added multi-form support

function itsg_ajaxupload_restore_input( ajaxupload_input ) {
    var ajaxupload_gf_input = ajaxupload_input.prev();
    var ajaxupload_progress = ajaxupload_input.siblings( '.progress' );
    var ajaxupload_results = ajaxupload_input.siblings( '.results' );
    var ajaxupload_cancel_button = ajaxupload_input.siblings( '.itsg_single_ajax_cancel' );
    var ajaxupload_remove_button = ajaxupload_input.siblings( '.itsg_single_ajax_remove' );

    ajaxupload_input.show();
    ajaxupload_gf_input.val( '' );
    ajaxupload_progress.remove();
    ajaxupload_results.remove();
    ajaxupload_cancel_button.remove();
    ajaxupload_remove_button.remove();

    ajaxupload_input.focus();
}

function itsg_ajaxupload_maybe_restore_buttons( form_id ) {
    if ( ! window[ 'itsg_gf_ajaxupload_uploading_' + form_id ] ) {

        jQuery( '#gform_' + form_id + ' .gform_next_button:visible' ).attr( 'value', window[ 'itsg_gf_ajaxupload_next_value_' + form_id ] );
        jQuery( '#gform_' + form_id + ' .gform_previous_button:visible' ).attr( 'value', window[ 'itsg_gf_ajaxupload_previous_value_' + form_id ] );
        jQuery( '#gform_' + form_id + ' .gform_button[type="submit"]:visible' ).attr( 'value', window[ 'itsg_gf_ajaxupload_submit_value_' + form_id ] );
        jQuery( '#gform_' + form_id + ' a.gform_save_link:not(.top_button):visible' ).text( window[ 'itsg_gf_ajaxupload_save_value_' + form_id ] );
    }
}

// remove uploaded file from server, if current user has permission. There is also a server side check.
function itsg_ajaxupload_remove_upload( ajaxupload_gf_input_value, ajaxupload_input ) {
    // load localized settings
    var ajax_url = itsg_gf_ajaxupload_js_settings.ajax_url;
    var allowdelete = itsg_gf_ajaxupload_js_settings.allowdelete;
    var form_id = itsg_gf_ajaxupload_js_settings.form_id;
    var entry_user_id = itsg_gf_ajaxupload_js_settings.entry_user_id;

    if( '' != ajaxupload_gf_input_value && 'null' != ajaxupload_gf_input_value && undefined != ajaxupload_gf_input_value ) {
        if ( '1' == allowdelete ) {
            var file_name = decodeURIComponent( ajaxupload_gf_input_value.split( '/' ).pop() );
            var data = {
                'action': 'itsg_ajaxupload_delete_file',
                'file_name': file_name,
                'form_id': form_id,
                'entry_user_id': entry_user_id
                };

            var req = jQuery.ajax({
                url: ajax_url,
                type: 'POST',
                data: data
                });
        }
    }
    itsg_ajaxupload_restore_input( ajaxupload_input );
}

function itsg_gf_ajaxupload_display_upload( ajaxupload_input ){
    // load localized settings
    var thumbnail_enable = itsg_gf_ajaxupload_js_settings.thumbnail_enable;
    var thumbnail_width = parseInt( itsg_gf_ajaxupload_js_settings.thumbnail_width );
    var text_file = itsg_gf_ajaxupload_js_settings.text_file;
    var text_new_window = itsg_gf_ajaxupload_js_settings.text_new_window;
    var text_remove = itsg_gf_ajaxupload_js_settings.text_remove;

    var ajaxupload_gf_input = ajaxupload_input.prev();
    var ajaxupload_gf_input_value = ajaxupload_input.prev().val();

    var file_name = decodeURIComponent( ajaxupload_gf_input_value.split('/').pop() );  // get file name out of the input URL
    var file_url = ajaxupload_gf_input_value;  // get file  URL
    var file_extension = file_name.substr( file_name.lastIndexOf('.') + 1 ).toLowerCase();

