/**
 * {}
 * @author yutent<yutent.io@gmail.com>
 * @date 2024/03/08 10:59:09
 */

import eve from './eve.js'

import {
  doc,
  win,
  CSS_ATTR,
  xmlns,
  T_COMMAND,
  PATH_VALUES
} from './lib/constants.js'

import { Matrix } from './matrix.js'

import {
  $,
  is,
  uuid,
  clone,
  preload,
  cacher,
  jsonFiller,
  extend
} from './utils.js'

let has = 'hasOwnProperty',
  math = Math,
  abs = math.abs,
  E = '',
  S = ' ',
  objectToString = Object.prototype.toString,
  hub = {}

export function make(name, parent) {
  let res = $(name)
  parent.appendChild(res)
  let el = wrap(res)
  return el
}

export function wrap(dom) {
  if (!dom) {
    return dom
  }
  if (dom instanceof SnapElement || dom instanceof Fragment) {
    return dom
  }
  if (dom.tagName.toLowerCase() === 'svg') {
    return new Paper(dom)
  }
  if (
    dom.tagName &&
    dom.tagName.toLowerCase() == 'object' &&
    dom.type == 'image/svg+xml'
  ) {
    return new Paper(dom.contentDocument.getElementsByTagName('svg')[0])
  }
  return new SnapElement(dom)
}

/*\
 **
 * Wraps a DOM element specified by CSS selector as @SnapElement
 - query (string) CSS selector of the element
 = (SnapElement) the current element
\*/
export function select(query = '') {
  query = query.replace(/([^\\]):/g, '$1\\:')
  return wrap(doc.querySelector(query))
}
/*\

**
* Wraps DOM elements specified by CSS selector as set or array of @SnapElement
- query (string) CSS selector of the element
= (SnapElement) the current element
\*/
export function selectAll(query = '') {
  let nodelist = doc.querySelectorAll(query),
    set = []
  for (let i = 0; i < nodelist.length; i++) {
    set.push(wrap(nodelist[i]))
  }
  return set
}

export class Fragment {
  constructor(frag) {
    this.node = frag
  }
}

export class Snap {
  static _ = { $ }

  /*
   **
   * Parses SVG fragment and converts it into a @Fragment
   **
   */
  static parse(svg) {
    let f = doc.createDocumentFragment(),
      full = true,
      div = doc.createElement('div')
    svg = String(svg)
    if (!svg.match(/^\s*<\s*svg(?:\s|>)/)) {
      svg = '<svg>' + svg + '</svg>'
      full = false
    }
    div.innerHTML = svg
    svg = div.getElementsByTagName('svg')[0]
    if (svg) {
      if (full) {
        f = svg
      } else {
        while (svg.firstChild) {
          f.appendChild(svg.firstChild)
        }
      }
    }
    return new Fragment(f)
  }

  /*\
 **
 * Creates a DOM fragment from a given list of elements or strings
 **
 - varargs (…) SVG string
\*/
  static fragment(...args) {
    let f = doc.createDocumentFragment()
    for (let i = 0, ii = args.length; i < ii; i++) {
      let item = args[i]
      if (item.node && item.node.nodeType) {
        f.appendChild(item.node)
      }
      if (item.nodeType) {
        f.appendChild(item)
      }
      if (typeof item == 'string') {
        f.appendChild(Snap.parse(item).node)
      }
    }
    return new Fragment(f)
  }

  /*\
 **
 * Returns closest point to a given one on a given path.
 - path (SnapElement) path element
 - x (number) x coord of a point
 - y (number) y coord of a point
 = (object) in format
 {
    x (number) x coord of the point on the path
    y (number) y coord of the point on the path
    length (number) length of the path to the point
    distance (number) distance from the given point to the path
 }
\*/
  // Copied from http://bl.ocks.org/mbostock/8027637
  static closestPoint(path, x, y) {
    function distance2(p) {
      let dx = p.x - x,
        dy = p.y - y
      return dx * dx + dy * dy
    }
    let pathNode = path.node,
      pathLength = pathNode.getTotalLength(),
      precision = (pathLength / pathNode.pathSegList.numberOfItems) * 0.125,
      best,
      bestLength,
      bestDistance = Infinity

