJI_SHORTCODE_REGEX.captures(remaining) {
                        let emoji = caps.get(1).map(|m| m.as_str()).unwrap_or("");
                        elements.push(Element::EmojiShortcode(emoji.to_string()));
                        remaining = &remaining[match_obj.end()..];
                    } else {
                        elements.push(Element::Text(":".to_string()));
                        remaining = &remaining[1..];
                    }
                }
                "html_entity" => {
                    // HTML entities are captured whole
                    elements.push(Element::HtmlEntity(remaining[..match_obj.end()].to_string()));
                    remaining = &remaining[match_obj.end()..];
                }
                "html_tag" => {
                    // HTML tags are captured whole
                    elements.push(Element::HtmlTag(remaining[..match_obj.end()].to_string()));
                    remaining = &remaining[match_obj.end()..];
                }
                _ => {
                    // Unknown pattern, treat as text
                    elements.push(Element::Text("[".to_string()));
                    remaining = &remaining[1..];
                }
            }
        } else {
            // Process non-link special characters

            // Add any text before the special character
            if next_special > 0 && next_special < remaining.len() {
                elements.push(Element::Text(remaining[..next_special].to_string()));
                remaining = &remaining[next_special..];
            }

            // Process the special element
            match special_type {
                "code" => {
                    // Find end of code
                    if let Some(code_end) = remaining[1..].find('`') {
                        let code = &remaining[1..1 + code_end];
                        elements.push(Element::Code(code.to_string()));
                        remaining = &remaining[1 + code_end + 1..];
                    } else {
                        // No closing backtick, treat as text
                        elements.push(Element::Text(remaining.to_string()));
                        break;
                    }
                }
                "bold" => {
                    // Check for bold text
                    if let Some(bold_end) = remaining[2..].find("**") {
                        let bold_text = &remaining[2..2 + bold_end];
                        elements.push(Element::Bold(bold_text.to_string()));
                        remaining = &remaining[2 + bold_end + 2..];
                    } else {
                        // No closing **, treat as text
                        elements.push(Element::Text("**".to_string()));
                        remaining = &remaining[2..];
                    }
                }
                "italic" => {
                    // Check for italic text
                    if let Some(italic_end) = remaining[1..].find('*') {
                        let italic_text = &remaining[1..1 + italic_end];
                        elements.push(Element::Italic(italic_text.to_string()));
                        remaining = &remaining[1 + italic_end + 1..];
                    } else {
                        // No closing *, treat as text
                        elements.push(Element::Text("*".to_string()));
                        remaining = &remaining[1..];
                    }
                }
                _ => {
                    // No special elements found, add all remaining text
                    elements.push(Element::Text(remaining.to_string()));
                    break;
                }
            }
        }
    }

    elements
}

/// Reflow elements for sentence-per-line mode
fn reflow_elements_sentence_per_line(elements: &[Element]) -> Vec<String> {
    let mut lines = Vec::new();
    let mut current_line = String::new();

    for element in elements.iter() {
        let element_str = format!("{element}");

        // For text elements, split into sentences
        if let Element::Text(text) = element {
            // Simply append text - it already has correct spacing from tokenization
            let combined = format!("{current_line}{text}");
            let sentences = split_into_sentences(&combined);

            if sentences.len() > 1 {
                // We found sentence boundaries
                for (i, sentence) in sentences.iter().enumerate() {
                    if i == 0 {
                        // First sentence might continue from previous elements
                        // But check if it ends with an abbreviation
                        let trimmed = sentence.trim();
                        let ends_with_sentence_punct =
                            trimmed.ends_with('.') || trimmed.ends_with('!') || trimmed.ends_with('?');
                        let ends_with_abbreviation = if ends_with_sentence_punct {
                            // Strip the final punctuation before checking abbreviations
                            let without_punct = trimmed
                                .trim_end_matches('.')
                                .trim_end_matches('!')
                                .trim_end_matches('?');
                            let ignored_words = [
                                "ie", "i.e", "eg", "e.g", "etc", "ex", "vs", "Mr", "Mrs", "Dr", "Ms", "Prof", "Sr",
                                "Jr",
                            ];
                            ignored_words
                                .iter()
                                .any(|word| without_punct.to_lowercase().ends_with(&word.to_lowercase()))
                        } else {
                            false
                        };

                        if ends_with_abbreviation {
                            // Don't emit yet - this sentence ends with abbreviation, continue accumulating
                            current_line = sentence.to_string();
                        } else {
                            // Normal case - emit the first sentence
                            lines.push(sentence.to_string());
                            current_line.clear();
                        }
                    } else if i == sentences.len() - 1 {
                        // Last sentence: check if it's complete or incomplete
                        let trimmed = sentence.trim();
                        let ends_with_sentence_punct =
                            trimmed.ends_with('.') || trimmed.ends_with('!') || trimmed.ends_with('?');

                        // Check if it ends with an abbreviation
                        let ends_with_abbreviation = if ends_with_sentence_punct {
                            // Strip the final punctuation before checking abbreviations
                            let without_punct = trimmed
                                .trim_end_matches('.')
                                .trim_end_matches('!')
                                .trim_end_matches('?');
                            let ignored_words = [
                                "ie", "i.e", "eg", "e.g", "etc", "ex", "vs", "Mr", "Mrs", "Dr", "Ms", "Prof", "Sr",
                                "Jr",
                            ];
                            ignored_words
                                .iter()
                                .any(|word| without_punct.to_lowercase().ends_with(&word.to_lowercase()))
                        } else {
                            false
                        };

                        if ends_with_sentence_punct && !ends_with_abbreviation {
                            // Complete sentence - emit it immediately
                            lines.push(sentence.to_string());
                            current_line.clear();
                        } else {
                            // Incomplete sentence - save for next iteration
                            current_line = sentence.to_string();
                        }
                    } else {
                        // Complete sentences in the middle
                        lines.push(sentence.to_string());
                    }
                }
            } else {
                // No sentence boundary found, continue accumulating
                current_line = combined;
            }
        } else {
            // Non-text elements (Code, Bold, Italic, etc.)
            // Add space before element if needed (unless it's after an opening paren/bracket)
            if !current_line.is_empty()
                && !current_line.ends_with(' ')
                && !current_line.ends_with('(')
                && !current_line.ends_with('[')
            {
                current_line.push(' ');
            }
            current_line.push_str(&element_str);
        }
    }

