use crate::formats::shared::{following_lines, max_boundary_offset};
pub(crate) fn block_end(
lines: &[String],
read_start: usize,
start_offset: usize,
viewport_bottom: usize,
) -> Option<usize> {
let max_offset = max_boundary_offset(lines, read_start, viewport_bottom)?;
let start_level = heading_level(lines.get(start_offset)?)?;
for (offset, line) in following_lines(lines, start_offset, max_offset) {
if heading_level(line).is_some_and(|level| level <= start_level) {
return Some(read_start + offset.saturating_sub(1));
}
}
None
}
pub(crate) fn is_heading(line: &str) -> bool {
heading_level(line).is_some()
}
fn heading_level(line: &str) -> Option<usize> {
let trimmed = line.trim_start();
let hashes = trimmed.bytes().take_while(|byte| *byte == b'#').count();
((1..=6).contains(&hashes)
&& trimmed
.as_bytes()
.get(hashes)
.is_some_and(u8::is_ascii_whitespace))
.then_some(hashes)
}