「裏は緻密なプログラム、表は平易で明快な日本語表現」：
〜技術の難しさを空気のように消し去る「お客様への3つのお約束」とわかりやすい案内設計の知恵〜

#![forbid(unsafe_code)]

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct ToneViolation<'a> {
    pub forbidden_term: &'a str,
    pub byte_offset: usize,
    pub line_number: usize,
}

/// Computes the byte offset and 1-based line number of any forbidden internal jargon
/// inside human-facing HTML layers (excluding 第3章 `#monograph` blocks).
pub fn audit_human_facing_tone<'a>(
    html_source: &'a str,
    forbidden_jargon: &'a [&'a str],
) -> Result<(), ToneViolation<'a>> {
    // Strip out the 第3章 `#monograph` section where formal technical specs belong
    let visible_human_region = match html_source.find("id=\"monograph\"") {
        Some(idx) => &html_source[..idx],
        None => html_source,
    };

    for &term in forbidden_jargon {
        if term.is_empty() {
            continue;
        }
        if let Some(pos) = visible_human_region.find(term) {
            let line_number = visible_human_region[..pos]
                .bytes()
                .filter(|&b| b == b'
')
                .count()
                + 1;
            return Err(ToneViolation {
                forbidden_term: term,
                byte_offset: pos,
                line_number,
            });
        }
    }
    Ok(())
}