misc/ebrowser/webview.js

   1 /* Copyright (C) 2024 Richard Hao Cao
   2 Ebrowser is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
   3
   4 Ebrowser is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
   5
   6 You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>.
   7 */
   8 const {
   9   app, BrowserWindow, Menu, shell, clipboard,
  10   session, protocol, dialog, ipcMain
  11 } = require('electron')
  12 let win;
  13
  14 if(!app.requestSingleInstanceLock())
  15   app.quit()
  16 else {
  17   app.on('ready', createWindow);
  18   app.on('second-instance', (event, args, cwd) => {
  19     if (win) {
  20       if (win.isMinimized()) {
  21         win.restore()
  22       }
  23       win.show()
  24       win.focus()
  25       cmdlineProcess(args,cwd,1);
  26     }else
  27       createWindow();
  28   })
  29 }
  30 Menu.setApplicationMenu(null);
  31 const fs = require('fs');
  32 const path = require('path')
  33 const https = require('https');
  34 const url = require('url');
  35 var translateRes;
  36 {
  37   let langs = app.getPreferredSystemLanguages();
  38   if(langs.length==0 || langs[0].startsWith('en'))
  39     topMenu();
  40   else
  41     initTranslateRes(langs[0]);
  42 }
  43
  44 var repositoryurl = "https://gitlab.com/jamesfengcao/uweb/-/raw/master/misc/ebrowser/";
  45 const readline = require('readline');
  46 const process = require('process')
  47 var gredirects = [];
  48 var gredirect;
  49 var redirects;
  50 var bRedirect = true;
  51 var bJS = true;
  52 var bForwardCookie = true;
  53 var proxies = {};
  54 var proxy;
  55 var useragents = {};
  56 var downloadMenus; //[]
  57 var selectMenus = [];
  58 var defaultUA;
  59 {
  60   let sys = "X11; Linux x86_64";
  61   if (process.platform === "win32")
  62     sys = "Window NT 10.0; Win64; x64";
  63   else if (process.platform === "darwin")
  64     sys = "Macintosh; Intel Mac OS X 10_15_7";
  65   defaultUA =
  66     `Mozilla/5.0 (${sys}) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/` +
  67     process.versions.chrome +" Safari/537.36";
  68 }
  69 app.userAgentFallback = defaultUA;
  70
  71 fs.readFile(path.join(__dirname,'redirect.json'), 'utf8', (err, jsonString) => {
  72   if (err) return;
  73   try {
  74     redirects = JSON.parse(jsonString);
  75   } catch (e){console.log(e)}
  76 });
  77
  78 async function createWindow () {
  79   try {
  80     let json = await fs.promises.readFile(path.join(__dirname,'uas.json'), 'utf8');
  81     useragents = JSON.parse(json);
  82   } catch (e){console.log(e)}
  83
  84   protocol.handle("i",(req)=>{return null;});
  85   await (async ()=>{
  86     try{
  87       const readInterface = readline.createInterface ({
  88         input: fs.createReadStream (path.join(__dirname,'config'), 'utf8'),
  89       });
  90
  91       for await (const line of readInterface) {
  92         addrCommand(line);
  93       }
  94     }catch(e){console.log(e);}
  95   })();
  96
  97   win = new BrowserWindow(
  98     {width: 800, height: 600,autoHideMenuBar: true,
  99      webPreferences: {
 100        nodeIntegration: true,
 101        contextIsolation: false,
 102        webviewTag: true,
 103      }});
 104   win.setMenuBarVisibility(false);
 105   win.on('closed', function () {
 106     win = null
 107   })
 108
 109   win.loadFile('index.html');
 110   fs.readFile(path.join(__dirname,'gredirect.json'), 'utf8', (err, jsonString) => {
 111     if (err) return;
 112     try {
 113       gredirects = JSON.parse(jsonString);
 114     } catch (e){console.log(e)}
 115   });
 116
 117   fs.readFile(path.join(__dirname,'proxy.json'), 'utf8', (err, jsonString) => {
 118     if (err) return;
 119     try {
 120       proxies = JSON.parse(jsonString);
 121       let match = jsonString.match(/"([^"]+)"/);
 122       if(match)
 123         proxy = proxies[match[1]];
 124     } catch (e){console.log(e)}
