standout_render/tabular/

util.rs

//! Utility functions for ANSI-aware text measurement, truncation, and padding.
//!
//! All functions in this module correctly handle ANSI escape codes: they are
//! preserved in output but don't count toward display width calculations.

use console::{measure_text_width, pad_str, Alignment};
use standout_bbparser::strip_tags;

/// Returns the display width of a string, ignoring ANSI escape codes.
///
/// **Warning:** This only strips ANSI escape codes, not BBCode tags like
/// `[bold]...[/bold]`. For user-facing content that may contain BBCode markup,
/// use [`visible_width`] instead.
///
/// # Example
///
/// ```rust
/// use standout_render::tabular::display_width;
///
/// assert_eq!(display_width("hello"), 5);
/// assert_eq!(display_width("\x1b[31mred\x1b[0m"), 3);  // ANSI codes ignored
/// assert_eq!(display_width("日本"), 4);  // CJK characters are 2 columns each
/// ```
pub fn display_width(s: &str) -> usize {
    measure_text_width(s)
}

/// Returns the visible display width of a string, stripping both BBCode tags
/// and ANSI escape codes before measurement.
///
/// Use this for any text that may contain markup. For strings known to be
/// tag-free (e.g., separator literals), [`display_width`] avoids the overhead.
///
/// # Example
///
/// ```rust
/// use standout_render::tabular::visible_width;
///
/// assert_eq!(visible_width("hello"), 5);
/// assert_eq!(visible_width("[bold]hello[/bold]"), 5);
/// assert_eq!(visible_width("\x1b[31m[red]hi[/red]\x1b[0m"), 2);
/// ```
pub fn visible_width(s: &str) -> usize {
    display_width(&strip_tags(s))
}

/// Truncates a string from the end to fit within a maximum display width.
///
/// If the string already fits, it is returned unchanged. Otherwise, characters
/// are removed from the end and the ellipsis is appended.
///
/// ANSI escape codes are preserved but don't count toward display width.
///
/// # Arguments
///
/// * `s` - The string to truncate
/// * `max_width` - Maximum display width in terminal columns
/// * `ellipsis` - String to append when truncation occurs (e.g., "…" or "...")
///
/// # Example
///
/// ```rust
/// use standout_render::tabular::truncate_end;
///
/// assert_eq!(truncate_end("Hello World", 8, "…"), "Hello W…");
/// assert_eq!(truncate_end("Short", 10, "…"), "Short");
/// ```
pub fn truncate_end(s: &str, max_width: usize, ellipsis: &str) -> String {
    let width = measure_text_width(s);
    if width <= max_width {
        return s.to_string();
    }

    let ellipsis_width = measure_text_width(ellipsis);
    if max_width < ellipsis_width {
        // Not enough room even for ellipsis - truncate ellipsis itself
        return truncate_to_display_width(ellipsis, max_width);
    }
    if max_width == ellipsis_width {
        // Exactly enough room for ellipsis only
        return ellipsis.to_string();
    }

    let target_width = max_width - ellipsis_width;
    let mut result = truncate_to_display_width(s, target_width);
    result.push_str(ellipsis);
    result
}

/// Truncates a string from the start to fit within a maximum display width.
///
/// Characters are removed from the beginning, and the ellipsis is prepended.
/// Useful for paths where the filename at the end is more important than
/// the directory prefix.
///
/// ANSI escape codes are preserved but don't count toward display width.
///
/// # Example
///
/// ```rust
/// use standout_render::tabular::truncate_start;
///
/// assert_eq!(truncate_start("Hello World", 8, "…"), "…o World");
/// assert_eq!(truncate_start("/path/to/file.rs", 12, "…"), "…/to/file.rs");
/// ```
pub fn truncate_start(s: &str, max_width: usize, ellipsis: &str) -> String {
    let width = measure_text_width(s);
    if width <= max_width {
        return s.to_string();
    }

    let ellipsis_width = measure_text_width(ellipsis);
    if max_width < ellipsis_width {
        // Not enough room even for ellipsis - truncate ellipsis itself
        return truncate_to_display_width(ellipsis, max_width);
    }
    if max_width == ellipsis_width {
        // Exactly enough room for ellipsis only
        return ellipsis.to_string();
    }

    let target_width = max_width - ellipsis_width;
    let truncated = find_suffix_with_width(s, target_width);
    format!("{}{}", ellipsis, truncated)
}

