'use strict';

class SlidingWindow {
    _WINDOW_SIZE;
    _compare;
    _window;
    _front;
    _end;
    _size;
    _leftBoundary;
    _rightBoundary;
    constructor(props) {
        const { WINDOW_SIZE, startIndex = 0, compare } = props;
        this._WINDOW_SIZE = WINDOW_SIZE;
        this._compare = compare;
        this._window = new Array(WINDOW_SIZE);
        this._front = 0;
        this._end = -1;
        this._size = 0;
        this._leftBoundary = startIndex;
        this._rightBoundary = startIndex;
    }
    reset(options = {}) {
        const { startIndex = 0, WINDOW_SIZE = this._WINDOW_SIZE } = options;
        this._WINDOW_SIZE = WINDOW_SIZE;
        this._window.length = WINDOW_SIZE;
        this._front = 0;
        this._end = -1;
        this._size = 0;
        this._leftBoundary = startIndex;
        this._rightBoundary = startIndex;
    }
    forwardRightBoundary(steps = 1) {
        if (steps < 1)
            return;
        const { _WINDOW_SIZE, _window, _compare } = this;
        let { _rightBoundary, _front, _end, _size } = this;
        const nextRightBoundary = _rightBoundary + steps;
        const nextLeftBoundary = Math.max(this._leftBoundary, nextRightBoundary - _WINDOW_SIZE);
        if (_rightBoundary < nextLeftBoundary)
            _rightBoundary = nextLeftBoundary;
        while (_size > 0 && _window[_front] < nextLeftBoundary) {
            _front = this._forwardIndex(_front);
            _size -= 1;
        }
        for (; _rightBoundary < nextRightBoundary; ++_rightBoundary) {
            for (; _size > 0; --_size) {
                if (_compare(_window[_end], _rightBoundary) < 0)
                    break;
                _end = this._backwardIndex(_end);
            }
            _end = this._forwardIndex(_end);
            _window[_end] = _rightBoundary;
            _size += 1;
        }
        this._front = _front;
        this._end = _end;
        this._size = _size;
        this._leftBoundary = nextLeftBoundary;
        this._rightBoundary = nextRightBoundary;
    }
    forwardLeftBoundary(steps = 1) {
        if (steps < 1)
            return;
        const nextLeftBoundary = this._leftBoundary + steps;
        const { _window } = this;
        while (this._size > 0 && _window[this._front] < nextLeftBoundary) {
            this._front = this._forwardIndex(this._front);
            this._size -= 1;
        }
        this._leftBoundary = nextLeftBoundary;
    }
    min() {
        return this._size > 0 ? this._window[this._front] : undefined;
    }
    _forwardIndex(index) {
        const nextIndex = index + 1;
        return nextIndex === this._WINDOW_SIZE ? 0 : nextIndex;
    }
    _backwardIndex(index) {
        const nextIndex = index - 1;
        return nextIndex < 0 ? this._WINDOW_SIZE - 1 : nextIndex;
    }
}

exports.SlidingWindow = SlidingWindow;