 125   });
 126
 127   cmdlineProcess(process.argv, process.cwd(), 0);
 128   //app.commandLine.appendSwitch ('trace-warnings');
 129
 130   fs.readFile(path.join(__dirname,'download.json'), 'utf8', (err, jsonStr) => {
 131     if (err) return;
 132     try {
 133       downloadMenus = JSON.parse(jsonStr);
 134     }catch (e){console.log(e)}
 135   });
 136
 137   fs.readFile(path.join(__dirname,'select.json'), 'utf8', (err, jsonStr) => {
 138     if (err) return;
 139     try {
 140       selectMenus = JSON.parse(jsonStr);
 141     }catch (e){console.log(e)}
 142   });
 143
 144   win.webContents.on('page-title-updated',(event,cmd)=>{
 145     addrCommand(cmd);
 146   });
 147
 148   session.defaultSession.on("will-download", async (e, item) => {
 149     //item.setSavePath(save)
 150     if(!downloadMenus) return;
 151     let menuT = downloadContextMenuTemp(item.getURL());
 152     let button = await promiseContextMenu(menuT);
 153     if(-1===button) return;
 154     e.preventDefault();
 155   });
 156
 157   win.webContents.on('console-message',cbConsoleMsg);
 158 }
 159
 160 app.on('window-all-closed', function () {
 161   app.quit()
 162 })
 163
 164 app.on('activate', function () {
 165   if (win === null) {
 166     createWindow()
 167   }
 168 })
 169
 170 app.on('will-quit', () => {
 171 })
 172
 173 app.on ('web-contents-created', (event, contents) => {
 174   if (contents.getType () === 'webview') {
 175     contents.setWindowOpenHandler(cbWindowOpenHandler);
 176     contents.on('context-menu',onContextMenu);
 177     contents.on('page-title-updated',cbTitleUpdate);
 178     contents.session.webRequest.onBeforeRequest(interceptRequest);
 179   }
 180 });
 181
 182 ipcMain.on('command', (event, cmd) => {
 183   addrCommand(cmd);
 184 });
 185
 186 function addrCommand(cmd){
 187   if(cmd.length<3) return;
 188   let c0 = cmd.charCodeAt(0);
 189   switch(c0){
 190   case 33://"!"
 191     bangcommand(q,1);
 192     return;
 193   case 58: //':'
 194     args = cmd.substring(1).split(/\s+/);
 195     switch(args[0]){
 196     case "cert":
 197       if(args.length==1)
 198         session.defaultSession.setCertificateVerifyProc((request, callback) => {
 199           callback(0);
 200         });
 201       else
 202         session.defaultSession.setCertificateVerifyProc(null);
 203       return;
 204     case "clear":
 205       if(args.length==1){
 206         session.defaultSession.clearData();
 207         return;
 208       }
 209       switch(args[1]){
 210       case "cache":
 211         session.defaultSession.clearCache();
 212         return;
 213       case "dns":
 214         session.defaultSession.clearHostResolverCache();
 215         return;
 216       case "storage":
 217         session.defaultSession.clearStorageData();
 218         return;
 219       default:
 220         try {
 221           let opts = JSON.parse(args.slice(1).join(""));
 222           session.defaultSession.clearData(opts);
 223         }catch(e){console.log(e)}
 224       }
 225       return;
 226     case "exit":
 227       win.close();
 228       return;
 229     case "ext":
 230       session.defaultSession.loadExtension(args[1]);
 231       return;
 232     case "gr":
 233       if(args.length<2) {
 234         gredirect_enable(0);
 235         return;
 236       }
 237       let i = parseInt(args[1]);
 238       if(i>=0 && i<gredirects.length)
 239         gredirect_enable(i);
 240       else
 241         gredirect_disable();
 242       return;
 243     case "js"://execute js
 244       eval(cmd.slice(4));
 245       return;
 246     case "nc":
 247       bForwardCookie = false;
 248       msgbox_info("Cookie forwarding disabled");
 249       return;
 250     case "uc":
 251       if(bForwardCookie) {
 252         msgbox_info("Cookie forwarding enabled for global redirection");
 253         return;
 254       }
 255       forwardCookie();
 256       return;