    // linear scan for coarse approximation
    for (
      let scan, scanLength = 0, scanDistance;
      scanLength <= pathLength;
      scanLength += precision
    ) {
      if (
        (scanDistance = distance2(
          (scan = pathNode.getPointAtLength(scanLength))
        )) < bestDistance
      ) {
        best = scan
        bestLength = scanLength
        bestDistance = scanDistance
      }
    }

    // binary search for precise estimate
    precision *= 0.5
    while (precision > 0.5) {
      let before,
        after,
        beforeLength,
        afterLength,
        beforeDistance,
        afterDistance
      if (
        (beforeLength = bestLength - precision) >= 0 &&
        (beforeDistance = distance2(
          (before = pathNode.getPointAtLength(beforeLength))
        )) < bestDistance
      ) {
        best = before
        bestLength = beforeLength
        bestDistance = beforeDistance
      } else if (
        (afterLength = bestLength + precision) <= pathLength &&
        (afterDistance = distance2(
          (after = pathNode.getPointAtLength(afterLength))
        )) < bestDistance
      ) {
        best = after
        bestLength = afterLength
        bestDistance = afterDistance
      } else {
        precision *= 0.5
      }
    }

    best = {
      x: best.x,
      y: best.y,
      length: bestLength,
      distance: Math.sqrt(bestDistance)
    }
    return best
  }

  /*\
 **
 * Snaps given value to given grid
 - values (array|number) given array of values or step of the grid
 - value (number) value to adjust
 - tolerance (number) #optional maximum distance to the target value that would trigger the snap. Default is `10`.
 = (number) adjusted value
\*/
  static snapTo(values, value, tolerance) {
    tolerance = is(tolerance, 'finite') ? tolerance : 10
    if (is(values, 'array')) {
      let i = values.length
      while (i--)
        if (abs(values[i] - value) <= tolerance) {
          return values[i]
        }
    } else {
      values = +values
      let rem = value % values
      if (rem < tolerance) {
        return value - rem
      }
      if (rem > values - tolerance) {
        return value - rem + values
      }
    }
    return value
  }

  /*
 **
 * Returns you topmost element under given point.
 **
 = (object) Snap element object
 - x (number) x coordinate from the top left corner of the window
 - y (number) y coordinate from the top left corner of the window
 > Usage
 | Snap.getElementByPoint(mouseX, mouseY).attr({stroke: "#f00"});
*/
  static getElementByPoint(x, y) {
    let target = doc.elementFromPoint(x, y)

    if (!target) {
      return null
    }
    return wrap(target)
  }

  constructor(w, h) {
    if (w) {
      if (w.nodeType) {
        return wrap(w)
      }

      if (w instanceof SnapElement) {
        return w
      }
      if (h == null) {
        try {
          w = doc.querySelector(String(w))
          return wrap(w)
        } catch (e) {
          return null
        }
      }
    }
    w = w == null ? '100%' : w
    h = h == null ? '100%' : h
    return new Paper(w, h)
  }
}

// Transformations
/*\
 **
 * Utility method
 **
 * Parses given path string into an array of arrays of path segments
 - pathString (string|array) path string or array of segments (in the last case it is returned straight away)
 = (array) array of segments
\*/
Snap.parsePathString = function (pathString) {
  if (!pathString) {
    return null
  }
  let pth = Snap.path(pathString)
  if (pth.arr) {
    return Snap.path.clone(pth.arr)
  }

