app.js

/** Copyright Stewart Allen <sa@grid.space> -- All Rights Reserved */

// ensure each app gets a local version-specific copy, not shared
function require_fresh(path) {
    const rpa = require.resolve(path);
    delete require.cache[rpa];
    return require(rpa);
}

const fs = require('fs');
const uglify = require('uglify-js');
const moment = require('moment');
const agent = require('express-useragent');
const license = require_fresh('./src/moto/license.js');
const version = license.VERSION || "rogue";
const netdb = require('@gridspace/net-level-client');
const PATH = require('path');

const fileCache = {};
const code_src = {};
const code = {};
const mods = {};
const load = [];
const synth = {};
const api = {};
const wrap = {};

let forceUseCache = false;
let serviceWorker = true;
let crossOrigin = false;
let setupFn;
let cacheDir;
let startTime;
let oversion;
let dversion;
let lastmod;
let logger;
let debug;
let over;
let http;
let util;
let dir;
let log;

const EventEmitter = require('events');
class AppEmitter extends EventEmitter {}
const events = new AppEmitter();

netdb.create = async function(map = {}) {
    if (util.isfile(map.conf)) {
        Object.assign(map, JSON.parse(fs.readFileSync(map.conf)));
    }
    const client = new netdb();
    if (map.host && map.port) await client.open(map.host, map.port);
    if (map.user && map.pass) await client.auth(map.user, map.pass);
    if (map.base) await client.use(map.base);
    logger.log({ netdb: map.host, user: map.user, base: map.base });
    return client;
};

// experimental wrapping of esm modules using embedded data urls
function wrap_module(buf, as) {
    const base64 = Buffer.from(buf).toString('base64');
    const path = as.split('.');
    const exp = path.pop();
    return [
        `gapp.register("${path.join('.')}", [], (root, exports) => {`,
        `const url = "data:text/javascript;base64,${base64}";`,
        `exports({ ["${exp}"]: import(url) });`,
        "});"
    ].join('\n');
}

function addonce(array, v) {
    if (array.indexOf(v) < 0) {
        array.push(v);
    }
};

function init(mod) {
    const ENV = mod.env;

    startTime = time();
    lastmod = mod.util.lastmod;
    logger = mod.log;
    debug = ENV.debug || mod.meta.debug;
    oversion = ENV.over || mod.meta.over;
    crossOrigin = ENV.xorigin || mod.meta.xorigin || false;
    serviceWorker = (ENV.service || mod.meta.service) !== false;
    http = mod.http;
    util = mod.util;
    dir = mod.dir;
    log = mod.log;

    if (ENV.single) console.log({ cwd: process.cwd(), env: ENV });
    dversion = debug ? `_${version}` : version;
    cacheDir = ENV.cache || mod.util.datadir("cache");
    if (ENV.single) logger.log({ cacheDir });
    forceUseCache = ENV.cache ? true : false;

    const approot = PATH.join("main","gapp");
    const refcache = {};
    const callstack = [];
    let xxxx = false;

    function find_refs(cache, path, ismod) {
        let rec = refcache[path];
        if (rec) {
            let crec = cache[path];
            if (!crec) {
                cache[path] = rec;
                for (let d of rec.deps) find_refs(cache, d);
                for (let u of rec.uses) find_refs(cache, u);
            }
            return;
        }
        callstack.push(path);
        rec = cache[path] = refcache[path] = {
            uses: [],
            deps: [ approot ]
        };
        let full = PATH.join(dir,"src",`${path}.js`);
        try {
            fs.lstatSync(full);
        } catch (e) {
            console.log({missing: full, callstack});
            throw e;
        }
        // skip interrogating file if it's a module (external compacted)
        if (ismod) {
            wrap[`src/${path}.js`] = path.replaceAll('/','.');
            return;
        }
        let lines = fs.readFileSync(full)
            .toString()
            .split('\n');
        for (let line of lines) {
            let arr, pos;
            let upos = line.indexOf('// use:');
            if (upos >= 0) {
                arr = rec.uses;
                pos = upos + 7;
            }
            let dpos = line.indexOf('// dep:');
            if (dpos >= 0) {
                arr = rec.deps;
                pos = dpos + 7;
            }
            let mpos = line.indexOf('// mod:');
            if (mpos >= 0) {
                arr = rec.deps;
                pos = mpos + 7;
            }
            if (upos >= 0 && dpos >= 0) {
                console.log(`invalid line: ${line}`);
                process.exit();
            }
            if (arr && pos >= 0) {
                let path = line.substring(pos).trim().replace(/\./g,'/').trim();
                addonce(arr, path);
                find_refs(cache, path, mpos >= 0);
            }
        }
        // if (xxxx) console.log({path, ...rec});
        if (false) {
            let seek = 'mesh/api';
            if (rec.uses.indexOf(seek) >= 0 || rec.deps.indexOf(seek) >= 0) {
                console.log({PULLS:seek, path});
            }
        }
        callstack.pop();
    }

