use std::ops::AsyncFn;
use std::path::Path;

use futures::future::BoxFuture;
use futures::FutureExt;
use tokio::fs::DirEntry;

use crate::error::CustomError;

pub(crate) fn walk_fs<'p, P: AsRef<Path> + std::marker::Send + 'p>(
    root: P,
    predicate: fn(&DirEntry) -> Result<bool, CustomError>,
) -> BoxFuture<'p, Result<Vec<DirEntry>, CustomError>> {
    async move {
        let mut ret = Vec::new();
        let mut entries = tokio::fs::read_dir(root).await?;
        while let Some(entry) = entries.next_entry().await? {
            let file_type = entry.file_type().await?;
            if file_type.is_dir() {
                let child_entries = walk_fs(entry.path(), predicate).await?;
                ret.extend(child_entries);
            }
            if predicate(&entry)? {
                ret.push(entry);
            }
        }

        Ok(ret)
    }
    .boxed()
}