/// Truncates a string from the middle to fit within a maximum display width.
///
/// Characters are removed from the middle, preserving both start and end.
/// The ellipsis is placed in the middle. Useful for identifiers or filenames
/// where both prefix and suffix are meaningful.
///
/// ANSI escape codes are preserved but don't count toward display width.
///
/// # Example
///
/// ```rust
/// use standout_render::tabular::truncate_middle;
///
/// assert_eq!(truncate_middle("Hello World", 8, "…"), "Hel…orld");
/// assert_eq!(truncate_middle("abcdefghij", 7, "..."), "ab...ij");
/// ```
pub fn truncate_middle(s: &str, max_width: usize, ellipsis: &str) -> String {
    let width = measure_text_width(s);
    if width <= max_width {
        return s.to_string();
    }

    let ellipsis_width = measure_text_width(ellipsis);
    if max_width < ellipsis_width {
        // Not enough room even for ellipsis - truncate ellipsis itself
        return truncate_to_display_width(ellipsis, max_width);
    }
    if max_width == ellipsis_width {
        // Exactly enough room for ellipsis only
        return ellipsis.to_string();
    }

    let available = max_width - ellipsis_width;
    let right_width = available.div_ceil(2); // Bias toward end (more useful info usually)
    let left_width = available - right_width;

    let left = truncate_to_display_width(s, left_width);
    let right = find_suffix_with_width(s, right_width);

    format!("{}{}{}", left, ellipsis, right)
}

/// Pads a string on the left (right-aligns) to reach the target width.
///
/// ANSI escape codes are preserved and don't count toward width calculations.
///
/// **Warning:** This does not strip BBCode tags—they will be counted toward
/// the display width. For tagged content, compute padding manually using
/// [`visible_width`] and `" ".repeat(padding)`.
///
/// # Example
///
/// ```rust
/// use standout_render::tabular::pad_left;
///
/// assert_eq!(pad_left("42", 5), "   42");
/// assert_eq!(pad_left("hello", 3), "hello");  // No truncation
/// ```
pub fn pad_left(s: &str, width: usize) -> String {
    pad_str(s, width, Alignment::Right, None).into_owned()
}

/// Pads a string on the right (left-aligns) to reach the target width.
///
/// ANSI escape codes are preserved and don't count toward width calculations.
///
/// **Warning:** This does not strip BBCode tags—they will be counted toward
/// the display width. For tagged content, compute padding manually using
/// [`visible_width`] and `" ".repeat(padding)`.
///
/// # Example
///
/// ```rust
/// use standout_render::tabular::pad_right;
///
/// assert_eq!(pad_right("42", 5), "42   ");
/// assert_eq!(pad_right("hello", 3), "hello");  // No truncation
/// ```
pub fn pad_right(s: &str, width: usize) -> String {
    pad_str(s, width, Alignment::Left, None).into_owned()
}

/// Pads a string on both sides (centers) to reach the target width.
///
/// When the remaining space is odd, the extra space goes on the right.
/// ANSI escape codes are preserved and don't count toward width calculations.
///
/// **Warning:** This does not strip BBCode tags—they will be counted toward
/// the display width. For tagged content, compute padding manually using
/// [`visible_width`] and `" ".repeat(padding)`.
///
/// # Example
///
/// ```rust
/// use standout_render::tabular::pad_center;
///
/// assert_eq!(pad_center("hi", 6), "  hi  ");
/// assert_eq!(pad_center("hi", 5), " hi  ");  // Extra space on right
/// ```
pub fn pad_center(s: &str, width: usize) -> String {
    pad_str(s, width, Alignment::Center, None).into_owned()
}

