use std::collections::{BTreeMap, HashMap};
use regex::Regex;
use serde::Serialize;
use crate::Error;
use crate::morphology::Morphology;
use crate::text::{heading, is_list_item, mask_html_comments};
const TEMPLATE_HEADING_WORDS: &[&str] = &[
"はじめに",
"背景",
"概要",
"本記事について",
"この記事について",
"まとめと今後",
"今後の展望",
"今後の課題",
"今後について",
"まとめ",
"おわりに",
"終わりに",
"さいごに",
"最後に",
"結論",
"総括",
"conclusion",
"introduction",
"summary",
];
#[derive(Clone, Debug, Serialize)]
pub struct OutlineEntry {
pub line: usize,
pub kind: String,
pub level: Option<usize>,
pub text: String,
}
#[derive(Clone, Debug, Serialize)]
pub struct TemplateHit {
pub line: usize,
pub text: String,
pub matched: String,
}
#[derive(Clone, Debug, Serialize)]
pub struct HeadingGroupStats {
pub count: usize,
pub length_mean: f64,
pub length_cv: f64,
pub nominal_ending_ratio: f64,
pub dominant_pos_signature_ratio: f64,
pub template_hits: Vec<TemplateHit>,
pub structural_pattern_ratio: f64,
}
#[derive(Clone, Debug, Serialize)]
pub struct HeadingStats {
pub total_headings: usize,
pub level_distribution: BTreeMap<String, usize>,
pub by_level: BTreeMap<String, HeadingGroupStats>,
pub overall: HeadingGroupStats,
}
#[derive(Clone, Debug, Serialize)]
pub struct OutlineReport {
pub outline: Vec<OutlineEntry>,
pub heading_stats: HeadingStats,
}
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
enum BlockKind {
Lead,
Bullets,
Quote,
Table,
}
fn block_kind(line: &str) -> BlockKind {
let trimmed = line.trim_start();
if is_list_item(line) {
BlockKind::Bullets
} else if trimmed.starts_with('>') {
BlockKind::Quote
} else if (trimmed.starts_with('|') && trimmed.matches('|').count() >= 2)
|| (trimmed.contains('|')
&& trimmed
.chars()
.all(|ch| ch.is_whitespace() || matches!(ch, '|' | '-' | ':')))
{
BlockKind::Table
} else {
BlockKind::Lead
}
}
fn flush_block(buffer: &mut Vec<(usize, String)>, output: &mut Vec<OutlineEntry>) {
let Some((first_line_no, first_line)) = buffer.first() else {
return;
};
match block_kind(first_line) {
BlockKind::Bullets => {
let count = buffer.iter().filter(|(_, line)| is_list_item(line)).count();
output.push(OutlineEntry {
line: *first_line_no,
kind: "bullets".to_owned(),
level: None,
text: format!("(箇条書き {count} 項目)"),
});
}
BlockKind::Lead => {
let end = first_line
.char_indices()
.find(|(_, ch)| matches!(ch, '。' | '！' | '？'))
.map_or(first_line.len(), |(byte, ch)| byte + ch.len_utf8());
let text = first_line[..end].trim();
if !text.is_empty() {
output.push(OutlineEntry {
line: *first_line_no,
kind: "lead".to_owned(),
level: None,
text: text.to_owned(),
});
}
}
BlockKind::Quote | BlockKind::Table => {}
}
buffer.clear();
}
pub fn build_outline(raw_text: &str) -> Vec<OutlineEntry> {
let text = mask_html_comments(raw_text);
let mut output = Vec::new();
let mut buffer = Vec::new();
let mut fence: Option<(char, usize)> = None;
let mut front_matter = false;
for (index, line) in text.split('\n').enumerate() {
let line_no = index + 1;
if index == 0 && line.trim() == "---" {
front_matter = true;
continue;
}
if front_matter {
if line.trim() == "---" {
front_matter = false;
}
continue;
}
let trimmed = line.trim_start();
let fence_run = trimmed
.chars()
.next()
.filter(|ch| *ch == '`' || *ch == '~')
.map(|ch| {
(
ch,
trimmed
.chars()
.take_while(|candidate| candidate == &ch)
.count(),
)
});
if let Some((open_char, open_len)) = fence {
if fence_run.is_some_and(|(ch, len)| {
ch == open_char && len >= open_len && trimmed[len..].trim().is_empty()
}) {
fence = None;
}
continue;
}
if let Some((ch, len)) = fence_run.filter(|(_, len)| *len >= 3) {
flush_block(&mut buffer, &mut output);
fence = Some((ch, len));
continue;
}
if line.trim().is_empty() {
flush_block(&mut buffer, &mut output);
continue;
}
if let Some((level, text)) = heading(line) {
flush_block(&mut buffer, &mut output);
output.push(OutlineEntry {
line: line_no,
kind: "heading".to_owned(),
level: Some(level),
text,
});
continue;
}
if let Some((_, first)) = buffer.first() {
let current = block_kind(first);
let next = block_kind(line);
let indented_bullet_continuation = current == BlockKind::Bullets
