// Copyright (c) 2005 Just Objects B.V. <just@justobjects.nl>
// Distributable under LGPL license. See terms of license at gnu.org.

/*
 * API for requests to KW server.
 *
 * PURPOSE
 * This library can be used for any request to KW server. Mostly prepared
 * queries. Each request returns an XML document.  SRV.get() is a varargs function.
 * The first parameter identifies a "command", specific to the application.
 *
 * USAGE
 * SRV.init()
 * SRV.get("q-get-active-tracks", myfun, "state", "3", "name", "piet);
 *
 * Author: Just van den Broecke
 * $Id: server.js,v 1.9 2005/10/06 10:26:57 just Exp $
 */

//
// API to invoke commands on KW server
//
var SRV = {
  // Query/get data URL to server
  url: '/gt/get.jsp?',
  initialized: false,

  // Initialization: must be called before anything
  init: function() {
    if (SRV.initialized) {
      return;
    }

    // Need DHTML lib...
    if (!DH) {
    	alert('dhtml.js not found; is it imported before server.js?');
    	return;
    }

    // Init DHTML lib
    DH.init();

    SRV.initialized = true;
  },

  // Generic varargs command function for all requests to server.
  // arg[0] command
  // arg[1] user supplied callback function
  // arg[2]...arg[2+2N] N arguments specific to command
  // each argument has a name and a value like "tables", "person"
  // example:
  // SRV.get("q-get-active-tracks", myfun, "state", "3", "name", "piet);
  get: function(aCmd, aCallback, theOtherArgs) {
    var argv = SRV.get.arguments;
    var argc = arguments.length;
    if (argc < 2) {
      alert('get command must have at least 2 argv (cmd+callback)');
      return;
    }

    /*var s='argv=';
    for (var i=0; i < argc; i++) {
      s+= ('argv[' + i + ']=' + argv[i]);
    }

    alert('argc=' + argc + ' ' + s); */
    var cmd = aCmd;
    var callback = aCallback;

    // Use remaining args to form URL-query string
    var qs = 'cmd=' + cmd;
    for (var i=2; i < argc; i++) {
      qs = SRV._xpand(qs, argv[i], argv[++i]);
    }

    // Query commands get intercepted to convert to Record array
    var url = SRV.url + qs;

    if (cmd.indexOf("q-") != -1) {
      // Query-type request: intercept and convert result to records
      // before doing callback
      qr = new SRV._queryRspHandler(callback);
      DH.getXML(url, qr.onQueryRsp);
	} else {
	  DH.getXML(url, callback);
	}
  },

  // Do generic query to KW server
  query: function(callback, tables, fields, where, rels, orderby, directions) {
    var qs = 'cmd=q-store';
    qs = SRV._xpand(qs, 'tables', tables);
	qs = SRV._xpand(qs, 'fields', fields);
	qs = SRV._xpand(qs, 'where', where);
	qs = SRV._xpand(qs, 'rels', rels);
	qs = SRV._xpand(qs, 'orderby', orderby);
	qs = SRV._xpand(qs, 'directions', directions);
    qr = new SRV._queryRspHandler(callback);
	DH.getXML(SRV.url + qs, qr.onQueryRsp);
  },

  // Internal util object to allow interception of callback
  _queryRspHandler: function(cb) {

    // This is needed since JS only allows local scope vars for
    // callbacks. See also http://w3future.com/html/stories/callbacks.xml
    var userCallback = cb;
    this.onQueryRsp = function(xml) {
	  var records = [];
      if (!xml) {
        return records;
      }

      // Convert xml doc to array of Record objects
      var recordElements = xml.documentElement.getElementsByTagName('record');
	  for (i = 0; i < recordElements.length; i++) {
		 records.push(new Record(recordElements[i]));
      }

      // Call original user
      userCallback(records);
    }
  },

  // Internal util to expand name value pairs into URL query part.
  _xpand: function(qs, name, value) {
    if (value && value != null) {
      qs += ('&' + name + '=' + value);
    }
    return qs;
  }
} // END SRV functions

// Class to represent KeyWorx Oase Record
function Record(xmlElement) {
  this.xml = xmlElement;
  this.id = -1;
  if (this.xml.attributes && this.xml.attributes[0]) {
    this.id = this.xml.attributes[0].value;
  }
}

// Get any text/numeric field by name
Record.prototype.getField = function(name) {
  var field = this.getXMLField(name);
  if (field != null && field.childNodes.length > 0) {
    return field.childNodes[0].nodeValue;
  } else {
    return null;
  }
}

// Get XML field by name; returns XML DOM Element
Record.prototype.getXMLField = function(name) {
  var list = this.xml.getElementsByTagName(name);
  if (list && list.length > 0) {
    return list[0];
  } else {
    alert('cannot getXMLField ' + name);
    return null;
  }
}

// Debug: render HTML to show record content.
Record.prototype.toHTML = function() {
	var html = '<pre>';
	var xml = this.xml;
	html += (xml.tagName + ' id=' + this.id + '\n');

	var fields = xml.childNodes;
	var fieldCount = fields.length;
	var nextField;
	for (j = 0; j < fieldCount; j++) {
	  nextField = fields[j];
	  html += (nextField.tagName + '=');

	  if (nextField.childNodes[0]) {
		html += nextField.childNodes[0].nodeValue;
	  }

	  html += '\n';
	}

	html += '\n</pre>';
	return html;
}