  let paramCounts = {
      a: 7,
      c: 6,
      o: 2,
      h: 1,
      l: 2,
      m: 2,
      r: 4,
      q: 4,
      s: 4,
      t: 2,
      v: 1,
      u: 3,
      z: 0
    },
    data = []
  if (is(pathString, 'array') && is(pathString[0], 'array')) {
    // rough assumption
    data = Snap.path.clone(pathString)
  }
  if (!data.length) {
    String(pathString).replace(pathCommand, function (a, b, c) {
      let params = [],
        name = b.toLowerCase()
      c.replace(PATH_VALUES, function (a, b) {
        b && params.push(+b)
      })
      if (name == 'm' && params.length > 2) {
        data.push([b].concat(params.splice(0, 2)))
        name = 'l'
        b = b == 'm' ? 'l' : 'L'
      }
      if (name == 'o' && params.length == 1) {
        data.push([b, params[0]])
      }
      if (name == 'r') {
        data.push([b].concat(params))
      } else
        while (params.length >= paramCounts[name]) {
          data.push([b].concat(params.splice(0, paramCounts[name])))
          if (!paramCounts[name]) {
            break
          }
        }
    })
  }
  data.toString = Snap.path.toString
  pth.arr = Snap.path.clone(data)
  return data
}
/*\
 **
 * Utility method
 **
 * Parses given transform string into an array of transformations
 - TString (string|array) transform string or array of transformations (in the last case it is returned straight away)
 = (array) array of transformations
\*/
let parseTransformString = (Snap.parseTransformString = function (TString) {
  if (!TString) {
    return null
  }
  let paramCounts = { r: 3, s: 4, t: 2, m: 6 },
    data = []
  if (is(TString, 'array') && is(TString[0], 'array')) {
    // rough assumption
    data = Snap.path.clone(TString)
  }
  if (!data.length) {
    String(TString).replace(T_COMMAND, function (a, b, c) {
      let params = [],
        name = b.toLowerCase()
      c.replace(PATH_VALUES, function (a, b) {
        b && params.push(+b)
      })
      data.push([b].concat(params))
    })
  }
  data.toString = Snap.path.toString
  return data
})
function svgTransform2string(tstr) {
  let res = []
  tstr = tstr.replace(
    /(?:^|\s)(\w+)\(([^)]+)\)/g,
    function (all, name, params) {
      params = params.split(/\s*,\s*|\s+/)
      if (name == 'rotate' && params.length == 1) {
        params.push(0, 0)
      }
      if (name == 'scale') {
        if (params.length > 2) {
          params = params.slice(0, 2)
        } else if (params.length == 2) {
          params.push(0, 0)
        }
        if (params.length == 1) {
          params.push(params[0], 0, 0)
        }
      }
      if (name == 'skewX') {
        res.push(['m', 1, 0, math.tan(rad(params[0])), 1, 0, 0])
      } else if (name == 'skewY') {
        res.push(['m', 1, math.tan(rad(params[0])), 0, 1, 0, 0])
      } else {
        res.push([name.charAt(0)].concat(params))
      }
      return all
    }
  )
  return res
}
Snap._.svgTransform2string = svgTransform2string
Snap._.rgTransform = /^[a-z][\s]*-?\.?\d/i

function transform2matrix(tstr, bbox) {
  let tdata = parseTransformString(tstr),
    m = new Matrix()
  if (tdata) {
    for (let i = 0, ii = tdata.length; i < ii; i++) {
      let t = tdata[i],
        tlen = t.length,
        command = String(t[0]).toLowerCase(),
        absolute = t[0] != command,
        inver = absolute ? m.invert() : 0,
        x1,
        y1,
        x2,
        y2,
        bb
      if (command == 't' && tlen == 2) {
        m.translate(t[1], 0)
      } else if (command == 't' && tlen == 3) {
        if (absolute) {
          x1 = inver.x(0, 0)
          y1 = inver.y(0, 0)
          x2 = inver.x(t[1], t[2])
          y2 = inver.y(t[1], t[2])
          m.translate(x2 - x1, y2 - y1)
        } else {
          m.translate(t[1], t[2])
        }
      } else if (command == 'r') {
        if (tlen == 2) {
          bb = bb || bbox
          m.rotate(t[1], bb.x + bb.width / 2, bb.y + bb.height / 2)
        } else if (tlen == 4) {
          if (absolute) {
            x2 = inver.x(t[2], t[3])
            y2 = inver.y(t[2], t[3])
            m.rotate(t[1], x2, y2)
          } else {
            m.rotate(t[1], t[2], t[3])
          }
        }
      } else if (command == 's') {
        if (tlen == 2 || tlen == 3) {
          bb = bb || bbox
          m.scale(t[1], t[tlen - 1], bb.x + bb.width / 2, bb.y + bb.height / 2)
        } else if (tlen == 4) {
          if (absolute) {
            x2 = inver.x(t[2], t[3])
            y2 = inver.y(t[2], t[3])
            m.scale(t[1], t[1], x2, y2)
          } else {
            m.scale(t[1], t[1], t[2], t[3])
          }
        } else if (tlen == 5) {
          if (absolute) {
            x2 = inver.x(t[3], t[4])
            y2 = inver.y(t[3], t[4])
            m.scale(t[1], t[2], x2, y2)
          } else {
            m.scale(t[1], t[2], t[3], t[4])
          }
        }
      } else if (command == 'm' && tlen == 7) {
        m.add(t[1], t[2], t[3], t[4], t[5], t[6])
      }
    }
  }
  return m
}