    // Add any remaining content
    if !current_line.is_empty() {
        lines.push(current_line.trim().to_string());
    }
    lines
}

/// Reflow elements into lines that fit within the line length
fn reflow_elements(elements: &[Element], options: &ReflowOptions) -> Vec<String> {
    let mut lines = Vec::new();
    let mut current_line = String::new();
    let mut current_length = 0;

    for element in elements {
        let element_str = format!("{element}");
        let element_len = element.len();

        // For text elements that might need breaking
        if let Element::Text(text) = element {
            // If this is a text element, always process it word by word
            let words: Vec<&str> = text.split_whitespace().collect();

            for word in words {
                let word_len = word.chars().count();
                if current_length > 0 && current_length + 1 + word_len > options.line_length {
                    // Start a new line
                    lines.push(current_line.trim().to_string());
                    current_line = word.to_string();
                    current_length = word_len;
                } else {
                    // Add word to current line
                    if current_length > 0 {
                        current_line.push(' ');
                        current_length += 1;
                    }
                    current_line.push_str(word);
                    current_length += word_len;
                }
            }
        } else {
            // For non-text elements (code, links, references), treat as atomic units
            // These should never be broken across lines
            if current_length > 0 && current_length + 1 + element_len > options.line_length {
                // Start a new line
                lines.push(current_line.trim().to_string());
                current_line = element_str;
                current_length = element_len;
            } else {
                // Add element to current line
                if current_length > 0 {
                    current_line.push(' ');
                    current_length += 1;
                }
                current_line.push_str(&element_str);
                current_length += element_len;
            }
        }
    }

    // Don't forget the last line
    if !current_line.is_empty() {
        lines.push(current_line.trim_end().to_string());
    }

    lines
}

/// Reflow markdown content preserving structure
pub fn reflow_markdown(content: &str, options: &ReflowOptions) -> String {
    let lines: Vec<&str> = content.lines().collect();
    let mut result = Vec::new();
    let mut i = 0;

    while i < lines.len() {
        let line = lines[i];
        let trimmed = line.trim();

        // Preserve empty lines
        if trimmed.is_empty() {
            result.push(String::new());
            i += 1;
            continue;
        }

        // Preserve headings as-is
        if trimmed.starts_with('#') {
            result.push(line.to_string());
            i += 1;
            continue;
        }

        // Preserve fenced code blocks
        if trimmed.starts_with("```") || trimmed.starts_with("~~~") {
            result.push(line.to_string());
            i += 1;
            // Copy lines until closing fence
            while i < lines.len() {
                result.push(lines[i].to_string());
                if lines[i].trim().starts_with("```") || lines[i].trim().starts_with("~~~") {
                    i += 1;
                    break;
                }
                i += 1;
            }
            continue;
        }

        // Preserve indented code blocks (4+ spaces or 1+ tab)
        if line.starts_with("    ") || line.starts_with("\t") {
            // Collect all consecutive indented lines
            result.push(line.to_string());
            i += 1;
            while i < lines.len() {
                let next_line = lines[i];
                // Continue if next line is also indented or empty (empty lines in code blocks are ok)
                if next_line.starts_with("    ") || next_line.starts_with("\t") || next_line.trim().is_empty() {
                    result.push(next_line.to_string());
                    i += 1;
                } else {
                    break;
                }
            }
            continue;
        }

        // Preserve block quotes (but reflow their content)
        if trimmed.starts_with('>') {
            let quote_prefix = line[0..line.find('>').unwrap() + 1].to_string();
            let quote_content = &line[quote_prefix.len()..].trim_start();

            let reflowed = reflow_line(quote_content, options);
            for reflowed_line in reflowed.iter() {
                result.push(format!("{quote_prefix} {reflowed_line}"));
            }
            i += 1;
            continue;
        }

        // Preserve horizontal rules first (before checking for lists)
        if is_horizontal_rule(trimmed) {
            result.push(line.to_string());
            i += 1;
            continue;
        }

        // Preserve lists (but not horizontal rules)
        if (trimmed.starts_with('-') && !is_horizontal_rule(trimmed))
            || (trimmed.starts_with('*') && !is_horizontal_rule(trimmed))
            || trimmed.starts_with('+')
            || is_numbered_list_item(trimmed)
        {
            // Find the list marker and preserve indentation
            let indent = line.len() - line.trim_start().len();
            let indent_str = " ".repeat(indent);

            // For numbered lists, find the period and the space after it
            // For bullet lists, find the marker and the space after it
            let mut marker_end = indent;
            let mut content_start = indent;

            if trimmed.chars().next().is_some_and(|c| c.is_numeric()) {
                // Numbered list: find the period
                if let Some(period_pos) = line[indent..].find('.') {
                    marker_end = indent + period_pos + 1; // Include the period
                    content_start = marker_end;
                    // Skip any spaces after the period to find content start
                    while content_start < line.len() && line.chars().nth(content_start) == Some(' ') {
                        content_start += 1;
                    }
                }
            } else {
                // Bullet list: marker is single character
                marker_end = indent + 1; // Just the marker character
                content_start = marker_end;
                // Skip any spaces after the marker
                while content_start < line.len() && line.chars().nth(content_start) == Some(' ') {
                    content_start += 1;
                }
            }

            let marker = &line[indent..marker_end];

            // Collect all content for this list item (including continuation lines)
            // Preserve hard breaks (2 trailing spaces) while trimming excessive whitespace
            let mut list_content = vec![trim_preserving_hard_break(&line[content_start..])];
            i += 1;