 257     case "np":
 258       session.defaultSession.setProxy ({mode:"direct"});
 259       bRedirect = true;
 260       return;
 261     case "up":
 262       if(args.length>1)
 263         proxy = proxies[args[1]]; //retrieve proxy
 264       if(proxy){
 265         session.defaultSession.setProxy(proxy)
 266           .then(() => {gredirect_disable()})
 267           .catch((error) => {
 268             console.error('Failed to set proxy:', error);
 269           });
 270       }
 271       return;
 272     case "nr":
 273       bRedirect = false; return;
 274     case "ur":
 275       bRedirect = true; return;
 276     case "ua":
 277       if(args.length==2){
 278         let ua = useragents[args[1]];
 279         if(ua)
 280           session.defaultSession.setUserAgent(ua);
 281       }else
 282         session.defaultSession.setUserAgent(defaultUA);
 283       return;
 284     case "update":
 285       let updateurl;
 286       if(1==args.length)
 287         updateApp(repositoryurl);
 288       else {
 289         filename = args[1];
 290         let iSlash = filename.lastIndexOf('/');
 291         if(iSlash>0){
 292           let folder = path.join(__dirname,filename.substring(0,iSlash));
 293           fs.mkdirSync(folder,{ recursive: true });
 294         }
 295         fetch2file(repositoryurl,filename);
 296       }
 297       return;
 298     }
 299   }
 300 }
 301
 302 function gredirect_disable(){
 303   if(gredirect){
 304     gredirect=null;
 305     unregisterHandler();
 306   }
 307   bRedirect = true;
 308 }
 309 function gredirect_enable(i){
 310   if(i>=gredirects.length) return;
 311   if(!gredirect) registerHandler();
 312   gredirect=gredirects[i];
 313 }
 314
 315 function cbConsoleMsg(e, level, msg, line, sourceid){
 316   console.log(line);
 317   console.log(sourceid);
 318   console.log(msg);
 319 }
 320
 321 function interceptRequest(details, callback){
 322   let url = details.url;
 323   if(58===url.charCodeAt(1) || (!bJS && url.endsWith(".js"))){
 324     callback({ cancel: true });
 325     return;
 326   }
 327   do {
 328     if(gredirect || !bRedirect ||(details.resourceType !== 'mainFrame' &&
 329                      details.resourceType !== 'subFrame')) break;
 330     let oURL = new URL(url);
 331     let domain = oURL.hostname;
 332     let newUrl;
 333     try{
 334       let newDomain = redirects[domain];
 335       if(!newDomain) break;
 336       newUrl = "https://"+newDomain+oURL.pathname+oURL.search+oURL.hash;
 337     }catch(e){break;}
 338     callback({ cancel: false, redirectURL: newUrl });
 339     return;
 340   }while(false);
 341   callback({ cancel: false });
 342 }
 343
 344 function cbWindowOpenHandler(details){
 345   let url = details.url;
 346   let js = "newTab();tabs.children[tabs.children.length-1].src='"+
 347       url+"';";
 348   switch(details.disposition){
 349   case "foreground-tab":
 350   case "new-window":
 351     js = js + "switchTab(tabs.children.length-1)";
 352   }
 353   win.webContents.executeJavaScript(js,false);
 354   return { action: "deny" };
 355 }
 356 function cbTitleUpdate(event,title){
 357   win.setTitle(title);
 358 }
 359 function menuSelection(menuTemplate, text){
 360   for(let i=0; i<selectMenus.length-1;i++){
 361     menuTemplate.push({
 362       label: selectMenus[i],
 363       click: () => {
 364         let cmd = selectMenus[i+1].replace('%s',text);
 365         let js = `handleQueries(\`${cmd}\`)`;
 366         win.webContents.executeJavaScript(js,false);
 367       }
 368     });
 369   }
 370 }
 371 function menuDownload(menuTemplate, labelprefix, linkUrl){
 372   for(let i=0; i<downloadMenus.length-1;i++){
 373     menuTemplate.push({
 374       label: labelprefix+downloadMenus[i],
 375       click: () => {
 376         let cmd = downloadMenus[i+1].replace('%u',linkUrl);
 377         let js = `handleQueries(\`${cmd}\`)`;