Snap._.transform2matrix = transform2matrix

export function getSomeDefs(el) {
  let p =
      (el.node.ownerSVGElement && wrap(el.node.ownerSVGElement)) ||
      (el.node.parentNode && wrap(el.node.parentNode)) ||
      select('svg') ||
      new Snap(0, 0),
    pdefs = p.select('defs'),
    defs = pdefs == null ? false : pdefs.node
  if (!defs) {
    defs = make('defs', p.node).node
  }
  return defs
}

function getSomeSVG(el) {
  return (
    (el.node.ownerSVGElement && wrap(el.node.ownerSVGElement)) || select('svg')
  )
}

export function unit2px(el, name, value) {
  let svg = getSomeSVG(el).node,
    out = {},
    mgr = svg.querySelector('.svg---mgr')
  if (!mgr) {
    mgr = $('rect')
    $(mgr, {
      x: -9e9,
      y: -9e9,
      width: 10,
      height: 10,
      class: 'svg---mgr',
      fill: 'none'
    })
    svg.appendChild(mgr)
  }
  function getW(val) {
    if (val == null) {
      return E
    }
    if (val == +val) {
      return val
    }
    $(mgr, { width: val })
    try {
      return mgr.getBBox().width
    } catch (e) {
      return 0
    }
  }
  function getH(val) {
    if (val == null) {
      return E
    }
    if (val == +val) {
      return val
    }
    $(mgr, { height: val })
    try {
      return mgr.getBBox().height
    } catch (e) {
      return 0
    }
  }
  function set(nam, f) {
    if (name == null) {
      out[nam] = f(el.attr(nam) || 0)
    } else if (nam == name) {
      out = f(value == null ? el.attr(nam) || 0 : value)
    }
  }
  switch (el.type) {
    case 'rect':
      set('rx', getW)
      set('ry', getH)
    case 'image':
      set('width', getW)
      set('height', getH)
    case 'text':
      set('x', getW)
      set('y', getH)
      break
    case 'circle':
      set('cx', getW)
      set('cy', getH)
      set('r', getW)
      break
    case 'ellipse':
      set('cx', getW)
      set('cy', getH)
      set('rx', getW)
      set('ry', getH)
      break
    case 'line':
      set('x1', getW)
      set('x2', getW)
      set('y1', getH)
      set('y2', getH)
      break
    case 'marker':
      set('refX', getW)
      set('markerWidth', getW)
      set('refY', getH)
      set('markerHeight', getH)
      break
    case 'radialGradient':
      set('fx', getW)
      set('fy', getH)
      break
    case 'tspan':
      set('dx', getW)
      set('dy', getH)
      break
    default:
      set(name, getW)
  }
  svg.removeChild(mgr)
  return out
}

function add2group(list) {
  if (!is(list, 'array')) {
    list = Array.prototype.slice.call(arguments, 0)
  }
  let i = 0,
    j = 0,
    node = this.node
  while (this[i]) delete this[i++]
  for (i = 0; i < list.length; i++) {
    if (list[i].type == 'set') {
      list[i].forEach(function (el) {
        node.appendChild(el.node)
      })
    } else {
      node.appendChild(list[i].node)
    }
  }
  let children = node.childNodes
  for (i = 0; i < children.length; i++) {
    this[j++] = wrap(children[i])
  }
  return this
}
// Hub garbage collector every 10s
setInterval(function () {
  for (let key in hub)
    if (hub[has](key)) {
      let el = hub[key],
        node = el.node
      if (
        (el.type != 'svg' && !node.ownerSVGElement) ||
        (el.type == 'svg' &&
          (!node.parentNode ||
            ('ownerSVGElement' in node.parentNode && !node.ownerSVGElement)))
      ) {
        delete hub[key]
      }
    }
}, 1e4)

export class Paper {
  constructor(w, h) {
    let res, desc, defs
    if (w && w.tagName && w.tagName.toLowerCase() == 'svg') {
      if (w.snap in hub) {
        return hub[w.snap]
      }
      let doc = w.ownerDocument
      res = new SnapElement(w)
      desc = w.getElementsByTagName('desc')[0]
      defs = w.getElementsByTagName('defs')[0]
      if (!desc) {
        desc = $('desc')
        desc.appendChild(doc.createTextNode('Created with Snap'))
        res.node.appendChild(desc)
      }
      if (!defs) {
        defs = $('defs')
        res.node.appendChild(defs)
      }
      res.defs = defs
      extend(res, Paper.prototype)
      res.paper = res.root = res
    } else {
      res = make('svg', doc.body)
      $(res.node, {
        width: w,
        height: h,
        version: 1.1,
        xmlns
      })
    }
    return res
  }