            // Collect continuation lines (indented lines that are part of this list item)
            while i < lines.len() {
                let next_line = lines[i];
                let next_trimmed = next_line.trim();

                // Stop if we hit an empty line or another list item or special block
                if next_trimmed.is_empty()
                    || next_trimmed.starts_with('#')
                    || next_trimmed.starts_with("```")
                    || next_trimmed.starts_with("~~~")
                    || next_trimmed.starts_with('>')
                    || next_trimmed.starts_with('|')
                    || (next_trimmed.starts_with('[') && next_line.contains("]:"))
                    || is_horizontal_rule(next_trimmed)
                    || (next_trimmed.starts_with('-')
                        && (next_trimmed.len() == 1 || next_trimmed.chars().nth(1) == Some(' ')))
                    || (next_trimmed.starts_with('*')
                        && (next_trimmed.len() == 1 || next_trimmed.chars().nth(1) == Some(' ')))
                    || (next_trimmed.starts_with('+')
                        && (next_trimmed.len() == 1 || next_trimmed.chars().nth(1) == Some(' ')))
                    || is_numbered_list_item(next_trimmed)
                    || is_definition_list_item(next_trimmed)
                {
                    break;
                }

                // Check if this line is indented (continuation of list item)
                let next_indent = next_line.len() - next_line.trim_start().len();
                if next_indent >= content_start {
                    // This is a continuation line - add its content
                    // Preserve hard breaks while trimming excessive whitespace
                    let trimmed_start = next_line.trim_start();
                    list_content.push(trim_preserving_hard_break(trimmed_start));
                    i += 1;
                } else {
                    // Not indented enough, not part of this list item
                    break;
                }
            }

            // Join content, but respect hard breaks (lines ending with 2 spaces or backslash)
            // Hard breaks should prevent joining with the next line
            let combined_content = if options.preserve_breaks {
                list_content[0].clone()
            } else {
                // Check if any lines have hard breaks - if so, preserve the structure
                let has_hard_breaks = list_content.iter().any(|line| has_hard_break(line));
                if has_hard_breaks {
                    // Don't join lines with hard breaks - keep them separate with newlines
                    list_content.join("\n")
                } else {
                    // No hard breaks, safe to join with spaces
                    list_content.join(" ")
                }
            };

            // Calculate the proper indentation for continuation lines
            let trimmed_marker = marker;
            let continuation_spaces = content_start;

            // Adjust line length to account for list marker and space
            let prefix_length = indent + trimmed_marker.len() + 1;

            // Create adjusted options with reduced line length
            let adjusted_options = ReflowOptions {
                line_length: options.line_length.saturating_sub(prefix_length),
                ..options.clone()
            };

            let reflowed = reflow_line(&combined_content, &adjusted_options);
            for (j, reflowed_line) in reflowed.iter().enumerate() {
                if j == 0 {
                    result.push(format!("{indent_str}{trimmed_marker} {reflowed_line}"));
                } else {
                    // Continuation lines aligned with text after marker
                    let continuation_indent = " ".repeat(continuation_spaces);
                    result.push(format!("{continuation_indent}{reflowed_line}"));
                }
            }
            continue;
        }

        // Preserve tables
        if trimmed.contains('|') {
            result.push(line.to_string());
            i += 1;
            continue;
        }

        // Preserve reference definitions
        if trimmed.starts_with('[') && line.contains("]:") {
            result.push(line.to_string());
            i += 1;
            continue;
        }

        // Preserve definition list items (extended markdown)
        if is_definition_list_item(trimmed) {
            result.push(line.to_string());
            i += 1;
            continue;
        }

        // Check if this is a single line that doesn't need processing
        let mut is_single_line_paragraph = true;
        if i + 1 < lines.len() {
            let next_line = lines[i + 1];
            let next_trimmed = next_line.trim();
            // Check if next line starts a new block
            if !next_trimmed.is_empty()
                && !next_trimmed.starts_with('#')
                && !next_trimmed.starts_with("```")
                && !next_trimmed.starts_with("~~~")
                && !next_trimmed.starts_with('>')
                && !next_trimmed.starts_with('|')
                && !(next_trimmed.starts_with('[') && next_line.contains("]:"))
                && !is_horizontal_rule(next_trimmed)
                && !(next_trimmed.starts_with('-')
                    && !is_horizontal_rule(next_trimmed)
                    && (next_trimmed.len() == 1 || next_trimmed.chars().nth(1) == Some(' ')))
                && !(next_trimmed.starts_with('*')
                    && !is_horizontal_rule(next_trimmed)
                    && (next_trimmed.len() == 1 || next_trimmed.chars().nth(1) == Some(' ')))
                && !(next_trimmed.starts_with('+')
                    && (next_trimmed.len() == 1 || next_trimmed.chars().nth(1) == Some(' ')))
                && !is_numbered_list_item(next_trimmed)
            {
                is_single_line_paragraph = false;
            }
        }

        // If it's a single line that fits, just add it as-is
        if is_single_line_paragraph && line.chars().count() <= options.line_length {
            result.push(line.to_string());
            i += 1;
            continue;
        }

        // For regular paragraphs, collect consecutive lines
        let mut paragraph_parts = Vec::new();
        let mut current_part = vec![line];
        i += 1;

        // If preserve_breaks is true, treat each line separately
        if options.preserve_breaks {
            // Don't collect consecutive lines - just reflow this single line
            let hard_break_type = if line.strip_suffix('\r').unwrap_or(line).ends_with('\\') {
                Some("\\")
            } else if line.ends_with("  ") {
                Some("  ")
            } else {
                None
            };
            let reflowed = reflow_line(line, options);

            // Preserve hard breaks (two trailing spaces or backslash)
            if let Some(break_marker) = hard_break_type {
                if !reflowed.is_empty() {
                    let mut reflowed_with_break = reflowed;
                    let last_idx = reflowed_with_break.len() - 1;
                    if !has_hard_break(&reflowed_with_break[last_idx]) {
                        reflowed_with_break[last_idx].push_str(break_marker);
                    }
                    result.extend(reflowed_with_break);
                }
            } else {
                result.extend(reflowed);
            }
        } else {
            // Original behavior: collect consecutive lines into a paragraph
            while i < lines.len() {
                let prev_line = if !current_part.is_empty() {
                    current_part.last().unwrap()
                } else {
                    ""
                };
                let next_line = lines[i];
                let next_trimmed = next_line.trim();

