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use rand::{rngs::SmallRng, seq::SliceRandom, SeedableRng};
use std::{cmp::Ordering, iter::from_generator};

/// Sorts a slice of data using the [bogo sort](https://en.wikipedia.org/wiki/Bogosort) in `O(n!)`.
///
/// # Examples
///
/// ```
/// # use sort_steps::bogo_sort;
/// let numbers = [2, 1, 3, 4];
/// println!("Bogo Sort Steps:");
/// for (i, v) in bogo_sort(&numbers).enumerate() {
///     println!("#{:02}: {:?}", i, v);
/// }
/// ```
pub fn bogo_sort<T>(v: &[T]) -> impl Iterator<Item = Vec<T>>
where
    T: PartialOrd + Clone,
{
    bogo_sort_by(v, |a, b| a.partial_cmp(b))
}

/// Sorts a slice of data using the [bogo sort](https://en.wikipedia.org/wiki/Bogosort) with a custom comparator.
///
/// # Examples
///
/// ```
/// # use sort_steps::{bogo_sort_by};
/// let numbers = [2, 1, 3, 4];
/// println!("Bogo Sort Steps:");
/// for (i, v) in bogo_sort_by(&numbers, |a, b| a.partial_cmp(b)).enumerate() {
///     println!("#{:02}: {:?}", i, v);
/// }
/// ```
pub fn bogo_sort_by<T, F>(v: &[T], compare: F) -> impl Iterator<Item = Vec<T>>
where
    F: Fn(&T, &T) -> Option<Ordering> + Copy,
    T: Clone,
{
    let mut state = v.to_vec();
    let mut rng = SmallRng::seed_from_u64(state.len() as u64);
    from_generator(move || {
        yield state.to_vec();
        while !state.is_sorted_by(compare) {
            state.shuffle(&mut rng);
            yield state.to_vec();
        }
    })
}