PLT-3487 Preview uploaded txt file (#4145)

* fix filename

* Add 'txt' to hilighted language

webapp/utils/syntax_highlighting.jsx

@@ -0,0 +1,159 @@
+// Copyright (c) 2016 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+import * as TextFormatting from './text_formatting.jsx';
+import Constants from './constants.jsx';
+
+import hlJS from 'highlight.js/lib/highlight.js';
+
+import hljsActionscript from 'highlight.js/lib/languages/actionscript.js';
+import hljsApplescript from 'highlight.js/lib/languages/applescript.js';
+import hljsBash from 'highlight.js/lib/languages/bash.js';
+import hljsClojure from 'highlight.js/lib/languages/clojure.js';
+import hljsCoffeescript from 'highlight.js/lib/languages/coffeescript.js';
+import hljsCpp from 'highlight.js/lib/languages/cpp.js';
+import hljsCs from 'highlight.js/lib/languages/cs.js';
+import hljsCss from 'highlight.js/lib/languages/css.js';
+import hljsD from 'highlight.js/lib/languages/d.js';
+import hljsDart from 'highlight.js/lib/languages/dart.js';
+import hljsDelphi from 'highlight.js/lib/languages/delphi.js';
+import hljsDiff from 'highlight.js/lib/languages/diff.js';
+import hljsDjango from 'highlight.js/lib/languages/django.js';
+import hljsDockerfile from 'highlight.js/lib/languages/dockerfile.js';
+import hljsErlang from 'highlight.js/lib/languages/erlang.js';
+import hljsFortran from 'highlight.js/lib/languages/fortran.js';
+import hljsFsharp from 'highlight.js/lib/languages/fsharp.js';
+import hljsGcode from 'highlight.js/lib/languages/gcode.js';
+import hljsGo from 'highlight.js/lib/languages/go.js';
+import hljsGroovy from 'highlight.js/lib/languages/groovy.js';
+import hljsHandlebars from 'highlight.js/lib/languages/handlebars.js';
+import hljsHaskell from 'highlight.js/lib/languages/haskell.js';
+import hljsHaxe from 'highlight.js/lib/languages/haxe.js';
+import hljsJava from 'highlight.js/lib/languages/java.js';
+import hljsJavascript from 'highlight.js/lib/languages/javascript.js';
+import hljsJson from 'highlight.js/lib/languages/json.js';
+import hljsJulia from 'highlight.js/lib/languages/julia.js';
+import hljsKotlin from 'highlight.js/lib/languages/kotlin.js';
+import hljsLess from 'highlight.js/lib/languages/less.js';
+import hljsLisp from 'highlight.js/lib/languages/lisp.js';
+import hljsLua from 'highlight.js/lib/languages/lua.js';
+import hljsMakefile from 'highlight.js/lib/languages/makefile.js';
+import hljsMarkdown from 'highlight.js/lib/languages/markdown.js';
+import hljsMatlab from 'highlight.js/lib/languages/matlab.js';
+import hljsObjectivec from 'highlight.js/lib/languages/objectivec.js';
+import hljsOcaml from 'highlight.js/lib/languages/ocaml.js';
+import hljsPerl from 'highlight.js/lib/languages/perl.js';
+import hljsPhp from 'highlight.js/lib/languages/php.js';
+import hljsPowershell from 'highlight.js/lib/languages/powershell.js';
+import hljsPuppet from 'highlight.js/lib/languages/puppet.js';
+import hljsPython from 'highlight.js/lib/languages/python.js';
+import hljsR from 'highlight.js/lib/languages/r.js';
+import hljsRuby from 'highlight.js/lib/languages/ruby.js';
+import hljsRust from 'highlight.js/lib/languages/rust.js';
+import hljsScala from 'highlight.js/lib/languages/scala.js';
+import hljsScheme from 'highlight.js/lib/languages/scheme.js';
+import hljsScss from 'highlight.js/lib/languages/scss.js';
+import hljsSmalltalk from 'highlight.js/lib/languages/smalltalk.js';
+import hljsSql from 'highlight.js/lib/languages/sql.js';
+import hljsSwift from 'highlight.js/lib/languages/swift.js';
+import hljsTex from 'highlight.js/lib/languages/tex.js';
+import hljsVbnet from 'highlight.js/lib/languages/vbnet.js';
+import hljsVbscript from 'highlight.js/lib/languages/vbscript.js';
