use std::path::Path;
use std::fs::{ReadDir, DirEntry};
use std::vec::*;
use std::io;

pub struct DirectoryIterator<P>
{
    root: P,
    dirs: Vec<DirEntry>,
}

fn traverse<P>(path: P, out: &mut Vec<DirEntry>) -> io::Result<()>
where P:AsRef<Path>
{
    for entry in std::fs::read_dir(path)? {
	match entry {
	    Ok(entry) => out.push(entry),
	    Err(_) => (),
	}
    }
    
    Ok(())
}

impl<P> DirectoryIterator<P>
where P: AsRef<Path>
{
    pub fn begin(path: P) -> Result<Self, std::io::Error> {

	let mut cache = Vec::new();

	traverse(&path, &mut cache)?;

	Ok(Self{
	    root: path,
	    dirs: cache,
	})
    }

}

impl<P: AsRef<Path>> Iterator for DirectoryIterator<P>
{
    type Item = String;

    fn next(&mut self) -> Option<Self::Item>
    {	
	let current = self.dirs.pop();

	if let Some(current) = current {
	    let path = current.path();
	    
	    if path.is_dir() {
		let _ = traverse(&path, &mut self.dirs);
		self.next()
	    } else {

		match path.as_path().to_str() {
		    Some(path) => Some(path.to_string()),
		    None => self.next(),
		}
	    }
	} else {
	    None
	}
    }
}