Function updateViewItem

web/src/js/ducks/flows/_utils.ts:40–77

(
    prevView: T[],
    prevViewIndex: Map<string, number>,
    item: T,
    sort: Comparer<T>,
)

}

export function updateViewItem<T extends Item>(
    prevView: T[],
    prevViewIndex: Map<string, number>,
    item: T,
    sort: Comparer<T>,
): { view: T[]; _viewIndex: Map<string, number> } {
    const view = [...prevView];
    const len = view.length;
    let _viewIndex = prevViewIndex,
        pos = _viewIndex.get(item.id)!;

    // is this overoptimized? yes.
    // was it fun? also yes.
    if (pos + 1 < len && sort(item, view[pos + 1]) > 0) {
        // move up
        _viewIndex = new Map(_viewIndex);
        do {
            const move = view[pos + 1];
            view[pos] = move;
            _viewIndex.set(move.id, pos);
            pos++;
        } while (pos + 1 < len && sort(item, view[pos + 1]) > 0);
        _viewIndex.set(item.id, pos);
    } else if (pos > 0 && sort(item, view[pos - 1]) < 0) {
        // move down
        _viewIndex = new Map(_viewIndex);
        do {
            const move = view[pos - 1];
            view[pos] = move;
            _viewIndex.set(move.id, pos);
            pos--;
        } while (pos > 0 && sort(item, view[pos - 1]) < 0);
        _viewIndex.set(item.id, pos);
    }
    view[pos] = item;

    return { view, _viewIndex };
}

export function insertViewItem<T extends Item>(
    prevView: T[],