                // Stop at empty lines or special blocks
                if next_trimmed.is_empty()
                    || next_trimmed.starts_with('#')
                    || next_trimmed.starts_with("```")
                    || next_trimmed.starts_with("~~~")
                    || next_trimmed.starts_with('>')
                    || next_trimmed.starts_with('|')
                    || (next_trimmed.starts_with('[') && next_line.contains("]:"))
                    || is_horizontal_rule(next_trimmed)
                    || (next_trimmed.starts_with('-')
                        && !is_horizontal_rule(next_trimmed)
                        && (next_trimmed.len() == 1 || next_trimmed.chars().nth(1) == Some(' ')))
                    || (next_trimmed.starts_with('*')
                        && !is_horizontal_rule(next_trimmed)
                        && (next_trimmed.len() == 1 || next_trimmed.chars().nth(1) == Some(' ')))
                    || (next_trimmed.starts_with('+')
                        && (next_trimmed.len() == 1 || next_trimmed.chars().nth(1) == Some(' ')))
                    || is_numbered_list_item(next_trimmed)
                    || is_definition_list_item(next_trimmed)
                {
                    break;
                }

                // Check if previous line ends with hard break (two spaces or backslash)
                if has_hard_break(prev_line) {
                    // Start a new part after hard break
                    paragraph_parts.push(current_part.join(" "));
                    current_part = vec![next_line];
                } else {
                    current_part.push(next_line);
                }
                i += 1;
            }

            // Add the last part
            if !current_part.is_empty() {
                if current_part.len() == 1 {
                    // Single line, don't add trailing space
                    paragraph_parts.push(current_part[0].to_string());
                } else {
                    paragraph_parts.push(current_part.join(" "));
                }
            }

            // Reflow each part separately, preserving hard breaks
            for (j, part) in paragraph_parts.iter().enumerate() {
                let reflowed = reflow_line(part, options);
                result.extend(reflowed);

                // Preserve hard break by ensuring last line of part ends with hard break marker
                // Use two spaces as the default hard break format for reflows
                if j < paragraph_parts.len() - 1 && !result.is_empty() {
                    let last_idx = result.len() - 1;
                    if !has_hard_break(&result[last_idx]) {
                        result[last_idx].push_str("  ");
                    }
                }
            }
        }
    }

    // Preserve trailing newline if the original content had one
    let result_text = result.join("\n");
    if content.ends_with('\n') && !result_text.ends_with('\n') {
        format!("{result_text}\n")
    } else {
        result_text
    }
}

/// Information about a reflowed paragraph
#[derive(Debug, Clone)]
pub struct ParagraphReflow {
    /// Starting byte offset of the paragraph in the original content
    pub start_byte: usize,
    /// Ending byte offset of the paragraph in the original content
    pub end_byte: usize,
    /// The reflowed text for this paragraph
    pub reflowed_text: String,
}

/// Reflow a single paragraph at the specified line number
///
/// This function finds the paragraph containing the given line number,
/// reflows it according to the specified line length, and returns
/// information about the paragraph location and its reflowed text.
///
/// # Arguments
///
/// * `content` - The full document content
/// * `line_number` - The 1-based line number within the paragraph to reflow
/// * `line_length` - The target line length for reflowing
///
/// # Returns
///
/// Returns `Some(ParagraphReflow)` if a paragraph was found and reflowed,
/// or `None` if the line number is out of bounds or the content at that
/// line shouldn't be reflowed (e.g., code blocks, headings, etc.)
pub fn reflow_paragraph_at_line(content: &str, line_number: usize, line_length: usize) -> Option<ParagraphReflow> {
    if line_number == 0 {
        return None;
    }

    let lines: Vec<&str> = content.lines().collect();

    // Check if line number is valid (1-based)
    if line_number > lines.len() {
        return None;
    }

    let target_idx = line_number - 1; // Convert to 0-based
    let target_line = lines[target_idx];
    let trimmed = target_line.trim();

    // Don't reflow special blocks
    if trimmed.is_empty()
        || trimmed.starts_with('#')
        || trimmed.starts_with("```")
        || trimmed.starts_with("~~~")
        || target_line.starts_with("    ")
        || target_line.starts_with('\t')
        || trimmed.starts_with('>')
        || trimmed.contains('|') // Tables
        || (trimmed.starts_with('[') && target_line.contains("]:")) // Reference definitions
        || is_horizontal_rule(trimmed)
        || ((trimmed.starts_with('-') || trimmed.starts_with('*') || trimmed.starts_with('+'))
            && !is_horizontal_rule(trimmed)
            && (trimmed.len() == 1 || trimmed.chars().nth(1) == Some(' ')))
        || is_numbered_list_item(trimmed)
        || is_definition_list_item(trimmed)
    {
        return None;
    }

    // Find paragraph start - scan backward until blank line or special block
    let mut para_start = target_idx;
    while para_start > 0 {
        let prev_idx = para_start - 1;
        let prev_line = lines[prev_idx];
        let prev_trimmed = prev_line.trim();