    // if results already exist - stop
    if ( typeof( ajaxupload_input.next( '.results' ) ) !== 'undefined' && ajaxupload_input.next( '.results' ).length ) return;

    if( ajaxupload_gf_input_value != '' && ajaxupload_gf_input_value != 'null' && ajaxupload_gf_input_value != undefined ) {
        // create results bar
        ajaxupload_input.after(
            jQuery('<div/>', {
                'class': 'results'
                }).append(
                    jQuery('<div/>', {
                        'class': 'results-bar results-bar-success'
                    })
                )
        );

        var ajaxupload_results = ajaxupload_input.next( '.results' );
        var ajaxupload_results_div = ajaxupload_input.next( '.results' ).children().first();
        var time = jQuery.now();

        // create remove button
        jQuery('<input/>', {
            'class': 'button itsg_single_ajax_button itsg_single_ajax_remove',
            'type': 'button',
            'value': text_remove,
            'aria-describedby': 'remove_' + time
            }).append(
                jQuery('<span/>', {
                        'id': 'remove_' + time,
                        'class': 'sr-only',
                        'text': text_remove + ' ' + text_file + ' ' + file_name
                })
                ).insertAfter( ajaxupload_input.next( '.results' ) ).click( function() {
                itsg_ajaxupload_remove_upload( ajaxupload_gf_input_value, ajaxupload_input );
                jQuery( this ).remove(); // delete the remove button
            } );

        ajaxupload_input.hide();
        ajaxupload_results.show();

        // if thumbnails enabled and upload is jpg, png, gif, jpeg
        if ( ( '1' == thumbnail_enable ) && 'jpg' == file_extension || 'png' == file_extension || 'gif' == file_extension || 'jpeg' == file_extension ) {
            var file_name_encoded = ajaxupload_gf_input_value.split('/').pop();  // get file name out of the input URL
            var thumb_url = ajaxupload_gf_input_value.replace( file_name_encoded, 'thumbnail/' + file_name_encoded );  // get file  URL
            ajaxupload_results_div.append(
                jQuery('<a/>', {
                    'href': file_url,
                    'target': '_blank',
                    'class': 'thumbnail-link',
                    'title': text_new_window
                    }).append(
                        jQuery('<img/>', {
                            'src': thumb_url,
                            'class': 'thumbnail',
                            'onerror': 'if (this.src != \'' + file_url + '\') this.src = \'' + file_url + '\';',
                            'alt': file_name,
                            'title': file_name
                        })
                    )
            );
            ajaxupload_input.parent( 'td.gfield_list_cell' ).css( 'width', '200px' );
            ajaxupload_results.addClass( 'done-thumbnail' );
        } else {
            if ( typeof( file_name ) !== 'undefined' && file_name.length > 60 ) {
                var file_name = file_name.substring( 0, 60 );
            }
            ajaxupload_results_div.append(
                jQuery('<a/>', {
                    'href': file_url,
                    'target': '_blank',
                    'alt': file_name,
                    'title': text_new_window,
                    'text': file_name
                })
            );
            ajaxupload_results.addClass( 'done' );
        }
        ajaxupload_results_div.find( 'a' ).focus();
    }
}

function itsg_gf_ajaxupload_init(){
    // load localized settings
    var ajax_url = itsg_gf_ajaxupload_js_settings.ajax_url;
    var file_size_kb = parseInt( itsg_gf_ajaxupload_js_settings.file_size_kb );
    var file_types = itsg_gf_ajaxupload_js_settings.file_types;
    var text_not_accepted_file_type = itsg_gf_ajaxupload_js_settings.text_not_accepted_file_type;
    var text_file_size_too_big = itsg_gf_ajaxupload_js_settings.text_file_size_too_big;
    var text_uploading = itsg_gf_ajaxupload_js_settings.text_uploading;
    var text_error_title = itsg_gf_ajaxupload_js_settings.text_error_title;
    var displayscripterrors = itsg_gf_ajaxupload_js_settings.displayscripterrors;
    var text_complete = itsg_gf_ajaxupload_js_settings.text_complete;
    var text_cancel = itsg_gf_ajaxupload_js_settings.text_cancel;
    var text_remove = itsg_gf_ajaxupload_js_settings.text_remove;
    var thumbnail_enable = itsg_gf_ajaxupload_js_settings.thumbnail_enable;
    var file_chunk_size = parseInt( itsg_gf_ajaxupload_js_settings.file_chunk_size );
    var form_id = itsg_gf_ajaxupload_js_settings.form_id;
    var user_id = itsg_gf_ajaxupload_js_settings.user_id;
    var entry_user_id = itsg_gf_ajaxupload_js_settings.entry_user_id;
    var text_error_0 = itsg_gf_ajaxupload_js_settings.text_error_0;
    var text_error_404 = itsg_gf_ajaxupload_js_settings.text_error_404;
    var text_error_500 = itsg_gf_ajaxupload_js_settings.text_error_500;
    var text_error_parse = itsg_gf_ajaxupload_js_settings.text_error_parse;
    var text_error_timeout = itsg_gf_ajaxupload_js_settings.text_error_timeout;
    var text_error_uncaught = itsg_gf_ajaxupload_js_settings.text_error_uncaught;
    var text_file = itsg_gf_ajaxupload_js_settings.text_file;

