int-interval-stack 0.3.0

use crate::change_point::test_support::oracle_points;

use super::*;
use int_interval::I32CO;
use proptest::{prelude::*, test_runner::TestCaseResult};

pub(crate) fn iv_i32(start: i32, end_excl: i32) -> I32CO {
    I32CO::try_new(start, end_excl).unwrap()
}

pub(crate) fn naive_height_at(intervals: &[(i32, i32)], x: i32) -> usize {
    intervals.iter().filter(|&&(s, e)| s <= x && x < e).count()
}

pub(crate) fn oracle_segments(intervals: &[(i32, i32)]) -> Vec<((i32, i32), usize)> {
    oracle_points(intervals)
        .windows(2)
        .filter_map(|w| {
            let start = w[0].at;
            let end_excl = w[1].at;
            let height = w[0].height_after;

            (height != 0).then_some(((start, end_excl), height))
        })
        .collect()
}

pub(crate) fn collect_segments(
    iter: impl Iterator<Item = HeightSegment<I32CO>>,
) -> Vec<((i32, i32), usize)> {
    iter.map(|segment| {
        (
            (segment.interval.start(), segment.interval.end_excl()),
            segment.height.get(),
        )
    })
    .collect()
}

pub(crate) fn prop_assert_canonical(points: &[ChangePoint<i32>]) -> TestCaseResult {
    for w in points.windows(2) {
        prop_assert!(w[0].at < w[1].at);
        prop_assert_ne!(w[0].height_after, w[1].height_after);
    }
    if let Some(last) = points.last() {
        prop_assert_eq!(last.height_after, 0);
    }
    Ok(())
}

prop_compose! {
    pub(crate) fn interval_strategy()(
        start in -24i32..=24,
        len in 1i32..=24,
    ) -> (i32, i32) {
        (start, start + len)
    }
}

pub(crate) fn intervals_strategy(
    range: std::ops::Range<usize>,
) -> impl Strategy<Value = Vec<(i32, i32)>> {
    prop::collection::vec(interval_strategy(), range)
}

#[inline]
pub(crate) fn stack_from_intervals(intervals: &[(i32, i32)]) -> IntCOStack<I32CO> {
    intervals
        .iter()
        .copied()
        .map(|(s, e)| iv_i32(s, e))
        .collect()
}