/// Wraps text to fit within a maximum display width, breaking at word boundaries.
///
/// Returns a vector of lines, each fitting within the specified width.
/// Words longer than the width are force-broken to fit.
///
/// ANSI escape codes are preserved and don't count toward width calculations.
///
/// # Arguments
///
/// * `s` - The string to wrap
/// * `width` - Maximum display width for each line
///
/// # Example
///
/// ```rust
/// use standout_render::tabular::wrap;
///
/// let lines = wrap("hello world foo", 11);
/// assert_eq!(lines, vec!["hello world", "foo"]);
///
/// let lines = wrap("short", 20);
/// assert_eq!(lines, vec!["short"]);
///
/// // Long words are force-broken with ellipsis markers
/// let lines = wrap("supercalifragilistic", 10);
/// assert!(lines.len() >= 2);
/// for line in &lines {
///     assert!(standout_render::tabular::display_width(line) <= 10);
/// }
/// ```
pub fn wrap(s: &str, width: usize) -> Vec<String> {
    wrap_indent(s, width, 0)
}

/// Wraps text with a continuation indent on subsequent lines.
///
/// The first line uses the full width. Subsequent lines are indented by the
/// specified amount, reducing their effective width.
///
/// ANSI escape codes are preserved and don't count toward width calculations.
///
/// # Arguments
///
/// * `s` - The string to wrap
/// * `width` - Maximum display width for each line
/// * `indent` - Number of spaces to indent continuation lines
///
/// # Example
///
/// ```rust
/// use standout_render::tabular::wrap_indent;
///
/// let lines = wrap_indent("hello world foo bar", 12, 2);
/// assert_eq!(lines, vec!["hello world", "  foo bar"]);
/// ```
pub fn wrap_indent(s: &str, width: usize, indent: usize) -> Vec<String> {
    if width == 0 {
        return vec![];
    }

    let s = s.trim();
    if s.is_empty() {
        return vec![];
    }

    // If the whole string fits, return it directly
    if measure_text_width(s) <= width {
        return vec![s.to_string()];
    }

    let mut lines = Vec::new();
    let mut current_line = String::new();
    let mut current_width = 0;
    let mut is_first_line = true;

    // Split on whitespace, preserving the structure
    for word in s.split_whitespace() {
        let word_width = measure_text_width(word);
        let effective_width = if is_first_line {
            width
        } else {
            width.saturating_sub(indent)
        };

        // Handle words longer than available width
        if word_width > effective_width {
            // Finish current line if it has content
            if !current_line.is_empty() {
                lines.push(current_line);
                current_line = String::new();
                current_width = 0;
                is_first_line = false;
            }

            // Force-break the long word
            let broken = break_long_word(word, effective_width, indent, is_first_line);
            let broken_len = broken.len();
            for (i, part) in broken.into_iter().enumerate() {
                if i == 0 && is_first_line {
                    lines.push(part);
                    is_first_line = false;
                } else if i < broken_len - 1 {
                    // Not the last part - push as complete line
                    lines.push(part);
                } else {
                    // Last part - becomes the start of the next line
                    current_line = part;
                    current_width = measure_text_width(&current_line);
                }
            }
            continue;
        }

        // Check if word fits on current line
        let needed_width = if current_line.is_empty() {
            word_width
        } else {
            current_width + 1 + word_width // +1 for space
        };

        if needed_width <= effective_width {
            // Word fits - add to current line
            if !current_line.is_empty() {
                current_line.push(' ');
                current_width += 1;
            }
            current_line.push_str(word);
            current_width += word_width;
        } else {
            // Word doesn't fit - start new line
            if !current_line.is_empty() {
                lines.push(current_line);
            }
            is_first_line = false;

            // Start new line with indent
            let indent_str: String = " ".repeat(indent);
            current_line = format!("{}{}", indent_str, word);
            current_width = indent + word_width;
        }
    }

