// XHR -- XMLHttpRequest

// Argmunets
//
// url
// method
// data
// headers
//   Accept
//   Referer
//   User-Agent etc...
// onload
// onerror
// onreadeychange
// async (default: true)

// Arguments of onload/onerror
//
// channel
// responseText
// responseHeaders
// requestHeaders
// status
// finalUrl
// etc...

// TODO:
//  authentication

// Example
/*

var opt = {
    url : 'http://localhost/index.rdf'
    , method : 'head'
    , headers : {
        'Referer' : 'http://example.com/referer'
        , 'User-Agent' : 'Mozilla/5.0 foo bar baz'
    }
    , onload : function(response){
        alert('onload \n\n' + response.responseXML)
        alert('onload \n\n' + response.requestHeaders)
    }
    , onerror : function(response){
        alert('onerror \n\n' + response.responseXML)
    }
}
XHR(opt);

*/



function XHR({method,url,headers,data,onload,onerror,onreadystatechange,overrideMimeType,async}){

    const Ci = Components.interfaces;
    const Cc = Components.classes;

    async = (typeof async == 'undefined') ? true : !!async;

    var cancel = false;
    var xhr = new XMLHttpRequest();
    xhr.mozBackgroundRequest = async;
    xhr.open(method || (method = data ? "post" : "get"), url, async);

    if(overrideMimeType) xhr.overrideMimeType(overrideMimeType);
    xhr.onload = function(){
        addHeadersInfo();
        if(onload && !cancel) onload(xhr);
    };
    xhr.onerror = function(){
        addHeadersInfo();
        if(onerror && !cancel) onerror(xhr);
    };

    if(method == "post") xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");

    var referrer;
    if(headers){
        for(var header in headers){
            if(headers.hasOwnProperty(header)){
                if(header == "Referer"){
                    referrer = headers[header];
                }else{
                    xhr.setRequestHeader(header, headers[header]);
                }
            }
        }
    }

    if(referrer){
        var RefererSetter = {
          observe: function(aSubject, aTopic, aData){
              if ((aTopic == 'http-on-modify-request')
                  && (typeof Components != "undefined")) {
                  aSubject.QueryInterface(Ci.nsIHttpChannel);
                  if(aSubject.originalURI.spec == url){
                      observer.removeObserver(RefererSetter, aTopic, false);
                      aSubject.setRequestHeader('Referer',referrer,false);
                  }
              }
          }
        };
        var observer = Cc["@mozilla.org/observer-service;1"].getService(Ci.nsIObserverService);
        observer.addObserver(RefererSetter, "http-on-modify-request", false);
    }

    function addHeadersInfo(){
        if(!xhr.channel.contentCharset && !overrideMimeType){ // wrong charset
            var mimeType = getEncoding(xhr.responseText);
            if(mimeType){
                cancel = true;
                XHR({ method: method
                      , url: url
                      , headers: headers
                      , data: data
                      , onload: onload
                      , onerror: onerror
                      , onreadystatechange: onreadystatechange
                      , overrideMimeType: mimeType
                      , async: async
                    });
                return;
            }
        }

        xhr.channel.QueryInterface(Ci.nsIHttpChannel);
        xhr.responseHeaders = {};
        xhr.channel.visitResponseHeaders({visitHeader: function(aHeader,aValue){xhr.responseHeaders[aHeader] = aValue}});

        xhr.requestHeaders = {};
        xhr.channel.visitRequestHeaders({visitHeader: function(aHeader,aValue){xhr.requestHeaders[aHeader] = aValue}});

        xhr.finalUrl = xhr.channel.URI.spec;
    }

    function getEncoding(text){
        var matched = text.match(new RegExp("<meta.+?http-equiv.+?Content-Type.+?content=([\"'])([^\\1]+?)\\1",'i'));
        return (matched && !matched[2].match(/UTF-8/i) && matched[2]);
    }

    xhr.send(data || null);
    return xhr;
}
XHR.Test = function(){
    XHR({
//            url: "http://white.s151.xrea.com/wiki/index.php?cmd=edit&page=FrontPage" // test 401
        url: "http://white.s151.xrea.com/blog/"
        , onload: function(response){log('XHR load',response)}
        , onerror: function(response){log('XHR error',response)}
        , headers: {'Referer':'http://example.org/referrer'}
    });
}


// XHR.JSDeferred ---
XHR.JSDeferred = function(opt){
    var d = Deferred();
    var stop = false;
    try{
        opt.onload = function(res){
            if(stop) return;
            d.call(res);
        }
        opt.onerror = function(res){ d.fail(res); }
        var xhr = XHR(opt);
        d.canceller = function(){ xhr.abort(); }
    }catch(e){
        d.fail(e);
    }
    return d;
}
XHR.JSDeferred.Test = function(){
    XHR.JSDeferred({  url: "http://white.s151.xrea.com/blog/"
                    , headers: {'Referer':'http://example.org/referrer'}
    })
    .next(function(d){
        log('XHR.JSDeferred ', d);
    })
}
XHR.JSDeferred.ParallelTest = function(){
    Deferred.parallel({
        root: XHR.JSDeferred({ url:"http://white.s151.xrea.com/",      headers:{'Referer':'http://example.org/referrer'}})
      , blog: XHR.JSDeferred({ url:"http://white.s151.xrea.com/blog/", headers:{'Referer':'http://example.org/referrer'}})
      , wiki: XHR.JSDeferred({ url:"http://white.s151.xrea.com/wiki/", headers:{'Referer':'http://example.org/referrer'}})
    })
    .next(function(d){
        log('XHR.JSDeferred.ParallelTest ', d);
    })
}

// XHR.Arrow ---
XHR.Arrow = function(opt){
    return Arrow.fromCPS(function(x, k){
        var stop = false;
        try {
            opt.onload = function(res){
                if(stop) return;
                k(res);
            }
            opt.onerror = function(res){
                k(Arrow.Error(xhr));
            }
            XHR(opt);
        } catch (e) {
            k(Arrow.Error(e));
        }
        this.cancel = function() { stop = true };
    });
}
XHR.Arrow.Test = function(){
    var arrow = ((XHR.Arrow({url: "http://white.s151.xrea.com/blog/"
                             , headers: {'Referer':'http://example.org/referrer'}
                 }))
                 ['>>>']
                 (Arrow.fromCPS(function(x, k){
                     log('XHR.Arrow ', x)
                 })));
    arrow.run();
}

//  XHR.ArrowParallel ---
XHR.ArrowParallel = function(opts){
    var arrow = new Arrow;
    arrow.cpsFunction = function(x, k) {
        var arrows = this.arrows;
        var results = [];
        var count = arrows.length;
        for (var i = 0; i < arrows.length; i++) {
            with ({ i: i }) {
                arrows[i].callCPS(x, function(y) { results[i] = y; if (!--count) k(results) });
            }
        }
    }
    arrow.type = '&&&';
    arrow.arrows = opts.map(function(opt){
        return XHR.Arrow(opt);
    });
    return arrow;
}
XHR.ArrowParallel.Test = function(){
 ((XHR.ArrowParallel([{url: "http://white.s151.xrea.com/"},
                      {url: "http://white.s151.xrea.com/wiki/"},
                      {url: "http://white.s151.xrea.com/blog/"}]))
  ['>>>']
  (Arrow.fromCPS(function(x, k){
      log('xhr response list:', x)
  }))).run();
}