    // return record position indicated by path
    function pos(path, list) {
        for (let i=0; i<list.length; i++) {
            if (list[i].path === path) {
                return i;
            }
        }
        console.trace(`not found: ${path}`);
        process.exit();
    }

    function order_refs(cache) {
        const recs = Object.entries(cache).map(entry => {
            return { path: entry[0], deps: entry[1].deps }
        }).sort((a,b) => {
            return a.path === b.path ? 0 : a.path < b.path ? -1 : 1;
        });
        if (xxxx) console.log({ordering: recs});

        // for each rec, ensure that dependencies are inserted before it
        let lrec = recs.slice();
        for (let rec of lrec) {
            let { path, deps } = rec;
            for (let dep of deps) {
                let rpos = pos(path, recs);
                let dpos = pos(dep, recs);
                if (dpos > rpos) {
                    let drec = recs[dpos];
                    // remove old dep record
                    recs.splice(dpos, 1);
                    // insert dep before
                    recs.splice(rpos, 0, drec);
                    let nrpos = pos(path, recs);
                    let ndpos = pos(dep, recs);
                    let fail = nrpos != ndpos + 1;
                    // if (xxxx) { console.log({move: dep, dpos, before: path, rpos}); }
                    if (fail) {
                        console.log({move: dep, dpos, before: path, rpos, ndpos, nrpos, recs: recs.slice(0,10)});
                        process.exit();
                    }
                }
            }
        }
        if (xxxx) console.log({recs});
        return recs.map(rec => rec.path);
    }

    // process script dependencies, expand paths
    for (let [ key, val ] of Object.entries(script)) {
        if (val.indexOf(approot) < 0) {
            val = [ approot, ...val ];
        }
        const list = val.map(p => p.charAt(0) === '&' ? p.substring(1) : p);
        const cache = {};
        const roots = [];
        // xxxx = key === "kiri_work";
        // for each path in the list, find deps and add to list
        for (let path of val) {
            let fc = path.charAt(0);
            if (fc === '@') {
                continue;
            }
            if (fc === '#') {
                continue;
            }
            if (fc === '&') {
                path = path.substring(1);
                addonce(roots, path);
            }
            find_refs(cache, path);
        }
        if (xxxx) console.log({ processing: key, val });
        let refs = order_refs(cache).filter(p => roots.indexOf(p) < 0);
        // remove paths that are in refs
        let paths = list.filter(p => {
            if (p.charAt(0) === '&') {
                p = p.substring(1);
            }
            return refs.indexOf(p) < 0 && roots.indexOf(p) < 0;
        });
        // when dependency roots exist, re-write val array
        if (roots.length) {
            val = [...refs, ...paths, ...roots];
        }
        // val.splice(1, 0, ...roots);
        if (xxxx) console.log({key, cache, refs, paths, roots, val});
        script[key] = val.map(p => {
            let fc = p.charAt(0);
            if (fc === '@') return p;
            if (fc === '#') {
                fc = p.split('#');
                let nupath = `src/${fc[1]}.js`;
                wrap[nupath] = fc[1].replaceAll('/','.');
                return nupath;
            }
            return `src/${p}.js`;
        });
        // console.log({script: key, files: script[key]});
    }