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

    // Handle edge case where we produced no lines (shouldn't happen with non-empty input)
    if lines.is_empty() && !s.is_empty() {
        lines.push(truncate_to_display_width(s, width));
    }

    lines
}

/// Break a word that's longer than the available width into multiple parts.
fn break_long_word(word: &str, width: usize, indent: usize, is_first: bool) -> Vec<String> {
    let mut parts = Vec::new();
    let mut remaining = word;
    let mut first_part = is_first;

    while !remaining.is_empty() {
        let effective_width = if first_part {
            width
        } else {
            width.saturating_sub(indent)
        };

        if effective_width == 0 {
            // Can't fit anything - just return what we have
            break;
        }

        let remaining_width = measure_text_width(remaining);
        if remaining_width <= effective_width {
            // Rest fits
            let prefix = if first_part {
                String::new()
            } else {
                " ".repeat(indent)
            };
            parts.push(format!("{}{}", prefix, remaining));
            break;
        }

        // Need to break - leave room for ellipsis to indicate continuation
        let break_width = effective_width.saturating_sub(1); // -1 for "…"
        if break_width == 0 {
            // Not enough room even for one char + ellipsis
            let prefix = if first_part {
                String::new()
            } else {
                " ".repeat(indent)
            };
            parts.push(format!("{}…", prefix));
            break;
        }

        let prefix = if first_part {
            String::new()
        } else {
            " ".repeat(indent)
        };
        let truncated = truncate_to_display_width(remaining, break_width);
        parts.push(format!("{}{}…", prefix, truncated));

        // Find where we actually cut in the original string
        let truncated_len = truncated.chars().count();
        remaining = &remaining[remaining
            .char_indices()
            .nth(truncated_len)
            .map(|(i, _)| i)
            .unwrap_or(remaining.len())..];
        first_part = false;
    }

    parts
}

// --- Internal helpers ---

/// Truncate string to fit display width, keeping characters from the start.
/// Handles ANSI escape codes properly.
fn truncate_to_display_width(s: &str, max_width: usize) -> String {
    if max_width == 0 {
        return String::new();
    }

    // Fast path: if string fits, return as-is
    if measure_text_width(s) <= max_width {
        return s.to_string();
    }

    // We need to walk through the string carefully, tracking both
    // printable width and ANSI escape sequences
    let mut result = String::new();
    let mut current_width = 0;
    let chars = s.chars().peekable();
    let mut in_escape = false;

    for c in chars {
        if c == '\x1b' {
            // Start of ANSI escape sequence - include it all
            result.push(c);
            in_escape = true;
            continue;
        }

        if in_escape {
            result.push(c);
            // ANSI CSI sequences end with a letter (@ through ~)
            if c.is_ascii_alphabetic() || c == '~' {
                in_escape = false;
            }
            continue;
        }

        // Regular character - check width
        let char_width = unicode_width::UnicodeWidthChar::width(c).unwrap_or(0);
        if current_width + char_width > max_width {
            break;
        }
        result.push(c);
        current_width += char_width;
    }

    result
}

/// Find the longest suffix of s that has display width <= max_width.
fn find_suffix_with_width(s: &str, max_width: usize) -> String {
    if max_width == 0 {
        return String::new();
    }

    let total_width = measure_text_width(s);
    if total_width <= max_width {
        return s.to_string();
    }

    // Linear scan from the start to find where to cut.
    // We need to skip (total_width - max_width) display columns.
    let skip_width = total_width - max_width;

    let mut current_width = 0;
    let mut byte_offset = 0;
    let mut in_escape = false;

    for (i, c) in s.char_indices() {
        if c == '\x1b' {
            in_escape = true;
            byte_offset = i + c.len_utf8();
            continue;
        }

        if in_escape {
            byte_offset = i + c.len_utf8();
            if c.is_ascii_alphabetic() || c == '~' {
                in_escape = false;
            }
            continue;
        }

        let char_width = unicode_width::UnicodeWidthChar::width(c).unwrap_or(0);
        current_width += char_width;
        byte_offset = i + c.len_utf8();

        if current_width >= skip_width {
            break;
        }
    }

    s[byte_offset..].to_string()
}

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

    // --- display_width tests ---

    #[test]
    fn display_width_ascii() {
        assert_eq!(display_width("hello"), 5);
        assert_eq!(display_width(""), 0);
        assert_eq!(display_width(" "), 1);
    }