        // Stop at blank line or special blocks
        if prev_trimmed.is_empty()
            || prev_trimmed.starts_with('#')
            || prev_trimmed.starts_with("```")
            || prev_trimmed.starts_with("~~~")
            || prev_line.starts_with("    ")
            || prev_line.starts_with('\t')
            || prev_trimmed.starts_with('>')
            || prev_trimmed.contains('|')
            || (prev_trimmed.starts_with('[') && prev_line.contains("]:"))
            || is_horizontal_rule(prev_trimmed)
            || ((prev_trimmed.starts_with('-') || prev_trimmed.starts_with('*') || prev_trimmed.starts_with('+'))
                && !is_horizontal_rule(prev_trimmed)
                && (prev_trimmed.len() == 1 || prev_trimmed.chars().nth(1) == Some(' ')))
            || is_numbered_list_item(prev_trimmed)
            || is_definition_list_item(prev_trimmed)
        {
            break;
        }

        para_start = prev_idx;
    }

    // Find paragraph end - scan forward until blank line or special block
    let mut para_end = target_idx;
    while para_end + 1 < lines.len() {
        let next_idx = para_end + 1;
        let next_line = lines[next_idx];
        let next_trimmed = next_line.trim();

        // Stop at blank line or special blocks
        if next_trimmed.is_empty()
            || next_trimmed.starts_with('#')
            || next_trimmed.starts_with("```")
            || next_trimmed.starts_with("~~~")
            || next_line.starts_with("    ")
            || next_line.starts_with('\t')
            || next_trimmed.starts_with('>')
            || next_trimmed.contains('|')
            || (next_trimmed.starts_with('[') && next_line.contains("]:"))
            || is_horizontal_rule(next_trimmed)
            || ((next_trimmed.starts_with('-') || next_trimmed.starts_with('*') || next_trimmed.starts_with('+'))
                && !is_horizontal_rule(next_trimmed)
                && (next_trimmed.len() == 1 || next_trimmed.chars().nth(1) == Some(' ')))
            || is_numbered_list_item(next_trimmed)
            || is_definition_list_item(next_trimmed)
        {
            break;
        }

        para_end = next_idx;
    }

    // Extract paragraph lines
    let paragraph_lines = &lines[para_start..=para_end];

    // Calculate byte offsets
    let mut start_byte = 0;
    for line in lines.iter().take(para_start) {
        start_byte += line.len() + 1; // +1 for newline
    }

    let mut end_byte = start_byte;
    for line in paragraph_lines.iter() {
        end_byte += line.len() + 1; // +1 for newline
    }

    // Track whether the byte range includes a trailing newline
    // (it doesn't if this is the last line and the file doesn't end with newline)
    let includes_trailing_newline = para_end != lines.len() - 1 || content.ends_with('\n');

    // Adjust end_byte if the last line doesn't have a newline
    if !includes_trailing_newline {
        end_byte -= 1;
    }

    // Join paragraph lines and reflow
    let paragraph_text = paragraph_lines.join("\n");

    // Create reflow options
    let options = ReflowOptions {
        line_length,
        break_on_sentences: true,
        preserve_breaks: false,
        sentence_per_line: false,
    };

    // Reflow the paragraph using reflow_markdown to handle it properly
    let reflowed = reflow_markdown(&paragraph_text, &options);

    // Ensure reflowed text matches whether the byte range includes a trailing newline
    // This is critical: if the range includes a newline, the replacement must too,
    // otherwise the next line will get appended to the reflowed paragraph
    let reflowed_text = if includes_trailing_newline {
        // Range includes newline - ensure reflowed text has one
        if reflowed.ends_with('\n') {
            reflowed
        } else {
            format!("{reflowed}\n")
        }
    } else {
        // Range doesn't include newline - ensure reflowed text doesn't have one
        if reflowed.ends_with('\n') {
            reflowed.trim_end_matches('\n').to_string()
        } else {
            reflowed
        }
    };

    Some(ParagraphReflow {
        start_byte,
        end_byte,
        reflowed_text,
    })
}

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

    #[test]
    fn test_list_item_trailing_whitespace_removal() {
        // Test for issue #76 - hard breaks (2 trailing spaces) should be preserved
        // and prevent reflowing
        let input = "1. First line with trailing spaces   \n    Second line with trailing spaces  \n    Third line\n";

        let options = ReflowOptions {
            line_length: 999999,
            break_on_sentences: true, // MD013 uses true by default
            preserve_breaks: false,
            sentence_per_line: false,
        };

        let result = reflow_markdown(input, &options);

        // Should not contain 3+ consecutive spaces (which would indicate
        // trailing whitespace became mid-line whitespace)
        assert!(
            !result.contains("   "),
            "Result should not contain 3+ consecutive spaces: {result:?}"
        );

        // Hard breaks should be preserved (exactly 2 trailing spaces)
        assert!(result.contains("  \n"), "Hard breaks should be preserved: {result:?}");

        // Should NOT be reflowed into a single line because hard breaks are present
        // The content should maintain its line structure
        assert!(
            result.lines().count() >= 2,
            "Should have multiple lines (not reflowed due to hard breaks), got: {}",
            result.lines().count()
        );
    }

    #[test]
    fn test_reflow_simple_text() {
        let options = ReflowOptions {
            line_length: 20,
            ..Default::default()
        };

        let input = "This is a very long line that needs to be wrapped";
        let result = reflow_line(input, &options);

        assert_eq!(result.len(), 3);
        assert!(result[0].chars().count() <= 20);
        assert!(result[1].chars().count() <= 20);
        assert!(result[2].chars().count() <= 20);
    }

    #[test]
    fn test_preserve_inline_code() {
        let options = ReflowOptions {
            line_length: 30,
            ..Default::default()
        };

        let result = reflow_line("This line has `inline code` that should be preserved", &options);
        // Verify inline code is not broken
        let joined = result.join(" ");
        assert!(joined.contains("`inline code`"));
    }

    #[test]
    fn test_preserve_links() {
        let options = ReflowOptions {
            line_length: 40,
            ..Default::default()
        };

        let text = "Check out [this link](https://example.com/very/long/url) for more info";
        let result = reflow_line(text, &options);

        // Verify link is preserved intact
        let joined = result.join(" ");
        assert!(joined.contains("[this link](https://example.com/very/long/url)"));
    }

    #[test]
    fn test_reference_link_patterns_fixed() {
        let options = ReflowOptions {
            line_length: 30,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: false,
        };

