use crate::utils::gt_by;
use std::{cmp::Ordering, iter::from_generator};

/// Sorts a slice of data using the insertion sort algorithm with a custom comparator.
///
/// # Examples
///
/// ```
/// # use sort_steps::{insertion_sort};
/// let numbers = [5, 9, 3, 6, 8, 2, 1, 7, 4];
/// println!("Heap Sort Steps:");
/// for (i, v) in insertion_sort(&numbers).enumerate() {
///     println!("#{:02}: {:?}", i, v);
/// }
/// ```
pub fn insertion_sort<T>(v: &[T]) -> impl Iterator<Item = Vec<T>>
where
    T: PartialOrd + Clone,
{
    insertion_sort_by(v, |a, b| a.partial_cmp(b))
}

/// Sorts a slice of data using the insertion sort algorithm with a custom comparator.
///
/// # Examples
///
/// ```
/// # use sort_steps::{insertion_sort_by};
/// let numbers = [5, 9, 3, 6, 8, 2, 1, 7, 4];
/// println!("Heap Sort Steps:");
/// for (i, v) in insertion_sort_by(&numbers, |a, b| a.partial_cmp(b)).enumerate() {
///     println!("#{:02}: {:?}", i, v);
/// }
/// ```
pub fn insertion_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();
    from_generator(move || {
        yield state.to_vec();
        for i in 1..state.len() {
            let mut j = i;
            while j > 0 && gt_by(&state[j - 1], &state[j], compare) {
                state.swap(j - 1, j);
                yield state.to_vec();
                j -= 1;
            }
        }
    })
}