  /*\
     **
     * Creates a nested SVG element.
     - x (number) @optional X of the element
     - y (number) @optional Y of the element
     - width (number) @optional width of the element
     - height (number) @optional height of the element
     - vbx (number) @optional viewbox X
     - vby (number) @optional viewbox Y
     - vbw (number) @optional viewbox width
     - vbh (number) @optional viewbox height
     **
     = (object) the `svg` element
     **
    \*/
  svg(x, y, width, height, vbx, vby, vbw, vbh) {
    let attrs = {}
    if (is(x, 'object') && y == null) {
      attrs = x
    } else {
      if (x != null) {
        attrs.x = x
      }
      if (y != null) {
        attrs.y = y
      }
      if (width != null) {
        attrs.width = width
      }
      if (height != null) {
        attrs.height = height
      }
      if (vbx != null && vby != null && vbw != null && vbh != null) {
        attrs.viewBox = [vbx, vby, vbw, vbh]
      }
    }
    return this.el('svg', attrs)
  }

  mask(first) {
    let attr,
      el = this.el('mask')
    if (arguments.length == 1 && first && !first.type) {
      el.attr(first)
    } else if (arguments.length) {
      el.add(Array.from(arguments))
    }
    return el
  }

  /*\
     **
     * Equivalent in behaviour to @Paper.g, except it’s a pattern.
     - x (number) @optional X of the element
     - y (number) @optional Y of the element
     - width (number) @optional width of the element
     - height (number) @optional height of the element
     - vbx (number) @optional viewbox X
     - vby (number) @optional viewbox Y
     - vbw (number) @optional viewbox width
     - vbh (number) @optional viewbox height
     **
     = (object) the `pattern` element
     **
    \*/
  ptrn(x, y, width, height, vx, vy, vw, vh) {
    if (is(x, 'object')) {
      let attr = x
    } else {
      attr = { patternUnits: 'userSpaceOnUse' }
      if (x) {
        attr.x = x
      }
      if (y) {
        attr.y = y
      }
      if (width != null) {
        attr.width = width
      }
      if (height != null) {
        attr.height = height
      }
      if (vx != null && vy != null && vw != null && vh != null) {
        attr.viewBox = [vx, vy, vw, vh]
      } else {
        attr.viewBox = [x || 0, y || 0, width || 0, height || 0]
      }
    }
    return this.el('pattern', attr)
  }
  /*\
       **
       * Creates a <use> element.
       - id (string) @optional id of element to link
       * or
       - id (SnapElement) @optional element to link
       **
       = (object) the `use` element
       **
      \*/
  use(id) {
    if (id != null) {
      if (id instanceof SnapElement) {
        if (!id.attr('id')) {
          id.attr({ id: uuid(id.type + 'S') })
        }
        id = id.attr('id')
      }
      if (String(id).charAt() == '#') {
        id = id.substring(1)
      }
      return this.el('use', { 'xlink:href': '#' + id })
    } else {
      return SnapElement.prototype.use.call(this)
    }
  }
  /*\
       **
       * Creates a <symbol> element.
       - vbx (number) @optional viewbox X
       - vby (number) @optional viewbox Y
       - vbw (number) @optional viewbox width
       - vbh (number) @optional viewbox height
       = (object) the `symbol` element
       **
      \*/
  symbol(vx, vy, vw, vh) {
    let attr = {}
    if (vx != null && vy != null && vw != null && vh != null) {
      attr.viewBox = [vx, vy, vw, vh]
    }