    #[test]
    fn display_width_ansi() {
        assert_eq!(display_width("\x1b[31mred\x1b[0m"), 3);
        assert_eq!(display_width("\x1b[1;32mbold green\x1b[0m"), 10);
        assert_eq!(display_width("\x1b[38;5;196mcolor\x1b[0m"), 5);
    }

    #[test]
    fn display_width_unicode() {
        assert_eq!(display_width("日本語"), 6); // 3 chars, 2 columns each
        assert_eq!(display_width("café"), 4);
        assert_eq!(display_width("🎉"), 2); // Emoji typically 2 columns
    }

    // --- truncate_end tests ---

    #[test]
    fn truncate_end_no_truncation() {
        assert_eq!(truncate_end("hello", 10, "…"), "hello");
        assert_eq!(truncate_end("hello", 5, "…"), "hello");
    }

    #[test]
    fn truncate_end_basic() {
        assert_eq!(truncate_end("hello world", 8, "…"), "hello w…");
        assert_eq!(truncate_end("hello world", 6, "…"), "hello…");
    }

    #[test]
    fn truncate_end_multi_char_ellipsis() {
        assert_eq!(truncate_end("hello world", 8, "..."), "hello...");
    }

    #[test]
    fn truncate_end_exact_fit() {
        assert_eq!(truncate_end("hello", 5, "…"), "hello");
    }

    #[test]
    fn truncate_end_tiny_width() {
        assert_eq!(truncate_end("hello", 1, "…"), "…");
        assert_eq!(truncate_end("hello", 0, "…"), "");
    }

    #[test]
    fn truncate_end_ansi() {
        let styled = "\x1b[31mhello world\x1b[0m";
        let result = truncate_end(styled, 8, "…");
        assert_eq!(display_width(&result), 8);
        assert!(result.contains("\x1b[31m")); // ANSI preserved
    }

    #[test]
    fn truncate_end_cjk() {
        assert_eq!(truncate_end("日本語テスト", 7, "…"), "日本語…"); // 3 chars (6 cols) + ellipsis
    }

    // --- truncate_start tests ---

    #[test]
    fn truncate_start_no_truncation() {
        assert_eq!(truncate_start("hello", 10, "…"), "hello");
    }

    #[test]
    fn truncate_start_basic() {
        assert_eq!(truncate_start("hello world", 8, "…"), "…o world");
    }

    #[test]
    fn truncate_start_path() {
        assert_eq!(truncate_start("/path/to/file.rs", 12, "…"), "…/to/file.rs");
    }

    #[test]
    fn truncate_start_tiny_width() {
        assert_eq!(truncate_start("hello", 1, "…"), "…");
        assert_eq!(truncate_start("hello", 0, "…"), "");
    }

    // --- truncate_middle tests ---

    #[test]
    fn truncate_middle_no_truncation() {
        assert_eq!(truncate_middle("hello", 10, "…"), "hello");
    }

    #[test]
    fn truncate_middle_basic() {
        assert_eq!(truncate_middle("hello world", 8, "…"), "hel…orld");
    }

    #[test]
    fn truncate_middle_multi_char_ellipsis() {
        assert_eq!(truncate_middle("abcdefghij", 7, "..."), "ab...ij");
    }

    #[test]
    fn truncate_middle_tiny_width() {
        assert_eq!(truncate_middle("hello", 1, "…"), "…");
        assert_eq!(truncate_middle("hello", 0, "…"), "");
    }

    #[test]
    fn truncate_middle_even_split() {
        // 10 chars, max 6, ellipsis 1 = 5 available, split 2/3 (bias toward end)
        assert_eq!(truncate_middle("abcdefghij", 6, "…"), "ab…hij");
    }

    // --- pad_left tests ---

    #[test]
    fn pad_left_basic() {
        assert_eq!(pad_left("42", 5), "   42");
        assert_eq!(pad_left("hello", 10), "     hello");
    }