 378         win.webContents.executeJavaScript(js,false);
 379       }
 380     });
 381   }
 382 }
 383 function menuArray(labelprefix, linkUrl){
 384   let menuTemplate = [
 385     {
 386       label: labelprefix+translate('Open'),
 387       click: () => {
 388         shell.openExternal(linkUrl);
 389       }
 390     },
 391     {
 392       label: labelprefix+translate('Copy'),
 393       click: () => {
 394         clipboard.writeText(linkUrl);
 395       }
 396     },
 397     {
 398       label: labelprefix+translate('Download'),
 399       click: () => {
 400         win.webContents.downloadURL(linkUrl);
 401       }
 402     },
 403   ];
 404   if(downloadMenus)
 405     menuDownload(menuTemplate, labelprefix, linkUrl);
 406   return menuTemplate;
 407 }
 408
 409 function onContextMenu(event, params){
 410   let url = params.linkURL;
 411   let mTemplate = [];
 412   if (url) {
 413     mTemplate.push({label:url,enabled:false});
 414     mTemplate.push.apply(mTemplate,menuArray("",url));
 415     if((url=params.srcURL))
 416       mTemplate.push.apply(mTemplate,menuArray("src: ",url));
 417   }else if((url=params.srcURL)){
 418     mTemplate.push({label:url,enabled:false});
 419     mTemplate.push.apply(mTemplate,menuArray("src: ",url));
 420   }else if((url=params.selectionText)){
 421     menuSelection(mTemplate,url);
 422   }else
 423     return;
 424
 425   const contextMenu = Menu.buildFromTemplate(mTemplate);
 426   contextMenu.popup();
 427 }
 428
 429 async function topMenu(){
 430   const menuTemplate = [];
 431   try {
 432     let json = await fs.promises.readFile(path.join(__dirname,'menu.json'), 'utf8');
 433     let menus = JSON.parse(json);
 434     if(menus.length>1){
 435       let submenu = [];
 436       for(let i=0;i<menus.length-1; i=i+2){
 437         let cmd = menus[i+1];
 438         let js = `handleQueries("${cmd}")`;
 439         submenu.push({
 440           label: menus[i], click: ()=>{
 441             win.webContents.executeJavaScript(js,false);
 442           }});
 443       }
 444       menuTemplate.push({
 445         label: translate('Tools'),
 446         submenu: submenu,
 447       });
 448     }
 449   }catch(e){console.log(e)}
 450   menuTemplate.push(
 451     {
 452       label: translate('Edit'),
 453       submenu: [
 454         { label: translate('Config folder'), click: ()=>{
 455           shell.openPath(__dirname);
 456         }},
 457       ]
 458     },
 459     {
 460       label: translate('Help'),
 461       submenu: [
 462         { label: translate('Check for updates'), click: ()=>{
 463           addrCommand(":update");
 464         }},
 465         { label: translate('Help'), accelerator: 'F1', click: ()=>{
 466           help();
 467         }},
 468         { label: translate('Stop'), accelerator: 'Ctrl+C', click: ()=>{
 469           let js="tabs.children[iTab].stop()"
 470           win.webContents.executeJavaScript(js,false)
 471         }},
 472         { label: translate('getURL'), accelerator: 'Ctrl+G', click: ()=>{
 473           let js="{let q=document.forms[0].q;q.focus();q.value=tabs.children[iTab].getURL();getWinTitle()}"
 474           win.webContents.executeJavaScript(js,false).then((r)=>{
 475             win.setTitle(r);
 476           });
 477         }},
 478         { label: translate('Select'), accelerator: 'Ctrl+L', click:()=>{
 479           win.webContents.executeJavaScript("document.forms[0].q.select()",false);
 480         }},
 481         { label: translate('New Tab'), accelerator: 'Ctrl+T', click:()=>{
 482           let js = "newTab();document.forms[0].q.select();switchTab(tabs.children.length-1)";
 483           win.webContents.executeJavaScript(js,false);
 484         }},
 485         { label: translate('Restore Tab'), accelerator: 'Ctrl+Shift+T', click:()=>{
 486           let js = "{let u=closedUrls.pop();if(u){newTab();switchTab(tabs.children.length-1);tabs.children[iTab].src=u}}";
