$(document).ready(function(){
  $('.slider').each(function(){
    var objSlider = $(this);
    var wrapper = $(objSlider).find('.slides-wrapper');
    var viewport = $(objSlider).find('.slider-viewport');
    var slidesCount = wrapper.children().length;
    var slideWidth = wrapper.children().outerWidth();
    var slidesPerPage = Math.round(viewport.innerWidth()/slideWidth);
    var slideNow = 0;
    var offsetNow = 0;
    var offsetSlider = 0;
    var isMouseDown = false;
    var xMouseDown = 0;
    $(objSlider).find('[data-toggle="next-slide"]').on('click', function(e){
      e.preventDefault();
      nextSlide();
    });
    $(objSlider).find('[data-toggle="prev-slide"]').on('click', function(e) {
      e.preventDefault();
      prevSlide();
    });
    viewport.on('mousedown', function(e) {
      xMouseDown = e.clientX;
      isMouseDown = true;
      wrapper.css('transition', 'none');
    });
    viewport.on('mouseup', function(e) {
      isMouseDown = false;
      offsetNow = offsetSlider;
      wrapper.css('transition', '');
      stabilizeSlide();
    });
    viewport.on('mousemove', function(e) {
      moveSlide(e);
    });
    $(window).resize(function() {
      slideWidth = wrapper.children().outerWidth();
      slidesPerPage = Math.round(viewport.innerWidth()/slideWidth);
      if (slideNow+slidesPerPage > slidesCount)
        slideNow = slidesCount - slidesPerPage;
      stabilizeSlide();
    });

    function nextSlide() {
      if (slideNow+slidesPerPage >= slidesCount) {
        slideNow = -1;
      }
      offsetNow = -slideWidth*(++slideNow);
      addOffset(offsetNow, objSlider);
    }

    function prevSlide() {
      if (slideNow == 0) {
        slideNow = slidesCount - slidesPerPage + 1;
      }
      offsetNow = -slideWidth*(--slideNow);
      addOffset(offsetNow, objSlider);
    }

    function stabilizeSlide() {
      offsetNow = -slideWidth*slideNow;
      addOffset(offsetNow, objSlider);
    }

    function moveSlide(event) {
      if (isMouseDown) {
        var offsetMouse = xMouseDown - event.clientX;
        offsetSlider = Math.abs(offsetNow) + offsetMouse;
        /*-------------------------------------------------------------------------
        Смещение слайдера вправо/влево при достижении первого/последнего слайда,
        при нажатой кнопке мыши - не более 1/3 ширины слайда.
        -------------------------------------------------------------------------*/
        if (offsetSlider < -slideWidth/3) {
          offsetSlider=-slideWidth/3;
        }
        if (offsetSlider > slideWidth*(slidesCount-slidesPerPage)+slideWidth/3) {
          offsetSlider = slideWidth*(slidesCount-slidesPerPage)+slideWidth/3;
        }
        slideNow = Math.abs(Math.round(offsetSlider/slideWidth));
        offsetSlider *= -1;
        addOffset(offsetSlider, objSlider);
      }
    }
  });
  function addOffset(offset, obj) {
    $(obj).find('.slides-wrapper').css('transform', 'translateX('+offset+'px)');
  }
});