    #[test]
    fn pad_left_no_padding_needed() {
        assert_eq!(pad_left("hello", 5), "hello");
        assert_eq!(pad_left("hello", 3), "hello"); // No truncation
    }

    #[test]
    fn pad_left_empty() {
        assert_eq!(pad_left("", 5), "     ");
    }

    #[test]
    fn pad_left_ansi() {
        let styled = "\x1b[31mhi\x1b[0m";
        let result = pad_left(styled, 5);
        assert!(result.ends_with("\x1b[0m"));
        assert_eq!(display_width(&result), 5);
    }

    // --- pad_right tests ---

    #[test]
    fn pad_right_basic() {
        assert_eq!(pad_right("42", 5), "42   ");
        assert_eq!(pad_right("hello", 10), "hello     ");
    }

    #[test]
    fn pad_right_no_padding_needed() {
        assert_eq!(pad_right("hello", 5), "hello");
        assert_eq!(pad_right("hello", 3), "hello");
    }

    #[test]
    fn pad_right_empty() {
        assert_eq!(pad_right("", 5), "     ");
    }

    // --- pad_center tests ---

    #[test]
    fn pad_center_basic() {
        assert_eq!(pad_center("hi", 6), "  hi  ");
    }

    #[test]
    fn pad_center_odd_space() {
        assert_eq!(pad_center("hi", 5), " hi  "); // Extra space on right
    }

    #[test]
    fn pad_center_no_padding() {
        assert_eq!(pad_center("hello", 5), "hello");
        assert_eq!(pad_center("hello", 3), "hello");
    }

    #[test]
    fn pad_center_empty() {
        assert_eq!(pad_center("", 4), "    ");
    }

    // --- Edge cases ---

    #[test]
    fn empty_string_operations() {
        assert_eq!(display_width(""), 0);
        assert_eq!(truncate_end("", 5, "…"), "");
        assert_eq!(truncate_start("", 5, "…"), "");
        assert_eq!(truncate_middle("", 5, "…"), "");
        assert_eq!(pad_left("", 0), "");
        assert_eq!(pad_right("", 0), "");
    }

    #[test]
    fn zero_width_target() {
        assert_eq!(truncate_end("hello", 0, "…"), "");
        assert_eq!(truncate_start("hello", 0, "…"), "");
        assert_eq!(truncate_middle("hello", 0, "…"), "");
    }

    // --- wrap tests ---

    #[test]
    fn wrap_single_line_fits() {
        assert_eq!(wrap("hello world", 20), vec!["hello world"]);
        assert_eq!(wrap("short", 10), vec!["short"]);
    }

    #[test]
    fn wrap_basic_multiline() {
        assert_eq!(wrap("hello world foo", 11), vec!["hello world", "foo"]);
        assert_eq!(
            wrap("one two three four", 10),
            vec!["one two", "three four"]
        );
    }

    #[test]
    fn wrap_exact_fit() {
        assert_eq!(wrap("hello", 5), vec!["hello"]);
        assert_eq!(wrap("hello world", 11), vec!["hello world"]);
    }

    #[test]
    fn wrap_empty_string() {
        let result: Vec<String> = wrap("", 10);
        assert!(result.is_empty());
    }

    #[test]
    fn wrap_whitespace_only() {
        let result: Vec<String> = wrap("   ", 10);
        assert!(result.is_empty());
    }

    #[test]
    fn wrap_zero_width() {
        let result: Vec<String> = wrap("hello", 0);
        assert!(result.is_empty());
    }

    #[test]
    fn wrap_single_word_per_line() {
        assert_eq!(wrap("a b c d", 1), vec!["a", "b", "c", "d"]);
    }

    #[test]
    fn wrap_long_word_force_break() {
        // "supercalifragilistic" is 20 chars, width 10
        // With ellipsis breaks: "supercali…" (10), "fragilis…" (10), "tic" (3)
        let result = wrap("supercalifragilistic", 10);
        assert!(result.len() >= 2, "should produce multiple lines");
        for line in &result {
            assert!(display_width(line) <= 10, "line '{}' exceeds width", line);
        }
    }

