// jsr_class.js
//
// JSONscriptRequest -- a simple class for making HTTP requests
// using dynamically generated script tags and JSON
//
// Author: Jason Levitt
// Date: December 7th, 2005
//
// Maptuit revision dated Sep. 25, 2006
//
// Sample Usage:
//
// <script type="text/javascript" src="json_script_request.js"></script>
// 
// function foo(jsonData) {
//      alert('Latitude = ' + jsonData.Address[0].Result[0].Lat + 
//            '  Longitude = ' + jsonData.Address[0].Result[0].Lon);
//      aObj.removeScriptTag();
// }
//
// request = 'http://...maptuit.com/.../json.php?config=...&service=geo'
//         + '&cmd=Geocode&Address0_CountryCode=ca&Address0_RegionCode=on'
//         + '&Address0_Area=Toronto&Address0_Street=King+St+E&Address0_House=133'
//         + '&callback=foo';
// aObj = new JSONscriptRequest(request);
// aObj.buildScriptTag();
// aObj.addScriptTag();
//


// Constructor -- pass a REST request URL to the constructor
//
function JSONscriptRequest(fullUrl) {
    // REST request path
    this.fullUrl = fullUrl; 
    // Keep IE from caching requests
    this.noCacheIE = '&noCacheIE=' + (new Date()).getTime();
    // Get the DOM location to put the script tag
    this.headLoc = document.getElementsByTagName("head").item(0);
    // Generate a unique script tag id
    this.scriptId = 'JscriptId' + JSONscriptRequest.scriptCounter++;
}

// Static script ID counter
JSONscriptRequest.scriptCounter = 1;

// buildScriptTag method
//
JSONscriptRequest.prototype.buildScriptTag = function () {

    // Create the script tag
    this.scriptObj = document.createElement("script");
    
    // Add script object attributes
    this.scriptObj.setAttribute("type", "text/javascript");
    this.scriptObj.setAttribute("charset", "utf-8");
    this.scriptObj.setAttribute("src", this.fullUrl + this.noCacheIE);
    this.scriptObj.setAttribute("id", this.scriptId);
}
 
// removeScriptTag method
// 
JSONscriptRequest.prototype.removeScriptTag = function () {
    // Destroy the script tag
    this.headLoc.removeChild(this.scriptObj);  
}

// addScriptTag method
//
JSONscriptRequest.prototype.addScriptTag = function () {
    // Create the script tag
    this.headLoc.appendChild(this.scriptObj);
}