        // Test cases that verify reference links are preserved as atomic units
        let test_cases = vec![
            // Reference link: [text][ref] - should be preserved intact
            ("Check out [text][ref] for details", vec!["[text][ref]"]),
            // Empty reference: [text][] - should be preserved intact
            ("See [text][] for info", vec!["[text][]"]),
            // Shortcut reference: [homepage] - should be preserved intact
            ("Visit [homepage] today", vec!["[homepage]"]),
            // Multiple reference links in one line
            (
                "Links: [first][ref1] and [second][ref2] here",
                vec!["[first][ref1]", "[second][ref2]"],
            ),
            // Mixed inline and reference links
            (
                "See [inline](url) and [reference][ref] links",
                vec!["[inline](url)", "[reference][ref]"],
            ),
        ];

        for (input, expected_patterns) in test_cases {
            println!("\nTesting: {input}");
            let result = reflow_line(input, &options);
            let joined = result.join(" ");
            println!("Result:  {joined}");

            // Verify all expected patterns are preserved
            for expected_pattern in expected_patterns {
                assert!(
                    joined.contains(expected_pattern),
                    "Expected '{expected_pattern}' to be preserved in '{input}', but got '{joined}'"
                );
            }

            // Verify no broken patterns exist (spaces inside brackets)
            assert!(
                !joined.contains("[ ") || !joined.contains("] ["),
                "Detected broken reference link pattern with spaces inside brackets in '{joined}'"
            );
        }
    }

    #[test]
    fn test_sentence_detection_basic() {
        // Test basic sentence detection
        assert!(is_sentence_boundary("Hello. World", 5));
        assert!(is_sentence_boundary("Test! Another", 4));
        assert!(is_sentence_boundary("Question? Answer", 8));

        // Test non-boundaries
        assert!(!is_sentence_boundary("Hello world", 5));
        assert!(!is_sentence_boundary("Test.com", 4));
        assert!(!is_sentence_boundary("3.14 pi", 1));
    }

    #[test]
    fn test_sentence_detection_abbreviations() {
        // Common abbreviations should not be treated as sentence boundaries
        assert!(!is_sentence_boundary("Mr. Smith", 2));
        assert!(!is_sentence_boundary("Dr. Jones", 2));
        assert!(!is_sentence_boundary("e.g. example", 3));
        assert!(!is_sentence_boundary("i.e. that is", 3));
        assert!(!is_sentence_boundary("etc. items", 3));

        // But sentence after abbreviation should be a boundary
        assert!(is_sentence_boundary("Mr. Smith arrived. Next sentence.", 17));
    }

    #[test]
    fn test_split_into_sentences() {
        let text = "First sentence. Second sentence. Third one!";
        let sentences = split_into_sentences(text);
        assert_eq!(sentences.len(), 3);
        assert_eq!(sentences[0], "First sentence.");
        assert_eq!(sentences[1], "Second sentence.");
        assert_eq!(sentences[2], "Third one!");

        // Test with abbreviations
        let text2 = "Mr. Smith met Dr. Jones.";
        let sentences2 = split_into_sentences(text2);
        assert_eq!(sentences2.len(), 1);
        assert_eq!(sentences2[0], "Mr. Smith met Dr. Jones.");

        // Test single sentence
        let text3 = "This is a single sentence.";
        let sentences3 = split_into_sentences(text3);
        assert_eq!(sentences3.len(), 1);
        assert_eq!(sentences3[0], "This is a single sentence.");
    }

    #[test]
    fn test_sentence_per_line_reflow() {
        let options = ReflowOptions {
            line_length: 80,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: true,
        };

        // Test basic sentence splitting
        let input = "First sentence. Second sentence. Third sentence.";
        let result = reflow_line(input, &options);
        assert_eq!(result.len(), 3);
        assert_eq!(result[0], "First sentence.");
        assert_eq!(result[1], "Second sentence.");
        assert_eq!(result[2], "Third sentence.");

        // Test with markdown elements
        let input2 = "This has **bold**. And [a link](url).";
        let result2 = reflow_line(input2, &options);
        assert_eq!(result2.len(), 2);
        assert_eq!(result2[0], "This has **bold**.");
        assert_eq!(result2[1], "And [a link](url).");
    }

    #[test]
    fn test_sentence_per_line_with_backticks() {
        let options = ReflowOptions {
            line_length: 80,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: true,
        };

        let input = "This sentence has `code` in it. And this has `more code` too.";
        let result = reflow_line(input, &options);
        assert_eq!(result.len(), 2);
        assert_eq!(result[0], "This sentence has `code` in it.");
        assert_eq!(result[1], "And this has `more code` too.");
    }

    #[test]
    fn test_sentence_per_line_with_backticks_in_parens() {
        let options = ReflowOptions {
            line_length: 80,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: true,
        };

        let input = "Configure in (`.rumdl.toml` or `pyproject.toml`). Next sentence.";
        let result = reflow_line(input, &options);
        assert_eq!(result.len(), 2);
        assert_eq!(result[0], "Configure in (`.rumdl.toml` or `pyproject.toml`).");
        assert_eq!(result[1], "Next sentence.");
    }

    #[test]
    fn test_sentence_per_line_with_questions_exclamations() {
        let options = ReflowOptions {
            line_length: 80,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: true,
        };

        let input = "Is this a question? Yes it is! And a statement.";
        let result = reflow_line(input, &options);
        assert_eq!(result.len(), 3);
        assert_eq!(result[0], "Is this a question?");
        assert_eq!(result[1], "Yes it is!");
        assert_eq!(result[2], "And a statement.");
    }

    #[test]
    fn test_split_sentences_issue_124() {
        // Test the actual text from issue #124
        let text = "If you are sure that all data structures exposed in a `PyModule` are thread-safe, then pass `gil_used = false` as a parameter to the `pymodule` procedural macro declaring the module or call `PyModule::gil_used` on a `PyModule` instance.  For example:";

        let sentences = split_into_sentences(text);

        // This should detect 2 sentences:
        // 1. "If you are sure ... on a `PyModule` instance."
        // 2. "For example:"
        assert_eq!(sentences.len(), 2, "Should detect 2 sentences in the text");
    }