    return this.el('symbol', attr)
  }
  /*\
       **
       * Draws a text string
       **
       - x (number) x coordinate position
       - y (number) y coordinate position
       - text (string|array) The text string to draw or array of strings to nest within separate `<tspan>` elements
       = (object) the `text` element
       **
       > Usage
       | let t1 = paper.text(50, 50, "Snap");
       | let t2 = paper.text(50, 50, ["S","n","a","p"]);
       | // Text path usage
       | t1.attr({textpath: "M10,10L100,100"});
       | // or
       | let pth = paper.path("M10,10L100,100");
       | t1.attr({textpath: pth});
      \*/
  text(x, y, text) {
    let attr = {}
    if (is(x, 'object')) {
      attr = x
    } else if (x != null) {
      attr = {
        x: x,
        y: y,
        text: text || ''
      }
    }
    return this.el('text', attr)
  }
  /*\
       **
       * Draws a line
       **
       - x1 (number) x coordinate position of the start
       - y1 (number) y coordinate position of the start
       - x2 (number) x coordinate position of the end
       - y2 (number) y coordinate position of the end
       = (object) the `line` element
       **
       > Usage
       | let t1 = paper.line(50, 50, 100, 100);
      \*/
  line(x1, y1, x2, y2) {
    let attr = {}
    if (is(x1, 'object')) {
      attr = x1
    } else if (x1 != null) {
      attr = {
        x1: x1,
        x2: x2,
        y1: y1,
        y2: y2
      }
    }
    return this.el('line', attr)
  }
  /*\
       **
       * Draws a polyline
       **
       - points (array) array of points
       * or
       - varargs (…) points
       = (object) the `polyline` element
       **
       > Usage
       | let p1 = paper.polyline([10, 10, 100, 100]);
       | let p2 = paper.polyline(10, 10, 100, 100);
      \*/
  polyline(points) {
    if (arguments.length > 1) {
      points = Array.from(arguments)
    }
    let attr = {}
    if (is(points, 'object') && !is(points, 'array')) {
      attr = points
    } else if (points != null) {
      attr = { points: points }
    }
    return this.el('polyline', attr)
  }
  /*\
       **
       * Draws a polygon. See @Paper.polyline
      \*/
  polygon(points) {
    if (arguments.length > 1) {
      points = Array.prototype.slice.call(arguments, 0)
    }
    let attr = {}
    if (is(points, 'object') && !is(points, 'array')) {
      attr = points
    } else if (points != null) {
      attr = { points: points }
    }
    return this.el('polygon', attr)
  }

  /*
 **
 * Creates an element on paper with a given name and no attributes
 **
 - name (string) tag name
 - attr (object) attributes
 = (SnapElement) the current element
 > Usage
 | let c = paper.circle(10, 10, 10); // is the same as...
 | let c = paper.el("circle").attr({
 |     cx: 10,
 |     cy: 10,
 |     r: 10
 | });
 | // and the same as
 | let c = paper.el("circle", {
 |     cx: 10,
 |     cy: 10,
 |     r: 10
 | });
*/
  el(name, attr) {
    let el = make(name, this.node)
    attr && el.attr(attr)
    return el
  }

  /*
    *
    * Draws a rectangle
    **
    - x (number) x coordinate of the top left corner
    - y (number) y coordinate of the top left corner
    - width (number) width
    - height (number) height
    - rx (number) #optional horizontal radius for rounded corners, default is 0
    - ry (number) #optional vertical radius for rounded corners, default is rx or 0
    = (object) the `rect` element
    **
    > Usage
    | // regular rectangle
    | let c = paper.rect(10, 10, 50, 50);
    | // rectangle with rounded corners
    | let c = paper.rect(40, 40, 50, 50, 10);
  */
  rect(x, y, w, h, rx, ry) {
    let attr
    if (ry == null) {
      ry = rx
    }
    if (is(x, 'object') && x == '[object Object]') {
      attr = x
    } else if (x != null) {
      attr = {
        x: x,
        y: y,
        width: w,
        height: h
      }
      if (rx != null) {
        attr.rx = rx
        attr.ry = ry
      }
    }
    return this.el('rect', attr)
  }

  /*\
     **
     * Draws a circle
     **
     - x (number) x coordinate of the centre
     - y (number) y coordinate of the centre
     - r (number) radius
     = (object) the `circle` element
     **
     > Usage
     | let c = paper.circle(50, 50, 40);
    \*/
  circle(cx, cy, r) {
    let attr
    if (is(cx, 'object') && cx == '[object Object]') {
      attr = cx
    } else if (cx != null) {
      attr = {
        cx: cx,
        cy: cy,
        r: r
      }
    }
    return this.el('circle', attr)
  }

