varurl 0.1.9

#![feature(let_chains)]

use daachorse::{
  errors::Result, CharwiseDoubleArrayAhoCorasick, CharwiseDoubleArrayAhoCorasickBuilder, MatchKind,
};
use mdli::{Kind, MdLi};

pub struct VarUrl {
  pub ac: CharwiseDoubleArrayAhoCorasick<usize>,
}

impl VarUrl {
  pub fn new<I, S: AsRef<str>>(prefix_li: I) -> Result<Self>
  where
    I: IntoIterator<Item = S>,
  {
    let ac = CharwiseDoubleArrayAhoCorasickBuilder::new()
      .match_kind(MatchKind::LeftmostLongest)
      .build(prefix_li)?;
    Ok(VarUrl { ac })
  }

  fn find_end<'a>(&self, before: &'a str, after: &'a str) -> Option<(usize, &'a str)> {
    if before.ends_with("](") {
      if let Some(url_end) = after.find(')') {
        return Some((url_end, &after[..url_end]));
      }
    }

    if before.ends_with("src=\"") || before.ends_with("href=\"") {
      if let Some(url_end) = after.find('"') {
        return Some((url_end, &after[..url_end]));
      }
    }

    None
  }

  pub fn replace(&self, mdli: &mut MdLi, from_lang: &str, to_lang: &str) -> Result<()> {
    let from_lang = format!("/{from_lang}/");
    let to_lang = format!("/{to_lang}/");

    // 就地修改每个 Md 元素
    for i in 0..mdli.0.len() {
      if mdli.0[i].kind != Kind::Txt {
        continue;
      }

      let md = &mdli.0[i].str;
      let mut pre_pos = 0;
      let mut new_str = String::new();
      let mut last_end = 0; // 记录上一次匹配的结束位置

      for m in self.ac.leftmost_find_iter(md) {
        let start = m.start();
        let end = m.end();

        // 如果当前开始位置小于上一次的结束位置，跳过这次匹配
        if start < last_end {
          continue;
        }

        let val = &md[start..end];

        let before = &md[..start];
        let after = &md[end..];

        if let Some((url_end, url_part)) = self.find_end(before, after) {
          let full_url = format!("{}{}", val, url_part);

          if full_url.contains(&from_lang) {
            let new_url = full_url.replace(&from_lang, &to_lang);

            // 添加前面的文本和新URL
            new_str.push_str(&md[pre_pos..start]);
            new_str.push_str(&new_url);
            pre_pos = end + url_end;
            last_end = pre_pos; // 更新上一次的结束位置
            continue;
          }
        }

        // 添加未匹配的部分
        new_str.push_str(&md[pre_pos..end]);
        pre_pos = end;
        last_end = end; // 更新上一次的结束位置
      }

      // 添加剩余的文本
      if pre_pos < md.len() {
        new_str.push_str(&md[pre_pos..]);
      }

      // 只有当文本有变化时才替换
      if new_str != *md {
        mdli.0[i].str = new_str;
      }
    }

    Ok(())
  }
}