/* Copyright (c) 2015 Hyunje Alex Jun and other contributors
 * Licensed under the MIT License
 */
'use strict';

var cls = require('../lib/class')
  , d = require('../lib/dom')
  , h = require('../lib/helper')
  , instances = require('./instances');

function getThumbSize(i, thumbSize) {
  if (i.settings.minScrollbarLength) {
    thumbSize = Math.max(thumbSize, i.settings.minScrollbarLength);
  }
  if (i.settings.maxScrollbarLength) {
    thumbSize = Math.min(thumbSize, i.settings.maxScrollbarLength);
  }
  return thumbSize;
}

function updateCss(element, i) {
  var xRailOffset = {width: i.railXWidth};
  if (i.isRtl) {
    xRailOffset.left = element.scrollLeft + i.containerWidth - i.contentWidth;
  } else {
    xRailOffset.left = element.scrollLeft;
  }
  if (i.isScrollbarXUsingBottom) {
    xRailOffset.bottom = i.scrollbarXBottom - element.scrollTop;
  } else {
    xRailOffset.top = i.scrollbarXTop + element.scrollTop;
  }
  d.css(i.scrollbarXRail, xRailOffset);

  var yRailOffset = {top: element.scrollTop, height: i.railYHeight};
  if (i.isScrollbarYUsingRight) {
    if (i.isRtl) {
      yRailOffset.right = i.contentWidth - element.scrollLeft - i.scrollbarYRight - i.scrollbarYOuterWidth;
    } else {
      yRailOffset.right = i.scrollbarYRight - element.scrollLeft;
    }
  } else {
    if (i.isRtl) {
      yRailOffset.left = element.scrollLeft + i.containerWidth * 2 - i.contentWidth - i.scrollbarYLeft - i.scrollbarYOuterWidth;
    } else {
      yRailOffset.left = i.scrollbarYLeft + element.scrollLeft;
    }
  }
  d.css(i.scrollbarYRail, yRailOffset);

  d.css(i.scrollbarX, {left: i.scrollbarXLeft, width: i.scrollbarXWidth - i.railBorderXWidth});
  d.css(i.scrollbarY, {top: i.scrollbarYTop, height: i.scrollbarYHeight - i.railBorderYWidth});
}

module.exports = function (element) {
  var i = instances.get(element);

  i.containerWidth = element.clientWidth;
  i.containerHeight = element.clientHeight;
  i.contentWidth = element.scrollWidth;
  i.contentHeight = element.scrollHeight;

  if (!element.contains(i.scrollbarXRail)) {
    d.appendTo(i.scrollbarXRail, element);
  }
  if (!element.contains(i.scrollbarYRail)) {
    d.appendTo(i.scrollbarYRail, element);
  }

  if (!i.settings.suppressScrollX && i.containerWidth + i.settings.scrollXMarginOffset < i.contentWidth) {
    i.scrollbarXActive = true;
    i.railXWidth = i.containerWidth - i.railXMarginWidth;
    i.railXRatio = i.containerWidth / i.railXWidth;
    i.scrollbarXWidth = getThumbSize(i, h.toInt(i.railXWidth * i.containerWidth / i.contentWidth));
    i.scrollbarXLeft = h.toInt(element.scrollLeft * (i.railXWidth - i.scrollbarXWidth) / (i.contentWidth - i.containerWidth));
  } else {
    i.scrollbarXActive = false;
    i.scrollbarXWidth = 0;
    i.scrollbarXLeft = 0;
    element.scrollLeft = 0;
  }

  if (!i.settings.suppressScrollY && i.containerHeight + i.settings.scrollYMarginOffset < i.contentHeight) {
    i.scrollbarYActive = true;
    i.railYHeight = i.containerHeight - i.railYMarginHeight;
    i.railYRatio = i.containerHeight / i.railYHeight;
    i.scrollbarYHeight = getThumbSize(i, h.toInt(i.railYHeight * i.containerHeight / i.contentHeight));
    i.scrollbarYTop = h.toInt(element.scrollTop * (i.railYHeight - i.scrollbarYHeight) / (i.contentHeight - i.containerHeight));
  } else {
    i.scrollbarYActive = false;
    i.scrollbarYHeight = 0;
    i.scrollbarYTop = 0;
    element.scrollTop = 0;
  }

  if (i.scrollbarXLeft >= i.railXWidth - i.scrollbarXWidth) {
    i.scrollbarXLeft = i.railXWidth - i.scrollbarXWidth;
  }
  if (i.scrollbarYTop >= i.railYHeight - i.scrollbarYHeight) {
    i.scrollbarYTop = i.railYHeight - i.scrollbarYHeight;
  }

  updateCss(element, i);

  cls[i.scrollbarXActive ? 'add' : 'remove'](element, 'ps-active-x');
  cls[i.scrollbarYActive ? 'add' : 'remove'](element, 'ps-active-y');
};