&& next == BlockKind::Lead
&& line.starts_with(char::is_whitespace);
if current != next && !indented_bullet_continuation {
flush_block(&mut buffer, &mut output);
}
}
buffer.push((line_no, line.to_owned()));
}
flush_block(&mut buffer, &mut output);
output
}
fn round(value: f64, digits: i32) -> f64 {
let scale = 10_f64.powi(digits);
(value * scale).round() / scale
}
fn stripped_heading(text: &str) -> String {
text.trim_start_matches(|ch: char| {
ch.is_whitespace()
|| ch.is_ascii_digit()
|| ch.is_ascii_punctuation()
|| matches!(
ch,
'０'..='９' | '．' | '、' | '（' | '）' | '【' | '】' | '・'
)
})
.trim()
.to_lowercase()
}
fn template_word(text: &str) -> Option<&'static str> {
let stripped = stripped_heading(text);
TEMPLATE_HEADING_WORDS
.iter()
.copied()
.find(|word| stripped.starts_with(&word.to_lowercase()))
}
fn structural_pattern(text: &str) -> bool {
let numbered =
Regex::new(r"^\s*([0-9０-９]+[.).、]|[①-⑳])\s*\S").expect("valid numbered-heading regex");
let bracketed =
Regex::new(r"^\s*[【\[［(（].+[】\]］)）]\s*$").expect("valid bracketed-heading regex");
let towa = Regex::new(r".+とは[?？]?\s*$").expect("valid definition-heading regex");
numbered.is_match(text) || bracketed.is_match(text) || towa.is_match(text)
}
fn summarize(
headings: &[&OutlineEntry],
morphology: &Morphology,
) -> Result<HeadingGroupStats, Error> {
if headings.is_empty() {
return Ok(HeadingGroupStats {
count: 0,
length_mean: 0.0,
length_cv: 0.0,
nominal_ending_ratio: 0.0,
dominant_pos_signature_ratio: 0.0,
template_hits: Vec::new(),
structural_pattern_ratio: 0.0,
});
}
let count = headings.len();
let lengths = headings
.iter()
.map(|heading| heading.text.chars().count() as f64)
.collect::<Vec<_>>();
let mean = lengths.iter().sum::<f64>() / count as f64;
let cv = if mean > 0.0 && count > 1 {
let variance = lengths
.iter()
.map(|length| (length - mean).powi(2))
.sum::<f64>()
/ count as f64;
variance.sqrt() / mean
} else {
0.0
};
let mut nominal_count = 0;
let mut signatures = HashMap::<Vec<String>, usize>::new();
for heading in headings {
let tokens = morphology.tokenize(&heading.text)?;
if tokens
.iter()
.rev()
.find(|token| !matches!(token.pos(0), "記号" | "補助記号" | "空白"))
.is_some_and(|token| matches!(token.pos(0), "名詞" | "代名詞"))
{
nominal_count += 1;
}
let signature = tokens
.iter()
.filter(|token| {
matches!(
token.pos(0),
"名詞" | "代名詞" | "形状詞" | "動詞" | "形容詞" | "副詞" | "接頭辞"
)
})
.map(|token| token.pos(0).to_owned())
.collect::<Vec<_>>();
if !signature.is_empty() {
*signatures.entry(signature).or_default() += 1;
}
}
let dominant = signatures.values().copied().max().unwrap_or_default();
let template_hits = headings
.iter()
.filter_map(|heading| {
template_word(&heading.text).map(|matched| TemplateHit {
line: heading.line,
text: heading.text.clone(),
matched: matched.to_owned(),
})
})
.collect();
let structural_count = headings
.iter()
.filter(|heading| structural_pattern(&heading.text))
.count();
Ok(HeadingGroupStats {
count,
length_mean: round(mean, 2),
length_cv: round(cv, 3),
nominal_ending_ratio: round(nominal_count as f64 / count as f64, 3),
dominant_pos_signature_ratio: round(dominant as f64 / count as f64, 3),
template_hits,
structural_pattern_ratio: round(structural_count as f64 / count as f64, 3),
})
}
pub fn analyze(raw_text: &str, morphology: &Morphology) -> Result<OutlineReport, Error> {
let outline = build_outline(raw_text);
let headings = outline
.iter()
.filter(|entry| entry.kind == "heading")
.collect::<Vec<_>>();
let mut grouped = BTreeMap::<usize, Vec<&OutlineEntry>>::new();
for entry in &headings {
grouped
.entry(entry.level.unwrap_or_default())
.or_default()
.push(entry);
}
let level_distribution = grouped
.iter()
.map(|(level, entries)| (level.to_string(), entries.len()))
.collect();
let mut by_level = BTreeMap::new();
for (level, entries) in grouped {
by_level.insert(level.to_string(), summarize(&entries, morphology)?);
}
let overall = summarize(&headings, morphology)?;
Ok(OutlineReport {
heading_stats: HeadingStats {
total_headings: headings.len(),
level_distribution,
by_level,
overall,
},
outline,
})
}