    mod.on.test((req) => {
        let cookie = cookieValue(req.headers.cookie, "version") || undefined;
        let vmatch = mod.meta.version || "*";
        if (!Array.isArray(vmatch)) {
            vmatch = [ vmatch ];
        }
        if (vmatch.indexOf("*") >= 0) {
            return true;
        }
        return vmatch.indexOf(cookie) >= 0;
    });

    mod.add(handleSetup);
    mod.add(handleOptions);
    mod.add(handleWasm);
    mod.add(fullpath({
        "/kiri"            : redir("/kiri/", 301),
        "/mesh"            : redir("/mesh/", 301),
        "/meta"            : redir("/meta/", 301),
        "/kiri/index.html" : redir("/kiri/", 301),
        "/mesh/index.html" : redir("/mesh/", 301),
        "/meta/index.html" : redir("/meta/", 301)
    }));
    mod.add(handleVersion);
    mod.add(prepath([
        [ "/code/", handleCode ],
        // [ "/wasm/", handleWasm ]
    ]));
    mod.add(fixedmap("/api/", api));
    if (debug) {
        mod.static("/mod/", "mod");
        mod.sync("/reload", () => {
            mod.reload();
            return "reload";
        });
    }
    mod.add(rewriteHtmlVersion);
    mod.add((req, res, next) => {
        const path = req.gs.path.substring(1);
        if (wrap[path]) {
            const data = getCachedFile(path, file => {
                console.log({ hot_wrap: file });
                return fs.readFileSync(file);
            });
            res.setHeader('Content-Type', 'application/javascript; charset=UTF-8');
            return res.end(data);
        }
        next();
    });
    mod.static("/src/", "src");
    mod.static("/obj/", "web/obj");
    mod.static("/font/", "web/font");
    mod.static("/fon2/", "web/fon2");
    mod.static("/mesh/", "web/mesh");
    mod.static("/moto/", "web/moto");
    mod.static("/meta/", "web/meta");
    mod.static("/kiri/", "web/kiri");

    // load modules
    lastmod(`${dir}/mod`) && fs.readdirSync(`${dir}/mod`).forEach(dir => {
        const modpath = `mod/${dir}`;
        if (dir.charAt(0) === '.') return;
        const stats = fs.lstatSync(`${mod.dir}/${modpath}`);
        if (!(stats.isDirectory() || stats.isSymbolicLink())) return;
        const isElectronMod = util.isfile(PATH.join(mod.dir,modpath,".electron"));
        if (ENV.electron && !isElectronMod) return;
        if (!ENV.electron && isElectronMod) return;
        try {
            loadModule(mod, modpath);
        } catch (error) {
            console.log({ module: dir, error });
        }
    });

    // run loads injected by modules
    while (load.length) {
        try {
            load.shift()();
        } catch (e) {
            logger.log({on_load_fail: e});
        }
    }

    // runs after module loads / injects
    prepareScripts();
};

// either add module assets to path or require(init.js)
function loadModule(mod, dir) {
    if (dir.indexOf('node_modules') >= 0) {
        return;
    }
    if (lastmod(`${mod.dir}/${dir}/.ignore`)) {
        return;
    }
    lastmod(`${mod.dir}/${dir}/init.js`) ?
        initModule(mod, `./${dir}/init.js`, dir) :
        mod.static("/", `${mod.dir}/${dir}`);
}

