Detailed explanation of the code of rust zip asynchronous compression and decompression

tokio = { version = "1.35.1", features = ["macros"] }
tokio-util = "0.7.10"
async_zip = { version = "0.0.17", features = ["tokio", "tokio-fs", "deflate"] }
futures-lite = "2.3.0"
anyhow = "1.0.44"

use anyhow::anyhow;
use async_zip::tokio::read::seek::ZipFileReader;
use async_zip::tokio::write::ZipFileWriter;
use async_zip::{Compression, DeflateOption, ZipEntryBuilder};
use futures_lite::AsyncWriteExt;
use std::path::{Path, PathBuf};
use tokio::fs::File;
use tokio::fs::{create_dir_all, OpenOptions};
use tokio::fs::{read_dir, remove_dir_all};
use tokio::io::{AsyncBufReadExt, AsyncReadExt, BufReader};
use tokio_util::compat::TokioAsyncWriteCompatExt;
use tokio_util::compat::{FuturesAsyncWriteCompatExt, TokioAsyncReadCompatExt};
//Read folder fileasync fn dirs(dir: PathBuf) -> Result<Vec<PathBuf>, anyhow::Error> {
    let mut dirs = vec![dir];
    let mut files = vec![];
    while !dirs.is_empty() {
        let mut dir_iter = read_dir((0)).await?;
        while let Some(entry) = dir_iter.next_entry().await? {
            let entry_path_buf = ();
            if entry_path_buf.is_dir() {
                (entry_path_buf);
            } else {
                (entry_path_buf);
            }
        }
    }
    Ok(files)
}
//Compress a single fileasync fn zip_entry(
    input_path: &Path,
    file_name: &str,
    zip_writer: &mut ZipFileWriter<File>,
) -> Result<(), anyhow::Error> {
    let mut input_file = File::open(input_path).await?;
    let builder = ZipEntryBuilder::new(file_name.into(), Compression::Deflate)
        .deflate_option(DeflateOption::Normal);
    let mut entry_writer = zip_writer.write_entry_stream(builder).await?;
    futures_lite::io::copy(&mut input_file.compat(), &mut entry_writer).await?;
    entry_writer.close().await?;
    return Ok(());
}
//compressionpub async fn zip(input_path: &Path, out_path: &Path) -> Result<(), anyhow::Error> {
    let file = File::create(out_path).await?;
    let mut writer = ZipFileWriter::with_tokio(file);
    let input_dir_str = input_path
        .as_os_str()
        .to_str()
        .ok_or(anyhow!("Input path not valid UTF-8."))?;
    if input_path.is_file() {
        let file_name = input_path
            .file_name()
            .ok_or(anyhow!("File name not found.".to_string()))?
            .to_string_lossy();
        zip_entry(input_path, &file_name, &mut writer).await?;
    } else {
        let entries = dirs(input_path.into()).await?;
        for entry_path_buf in entries {
            let entry_path = entry_path_buf.as_path();
            let entry_str = entry_path
                .as_os_str()
                .to_str()
                .ok_or(anyhow!("Directory file path not valid UTF-8."))?;
            let file_name = &entry_str[(input_dir_str.len() + 1)..];
            zip_entry(entry_path, file_name, &mut writer).await?;
        }
    }
    ().await?;
    Ok(())
}
//Decompressionpub async fn unzip<T: AsRef<Path>>(path: T, out_path: T) -> Result<(), anyhow::Error> {
    let out_path = out_path.as_ref();
    if out_path.exists() {
        remove_dir_all(out_path).await?;
    } else {
        create_dir_all(out_path).await?;
    }
    let path = path.as_ref();
    let file = File::open(path).await?;
    let reader = BufReader::new(file);
    let mut zip = ZipFileReader::with_tokio(reader).await?;
    for index in 0..().entries().len() {
        let entry = zip
            .file()
            .entries()
            .get(index)
            .ok_or(anyhow!("zip entry not found".to_string()))?;
        let raw = ().as_bytes();
        let mut file_name = &String::from_utf8_lossy(raw).to_string(); //It must be converted to utf8, otherwise there will be garbled code        let zip_path = out_path.join(file_name);
        if file_name.ends_with("/") {
            create_dir_all(&zip_path).await?;
            continue;
        }
        if let Some(p) = zip_path.parent() {
            if !() {
                create_dir_all(p).await?;
            }
        }
        let mut entry_reader = zip.reader_without_entry(index).await?;
        let mut writer = OpenOptions::new()
            .write(true)
            .create_new(true)
            .open(&zip_path)
            .await?;
        futures_lite::io::copy(&mut entry_reader, &mut writer.compat_write()).await?;
    }
    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    #[tokio::test]
    async fn test_zip() -> Result<(), anyhow::Error> {
        let path = Path::new("file/tmp/test");
        zip(path, Path::new("file/tmp/")).await?;
        Ok(())
    }
    #[tokio::test]
    async fn test_unzip() -> Result<(), anyhow::Error> {
        let path = Path::new("file/tmp/a/");
        unzip(path, Path::new("file/tmp")).await?;
        Ok(())
    }
}