    var url = ajax_url;
    var i = 0;

    //applies the fileupload function to the file input field
    jQuery( 'input.itsg_ajax_upload_browse' ).each(function () {
        jQuery( this ).fileupload({
            maxNumberOfFiles: 1,
            singleFileUploads: false,
            dropZone: jQuery( this ).parent( '.itsg_ajax_upload_dropzone' ),
            maxChunkSize: file_chunk_size,
            url: url,
            dataType: 'json',
            progressInterval: '500',
            add: function( e, data ) {
                // error if more than one file dropped in dropzone
                if ( typeof( data.files ) !== 'undefined' && data.files.length > 1 ){
                    alert( itsg_gf_ajaxupload_js_settings.text_only_one_file_message )
                    return false;
                }
                // stop upload if file already uploaded to file
                if ( typeof( jQuery( this ).siblings( '.results' ) ) !== 'undefined' && jQuery( this ).siblings( '.results' ).length >= 1  ) {
                    return false;
                }
                var ajaxupload_input = jQuery( this );
                var file_name = data.originalFiles[0]['name'];
                if ( itsg_gf_ajaxupload_js_settings.apostrophe_error_enable && file_name.indexOf("'") >= 0 ) {
                    alert( itsg_gf_ajaxupload_js_settings.text_apostrophe_error_message )
                    return false;
                }
                // make remove row button abort
                jQuery( document ).on( 'click', '.delete_list_item', function(){
                    // when row is deleted - run the delete function to remove uploaded images from server
                    //data.abort();
                    var row = jQuery(this).parents( 'tr.gfield_list_group, tr.gfield_list_row_even, tr.gfield_list_row_odd' );
                    itsg_gf_ajaxupload_remove_list_item( row );
                });

                var uploadErrors = [];

                // client side file type restrictions
                var acceptFileTypes = new RegExp( '(\.|\/)(' + file_types + ')$', 'i'); // ALLOWED FILE TYPES - CLIENT SIDE
                if( !acceptFileTypes.test( file_name ) ) {
                    uploadErrors.push( text_not_accepted_file_type );
                }

                // client side file size restrictions
                if ( data.originalFiles[0]['size'] > file_size_kb ) {  // MAX FILE SIZE - CLIENT SIDE
                    console.log( data.originalFiles[0]['size'] );
                    uploadErrors.push( text_file_size_too_big );
                }

                // if there were client side upload errors - display them
                if ( typeof( uploadErrors ) !== 'undefined' && uploadErrors.length > 0 ) {
                    alert( uploadErrors.join( '\n' ) );
                } else {
                    jQuery.blueimp.fileupload.prototype.options.add.call( this, e, data );

                    // all good - time to submit
                    data.submit();

                    // hide the ajaxupload field
                    ajaxupload_input.hide();

                    var time = jQuery.now();

                    // create cancel button
                    jQuery('<input/>', {
                        'class': 'button itsg_single_ajax_button itsg_single_ajax_cancel',
                        'type': 'button',
                        'value': text_cancel,
                        'aria-describedby': 'cancel_' + time
                    }).append(
                    jQuery('<span/>', {
                            'id': 'cancel_' + time,
                            'class': 'sr-only',
                            'text': text_cancel + ' ' + text_uploading + ' ' + text_file + ' ' + file_name
                    })
                    ).insertAfter( ajaxupload_input ).click( function() {
                            data.abort(); // abort the request
                            jQuery( this ).remove(); // delete the remove button
                            var form_id = jQuery( this ).closest( 'form' ).attr( 'id' ).split( '_' ).pop().trim();
                            itsg_ajaxupload_maybe_restore_buttons( form_id ); // restore buttons
                        });