    #[test]
    fn test_reference_link_edge_cases() {
        let options = ReflowOptions {
            line_length: 40,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: false,
        };

        // Test cases for edge cases and potential conflicts
        let test_cases = vec![
            // Escaped brackets should be treated as regular text
            ("Text with \\[escaped\\] brackets", vec!["\\[escaped\\]"]),
            // Nested brackets in reference links
            (
                "Link [text with [nested] content][ref]",
                vec!["[text with [nested] content][ref]"],
            ),
            // Reference link followed by inline link
            (
                "First [ref][link] then [inline](url)",
                vec!["[ref][link]", "[inline](url)"],
            ),
            // Shortcut reference that might conflict with other patterns
            ("Array [0] and reference [link] here", vec!["[0]", "[link]"]),
            // Empty reference with complex text
            (
                "Complex [text with *emphasis*][] reference",
                vec!["[text with *emphasis*][]"],
            ),
        ];

        for (input, expected_patterns) in test_cases {
            println!("\nTesting edge case: {input}");
            let result = reflow_line(input, &options);
            let joined = result.join(" ");
            println!("Result: {joined}");

            // Verify all expected patterns are preserved
            for expected_pattern in expected_patterns {
                assert!(
                    joined.contains(expected_pattern),
                    "Expected '{expected_pattern}' to be preserved in '{input}', but got '{joined}'"
                );
            }
        }
    }

    #[test]
    fn test_reflow_with_emphasis() {
        let options = ReflowOptions {
            line_length: 25,
            ..Default::default()
        };

        let result = reflow_line("This is *emphasized* and **strong** text that needs wrapping", &options);

        // Verify emphasis markers are preserved
        let joined = result.join(" ");
        assert!(joined.contains("*emphasized*"));
        assert!(joined.contains("**strong**"));
    }

    #[test]
    fn test_image_patterns_preserved() {
        let options = ReflowOptions {
            line_length: 30,
            ..Default::default()
        };

        // Test cases for image patterns
        let test_cases = vec![
            // Inline image
            (
                "Check out ![alt text](image.png) for details",
                vec!["![alt text](image.png)"],
            ),
            // Reference image
            ("See ![image][ref] for info", vec!["![image][ref]"]),
            // Empty reference image
            ("Visit ![homepage][] today", vec!["![homepage][]"]),
            // Multiple images
            (
                "Images: ![first](a.png) and ![second][ref2]",
                vec!["![first](a.png)", "![second][ref2]"],
            ),
        ];

        for (input, expected_patterns) in test_cases {
            println!("\nTesting: {input}");
            let result = reflow_line(input, &options);
            let joined = result.join(" ");
            println!("Result:  {joined}");

            for expected_pattern in expected_patterns {
                assert!(
                    joined.contains(expected_pattern),
                    "Expected '{expected_pattern}' to be preserved in '{input}', but got '{joined}'"
                );
            }
        }
    }

    #[test]
    fn test_extended_markdown_patterns() {
        let options = ReflowOptions {
            line_length: 40,
            ..Default::default()
        };

        let test_cases = vec![
            // Strikethrough
            ("Text with ~~strikethrough~~ preserved", vec!["~~strikethrough~~"]),
            // Wiki links
            (
                "Check [[wiki link]] and [[page|display]]",
                vec!["[[wiki link]]", "[[page|display]]"],
            ),
            // Math
            (
                "Inline $x^2 + y^2$ and display $$\\int f(x) dx$$",
                vec!["$x^2 + y^2$", "$$\\int f(x) dx$$"],
            ),
            // Emoji
            ("Use :smile: and :heart: emojis", vec![":smile:", ":heart:"]),
            // HTML tags
            (
                "Text with <span>tag</span> and <br/>",
                vec!["<span>", "</span>", "<br/>"],
            ),
            // HTML entities
            ("Non-breaking&nbsp;space and em&mdash;dash", vec!["&nbsp;", "&mdash;"]),
        ];

        for (input, expected_patterns) in test_cases {
            let result = reflow_line(input, &options);
            let joined = result.join(" ");

            for pattern in expected_patterns {
                assert!(
                    joined.contains(pattern),
                    "Expected '{pattern}' to be preserved in '{input}', but got '{joined}'"
                );
            }
        }
    }

    #[test]
    fn test_complex_mixed_patterns() {
        let options = ReflowOptions {
            line_length: 50,
            ..Default::default()
        };

        // Test that multiple pattern types work together
        let input = "Line with **bold**, `code`, [link](url), ![image](img), ~~strike~~, $math$, :emoji:, and <tag> all together";
        let result = reflow_line(input, &options);
        let joined = result.join(" ");

        // All patterns should be preserved
        assert!(joined.contains("**bold**"));
        assert!(joined.contains("`code`"));
        assert!(joined.contains("[link](url)"));
        assert!(joined.contains("![image](img)"));
        assert!(joined.contains("~~strike~~"));
        assert!(joined.contains("$math$"));
        assert!(joined.contains(":emoji:"));
        assert!(joined.contains("<tag>"));
    }

    #[test]
    fn test_footnote_patterns_preserved() {
        let options = ReflowOptions {
            line_length: 40,
            ..Default::default()
        };

        let test_cases = vec![
            // Single footnote
            ("This has a footnote[^1] reference", vec!["[^1]"]),
            // Multiple footnotes
            ("Text with [^first] and [^second] notes", vec!["[^first]", "[^second]"]),
            // Long footnote name
            ("Reference to [^long-footnote-name] here", vec!["[^long-footnote-name]"]),
        ];

        for (input, expected_patterns) in test_cases {
            let result = reflow_line(input, &options);
            let joined = result.join(" ");

            for expected_pattern in expected_patterns {
                assert!(
                    joined.contains(expected_pattern),
                    "Expected '{expected_pattern}' to be preserved in '{input}', but got '{joined}'"
                );
            }
        }
    }

