show only num_lines when file is in preview - also when receive new data

debomatic-webui/public/javascripts/page_distribution.js

 'use strict';
 
+/* global debug: false */
+/* global page_generic: false */
+
 // function to get all files in on click
 // event comes from HTML
 function download_all(div_id) {
@@ -66,6 +69,7 @@ function Page_Distrubion(socket) {
     var view = Utils.from_hash_to_view();
     var sidebarOffset = 0;
     var new_lines = [];
+    var current_file_in_preview = false;
 
     function __check_hash_makes_sense() {
         if (window.location.hash.indexOf('..') >= 0) {
@@ -100,6 +104,7 @@ function Page_Distrubion(socket) {
                 label += ' <a class="btn btn-link btn-lg" title="Download" href="' + view.file.path + '"> ' +
                     '<span class="glyphicon glyphicon-download-alt"></span></a>';
                 if (config.file.preview.indexOf(view.file.name) >= 0) {
+                    current_file_in_preview = true;
                     var view_all = $('<a id="get-whole-file" class="btn btn-link btn-lg" title="View the whole file"></a>');
                     view_all.html('<span class="glyphicon glyphicon-eye-open"></span>');
                     label += view_all.get(0).outerHTML;
@@ -230,7 +235,7 @@ function Page_Distrubion(socket) {
                 // update html
                 socket_data.package.sources.forEach(function (f) {
                     $('#sources ul').append('<li><a title="' + f.orig_name + '" href="' + f.path + '">' + f.name + '</a></li>');
-                })
+                });
                 $('#sources').show();
             }
             files.show();
@@ -284,7 +289,15 @@ function Page_Distrubion(socket) {
         },
         append: function (new_content) {
             var content = $('#file pre');
-            content.append(new_content);
+            if (!current_file_in_preview) {
+                content.append(new_content);
+            } else {
+                // always show only config.file.num_lines lines in preview
+                content = content.html().replace(/\n$/, '').split('\n');
+                content = content.concat(new_content.replace(/\n$/, '').split('\n'));
+                content = content.slice(-config.file.num_lines).join('\n');
+                $('#file pre').html(content);
+            }
 
             if (config.preferences.autoscroll) {
                 // scroll down if file is covering footer