 487           win.webContents.executeJavaScript(js,false);
 488         }},
 489         { label: translate('No redirect'), accelerator: 'Ctrl+R', click: ()=>{
 490           gredirect_disable();
 491         }},
 492         { label: translate('Redirect'), accelerator: 'Ctrl+Shift+R', click: ()=>{
 493           gredirect_enable(0);
 494         }},
 495         { label: translate('Close tab'), accelerator: 'Ctrl+W', click: ()=>{
 496           win.webContents.executeJavaScript("tabClose()",false).then((r)=>{
 497             if(""===r) win.close();
 498             else win.setTitle(r);
 499           });
 500         }},
 501         { label: translate('Next Tab'), accelerator: 'Ctrl+Tab', click: ()=>{
 502           let js="tabInc(1);getWinTitle()";
 503           win.webContents.executeJavaScript(js,false).then((r)=>{
 504             win.setTitle(r);
 505           });
 506         }},
 507         { label: translate('Previous Tab'), accelerator: 'Ctrl+Shift+Tab', click: ()=>{
 508           let js="tabDec(-1);getWinTitle()";
 509           win.webContents.executeJavaScript(js,false).then((r)=>{
 510             win.setTitle(r);
 511           });
 512         }},
 513         { label: translate('Go backward'), accelerator: 'Alt+Left', click: ()=>{
 514           let js="tabs.children[iTab].goBack()";
 515           win.webContents.executeJavaScript(js,false);
 516         }},
 517         { label: translate('Go forward'), accelerator: 'Alt+Right', click: ()=>{
 518           let js="tabs.children[iTab].goForward()";
 519           win.webContents.executeJavaScript(js,false);
 520         }},
 521         { label: translate('Zoom in'), accelerator: 'Ctrl+Shift+=', click: ()=>{
 522           let js="{let t=tabs.children[iTab];let s=t.getZoomFactor()*1.2;t.setZoomFactor(s)}";
 523           win.webContents.executeJavaScript(js,false);
 524         }},
 525         { label: translate('Zoom out'), accelerator: 'Ctrl+-', click: ()=>{
 526           let js="{let t=tabs.children[iTab];let s=t.getZoomFactor()/1.2;t.setZoomFactor(s)}";
 527           win.webContents.executeJavaScript(js,false);
 528         }},
 529         { label: translate('Default zoom'), accelerator: 'Ctrl+0', click: ()=>{
 530           let js="tabs.children[iTab].setZoomFactor(1)";
 531           win.webContents.executeJavaScript(js,false);
 532         }},
 533         { label: translate('No focus'), accelerator: 'Esc', click: ()=>{
 534           let js = `{let e=document.activeElement;
 535 if(e)e.blur();try{tabs.children[iTab].stopFindInPage('clearSelection')}catch(er){}}`;
 536           win.webContents.executeJavaScript(js,false);
 537         }},
 538         { label: translate('Reload'), accelerator: 'F5', click: ()=>{
 539           win.webContents.executeJavaScript("tabs.children[iTab].reload()",false);
 540         }},
 541         { label: translate('Devtools'), accelerator: 'F12', click: ()=>{
 542           let js = "try{tabs.children[iTab].openDevTools()}catch(e){console.log(e)}";
 543           win.webContents.executeJavaScript(js,false);
 544         }},
 545
 546       ],
 547     },
 548   );
 549   const menu = Menu.buildFromTemplate(menuTemplate);
 550   Menu.setApplicationMenu(menu);
 551 }
 552
 553 function cmdlineProcess(argv,cwd,extra){
 554   let i1st = 2+extra; //index for the first query item
 555   if(argv.length>i1st){
 556     if(i1st+1==argv.length){//local file
 557       let fname =  path.join(cwd, argv[i1st]);
 558       if(fs.existsSync(fname)){
 559         let js = "tabs.children[iTab].src='file://"+fname+"'";
 560         win.webContents.executeJavaScript(js,false);
 561         win.setTitle(argv[i1st]);
 562         return;
 563       }
 564     }
 565     let url=argv.slice(i1st).join(" ");
 566     win.webContents.executeJavaScript("handleQuery(`"+url+"`)",false);
 567     win.setTitle(url);
 568   }
 569 }
 570
 571 async function cbScheme_redir(req){