                    // create progress bar
                    ajaxupload_input.after(
                        jQuery('<div/>', {
                            'class': 'progress uploading'
                            }).append(
                                jQuery('<div/>', {
                                    'class': 'progress-bar progress-bar-striped active',
                                    'role': 'progressbar',
                                    'aria-valuemin': '0',
                                    'aria-valuemax': '100',
                                }).append(
                                    jQuery('<span/>', {
                                        'class': 'sr-only'
                                    })
                                )
                            )
                    );
                }
            },
            done: function( e, data ) {
                // upload has stopped
                var form_id = jQuery( this ).closest( 'form' ).attr( 'id' ).split( '_' ).pop().trim();
                window[ 'itsg_gf_ajaxupload_uploading_' + form_id ] = false;

                var ajaxupload_input = jQuery( this );

                jQuery.each( data.result.files, function( index, file ) {
                    // catch false positive server side error messages
                    if ( file.error ) {
                        alert( file.error );

                        itsg_ajaxupload_restore_input( ajaxupload_input );

                        return; // end the function
                    }
                    // set the file url to the gravity forms field
                    ajaxupload_input.prev().val( file.url );

                    // remove progress bar
                    ajaxupload_input.next().remove();

                    // display the uploaded file
                    itsg_gf_ajaxupload_display_upload( ajaxupload_input );

                    // remove cancel button
                    ajaxupload_input.parent().find( '.itsg_single_ajax_cancel' ).remove();

                    // remove dropzone
                    ajaxupload_input.parent( '.itsg_ajax_upload_dropzone' ).removeClass( 'itsg_ajax_upload_dropzone' );
                });
                var form_id = ajaxupload_input.closest( 'form' ).attr( 'id' ).split( '_' ).pop().trim();
                itsg_ajaxupload_maybe_restore_buttons( form_id );
            },
            error: function ( request, status, error ) {
                // upload has stopped
                var form_id = jQuery( this ).closest( 'form' ).attr( 'id' ).split( '_' ).pop().trim();
                window[ 'itsg_gf_ajaxupload_uploading_' + form_id ] = false;

                if ( '[object HTMLInputElement]' != error && '[object HTMLImageElement]' != error && '[object Object]' != error && 'abort' != error ) {
                     if ( request.status === 0 ) {
                        error_message = text_error_0;
                    } else if ( request.status == 404 ) {
                        error_message = text_error_404;
                    } else if ( request.status == 500 ) {
                        error_message = text_error_500;
                    } else if ( status === 'parsererror' ) {
                        error_message = text_error_parse;
                    } else if ( status === 'timeout' ) {
                        error_message = text_error_timeout;
                    } else {
                        error_message = text_error_uncaught + request.responseText;
                    }
                    if ( '1' == displayscripterrors ) {
                        alert( text_error_title + '\n\n' + error + '\n\n' + error_message );
                    } else {
                        alert( text_error_title  );
                    }
                    // log error message
                    console.log( text_error_title + ' ' + error + ' ' + error_message );
                }
            },
            progress: function( e, data ) {
                // upload has started
                // console.log(data.bitrate);
                var form_id = jQuery( this ).closest( 'form' ).attr( 'id' ).split( '_' ).pop().trim();
                window[ 'itsg_gf_ajaxupload_uploading_' + form_id ] = true;

                // get the form navigation button text values
                window[ 'itsg_gf_ajaxupload_next_value_' + form_id ] = jQuery( '#gform_' + form_id + ' .gform_next_button:visible' ).attr( 'value' );
                window[ 'itsg_gf_ajaxupload_previous_value_' + form_id ] = jQuery( '#gform_' + form_id + ' .gform_previous_button:visible' ).attr( 'value' );
                window[ 'itsg_gf_ajaxupload_submit_value_' + form_id ] = jQuery( '#gform_' + form_id + ' .gform_button[type="submit"]:visible' ).attr( 'value' );
                window[ 'itsg_gf_ajaxupload_save_value_' + form_id ] = jQuery( '#gform_' + form_id + ' a.gform_save_link:not(.top_button):visible' ).text();