// load module and call returned function with helper object
function initModule(mod, file, dir) {
    logger.log({module: file});
    require_fresh(file)({
        // express functions added here show up at "/api/" url root
        api: api,
        adm: {
            reload: prepareScripts,
            setver: (ver) => { oversion = ver },
            crossOrigin: (bool) => { crossOrigin = bool }
        },
        events,
        const: {
            args: {},
            meta: mod.meta,
            debug: debug,
            script: script,
            moddir: dir,
            rootdir: mod.dir,
            version: oversion || version
        },
        env: mod.env,
        pkg: {
            agent,
            moment,
            netdb,
        },
        mod: mods,
        util: {
            log: logger.log,
            time: time,
            guid: guid,
            mkdirs: util.mkdir,
            isfile: util.isfile,
            confdir: util.confdir,
            datadir: util.datadir,
            lastmod: lastmod,
            obj2string: obj2string,
            string2obj: string2obj,
            getCookieValue: cookieValue,
            logger: log.new
        },
        inject: (code, file, opt = {}) => {
            let codelist = script[code];
            if (!codelist) {
                return logger.log(`inject missing target "${code}"`);
            }
            const path = `${dir}/${file}`;
            codelist.push(path);
            if (opt.cachever) {
                cachever[path] = opt.cachever;
            }
        },
        path: {
            any: arg => { mod.add(arg) },
            pre: arg => { mod.add(prepath(arg)) },
            map: arg => { mod.add(fixedmap(arg)) },
            full: arg => { mod.add(fullpath(arg)) },
            static: (root, pre) => {
                mod.static(pre || "/", root);
            },
            code: (endpoint, path) => {
                let fpath = PATH.join(mod.dir, path);
                if (debug) {
                    code[endpoint] = fs.readFileSync(fpath);
                } else {
                    code[endpoint] = minify(fpath);
                }
                code_src[endpoint] = {
                    endpoint,
                    path: path,
                    mod: lastmod(fpath)
                };
            },
            redir: redir,
            remap: remap,
            setup: fn => { setupFn = fn }
        },
        handler: {
            addCORS: addCorsHeaders,
            redirect: http.redirect,
            reply404: http.reply404,
            decodePost: http.decodePost,
            reply: quickReply
        },
        ws: {
            register: mod.wss
        },
        onload: (fn) => {
            load.push(fn);
        },
        onexit: (fn) => {
            mod.on.exit(fn);
        }
    });
}

const script = {
    kiri : [
        "@devices",
        "@icons",
        "kiri/ui",
        "&main/kiri",
        "&kiri/lang-en"
    ],
    kiri_work : [
        "kiri-run/worker",
        "&main/kiri",
    ],
    kiri_pool : [
        "&kiri-run/minion",
        "&main/kiri",
    ],
    engine : [
        "&kiri-run/engine",
        "&main/kiri",
    ],
    frame : [
        "kiri-run/frame"
    ],
    meta : [
        "main/meta",
    ],
    mesh : [
        "&main/mesh"
    ],
    mesh_work : [
        "&mesh/work"
    ],
    mesh_pool : [
        "&mesh/pool"
    ],
    cache : [
        "moto/license",
        "main/service",
    ],
    service : [
        "moto/license",
        "moto/service"
    ]
};

// prevent caching of specified modules
const cachever = {};

function promise(resolve, reject) {
    return new Promise(resolve, reject);
}

function rval() {
    return (Math.round(Math.random()*0xffffffff)).toString(36);
}

function guid() {
    return time().toString(36)+rval()+rval()+rval();
}

function time() {
    return Date.now();
}

function obj2string(o) {
    return JSON.stringify(o);
}

function string2obj(s) {
    return JSON.parse(s);
}

function handleSetup(req, res, next) {
    if (setupFn) {
      setupFn(req, res, next);
    } else {
      next();
    }
}

function handleVersion(req, res, next) {
    let vstr = oversion || dversion || version;
    if (["/kiri/","/mesh/","/meta/"].indexOf(req.app.path) >= 0 && req.url.indexOf(vstr) < 0) {
        if (req.url.indexOf("?") > 0) {
            return http.redirect(res, `${req.url},ver:${vstr}`);
        } else {
            return http.redirect(res, `${req.url}?ver:${vstr}`);
        }
    } else {
        next();
    }
}

function handleOptions(req, res, next) {
    try {
        req.app.ua = agent.parse(req.headers['user-agent'] || '');
    } catch (e) {
        logger.log("ua parse error on : "+req.headers['user-agent']);
    }
    res.setHeader("Service-Worker-Allowed", "/");
    if (req.method === 'OPTIONS') {
        addCorsHeaders(req, res);
        res.end();
    } else {
        next();
    }
}