 572   if(!gredirect) return null;
 573   let oUrl = req.url;
 574   let newurl = gredirect+oUrl;
 575   const parsedUrl = url.parse(newurl);
 576   let headers = new Headers();
 577   for (var pair of req.headers.entries())
 578     headers.set(pair[0],pair[1]);
 579   if(bForwardCookie){
 580     let cookies = await session.defaultSession.cookies.get({url: oUrl});
 581     let cookieS = cookies.map (cookie => cookie.name  + '=' + cookie.value ).join(';');
 582     headers.set('Cookie',cookieS);
 583   }
 584   //missing referer header
 585   //headers.set('referer',);
 586   const options = {
 587     hostname: parsedUrl.hostname,
 588     port: parsedUrl.port,
 589     path: parsedUrl.path,
 590     method: req.method,
 591     headers: headers
 592   };
 593   return new Promise(async (resolve, reject) => {
 594     const nreq = https.request(options, (res) => {
 595       let body = [];
 596       res.on('data', (chunk) => {
 597         body.push(chunk);
 598       });
 599
 600       res.on('end', () => {
 601         try {
 602           body = Buffer.concat(body);
 603           const response = new Response(body, res);
 604           resolve(response);
 605         } catch (e) {
 606           reject(e);
 607         }
 608       });
 609     });
 610     nreq.on('error', (err) => {
 611       reject(err);
 612     });
 613     if (req.body){
 614      try {
 615       const reader = req.body.getReader();
 616       do {
 617         const { done, value } = await reader.read();
 618         if (done) {
 619           nreq.end();
 620           break;
 621         }
 622         nreq.write(value);
 623         console.log(headers);
 624         console.log(new TextDecoder("iso-8859-1").decode(value));
 625       }while (true);
 626      }catch(e){reject(e)}
 627     }else
 628       nreq.end();
 629   });
 630 }
 631
 632 function registerHandler(){
 633   protocol.handle("http",cbScheme_redir);
 634   protocol.handle("https",cbScheme_redir);
 635   protocol.handle("ws",cbScheme_redir);
 636   protocol.handle("wss",cbScheme_redir);
 637 }
 638 function unregisterHandler(){
 639   protocol.unhandle("http",cbScheme_redir);
 640   protocol.unhandle("https",cbScheme_redir);
 641   protocol.unhandle("ws",cbScheme_redir);
 642   protocol.unhandle("wss",cbScheme_redir);
 643 }
 644
 645 function forwardCookie(){
 646   const choice = dialog.showMessageBoxSync(null,  {
 647     type: 'warning',
 648     title: 'Confirm cookie forwarding with global redirection',
 649     message: 'Cookies are used to access your account. Forwarding cookies is vulnerable to global redirection server, proceed to enable cookie forwarding with global redirection?',
 650     buttons: ['No','Yes']
 651   })
 652   if(1===choice) bForwardCookie=true;
 653 }
 654 function msgbox_info(msg){
 655   dialog.showMessageBoxSync(null,  {
 656     type: 'info',
 657     title: msg,
 658     message: msg,
 659     buttons: ['OK']
 660   })
 661 }
 662
 663 async function updateApp(url){//url must ending with "/"
 664   let msg;
 665   do {
 666     try {
 667       let res = await fetch(url+"package.json");
 668       let packageS = await res.text();
 669       {//the last part of version string is the version number, must keep increasing
 670         let head = packageS.slice(2,40);
 671         let iV = head.indexOf("version");
 672         if(iV<0) {
 673           msg = "remote package.json corrupted"
 674           break;
 675         }
 676         iV = iV + 10;
 677         let iE = head.indexOf('"',iV+4);
 678         let iS = head.lastIndexOf('.',iE-1);
 679         let nLatestVer = parseInt(head.substring(iS+1,iE));
 680
 681         let ver = app.getVersion();
 682         iS = ver.lastIndexOf('.');
 683         let nVer = parseInt(ver.substring(iS+1));
 684         if(nVer>=nLatestVer){
 685           msg = `Current version ${ver} is already up to date`;
