// <init> :: status? -> result? -> HTTPResult
function HTTPResult(status,result) {
    this.status = 0;
    this.result = null;
    this._handlers = [];
    if ( status ) {
        this.set(status,result);
    }
}

HTTPResult.fromResponsePromise = function(promise,errorHandler) {
    var result = new HTTPResult();
    promise.then(function(response){
        result.set(response.statusCode,response.body);
    }, errorHandler && function(error){
        var ret = errorHandler(error);
        if ( ret.constructor === HTTPResult ) {
            ret.handle(result.set.bind(result));
        } else {
            result.set(500,ret);
        }
    });
    return result;
};

// isSet :: Bool
HTTPResult.prototype.isSet = function() {
    return this.status !== 0;
};

// set :: status -> result? -> ()
HTTPResult.prototype.set = function(status,result) {
    if ( this.isSet() ) { throw new Error("Result was already set."); }
    if ( typeof status !== 'number' ) { throw new Error("Status must be a number."); }
    this.status = status;
    this.result = result;
    for ( var i = 0; i < this._handlers.length; i++ ) {
        this._fire(this._handlers[i]);
    }
};

// _fire :: (status -> result -> Either HTTPResult Any) -> ()
HTTPResult.prototype._fire = function(f) {
    var ret = f(this.status,this.result);
    if ( ret.constructor === HTTPResult ) {
        ret.handle(f._next.set.bind(f._next));
    } else {
        f._next.set(this.status,ret);
    }
};

/* handle :: Either (status -> result -> Either HTTPResult Any)
 *                  {number: (result -> Either HTTPResult Any),
 *                   'default': (status -> result -> Either HTTPResult Any)}
 *           -> HTTPResult
 */
HTTPResult.prototype.handle = function(fOrObj) {
    var f = typeof fOrObj === 'function' ?
            fOrObj :
            function(status,result) {
                if ( status in fOrObj ) {
                    return fOrObj[status](result);
                } else if ( 'default' in fOrObj ) {
                    return fOrObj['default'](status,result);
                } else {
                    return result;
                }
            };
    f._next = new HTTPResult();
    if ( this.isSet() ) {
        this._fire(f);
    } else {
        this._handlers.push(f);
    }
    return f._next;
};

module.exports = HTTPResult;