                // replace with 'uploading' placeholeder text
                jQuery( '#gform_' + form_id + ' .gform_next_button:visible' ).attr( 'value', text_uploading );
                jQuery( '#gform_' + form_id + ' .gform_previous_button:visible' ).attr( 'value', text_uploading );
                jQuery( '#gform_' + form_id + ' .gform_button[type="submit"]:visible' ).attr( 'value', text_uploading );
                jQuery( '#gform_' + form_id + ' a.gform_save_link:not(.top_button):visible' ).text( text_uploading );

                // calculates percentage
                var progress_percent = parseInt( data.loaded / data.total * 100, 10 );
                // adds the uploading message to the progress field
                jQuery( this ).next().children().first().attr( 'aria-valuenow', progress_percent );
                jQuery( this ).next().children().first().css( 'width', progress_percent + '%' );
                jQuery( this ).next().children().first().attr( 'aria-valuetext', progress_percent + '% ' + text_complete );
                jQuery( this ).next().find( 'span.sr-only' ).text( progress_percent + '% ' + text_complete );
                if ( '100' == progress_percent ) {
                    jQuery( this ).next().addClass( '100' );
                }
                i = i + 1;
            },
            fail: function( e, data ) {
                var ajaxupload_input = jQuery( this );
                itsg_ajaxupload_restore_input( ajaxupload_input );
            },
        }).on({
            fileuploadsubmit: function( e, data ) {
                data.formData = {
                    'action': 'itsg_ajaxupload_upload_file',
                    'field_id': jQuery( this ).prev().attr( 'name' ).split( '_' ).pop().trim().replace( '[]', ''),
                    'user_id': user_id,
                    'form_id': jQuery( this ).closest( 'form' ).attr( 'id' ).split( '_' ).pop().trim(),
                    'entry_user_id':entry_user_id
                };
            }
        });
    });
}

function maybePreventDefault( event ) {
    var form_id = event.data.form_id;
    if ( window[ 'itsg_gf_ajaxupload_uploading_' + form_id ] ) {
        jQuery( '.gform_ajax_spinner' ).hide(); // TO DO - fix for multi forms on single page
        event.preventDefault();
    } else {
        return;
    }
}

function itsg_gf_ajaxupload_setup_dropzone_function() {
    // disable default behaviour
    jQuery( document ).bind( 'drop dragover', function (e) {
        return false;
    });

    // check is browser supports drop and drag file uploads
    var isAdvancedUpload = function() {
        var div = document.createElement('div');
        return (('draggable' in div) || ('ondragstart' in div && 'ondrop' in div)) && 'FormData' in window && 'FileReader' in window;
    }();

    // define drop zone
    var $form = jQuery( '.itsg_ajax_upload_dropzone' );

    if ( isAdvancedUpload ) {
        $form.addClass( 'has-advanced-upload' );
    }

    if ( isAdvancedUpload ) {
        $form.on( 'dragover dragenter', function() {
            var ajaxupload_input = jQuery( this ).find( 'input.itsg_ajax_upload_browse' );
            if ( typeof( ajaxupload_input.siblings( '.results' ) ) !== 'undefined' && ajaxupload_input.siblings( '.results' ).length < 1 ) {
                jQuery( this ).addClass( 'is-dragover' );
            }
        })
        .on( 'dragleave dragend drop', function() {
            jQuery( this ).removeClass( 'is-dragover' );
        });
    }
}

// when row is added - prepare row upload field, unbind and recreate fileupload
function itsg_gf_ajaxupload_add_list_item( new_row ) {
    jQuery( new_row ).find( 'input.itsg_ajax_upload_browse' ).each( function() {
        var ajaxupload_input = jQuery( this );
        ajaxupload_input.unbind().fileupload();
        ajaxupload_input.fileupload( 'destroy' );
        itsg_ajaxupload_restore_input( ajaxupload_input );
    });
    itsg_gf_ajaxupload_init();
}

