// PAPERWEB - GPLv3 licence
// Copyright 2006-2016 Yves Gablin
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.
//
// = Credits =
// Tutorial: http://robloche.free.fr/javascript/tuto_xhr/tuto_xhr.html

var ajax = {
  XML: 1,
  TXT: 2,

  // public class Connection
  // + start()
  // - xmlhttp
  Connection: function() {
    var xh;
    try {
      xh = new XMLHttpRequest();
    } catch (e1) { // IE
      try {
        xh = new ActiveXObject("Msxml2.XMLHTTP");
      } catch (e2) {
        try {
          xh = new ActiveXObject("Microsoft.XMLHTTP");
        } catch (e3) {
          xh = null;
        }
      }
    }
    this.xmlhttp = xh;
  },

  // private class Link
  // - connection: Connection
  // - urlBuilder: user-provided function
  // - resultHandler: user-provided function
  // - resultType: XML|TXT
  // - preventDefault : true|false = prevent default event consequence
  Link: function(pSource, pEvent, pUrlBuilder, pResultHandler, pType, pPreventDefault) {
    this.connection = new ajax.Connection();
    this.urlBuilder = pUrlBuilder;
    this.resultHandler = pResultHandler;
    this.resultType = pType;
    this.preventDefault = pPreventDefault;
    if (!pSource.ajaxLinks) {
      pSource.ajaxLinks = new Array();
      pSource.addEventListener(pEvent, this.evhSourceTrigger);
    }
    pSource.ajaxLinks[pSource.ajaxLinks.length] = this;
    if (pEvent != 'click') {
      this.evhSourceTrigger.call(pSource, null);
    }
  },

  // public static function link()
  link: function(pSource, pUrlBuilder, pDestHandler, pType, pPreventDefault) {
    var event;
    switch (pSource.tagName) {
    case 'SELECT':
    case 'TEXTAREA':
      event = 'change';
      break;
    case 'BUTTON':
      event = 'click';
      break;
    case 'INPUT':
      switch (pSource.type) {
      case 'text':
      case 'password':
      case 'file':
      case 'hidden':
        event = 'change';
        break;
      case 'checkbox':
      case 'radio':
      case 'submit':
      case 'reset':
      case 'image':
      case 'button':
        event = 'click';
        break;
      }
      break;
    }
    new ajax.Link(pSource, event, pUrlBuilder, pDestHandler, pType, pPreventDefault);
  },

  // public static function importNode()
  importNode: function(pSourceNode, pDestDoc) {
    var destNode;
    switch (pSourceNode.nodeType) {
    case 1: // Element
      destNode = pDestDoc.createElement(pSourceNode.tagName);
      break;
    case 3: // TextNode
      destNode = pDestDoc.createTextNode(pSourceNode.data);
      break;
    case 4: // CDATASection
      destNode = pDestDoc.createCDATASection(pSourceNode.data);
      break;
    case 5: // EntityReference
      destNode = pDestDoc.createEntityReference(pSourceNode.nodeName);
      break;
    case 7: // ProcessingInstruction
      destNode = pDestDoc.createProcessingInstruction(pSourceNode.nodeName, pSourceNode.nodeValue);
      break;
    case 8: // Comment
      destNode = pDestDoc.createComment(pSourceNode.data);
      break;
    case 9: // Document
      return ajax.importNode(pSourceNode.documentElement, pDestDoc);
    default:
      return null;
    }
    if (pSourceNode.attributes) {
      var att;
      for (var numAtt = 0; numAtt < pSourceNode.attributes.length; numAtt++) {
        att = pSourceNode.attributes[numAtt];
        destNode.setAttribute(att.name, att.value);
      }
    }
    if (pSourceNode.childNodes) {
      var child;
      for (var numCh = 0; numCh < pSourceNode.childNodes.length; numCh++) {
        child = ajax.importNode(pSourceNode.childNodes[numCh], pDestDoc);
        if (child != null) destNode.appendChild(child);
      }
    }
    return destNode;
  }
}

// public method Connection.start()
ajax.Connection.prototype.start = function(pUrl, pPostParams, pCallback, pType) {
  if (!this.xmlhttp || !pCallback) return;
  var xh = this.xmlhttp;
  var async = true;
  if (xh.ajaxConnectionConnected == true) {
    xh.abort();
  }
  if (pPostParams) {
    xh.open("POST", pUrl, async);
  } else {
    xh.open("GET", pUrl, async);
  }
  xh.onreadystatechange = function() {
    if (xh.readyState == 4) {
      var status = -1;
      try { status = xh.status; } catch (unreachable) { }
      if (xh.ajaxConnectionNotice) {
        xh.ajaxConnectionNotice.parentNode.removeChild(xh.ajaxConnectionNotice);
        xh.ajaxConnectionNotice = null;
      }
      var result = null;
      if (status == 200) {
        if (pType == ajax.XML) {
          result = xh.responseXML;
        } else {
          result = xh.responseText;
        }
      }
      xh.ajaxConnectionConnected = false;
      pCallback(result);
    }
  };
  var notice = document.createElement('div');
  notice.appendChild(document.createTextNode('...'));
  notice.className = 'ajax-connection-wait';
  xh.ajaxConnectionNotice = document.getElementsByTagName('body').item(0).appendChild(notice);

  if (pType == ajax.XML)
    xh.overrideMimeType("text/xml");
  xh.ajaxConnectionConnected = true;
  xh.send(pPostParams);
};

// public method Link.evhSourceTrigger()
ajax.Link.prototype.evhSourceTrigger = function(pEvt) {
  var link, prevent = false;
  for (var i = 0; i < this.ajaxLinks.length; i++) {
    link = this.ajaxLinks[i];
    link.connection.start(link.urlBuilder(this), null, link.resultHandler, link.resultType);
    prevent = prevent || link.preventDefault;
  }
  if (prevent) {
    pEvt.preventDefault();
  }
};