  /*\
     **
     * Places an image on the surface
     **
     - src (string) URI of the source image
     - x (number) x offset position
     - y (number) y offset position
     - width (number) width of the image
     - height (number) height of the image
     = (object) the `image` element
     * or
     = (object) Snap element object with type `image`
     **
     > Usage
     | let c = paper.image("apple.png", 10, 10, 80, 80);
    \*/
  image(src, x, y, width, height) {
    let el = this.el('image')
    if (is(src, 'object') && 'src' in src) {
      el.attr(src)
    } else if (src != null) {
      let set = {
        'xlink:href': src,
        preserveAspectRatio: 'none'
      }
      if (x != null && y != null) {
        set.x = x
        set.y = y
      }
      if (width != null && height != null) {
        set.width = width
        set.height = height
      } else {
        preload(src, function () {
          $(el.node, {
            width: this.offsetWidth,
            height: this.offsetHeight
          })
        })
      }
      $(el.node, set)
    }
    return el
  }

  /*\
     **
     * Draws an ellipse
     **
     - x (number) x coordinate of the centre
     - y (number) y coordinate of the centre
     - rx (number) horizontal radius
     - ry (number) vertical radius
     = (object) the `ellipse` element
     **
     > Usage
     | let c = paper.ellipse(50, 50, 40, 20);
    \*/
  ellipse(cx, cy, rx, ry) {
    let attr
    if (is(cx, 'object') && cx == '[object Object]') {
      attr = cx
    } else if (cx != null) {
      attr = {
        cx: cx,
        cy: cy,
        rx: rx,
        ry: ry
      }
    }
    return this.el('ellipse', attr)
  }

  path(d) {
    let attr
    if (is(d, 'object') && !is(d, 'array')) {
      attr = d
    } else if (d) {
      attr = { d: d }
    }
    return this.el('path', attr)
  }

  group(first) {
    let attr,
      el = this.el('g')
    if (arguments.length == 1 && first && !first.type) {
      el.attr(first)
    } else if (arguments.length) {
      el.add(Array.from(arguments))
    }
    return el
  }

  /*
    **
    * Creates a `<filter>` element
    **
    - filstr (string) SVG fragment of filter provided as a string
    = (object) @SnapElement
    * Note: It is recommended to use filters embedded into the page inside an empty SVG element.
    > Usage
    | let f = paper.filter('<feGaussianBlur stdDeviation="2"/>'),
    |     c = paper.circle(10, 10, 10).attr({
    |         filter: f
    |     });
  */
  filter(filstr) {
    let paper = this
    if (paper.type !== 'svg') {
      paper = paper.paper
    }
    let f = Snap.parse(String(filstr)),
      id = uuid((this.type || '') + 'S'),
      width = paper.node.offsetWidth,
      height = paper.node.offsetHeight,
      filter = $('filter')
    $(filter, {
      id: id,
      filterUnits: 'userSpaceOnUse'
    })
    filter.appendChild(f.node)
    paper.defs.appendChild(filter)
    return new SnapElement(filter)
  }

  toString() {
    let doc = this.node.ownerDocument,
      f = doc.createDocumentFragment(),
      d = doc.createElement('div'),
      svg = this.node.cloneNode(true),
      res
    f.appendChild(d)
    d.appendChild(svg)
    $(svg, { xmlns: 'http://www.w3.org/2000/svg' })
    res = d.innerHTML
    return res
  }

  /*\

    **
    * Removes all child nodes of the paper, except <defs>.
  */
  clear() {
    let node = this.node.firstChild,
      next
    while (node) {
      next = node.nextSibling
      if (node.tagName != 'defs') {
        node.parentNode.removeChild(node)
      } else {
        this.clear.call({ node: node })
      }
      node = next
    }
  }
}

export class SnapElement {
  constructor(el) {
    if (el.snap in hub) {
      return hub[el.snap]
    }
    let svg
    try {
      svg = el.ownerSVGElement
    } catch (e) {}
    /*\
     **
     * Gives you a reference to the DOM object, so you can assign event handlers or just mess around.
     > Usage
     | // draw a circle at coordinate 10,10 with radius of 10
     | let c = paper.circle(10, 10, 10);
     | c.node.onclick = function () {
     |     c.attr("fill", "red");
     | };
    \*/
    this.node = el
    if (svg) {
      this.paper = new Paper(svg)
    }
    /*\
     * SnapElement.type
     [ property (string) ]
     **
     * SVG tag name of the given element.
    \*/
    this.type = el.tagName || el.nodeName
    let id = (this.id = uuid((this.type || '') + 'S'))
    this.anims = {}
    this._ = {
      transform: []
    }
    el.snap = id
    hub[id] = this
    if (this.type == 'g') {
      this.add = add2group
    }
    if (this.type in { g: 1, mask: 1, pattern: 1, symbol: 1 }) {
      extend(this, Paper.prototype)
    }
  }

