#![feature(vec_remove_item)]

use std::collections::HashSet;

pub fn get_perms(items: Vec<String>) -> Result<HashSet<String>, String> {

	let mut permutations: HashSet<String> = HashSet::new();

	// Handles instances where either one or less items are passed to the function
	if items.len() < 1 {
		return Err("The Items Vec must have items dawg...".to_string())
	} else if items.len() == 1 {
		permutations.insert(items.clone().pop().unwrap());
		return Ok(permutations)
	}

	// Making items available after it gets consumed by iterator
	let items_clone = items.clone();

	for item in items {
		let mut items_copy = items_clone.clone();
		permutations.insert(item.clone());
		items_copy.remove_item(&item);
		complete_perms(&mut permutations, &item.clone(), &items_copy);
	}

	Ok(permutations)
}

fn complete_perms(permutations: &mut HashSet<String>, prepended: &String, items: &Vec<String>) {
	let mut items_copy = items.clone();

	if items.len() == 1 {
		permutations.insert(items_copy.pop().unwrap());
	} else {
		for item in items {
			let new_item = format!("{}{}", prepended, item);
			permutations.insert(new_item);
		}
		for item in items {
			let to_be_prepended = format!("{}{}", prepended, item);
			complete_perms(&mut *permutations, &to_be_prepended, &items_copy);
		}
	}
}

fn main() {
    let items = vec!["a".to_string(), "b".to_string(), "c".to_string()];
    let perms = get_perms(items);
    for perm in perms {
        println!("{:?}", perm);
    }
}