// when row is removed - run each ajaxupload field through remove function
function itsg_gf_ajaxupload_remove_list_item( row ) {
    jQuery( row ).find( 'input.itsg_ajax_upload_browse' ).each( function() {
        var ajaxupload_input = jQuery( this );
        var ajaxupload_gf_input_value = jQuery( this ).prev().val();
        itsg_ajaxupload_remove_upload( ajaxupload_gf_input_value, ajaxupload_input )
    });
}

/* catch all for JavaScript errors */
window.onerror = function( msg, url, linenumber ) {
    // load localized settings
    var text_error = itsg_gf_ajaxupload_js_settings.text_error;
    var text_line_number = itsg_gf_ajaxupload_js_settings.text_line_number;
    var displayscripterrors = itsg_gf_ajaxupload_js_settings.displayscripterrors;

    console.log( text_error + ':  ' + msg + ' URL: ' + url + ' ' + text_line_number + ': ' + linenumber );
    if ( '1' == displayscripterrors ) {
        alert( text_error + ': \n' + msg + '\nURL: ' + url + '\n' + text_line_number + ': ' + linenumber );
    }
    return true;
}

if ( '1' == itsg_gf_ajaxupload_js_settings.is_entry_detail ) {
    // runs the main function when the page loads -- entry editor -- configures any existing upload fields
    jQuery(document).ready( function($) {
        itsg_gf_ajaxupload_init();
        itsg_gf_ajaxupload_setup_dropzone_function();
        jQuery( 'input.itsg_ajax_upload_browse' ).each( function() {
            var ajaxupload_input = jQuery( this );
            itsg_gf_ajaxupload_display_upload( ajaxupload_input );
        });

        // when field is added to repeater, runs the main function passing the current row
        jQuery( '.gfield_list' ).on( 'click', '.add_list_item', function(){
            var new_row = jQuery( this ).parents( 'tr.gfield_list_group, tr.gfield_list_row_even, tr.gfield_list_row_odd' ).next( 'tr.gfield_list_group, tr.gfield_list_row_even, tr.gfield_list_row_odd' );
            itsg_gf_ajaxupload_add_list_item( new_row );
        });

    });
} else {
    // runs the main function when the page loads -- front end forms -- configures any existing upload fields
    jQuery( document ).bind( 'gform_post_render', function($) {
        itsg_gf_ajaxupload_init();
        itsg_gf_ajaxupload_setup_dropzone_function();

        jQuery( 'input.itsg_ajax_upload_browse' ).each( function() {
            var ajaxupload_input = jQuery( this );
            itsg_gf_ajaxupload_display_upload( ajaxupload_input );
        });

        // when field is added to repeater, runs the main function passing the current row
        jQuery( '.gfield_list' ).on( 'click', '.add_list_item', function(){
            var new_row = jQuery( this ).parents( 'tr.gfield_list_group, tr.gfield_list_row_even, tr.gfield_list_row_odd' ).next( 'tr.gfield_list_group, tr.gfield_list_row_even, tr.gfield_list_row_odd' );
            itsg_gf_ajaxupload_add_list_item( new_row );
        });

        // stop pages being navigated or form submitted when upload in progress

        jQuery( '.gform_wrapper form' ).each(function () {

            // get form id
            var form_id = jQuery( this ).attr( 'id' ).split( '_' ).pop().trim();

            jQuery( this ).bind( 'submit', { form_id: form_id }, maybePreventDefault );

            // get the form navigation button text values
        //  window[ 'itsg_gf_ajaxupload_next_value_' + form_id ] = jQuery( '#gform_' + form_id + ' .gform_next_button' ).first().attr( 'value' );
        //  window[ 'itsg_gf_ajaxupload_previous_value_' + form_id ] = jQuery( '#gform_' + form_id + ' .gform_previous_button' ).first().attr( 'value' );
        //  window[ 'itsg_gf_ajaxupload_submit_value_' + form_id ] = jQuery( '#gform_' + form_id + ' .gform_button[type="submit"]' ).first().attr( 'value' );
        //  window[ 'itsg_gf_ajaxupload_save_value_' + form_id ] = jQuery( '#gform_' + form_id + ' a.gform_save_link:not(.top_button)' ).first().text();
        });
    });
}