 686           break;
 687         }
 688         const choice = dialog.showMessageBoxSync(null,  {
 689           type: 'warning',
 690           title: `Update from ${url}`,
 691           message: `Proceed to update from ${ver} to ${head.substring(iV,iE)}?`,
 692           buttons: ['YES','NO']
 693         });
 694         if(1===choice) return;
 695       }
 696
 697       writeFile("package.json", packageS);
 698
 699       fetch2file(url,"webview.js");
 700       fetch2file(url,"index.html");
 701       msg = "Update completed";
 702     }catch(e){
 703       msg = "Fail to update"
 704     }
 705   }while(false);
 706   dialog.showMessageBoxSync(null,  {
 707     type: 'info',
 708     title: `Update from ${url}`,
 709     message: msg,
 710     buttons: ['OK']
 711   })
 712 }
 713
 714 async function fetch2file(urlFolder, filename, bOverwritten=true){
 715   let pathname=path.join(__dirname,filename);
 716   if(!bOverwritten && fs.existsSync(pathname)) return;
 717   let res = await fetch(urlFolder+filename);
 718   let str =  await res.text();
 719   writeFile(pathname, str);
 720 }
 721
 722 async function writeFile(filename, str){
 723   let pathname=filename+".new";
 724   fs.writeFile(pathname, str, (err) => {
 725     if(err) throw "Fail to write";
 726     fs.rename(pathname,filename,(e1)=>{
 727       if(e1) throw "Fail to rename";
 728     });
 729   });
 730 }
 731
 732 function help(){
 733   const readme = "README.md";
 734   const htmlFN = path.join(__dirname,readme);
 735   let js=`{let t=tabs.children[iTab];t.dataset.jsonce=BML_md;t.src="file://${htmlFN}"}`;
 736   win.webContents.executeJavaScript(js,false)
 737 }
 738
 739 function downloadContextMenuTemp(url){
 740   let mTemplate =
 741       [{label:url,enabled:false},
 742        {label: translate('Download')},
 743        {
 744          label: translate('Copy'),
 745          click: () => {
 746            clipboard.writeText(url);
 747          }
 748        },
 749       ];
 750   menuDownload(mTemplate, "", url);
 751   return mTemplate;
 752 }
 753 async function initTranslateRes(lang){
 754   let basename=path.join(__dirname,"translate.");
 755   let fname = basename+lang;
 756   if(!fs.existsSync(fname))
 757     fname = basename+lang.slice(0,2);
 758   try {
 759     let json = await fs.promises.readFile(fname,'utf8');
 760     translateRes = JSON.parse(json);
 761   } catch (e){}
 762   topMenu();
 763 }
 764
 765 function translate(str){
 766   let result;
 767   if(translateRes && (result=translateRes[str])) return result;
 768   return str;
 769 }
 770
 771 function promiseContextMenu(menuTemplate) {
 772   return new Promise((resolve, reject) => {
 773     menuTemplate[1].click = () => resolve(-1);
 774     const menu = Menu.buildFromTemplate(menuTemplate);
 775     menu.on('menu-will-close', () => resolve(-2));
 776     menu.popup();
 777   });
 778 }
 779
 780 function httpReq(url, method, filePath){
 781   fs.readFile(filePath, (err, fileData) => {
 782     if (err) {
 783       console.error(`Error reading file: ${err.message}`);
 784       return;
 785     }
 786
 787     let opts = {
 788       method: method,
 789       headers: {
 790         "Content-Type":'application/octet-stream',
 791       },
 792       body: fileData,
 793     };
 794     fetch(url,opts);
 795   });
 796 }
 797
 798 function bangcommand(q,offset){
 799   let iS = q.indexOf(' ',offset);
 800   if(iS<0) iS=q.length;
 801   let fname = q.substring(offset,iS);
 802   let fpath = path.join(__dirname,fname+'.js');
 803   if (fs.existsSync(fpath)) {
 804     fs.readFile(fpath, 'utf8',(err, js)=>{
 805       if (err) {
 806         console.log(err);
 807         return;
 808       }
 809       const prefix = "(function(){";
 810       const postfix = "})(`";
 811       const end ="`)";
 812       const fjs = `${prefix}${js}${postfix}${q}${end}`;
 813       eval(fjs);
 814     });
 815   }
 816 }
 817