    #[test]
    fn wrap_preserves_word_boundaries() {
        let result = wrap("hello world test", 10);
        // Should not break "hello" or "world" in the middle
        assert_eq!(result[0], "hello");
        assert_eq!(result[1], "world test");
    }

    #[test]
    fn wrap_multiple_spaces_normalized_when_wrapping() {
        // When wrapping occurs, multiple spaces between words get normalized
        // because we split_whitespace and rejoin with single spaces
        let result = wrap("hello    world    foo", 12);
        // "hello world" (11) fits, "foo" goes to next line
        assert_eq!(result, vec!["hello world", "foo"]);
    }

    // --- wrap_indent tests ---

    #[test]
    fn wrap_indent_basic() {
        let result = wrap_indent("hello world foo bar", 12, 2);
        assert_eq!(result.len(), 2);
        assert_eq!(result[0], "hello world");
        assert!(result[1].starts_with("  ")); // 2-space indent
    }

    #[test]
    fn wrap_indent_no_wrap_needed() {
        assert_eq!(wrap_indent("short", 20, 4), vec!["short"]);
    }

    #[test]
    fn wrap_indent_multiple_lines() {
        let result = wrap_indent("one two three four five six", 10, 2);
        // First line: no indent, up to 10 chars
        // Subsequent: 2-char indent, effective width 8
        assert!(!result[0].starts_with(' '));
        for line in result.iter().skip(1) {
            assert!(line.starts_with("  "), "continuation should be indented");
        }
    }

    #[test]
    fn wrap_indent_zero_indent() {
        // Same as regular wrap
        let result = wrap_indent("hello world foo", 11, 0);
        assert_eq!(result, vec!["hello world", "foo"]);
    }

    #[test]
    fn wrap_cjk_characters() {
        // CJK characters are 2 columns each
        // "日本語" is 6 columns
        let result = wrap("日本語 テスト", 8);
        assert_eq!(result.len(), 2);
        for line in &result {
            assert!(display_width(line) <= 8);
        }
    }
}

#[cfg(test)]
mod proptests {
    use super::*;
    use proptest::prelude::*;

    proptest! {
        #[test]
        fn truncate_end_respects_max_width(
            s in "[a-zA-Z0-9 ]{0,100}",
            max_width in 0usize..50,
        ) {
            let result = truncate_end(&s, max_width, "…");
            let result_width = display_width(&result);
            prop_assert!(
                result_width <= max_width,
                "truncate_end exceeded max_width: result '{}' has width {}, max was {}",
                result, result_width, max_width
            );
        }

        #[test]
        fn truncate_start_respects_max_width(
            s in "[a-zA-Z0-9 ]{0,100}",
            max_width in 0usize..50,
        ) {
            let result = truncate_start(&s, max_width, "…");
            let result_width = display_width(&result);
            prop_assert!(
                result_width <= max_width,
                "truncate_start exceeded max_width: result '{}' has width {}, max was {}",
                result, result_width, max_width
            );
        }

        #[test]
        fn truncate_middle_respects_max_width(
            s in "[a-zA-Z0-9 ]{0,100}",
            max_width in 0usize..50,
        ) {
            let result = truncate_middle(&s, max_width, "…");
            let result_width = display_width(&result);
            prop_assert!(
                result_width <= max_width,
                "truncate_middle exceeded max_width: result '{}' has width {}, max was {}",
                result, result_width, max_width
            );
        }

        #[test]
        fn truncate_preserves_short_strings(
            s in "[a-zA-Z0-9]{0,20}",
            extra_width in 0usize..30,
        ) {
            let width = display_width(&s);
            let max_width = width + extra_width;

            // If string fits, it should be unchanged
            prop_assert_eq!(truncate_end(&s, max_width, "…"), s.clone());
            prop_assert_eq!(truncate_start(&s, max_width, "…"), s.clone());
            prop_assert_eq!(truncate_middle(&s, max_width, "…"), s);
        }

