var Cache = require('../cache')
var templateCache = new Cache(100)

var map = {
  _default : [0, '', ''],
  legend   : [1, '<fieldset>', '</fieldset>'],
  tr       : [2, '<table><tbody>', '</tbody></table>'],
  col      : [
    2,
    '<table><tbody></tbody><colgroup>',
    '</colgroup></table>'
  ]
}

map.td =
map.th = [
  3,
  '<table><tbody><tr>',
  '</tr></tbody></table>'
]

map.option =
map.optgroup = [
  1,
  '<select multiple="multiple">',
  '</select>'
]

map.thead =
map.tbody =
map.colgroup =
map.caption =
map.tfoot = [1, '<table>', '</table>']

map.g =
map.defs =
map.symbol =
map.use =
map.image =
map.text =
map.circle =
map.ellipse =
map.line =
map.path =
map.polygon =
map.polyline =
map.rect = [
  1,
  '<svg ' +
    'xmlns="http://www.w3.org/2000/svg" ' +
    'xmlns:xlink="http://www.w3.org/1999/xlink" ' +
    'xmlns:ev="http://www.w3.org/2001/xml-events"' +
    'version="1.1">',
  '</svg>'
]

var TAG_RE = /<([\w:]+)/

/**
 * Convert a string template to a DocumentFragment.
 * Determines correct wrapping by tag types. Wrapping
 * strategy found in jQuery & component/domify.
 *
 * @param {String} templateString
 * @return {DocumentFragment}
 */

function stringToFragment (templateString) {
  // try a cache hit first
  var hit = templateCache.get(templateString)
  if (hit) {
    return hit
  }

  var frag = document.createDocumentFragment()
  var tagMatch = TAG_RE.exec(templateString)

  if (!tagMatch) {
    // text only, return a single text node.
    frag.appendChild(
      document.createTextNode(templateString)
    )
  } else {

    var tag    = tagMatch[1]
    var wrap   = map[tag] || map._default
    var depth  = wrap[0]
    var prefix = wrap[1]
    var suffix = wrap[2]
    var node   = document.createElement('div')

    node.innerHTML = prefix + templateString.trim() + suffix
    while (depth--) {
      node = node.lastChild
    }

    var child
    /* jshint boss:true */
    while (child = node.firstChild) {
      frag.appendChild(child)
    }
  }

  templateCache.put(templateString, frag)
  return frag
}

/**
 * Convert a template node to a DocumentFragment.
 *
 * @param {Node} node
 * @return {DocumentFragment}
 */

function nodeToFragment (node) {
  var tag = node.tagName
  // if its a template tag and the browser supports it,
  // its content is already a document fragment.
  if (
    tag === 'TEMPLATE' &&
    node.content instanceof DocumentFragment
  ) {
    return node.content
  }
  return tag === 'SCRIPT'
    ? stringToFragment(node.textContent)
    : stringToFragment(node.innerHTML)
}

/**
 * Process the template option and normalizes it into a
 * a DocumentFragment that can be used as a partial or a
 * instance template.
 *
 * @param {*} template
 *    Possible values include:
 *    - DocumentFragment object
 *    - Node object of type Template
 *    - id selector: '#some-template-id'
 *    - template string: '<div><span>{{msg}}</span></div>'
 * @param {Boolean} clone
 * @return {DocumentFragment|undefined}
 */

exports.parse = function (template, clone) {
  var node, frag

  // if the template is already a document fragment,
  // do nothing
  if (template instanceof DocumentFragment) {
    return clone
      ? template.cloneNode(true)
      : template
  }

  if (typeof template === 'string') {
    // id selector
    if (template.charAt(0) === '#') {
      // id selector can be cached too
      frag = templateCache.get(template)
      if (!frag) {
        node = document.getElementById(template.slice(1))
        if (node) {
          frag = nodeToFragment(node)
          // save selector to cache
          templateCache.put(template, frag)
        }
      }
    } else {
      // normal string template
      frag = stringToFragment(template)
    }
  } else if (template.nodeType) {
    // a direct node
    frag = nodeToFragment(template)
  }

  return frag && clone
    ? frag.cloneNode(true)
    : frag
}