    #[test]
    fn test_reflow_markdown_numbered_lists() {
        // Test for issue #83: numbered lists with proper formatting
        let options = ReflowOptions {
            line_length: 50,
            ..Default::default()
        };

        let content = r#"1. List `manifest` to find the manifest with the largest ID. Say it's `00000000000000000002.manifest` in this example.
2. Short item
3. Another long item that definitely exceeds the fifty character limit and needs wrapping"#;

        let result = reflow_markdown(content, &options);

        // Define exact expected output
        let expected = r#"1. List `manifest` to find the manifest with the
   largest ID. Say it's
   `00000000000000000002.manifest` in this
   example.
2. Short item
3. Another long item that definitely exceeds the
   fifty character limit and needs wrapping"#;

        assert_eq!(
            result, expected,
            "Numbered lists should be reflowed with proper markers and indentation.\nExpected:\n{expected}\nGot:\n{result}"
        );
    }

    #[test]
    fn test_reflow_markdown_bullet_lists() {
        let options = ReflowOptions {
            line_length: 40,
            ..Default::default()
        };

        let content = r#"- First bullet point with a very long line that needs wrapping
* Second bullet using asterisk
+ Third bullet using plus sign
- Short one"#;

        let result = reflow_markdown(content, &options);

        // Define exact expected output - each bullet type preserved with proper indentation
        let expected = r#"- First bullet point with a very long
  line that needs wrapping
* Second bullet using asterisk
+ Third bullet using plus sign
- Short one"#;

        assert_eq!(
            result, expected,
            "Bullet lists should preserve markers and indent continuations with 2 spaces.\nExpected:\n{expected}\nGot:\n{result}"
        );
    }

    #[test]
    fn test_ie_abbreviation_split_debug() {
        let input = "This results in extracting directly from the input object, i.e. `obj.extract()`, rather than trying to access an item or attribute.";

        let options = ReflowOptions {
            line_length: 80,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: true,
        };

        let result = reflow_line(input, &options);

        // Should be 1 sentence, not split after "i.e."
        assert_eq!(result.len(), 1, "Should not split after i.e. abbreviation");
    }

    #[test]
    fn test_ie_abbreviation_paragraph() {
        // Test the full paragraph from the file that's causing the issue
        let input = "The `pyo3(transparent)` attribute can be used on structs with exactly one field.\nThis results in extracting directly from the input object, i.e. `obj.extract()`, rather than trying to access an item or attribute.\nThis behaviour is enabled per default for newtype structs and tuple-variants with a single field.";

        let options = ReflowOptions {
            line_length: 80,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: true,
        };

        let result = reflow_markdown(input, &options);

        // Should be 3 sentences, not 4 (shouldn't split after "i.e.")
        let line_count = result.lines().count();
        assert_eq!(line_count, 3, "Should have 3 sentences, not {line_count}");

        // Verify the second line contains the full sentence
        let lines: Vec<&str> = result.lines().collect();
        assert!(lines.len() >= 2, "Should have at least 2 lines");
        assert!(lines[1].contains("i.e."), "Second line should contain 'i.e.'");
        assert!(
            lines[1].contains("`obj.extract()`"),
            "Second line should contain the code span"
        );
        assert!(
            lines[1].contains("attribute."),
            "Second line should end with 'attribute.'"
        );
    }

    #[test]
    fn test_definition_list_preservation() {
        let options = ReflowOptions {
            line_length: 80,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: true,
        };

        let content = "Term\n: Definition text here.";
        let result = reflow_markdown(content, &options);

        // Should NOT join into "Term : Definition text here."
        assert_eq!(result, "Term\n: Definition text here.");
    }

    #[test]
    fn test_definition_list_multiline() {
        let options = ReflowOptions {
            line_length: 80,
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: true,
        };

        let content = "Term\n: First sentence of definition. Second sentence.";
        let result = reflow_markdown(content, &options);

        // Term line should stay separate
        assert!(result.starts_with("Term\n"));
        // Definition list item (line starting with ": ") should be preserved as-is
        // We don't split sentences within definition list items
        assert!(result.contains("\n: First sentence of definition. Second sentence."));
    }

    #[test]
    fn test_definition_list_multiple() {
        let options = ReflowOptions {
            line_length: 80,
            sentence_per_line: true,
            ..Default::default()
        };

        let content = "Term 1\n: Definition 1\n: Another definition for term 1\n\nTerm 2\n: Definition 2";
        let result = reflow_markdown(content, &options);

        // All definition lines should preserve ": " at start
        assert!(result.lines().filter(|l| l.trim_start().starts_with(": ")).count() >= 3);
    }

    #[test]
    fn test_definition_list_with_paragraphs() {
        let options = ReflowOptions {
            line_length: 0, // No line length constraint
            break_on_sentences: true,
            preserve_breaks: false,
            sentence_per_line: true,
        };

        let content = "Regular paragraph. With multiple sentences.\n\nTerm\n: Definition.\n\nAnother paragraph.";
        let result = reflow_markdown(content, &options);

        // Paragraph should be reflowed (sentences on separate lines)
        assert!(result.contains("Regular paragraph."));
        assert!(result.contains("\nWith multiple sentences."));
        // Definition list should be preserved
        assert!(result.contains("Term\n: Definition."));
        // Another paragraph should be preserved (single sentence, stays as is)
        assert!(result.contains("Another paragraph."));
    }

    #[test]
    fn test_definition_list_edge_cases() {
        let options = ReflowOptions::default();

        // Indented definition
        let content1 = "Term\n  : Indented definition";
        let result1 = reflow_markdown(content1, &options);
        assert!(result1.contains("\n  : Indented definition"));

        // Multiple spaces after colon
        let content2 = "Term\n:   Definition";
        let result2 = reflow_markdown(content2, &options);
        assert!(result2.contains("\n:   Definition"));

        // Tab after colon
        let content3 = "Term\n:\tDefinition";
        let result3 = reflow_markdown(content3, &options);
        assert!(result3.contains("\n:\tDefinition"));
    }
}