var Box = {
  ImNotTouchingYou: ImNotTouchingYou,
  OverlapArea: OverlapArea,
  GetDimensions: GetDimensions,
  GetExplicitOffsets: GetExplicitOffsets
}

/**
 * Compares the dimensions of an element to a container and determines collision events with container.
 * @function
 * @param {jQuery} element - jQuery object to test for collisions.
 * @param {jQuery} parent - jQuery object to use as bounding container.
 * @param {Boolean} lrOnly - set to true to check left and right values only.
 * @param {Boolean} tbOnly - set to true to check top and bottom values only.
 * @default if no parent object passed, detects collisions with `window`.
 * @returns {Boolean} - true if collision free, false if a collision in any direction.
 */
function ImNotTouchingYou(element, parent, lrOnly, tbOnly, ignoreBottom) {
  return OverlapArea(element, parent, lrOnly, tbOnly, ignoreBottom) === 0;
}

function OverlapArea(element, parent, lrOnly, tbOnly, ignoreBottom) {
  var eleDims = GetDimensions(element),
  topOver, bottomOver, leftOver, rightOver;
  if (parent) {
    var parDims = GetDimensions(parent);

    bottomOver = (parDims.height + parDims.offset.top) - (eleDims.offset.top + eleDims.height);
    topOver    = eleDims.offset.top - parDims.offset.top;
    leftOver   = eleDims.offset.left - parDims.offset.left;
    rightOver  = (parDims.width + parDims.offset.left) - (eleDims.offset.left + eleDims.width);
  }
  else {
    bottomOver = (eleDims.windowDims.height + eleDims.windowDims.offset.top) - (eleDims.offset.top + eleDims.height);
    topOver    = eleDims.offset.top - eleDims.windowDims.offset.top;
    leftOver   = eleDims.offset.left - eleDims.windowDims.offset.left;
    rightOver  = eleDims.windowDims.width - (eleDims.offset.left + eleDims.width);
  }

  bottomOver = ignoreBottom ? 0 : Math.min(bottomOver, 0);
  topOver    = Math.min(topOver, 0);
  leftOver   = Math.min(leftOver, 0);
  rightOver  = Math.min(rightOver, 0);

  if (lrOnly) {
    return leftOver + rightOver;
  }
  if (tbOnly) {
    return topOver + bottomOver;
  }

  // use sum of squares b/c we care about overlap area.
  return Math.sqrt((topOver * topOver) + (bottomOver * bottomOver) + (leftOver * leftOver) + (rightOver * rightOver));
}

/**
 * Uses native methods to return an object of dimension values.
 * @function
 * @param {jQuery || HTML} element - jQuery object or DOM element for which to get the dimensions. Can be any element other that document or window.
 * @returns {Object} - nested object of integer pixel values
 * TODO - if element is window, return only those values.
 */
function GetDimensions(elem){
  elem = elem.length ? elem[0] : elem;

  if (elem === window || elem === document) {
    throw new Error("I'm sorry, Dave. I'm afraid I can't do that.");
  }

  var rect = elem.getBoundingClientRect(),
      parRect = elem.parentNode.getBoundingClientRect(),
      winRect = document.body.getBoundingClientRect(),
      winY = window.pageYOffset,
      winX = window.pageXOffset;

  return {
    width: rect.width,
    height: rect.height,
    offset: {
      top: rect.top + winY,
      left: rect.left + winX
    },
    parentDims: {
      width: parRect.width,
      height: parRect.height,
      offset: {
        top: parRect.top + winY,
        left: parRect.left + winX
      }
    },
    windowDims: {
      width: winRect.width,
      height: winRect.height,
      offset: {
        top: winY,
        left: winX
      }
    }
  }
}

/**
 * Returns an object of top and left integer pixel values for dynamically rendered elements,
 * such as: Tooltip, Reveal, and Dropdown. Maintained for backwards compatibility, and where
 * you don't know alignment, but generally from
 * 6.4 forward you should use GetExplicitOffsets, as GetOffsets conflates position and alignment.
 * @function
 * @param {jQuery} element - jQuery object for the element being positioned.
 * @param {jQuery} anchor - jQuery object for the element's anchor point.
 * @param {String} position - a string relating to the desired position of the element, relative to it's anchor
 * @param {Number} vOffset - integer pixel value of desired vertical separation between anchor and element.
 * @param {Number} hOffset - integer pixel value of desired horizontal separation between anchor and element.
 * @param {Boolean} isOverflow - if a collision event is detected, sets to true to default the element to full width - any desired offset.
 * TODO alter/rewrite to work with `em` values as well/instead of pixels
 */
function GetExplicitOffsets(element, anchor, position, alignment, vOffset, hOffset, isOverflow) {
  var $eleDims = GetDimensions(element),
      $anchorDims = anchor ? GetDimensions(anchor) : null;

      var topVal, leftVal;

  if ($anchorDims !== null) {
  // set position related attribute
  switch (position) {
    case 'top':
      topVal = $anchorDims.offset.top - ($eleDims.height + vOffset);
      break;
    case 'bottom':
      topVal = $anchorDims.offset.top + $anchorDims.height + vOffset;
      break;
    case 'left':
      leftVal = $anchorDims.offset.left - ($eleDims.width + hOffset);
      break;
    case 'right':
      leftVal = $anchorDims.offset.left + $anchorDims.width + hOffset;
      break;
  }

  // set alignment related attribute
  switch (position) {
    case 'top':
    case 'bottom':
      switch (alignment) {
        case 'left':
          leftVal = $anchorDims.offset.left + hOffset;
          break;
        case 'right':
          leftVal = $anchorDims.offset.left - $eleDims.width + $anchorDims.width - hOffset;
          break;
        case 'center':
          leftVal = isOverflow ? hOffset : (($anchorDims.offset.left + ($anchorDims.width / 2)) - ($eleDims.width / 2)) + hOffset;
          break;
      }
      break;
    case 'right':
    case 'left':
      switch (alignment) {
        case 'bottom':
          topVal = $anchorDims.offset.top - vOffset + $anchorDims.height - $eleDims.height;
          break;
        case 'top':
          topVal = $anchorDims.offset.top + vOffset
          break;
        case 'center':
          topVal = ($anchorDims.offset.top + vOffset + ($anchorDims.height / 2)) - ($eleDims.height / 2)
          break;
      }
      break;
  }
  }

  return {top: topVal, left: leftVal};
}

export {Box};