// Disables right menu for the control whose id is passed as argument.

function DisableContextMenu(id) {

    $("#" + id).bind("contextmenu", function(e) {

        return false;

    });

}



// When invoked, this function initializes autocomplete functionalities for

// the input field whose id is passed as argument.

function InitializeAutocomplete(settings) {

    if (typeof jQuery == 'undefined') {

        // jQuery is not loaded

        alert('jQuery not loaded');

        return;

    }

    if (!jQuery.ui) {

        // jQuery UI not loaded

        alert('jQuery UI not loaded');

        return;

    }

    if (settings.Id == undefined) {

        // Id of the input textbox not specified

        alert('Id of the input textbox not specified');

        return;

    }

    if (settings.Url == undefined) {

        // DataSource url not specified

        alert('Missing DataSource Url');

        return;

    }

    if (settings.ValueField == undefined) {

        // Value of the field to display is not specified

        alert('ValueField is not specified');

        return;

    }

    if (settings.LabelField == undefined) {

        // Value of the field to display after selection, is not specified

        alert('LabelField is not specified');

        return;

    }



    $(function() {

        DisableContextMenu(settings.Id);

        $("#" + settings.Id).autocomplete({

            source: function(request, response) {

                RemoteRequest(request, response, settings);

            }, // end source

            minLength: settings.MinChars,

            select: function(event, ui) {

                if (settings.SelectionCallback == null ||

                    ui.item.label == settings.NoResultsMessage ||

                    ui.item.label == "<" + settings.NoResultsMessage + ">" ||

                    ui.item.label == settings.ErrorMessage ||

                    ui.item.label == "<" + settings.ErrorMessage + ">") {

                    return;

                }

                settings.SelectionCallback(ui.item.object);

            }

        }); // end autocomplete

    });        // end document.ready

}



// Need to control ajax requests race conditions

var previousRequest;



// Invokes the url passed as argument expecting it to return a json result

function RemoteRequest(request, response, settings) {

    var httpMethod = (settings.HttpMethod == undefined || settings.HttpMethod == null) ?

                       "POST" : settings.HttpMethod;

    var contentType = (settings.HttpMethod == undefined || settings.HttpMethod == null) ?

                        "application/x-www-form-urlencoded; charset=utf-8" : "application/json; charset=utf-8";

    previousRequest = $.ajax({

        // Need to control ajax requests race conditions

        beforeSend: function() {

            if ((previousRequest != undefined) && (previousRequest.readyState != 4)) {

                previousRequest.abort();

            }

        },

        type: httpMethod,

        contentType: contentType,

        url: settings.Url,

        dataType: "json",

        data: { startsWith: request.term },

        success: function(data) {

            if ((data == null) || (data.length == 0)) {

                ReturnEmptyResultSet(response, settings.NoResultsMessage);

                return;

            }



            var labelUndefined = ((data[0])[settings.LabelField] == undefined);

            var valueUndefined = ((data[0])[settings.ValueField] == undefined);

            if (labelUndefined || valueUndefined) {

                if (settings.ErrorCallback != null) {

                    var error = "The following properties are not defined in the result object: ";

                    error = labelUndefined ? error + settings.LabelField : error;

                    error = valueUndefined ? error + " " + settings.ValueField : error;

                    settings.ErrorCallback(error);

                }

                ReturnEmptyResultSet(response, settings.ErrorMessage);

                return;

            }

            response($.map(data,

                           function(item) {

                               return MappingFunction(item, settings.LabelField, settings.ValueField);

                           }

                    ) // end map	  

            ); // end response

        }, // end success

        error: function(xmlHttpRequest, status, error) {

            if (settings.ErrorCallback != null) {

                var message = (error == undefined) ? status + ": " + xmlHttpRequest.status : error;

                settings.ErrorCallback(message);

            }

            ReturnEmptyResultSet(response, settings.ErrorMessage);

        } // end error

    });             // end ajax

}



// This function accepts an item and uses it to initialize an object with

// the properties: label, value and object.

// It expects that the item received is an instance of an object supporting

// two properties with the names corresponding to the strings 

// passed as the second and third parameters.

function MappingFunction(item, labelField, valueField) {

    return {

        label: item[labelField],

        value: item[valueField],

        object: item

    }

}



// Used to return an empty result set as autosuggest list.

// The list will be composed of a single line with the message

// passed as argument if it's not null, otherwise no list will appear.

function ReturnEmptyResultSet(response, errorMessage) {

    if (errorMessage != null) {

        var item = new Object();

        item.label = "<" + errorMessage + ">";

        item.value = "";

        response([item]);

    }

    else {

        response(null);

    }

}