+import hljsVerilog from 'highlight.js/lib/languages/verilog.js';
+import hljsXml from 'highlight.js/lib/languages/xml.js';
+import hljsYaml from 'highlight.js/lib/languages/yaml.js';
+
+hlJS.registerLanguage('actionscript', hljsActionscript);
+hlJS.registerLanguage('applescript', hljsApplescript);
+hlJS.registerLanguage('bash', hljsBash);
+hlJS.registerLanguage('clojure', hljsClojure);
+hlJS.registerLanguage('coffeescript', hljsCoffeescript);
+hlJS.registerLanguage('cpp', hljsCpp);
+hlJS.registerLanguage('cs', hljsCs);
+hlJS.registerLanguage('css', hljsCss);
+hlJS.registerLanguage('d', hljsD);
+hlJS.registerLanguage('dart', hljsDart);
+hlJS.registerLanguage('delphi', hljsDelphi);
+hlJS.registerLanguage('diff', hljsDiff);
+hlJS.registerLanguage('django', hljsDjango);
+hlJS.registerLanguage('dockerfile', hljsDockerfile);
+hlJS.registerLanguage('erlang', hljsErlang);
+hlJS.registerLanguage('fortran', hljsFortran);
+hlJS.registerLanguage('fsharp', hljsFsharp);
+hlJS.registerLanguage('gcode', hljsGcode);
+hlJS.registerLanguage('go', hljsGo);
+hlJS.registerLanguage('groovy', hljsGroovy);
+hlJS.registerLanguage('handlebars', hljsHandlebars);
+hlJS.registerLanguage('haskell', hljsHaskell);
+hlJS.registerLanguage('haxe', hljsHaxe);
+hlJS.registerLanguage('java', hljsJava);
+hlJS.registerLanguage('javascript', hljsJavascript);
+hlJS.registerLanguage('json', hljsJson);
+hlJS.registerLanguage('julia', hljsJulia);
+hlJS.registerLanguage('kotlin', hljsKotlin);
+hlJS.registerLanguage('less', hljsLess);
+hlJS.registerLanguage('lisp', hljsLisp);
+hlJS.registerLanguage('lua', hljsLua);
+hlJS.registerLanguage('makefile', hljsMakefile);
+hlJS.registerLanguage('markdown', hljsMarkdown);
+hlJS.registerLanguage('matlab', hljsMatlab);
+hlJS.registerLanguage('objectivec', hljsObjectivec);
+hlJS.registerLanguage('ocaml', hljsOcaml);
+hlJS.registerLanguage('perl', hljsPerl);
+hlJS.registerLanguage('php', hljsPhp);
+hlJS.registerLanguage('powershell', hljsPowershell);
+hlJS.registerLanguage('puppet', hljsPuppet);
+hlJS.registerLanguage('python', hljsPython);
+hlJS.registerLanguage('r', hljsR);
+hlJS.registerLanguage('ruby', hljsRuby);
+hlJS.registerLanguage('rust', hljsRust);
+hlJS.registerLanguage('scala', hljsScala);
+hlJS.registerLanguage('scheme', hljsScheme);
+hlJS.registerLanguage('scss', hljsScss);
+hlJS.registerLanguage('smalltalk', hljsSmalltalk);
+hlJS.registerLanguage('sql', hljsSql);
+hlJS.registerLanguage('swift', hljsSwift);
+hlJS.registerLanguage('tex', hljsTex);
+hlJS.registerLanguage('vbnet', hljsVbnet);
+hlJS.registerLanguage('vbscript', hljsVbscript);
+hlJS.registerLanguage('verilog', hljsVerilog);
+hlJS.registerLanguage('xml', hljsXml);
+hlJS.registerLanguage('yaml', hljsYaml);
+
+const HighlightedLanguages = Constants.HighlightedLanguages;
+
+export function highlight(lang, code) {
+    const language = lang.toLowerCase();
+
+    if (HighlightedLanguages[language]) {
+        try {
+            return hlJS.highlight(language, code).value;
+        } catch (e) {
+            // fall through if highlighting fails and handle below
+        }
+    }
+
+    return TextFormatting.sanitizeHtml(code);
+}
+
+export function getLanguageFromFileExtension(extension) {
+    for (var key in HighlightedLanguages) {
+        if (HighlightedLanguages[key].extensions.find((x) => x === extension)) {
+            return key;
+        }
+    }
+
+    return null;
+}
+
+export function canHighlight(language) {
+    return Boolean(HighlightedLanguages[language.toLowerCase()]);
+}
+
+export function getLanguageName(language) {
+    if (canHighlight(language)) {
+        return HighlightedLanguages[language.toLowerCase()].name;
+    }
+
+    return '';
+}