  /*
  **
  * Gets or sets given attributes of the element.
  **
  - params (object) contains key-value pairs of attributes you want to set
  * or
  - param (string) name of the attribute
  = (SnapElement) the current element
  * or
  = (string) value of attribute
  > Usage
  | el.attr({
  |     fill: "#fc0",
  |     stroke: "#000",
  |     strokeWidth: 2, // CamelCase...
  |     "fill-opacity": 0.5, // or dash-separated names
  |     width: "*=2" // prefixed values
  | });
  | console.log(el.attr("fill")); // #fc0
  * Prefixed values in format `"+=10"` supported. All four operations
  * (`+`, `-`, `*` and `/`) could be used. Optionally you can use units for `+`
  * and `-`: `"+=2em"`.
  */
  attr(params, value) {
    let node = this.node

    if (!params) {
      if (node.nodeType != 1) {
        return {
          text: node.nodeValue
        }
      }
      let attr = node.attributes,
        out = {}
      for (let i = 0, ii = attr.length; i < ii; i++) {
        out[attr[i].nodeName] = attr[i].nodeValue
      }

      return out
    }
    if (is(params, 'string')) {
      if (value !== void 0) {
        params = { [params]: value }
      } else {
        return eve('snap.util.getattr.' + params, this).firstDefined()
      }
    }
    for (let att in params) {
      eve('snap.util.attr.' + att, this, params[att])
    }
    return this
  }

  /*
  **
  * Returns array of all the children of the element.
  = (array) array of Elements
  */
  children() {
    let out = [],
      ch = this.node.childNodes
    for (let i = 0, ii = ch.length; i < ii; i++) {
      out[i] = new Snap(ch[i])
    }
    return out
  }

  /*\
 **
 * Returns object representation of the given element and all its children.
 = (object) in format
 o {
 o     type (string) this.type,
 o     attr (object) attributes map,
 o     childNodes (array) optional array of children in the same format
 o }
\*/
  toJSON() {
    let out = []
    jsonFiller([this], out)
    return out[0]
  }

  equal(name, b) {
    return eve('snap.util.equal', this, name, b).firstDefined()
  }

  addClass(value) {
    this.node.classList.add(value)
    return this
  }

  removeClass(value) {
    this.node.classList.remove(value)
    return this
  }

  hasClass(value) {
    return this.node.classList.contains(value)
  }

  toggleClass(value, flag) {
    this.node.classList.toggle(value, flag)
    return this
  }

  getAlign(way = 'center') {
    let bx = this.paper.getBBox()
    let bb = this.getBBox()
    let out = {
      toString() {
        return 'T' + this.dx + ',' + this.dy
      }
    }

    switch (way.toLowerCase()) {
      case 'top':
        out.dx = 0
        out.dy = bx.y - bb.y
        break
      case 'bottom':
        out.dx = 0
        out.dy = bx.y2 - bb.y2
        break
      case 'middle':
        out.dx = 0
        out.dy = bx.cy - bb.cy
        break
      case 'left':
        out.dx = bx.x - bb.x
        out.dy = 0
        break
      case 'right':
        out.dx = bx.x2 - bb.x2
        out.dy = 0
        break
      case 'center':
        out.dx = bx.cx - bb.cx
        out.dy = 0
        break
    }
    return out
  }

  align(way) {
    return this.transform('' + this.getAlign(way))
  }
}

// default
eve.on('snap.util.getattr', function () {
  let key = eve.nt().split('.').at(-1)
  let css = key.replace(/[A-Z]/g, function (letter) {
    return '-' + letter.toLowerCase()
  })
  if (CSS_ATTR[css]) {
    return this.node.ownerDocument.defaultView
      .getComputedStyle(this.node, null)
      .getPropertyValue(css)
  } else {
    return $(this.node, key)
  }
})

eve.on('snap.util.attr', function (value) {
  let key = eve.nt().split('.').at(-1)
  let attr = { [key]: value }

  let css = key.replace(/[A-Z]/g, function (letter) {
    return '-' + letter.toLowerCase()
  })
  if (CSS_ATTR[css]) {
    this.node.style[css] = value == null ? E : value
  } else {
    $(this.node, attr)
  }
})