/* Any copyright is dedicated to the Public Domain.
 * http://creativecommons.org/publicdomain/zero/1.0/ */

function xmlEncode(s){
  var i = 0, ch;
  s = String(s);
  while (i < s.length && (ch = s[i]) !== '&' && ch !== '<' &&
         ch !== '\"' && ch !== '\n' && ch !== '\r' && ch !== '\t') {
    i++;
  }
  if (i >= s.length) {
    return s;
  }
  var buf = s.substring(0, i);
  while (i < s.length) {
    ch = s[i++];
    switch (ch) {
      case '&':
        buf += '&amp;';
        break;
      case '<':
        buf += '&lt;';
        break;
      case '\"':
        buf += '&quot;';
        break;
      case '\n':
        buf += '&#xA;';
        break;
      case '\r':
        buf += '&#xD;';
        break;
      case '\t':
        buf += '&#x9;';
        break;
      default:
        buf += ch;
        break;
    }
  }
  return buf;
}

function DOMElement(name) {
  this.nodeName = name;
  this.childNodes = [];
  this.attributes = {};
  this.textContent = '';

  if (name === 'style') {
    this.sheet = {
      cssRules: [],
      insertRule: function (rule) {
        this.cssRules.push(rule);
      },
    };
  }
}

DOMElement.prototype = {

  getAttributeNS: function DOMElement_getAttributeNS(NS, name) {
    // Fast path
    if (name in this.attributes) {
      return this.attributes[name];
    }
    // Slow path - used by test/unit/display_svg_spec.js
    // Assuming that there is only one matching attribute for a given name,
    // across all namespaces.
    if (NS) {
      var suffix = ':' + name;
      for (var fullName in this.attributes) {
        if (fullName.slice(-suffix.length) === suffix) {
          return this.attributes[fullName];
        }
      }
    }
    return null;
  },

  setAttributeNS: function DOMElement_setAttributeNS(NS, name, value) {
    value = value || '';
    value = xmlEncode(value);
    this.attributes[name] = value;
  },

  appendChild: function DOMElement_appendChild(element) {
    var childNodes = this.childNodes;
    if (childNodes.indexOf(element) === -1) {
      childNodes.push(element);
    }
  },

  cloneNode: function DOMElement_cloneNode() {
    var newNode = new DOMElement(this.nodeName);
    newNode.childNodes = this.childNodes;
    newNode.attributes = this.attributes;
    newNode.textContent = this.textContent;
    return newNode;
  },

  // This method is offered for convenience. It is recommended to directly use
  // getSerializer because that allows you to process the chunks as they come
  // instead of requiring the whole image to fit in memory.
  toString: function DOMElement_toString() {
    var buf = [];
    var serializer = this.getSerializer();
    var chunk;
    while ((chunk = serializer.getNext()) !== null) {
      buf.push(chunk);
    }
    return buf.join('');
  },

  getSerializer: function DOMElement_getSerializer() {
    return new DOMElementSerializer(this);
  }
}

function DOMElementSerializer(node) {
  this._node = node;
  this._state = 0;
  this._loopIndex = 0;
  this._attributeKeys = null;
  this._childSerializer = null;
}
DOMElementSerializer.prototype = {
  /**
   * Yields the next chunk in the serialization of the element.
   *
   * @returns {string|null} null if the element has fully been serialized.
   */
  getNext: function DOMElementSerializer_getNext() {
    var node = this._node;
    switch (this._state) {
      case 0:  // Start opening tag.
        ++this._state;
        return '<' + node.nodeName;
      case 1:  // Add SVG namespace if this is the root element.
        ++this._state;
        if (node.nodeName === 'svg:svg') {
          return ' xmlns:xlink="http://www.w3.org/1999/xlink"' +
                 ' xmlns:svg="http://www.w3.org/2000/svg"';
        }
      case 2:  // Initialize variables for looping over attributes.
        ++this._state;
        this._loopIndex = 0;
        this._attributeKeys = Object.keys(node.attributes);
      case 3:  // Serialize any attributes and end opening tag.
        if (this._loopIndex < this._attributeKeys.length) {
          var name = this._attributeKeys[this._loopIndex++];
          return ' ' + name + '="' + xmlEncode(node.attributes[name]) + '"';
        }
        ++this._state;
        return '>';
      case 4:  // Serialize textContent for tspan/style elements.
        if (node.nodeName === 'svg:tspan' || node.nodeName === 'svg:style') {
          this._state = 6;
          return xmlEncode(node.textContent);
        }
        ++this._state;
        this._loopIndex = 0;
      case 5:  // Serialize child nodes (only for non-tspan/style elements).
        var value;
        while (true) {
          value = this._childSerializer && this._childSerializer.getNext();
          if (value !== null) {
            return value;
          }
          var nextChild = node.childNodes[this._loopIndex++];
          if (nextChild) {
            this._childSerializer = new DOMElementSerializer(nextChild);
          } else {
            this._childSerializer = null;
            ++this._state;
            break;
          }
        }
      case 6:  // Ending tag.
        ++this._state;
        return '</' + node.nodeName + '>';
      case 7:  // Done.
        return null;
      default:
        throw new Error('Unexpected serialization state: ' + this._state);
    }
  },
};

const document = {
  childNodes : [],

  get currentScript() {
    return { src: '' };
  },

  get documentElement() {
    return this;
  },

  createElementNS: function (NS, element) {
    var elObject = new DOMElement(element);
    return elObject;
  },

  createElement: function (element) {
    return this.createElementNS('', element);
  },

  getElementsByTagName: function (element) {
    if (element === 'head') {
      return [this.head || (this.head = new DOMElement('head'))];
    }
    return [];
  }
};

function Image () {
  this._src = null;
  this.onload = null;
}
Image.prototype = {
  get src () {
    return this._src;
  },
  set src (value) {
    this._src = value;
    if (this.onload) {
      this.onload();
    }
  }
}

exports.document = document;
exports.Image = Image;

var exported_symbols = Object.keys(exports);

exports.setStubs = function(namespace) {
  exported_symbols.forEach(function(key) {
    console.assert(!(key in namespace), 'property should not be set: ' + key);
    namespace[key] = exports[key];
  });
};
exports.unsetStubs = function(namespace) {
  exported_symbols.forEach(function(key) {
    console.assert(key in namespace, 'property should be set: ' + key);
    delete namespace[key];
  });
};