        #[test]
        fn pad_produces_exact_width_when_larger(
            s in "[a-zA-Z0-9]{0,20}",
            extra in 1usize..30,
        ) {
            let original_width = display_width(&s);
            let target_width = original_width + extra;

            prop_assert_eq!(display_width(&pad_left(&s, target_width)), target_width);
            prop_assert_eq!(display_width(&pad_right(&s, target_width)), target_width);
            prop_assert_eq!(display_width(&pad_center(&s, target_width)), target_width);
        }

        #[test]
        fn pad_preserves_content_when_smaller(
            s in "[a-zA-Z0-9]{1,30}",
        ) {
            let original_width = display_width(&s);
            let target_width = original_width.saturating_sub(5);

            // When target is smaller, string should be unchanged
            prop_assert_eq!(pad_left(&s, target_width), s.clone());
            prop_assert_eq!(pad_right(&s, target_width), s.clone());
            prop_assert_eq!(pad_center(&s, target_width), s);
        }

        #[test]
        fn truncate_end_contains_ellipsis_when_truncated(
            s in "[a-zA-Z0-9]{10,50}",
            max_width in 3usize..9,
        ) {
            let result = truncate_end(&s, max_width, "…");
            if display_width(&s) > max_width {
                prop_assert!(
                    result.contains("…"),
                    "truncated string should contain ellipsis"
                );
            }
        }

        #[test]
        fn truncate_start_contains_ellipsis_when_truncated(
            s in "[a-zA-Z0-9]{10,50}",
            max_width in 3usize..9,
        ) {
            let result = truncate_start(&s, max_width, "…");
            if display_width(&s) > max_width {
                prop_assert!(
                    result.contains("…"),
                    "truncated string should contain ellipsis"
                );
            }
        }

        #[test]
        fn truncate_middle_contains_ellipsis_when_truncated(
            s in "[a-zA-Z0-9]{10,50}",
            max_width in 3usize..9,
        ) {
            let result = truncate_middle(&s, max_width, "…");
            if display_width(&s) > max_width {
                prop_assert!(
                    result.contains("…"),
                    "truncated string should contain ellipsis"
                );
            }
        }

        #[test]
        fn wrap_all_lines_respect_width(
            s in "[a-zA-Z]{1,10}( [a-zA-Z]{1,10}){0,10}",
            width in 5usize..30,
        ) {
            let lines = wrap(&s, width);
            for line in &lines {
                let line_width = display_width(line);
                prop_assert!(
                    line_width <= width,
                    "wrap produced line '{}' with width {}, max was {}",
                    line, line_width, width
                );
            }
        }

        #[test]
        fn wrap_preserves_all_words(
            words in prop::collection::vec("[a-zA-Z]{1,8}", 1..10),
            width in 10usize..40,
        ) {
            let input = words.join(" ");
            let lines = wrap(&input, width);
            let rejoined = lines.join(" ");

            // All original words should appear in the output
            for word in &words {
                prop_assert!(
                    rejoined.contains(word),
                    "word '{}' missing from wrapped output",
                    word
                );
            }
        }

        #[test]
        fn wrap_indent_continuation_lines_are_indented(
            s in "[a-zA-Z]{1,5}( [a-zA-Z]{1,5}){3,8}",
            width in 10usize..20,
            indent in 1usize..4,
        ) {
            let lines = wrap_indent(&s, width, indent);
            if lines.len() > 1 {
                let indent_str: String = " ".repeat(indent);
                for line in lines.iter().skip(1) {
                    prop_assert!(
                        line.starts_with(&indent_str),
                        "continuation line '{}' should start with {} spaces",
                        line, indent
                    );
                }
            }
        }

        #[test]
        fn wrap_nonempty_input_produces_nonempty_output(
            s in "[a-zA-Z]{1,20}",
            width in 1usize..30,
        ) {
            let lines = wrap(&s, width);
            prop_assert!(
                !lines.is_empty(),
                "non-empty input '{}' should produce non-empty output",
                s
            );
        }
    }
}