use itertools::Itertools;

#[test]
fn tuples() {
    let v = [1, 2, 3, 4, 5];
    let mut iter = v.iter().cloned().tuples();
    assert_eq!(Some((1,)), iter.next());
    assert_eq!(Some((2,)), iter.next());
    assert_eq!(Some((3,)), iter.next());
    assert_eq!(Some((4,)), iter.next());
    assert_eq!(Some((5,)), iter.next());
    assert_eq!(None, iter.next());
    assert_eq!(None, iter.into_buffer().next());

    let mut iter = v.iter().cloned().tuples();
    assert_eq!(Some((1, 2)), iter.next());
    assert_eq!(Some((3, 4)), iter.next());
    assert_eq!(None, iter.next());
    itertools::assert_equal(vec![5], iter.into_buffer());

    let mut iter = v.iter().cloned().tuples();
    assert_eq!(Some((1, 2, 3)), iter.next());
    assert_eq!(None, iter.next());
    itertools::assert_equal(vec![4, 5], iter.into_buffer());

    let mut iter = v.iter().cloned().tuples();
    assert_eq!(Some((1, 2, 3, 4)), iter.next());
    assert_eq!(None, iter.next());
    itertools::assert_equal(vec![5], iter.into_buffer());
}

#[test]
fn tuple_windows() {
    let v = [1, 2, 3, 4, 5];

    let mut iter = v.iter().cloned().tuple_windows();
    assert_eq!(Some((1,)), iter.next());
    assert_eq!(Some((2,)), iter.next());
    assert_eq!(Some((3,)), iter.next());

    let mut iter = v.iter().cloned().tuple_windows();
    assert_eq!(Some((1, 2)), iter.next());
    assert_eq!(Some((2, 3)), iter.next());
    assert_eq!(Some((3, 4)), iter.next());
    assert_eq!(Some((4, 5)), iter.next());
    assert_eq!(None, iter.next());

    let mut iter = v.iter().cloned().tuple_windows();
    assert_eq!(Some((1, 2, 3)), iter.next());
    assert_eq!(Some((2, 3, 4)), iter.next());
    assert_eq!(Some((3, 4, 5)), iter.next());
    assert_eq!(None, iter.next());

    let mut iter = v.iter().cloned().tuple_windows();
    assert_eq!(Some((1, 2, 3, 4)), iter.next());
    assert_eq!(Some((2, 3, 4, 5)), iter.next());
    assert_eq!(None, iter.next());

    let v = [1, 2, 3];
    let mut iter = v.iter().cloned().tuple_windows::<(_, _, _, _)>();
    assert_eq!(None, iter.next());
}

#[test]
fn next_tuple() {
    let v = [1, 2, 3, 4, 5];
    let mut iter = v.iter();
    assert_eq!(iter.next_tuple().map(|(&x, &y)| (x, y)), Some((1, 2)));
    assert_eq!(iter.next_tuple().map(|(&x, &y)| (x, y)), Some((3, 4)));
    assert_eq!(iter.next_tuple::<(_, _)>(), None);
}

#[test]
fn collect_tuple() {
    let v = [1, 2];
    let iter = v.iter().cloned();
    assert_eq!(iter.collect_tuple(), Some((1, 2)));

    let v = [1];
    let iter = v.iter().cloned();
    assert_eq!(iter.collect_tuple::<(_, _)>(), None);

    let v = [1, 2, 3];
    let iter = v.iter().cloned();
    assert_eq!(iter.collect_tuple::<(_, _)>(), None);
}