/**
 * Returns a compact layout of a list of intervals
 *
 * Second options parameter
 * - `tight` places an interval with same ending as previous next to each other.
 */
export function layoutIntervals(intervals, { tight } = {}) {
    tight ??= true

    const canPlaceInterval = tight
        ? ({ start }, place) => place <= start
        : ({ start }, place) => place < start

    if (intervals.length === 0) {
        return []
    }

    // sort intervals by ".start"
    intervals.sort((a, b) => a.start - b.start)

    const stack = [{ lastEnd: -Infinity, intervals: [] }]

    for (const interval of intervals) {
        const s = stack.find(level => canPlaceInterval(interval, level.lastEnd))

        if (s) {
            s.intervals.push(interval)
            s.lastEnd = Math.max(s.lastEnd, interval.end)
        } else {
            stack.push({ lastEnd: interval.end, intervals: [interval] })
        }
    }

    return stack.map(({ intervals }) => intervals)
}

// //
// // Testing...
// //

// console.dir(
//     layoutIntervals([
//         { start: 0, end: 2 },
//         { start: 2, end: 4 },
//         { start: 1, end: 3 },
//         { start: 4, end: 6 },
//         { start: 3, end: 5 },
//         { start: 2, end: 4 },
//     ]),
//     { depth: null }
// )