/* Copyright 2005 Camptocamp SA. 
   Licensed under the GPL (www.gnu.org/copyleft/gpl.html) */

/*
 * Used by: AjaxHandler.js
 */

/**
 * Provides helper methods for AjaxHandler
 * i.e. form fields collector, query builder, event handler, findpos
 */
var AjaxHelper = {

    /**
     * General method that builds a request string from an HTMLFormElement and
     * returns a formatted string: 'elemeentName=elemeentValue' or 'elemeentName='
     * @param HTMLFormElement
     */
    buildQueryFrom: function(htmlElement) {
        
        if (htmlElement == undefined) {
            return '';
        }
        
        inputType = htmlElement.getAttribute('type');
        paramName = htmlElement.getAttribute('name');
        if (inputType == 'text') {
            paramValue = htmlElement.value;
        } else {
            paramValue = htmlElement.getAttribute('value');
        }
            
        if (paramValue != null) {
             return paramName + '=' + paramValue;
        } else {        
            // HTTP POST requests parameters HAVE TO be followed by '='
            // even when they have no associated value
             return paramName + '=';
         }
    },   


    /**
     * Returns the HTTP POST/GET string from the form specified by formId,
     * by creating a query string from all the given form's inputs and selects
     * but the submit, button and image inputs types.
     *
     * @param string Id of the form to parse.
     * @return string HTTP GET string from formId
     */
    buildQuery: function(formId) {
        
        var queryString = ''; // String to be returned
        formElement = document.getElementById(formId);

        /*
         * Process <input> elements
         */
        inputElements = formElement.getElementsByTagName('input');
        for (var i = 0; i < inputElements.length; i++) {
            // Collect the current input only if it's is not 'submit', 'image' or 'button'
            currentElement = inputElements.item(i);
            inputType = currentElement.getAttribute('type');
            
            if (inputType == 'radio' || inputType == 'checkbox') {
                if (currentElement.checked) {
                    queryString = queryString + this.buildQueryFrom(currentElement) + '&';
                }
            } else if (inputType == 'submit' || inputType == 'button' || inputType == 'image') {
                // Do nothing. Sending the submit inputs in POST Request would make
                // the serverside act like all buttons on the form were clicked.
                // And we don't want that.
            } else {    
                queryString = queryString + this.buildQueryFrom(currentElement) + '&';
            }
        }

        /*
         * Process <select> elements
         */
        selectElements = formElement.getElementsByTagName('select');
        for (var i = 0; i < selectElements.length; i++) {
            // Get the param name (i.e. fetch the name attr)
            currentElement = selectElements.item(i);
            paramName = currentElement.getAttribute('name');
            
            // Get the param value(s)
            // (i.e. fetch the checked options element's value attr)
            optionElements = currentElement.getElementsByTagName('option');
            for (var j = 0; j < optionElements.length; j++) {
                currentElement = optionElements.item(j);
                if (currentElement.selected) {
                    paramValue = currentElement.getAttribute('value');
                    if (paramValue == null) {
                        paramValue = '';
                    }
                    queryString = queryString + paramName + '='    + paramValue + '&';
                }
            }
        }
        return queryString;
    },
            
    /**
     * Returns the query string contained in the href attribute
     * of the given HTML <a> element object.
     * @param ahrefElement <a> element object
     * @return string HTTP GET string from ahrefElement
     */
    getQueryString: function(ahrefElement) {
        if (ahrefElement == undefined) {
            return;
        }
        // Retrieves the string after the '?' of the element's href attribute.
        startChar = ahrefElement.indexOf('?');
        endChar = ahrefElement.length;
        if (startChar != '-1') {
            return ahrefElement.substring(startChar+1, endChar);
        } else {
            return '';
        }
    },

    /**
     * Returns true if browserString is contained
     * in navigator.userAgent (case insensitive)
     * @param browserString String representing the browser name
     * @return bool True if browserString is contained in navigator.userAgent
     */
    isBrowser: function(browserString) {
        var detect = navigator.userAgent.toLowerCase();
        var string = browserString.toLowerCase();
        place = detect.indexOf(string) + 1;
        return place > 0;            
    },

    /**
     * Unescapes '&' ('&#38;') entity for Safari.
     * Safari doesn't decode responses' content correcty, so we need to
     * decode some for it.
     * @param string Escaped string
     * @return string Unescaped string
     */
    decodeForSafari: function(string) {
        if (this.isBrowser('safari')) {
            parts = string.split('&#38;');
            string = '';
            for (counter=0; counter<parts.length; counter++) {
                if (counter>0) {
                    string += '&';
                }
                string += parts[counter];
            }
        }
        return string;
    },
    
    /**
     * Cross-browser event handling (IE5/NS6/Moz/Gecko)
     * By Scott Andrew
     * @example addEvent(window, 'load', addListeners, false);
     * 
     * @param HTMLElement HTML DOM Element object to attach the listener on
     * @param string Type of the triggering event (i.e. click, change, ...)
     * @param string Funtion name to be called on event trigger
     * @param bool Prevent event from bubbling through the DOM
     */
    addEvent: function (elm, evType, fn, useCapture) {
        if (useCapture == undefined) {
            useCapture = false;
        }
        if (elm.addEventListener) {
            elm.addEventListener(evType, fn, useCapture);
            return true;
        } else if (elm.attachEvent) {
            var r = elm.attachEvent('on' + evType, fn);
            return r;
        } else {
            elm['on' + evType] = fn;
        }
    },
    
    getCurrentTool: function() {
        var selectedTool = null;
        inputElements = document.getElementsByTagName('input');
        for (var i=0; i < inputElements.length; i++) {
            currentElement = inputElements.item(i);
            inputType = currentElement.getAttribute('type');
            inputName = currentElement.getAttribute('name');
            if (inputType == 'radio' && inputName == 'tool') {
                if (currentElement.checked) {
                    selectedTool = currentElement.value;
                    break;
                }
            }                    
        }
        return selectedTool;
    },
    
    exists: function(variableName) {
        eval('variableType = typeof(' + variableName + ')');
        return variableType != 'undefined';
    },

    /* 
     * Finds clicked position on an element
     * (simulates the posting of a <input type="image" ...>)
     * Used by AjaxPlugins.Location.Actions.pan.buildPostRequest()
     *
     * This seems bogous on Safari!
     *
     * @param Event
     * @return Object Object with x and y properties, containing the clicked
     *                position, relative to the clicked element
     */
    getClickedPos: function(ev) {
    
        function findPosX(obj) {
            var curleft = 0;
            if (obj.offsetParent) {
                while (obj.offsetParent) {
                    curleft += obj.offsetLeft;
                    obj = obj.offsetParent;
                }
            } else if (obj.x) {
                curleft += obj.x;
            }
            return curleft;
        }
        
        function findPosY(obj) {
            var curtop = 0;
            if (obj.offsetParent) {
                while (obj.offsetParent){
                    curtop += obj.offsetTop;
                    obj = obj.offsetParent;
                }
            }
            else if (obj.y) {
                curtop += obj.y;
            }
            return curtop;
        }
    
        var e = window.event ? window.event : ev;
        var t = e.target ? e.target : e.srcElement;
        
        var mX, my;
        if (e.pageX && e.pageY) {
            mX = e.pageX;
            mY = e.pageY;
        } else {
            mX = e.clientX;
            mY = e.clientY;
        }
        
        mX += document.body.scrollLeft;
        mY += document.body.scrollTop;
        
        return {x: mX - findPosX(t),
                y: mY - findPosY(t)};
    }    
};