function handleWasm(req, res, next) {
    let file = req.app.path.split('/').pop();
    let ext = (file || '').split('.')[1];
    let path = PATH.join(dir,"src","wasm",file);
    let mod = lastmod(path);

    if (ext === 'wasm' && mod) {
        let imd = ifModifiedDate(req);
        if (imd && mod <= imd) {
            res.writeHead(304, "Not Modified");
            return res.end();
        }
        res.writeHead(200, {
            'Content-Type': 'application/wasm',
            'Cache-Control': 'public, max-age=600',
            'Last-Modified': new Date(mod).toGMTString(),
        });
        res.end(fs.readFileSync(path));
    } else {
        next();
    }
}

function handleCode(req, res, next) {
    let key = req.app.path.split('/')[2].split('.')[0],
        ck = code_src[key],
        js = code[key];

    if (!js) {
        return http.reply404(req, res);
    }
    if (ck) {
        let mpath = `${dir}/${ck.path}`;
        let mod = lastmod(mpath);
        if (mod > ck.mod) {
            if (debug) {
                js = code[ck.endpoint] = fs.readFileSync(mpath);
            } else {
                js = code[ck.endpoint] = minify(mpath);
            }
            ck.mod = mod;
        }
    }

    addCorsHeaders(req, res);
    serveCode(req, res, {
        code: js,
        mtime: startTime
    });
}

function serveCode(req, res, code) {
    if (code.deny) {
        return http.reply404(req, res);
    }

    let imd = ifModifiedDate(req);
    if (imd && code.mtime <= imd && !code.nocache) {
        res.writeHead(304, "Not Modified");
        res.end();
        return;
    }

    let cacheControl = code.nocache ?
        'private, max-age=0' :
        'public, max-age=600';

    res.writeHead(200, {
        'Content-Type': 'application/javascript',
        'Cache-Control': cacheControl,
        'Last-Modified': new Date(code.mtime).toGMTString(),
    });
    res.end(code.code);
}

function generateIcons() {
    let root = PATH.join(dir,"src","kiri-ico");
    let icos = {};
    fs.readdirSync(root).forEach(file => {
        let name = file.split(".")[0]   ;
        icos[name] = fs.readFileSync(`${root}/${file}`).toString();
    });
    synth.icons = `self.icons = ${JSON.stringify(icos)};`;
}

function generateDevices() {
    let root = PATH.join(dir,"src","kiri-dev");
    let devs = {};
    fs.readdirSync(root).forEach(type => {
        let map = devs[type] = devs[type] || {};
        fs.readdirSync(PATH.join(root,type)).forEach(device => {
            map[device] = JSON.parse(fs.readFileSync(PATH.join(root,type,device)));
        });
    });
    // console.log({ devs });
    synth.devices = `self.devices = ${JSON.stringify(devs)};`;
}

function prepareScripts() {
    generateIcons();
    generateDevices();
    for (let key of Object.keys(script)) {
        code[key] = concatCode(script[key]);
    }
}

function concatCode(array) {
    let code = [];
    let direct = array.filter(f => f.charAt(0) !== '@');
    let inject = array.filter(f => f.charAt(0) === '@').map(f => f.substring(1));

    synth.inject = "/* injection point */";

    // in debug mode, the script should load dependent
    // scripts instead of serving a complete bundle
    if (debug) {
        const code = [
            oversion ? `self.debug_version='${oversion}';self.enable_service=${serviceWorker};` : '',
            'self.debug=true;',
            '(function() { let load = [ '
        ];
        direct.forEach(file => {
            const vers = cachever[file] || oversion || dversion || version;
            code.push(`"/${file.replace(/\\/g,'/')}?${vers}",`);
        });
        code.push([
            ']; function load_next() {',
            'let file = load.shift();',
            'if (!file) return;',
            'if (!self.document) { importScripts(file); return load_next() }',
            'let s = document.createElement("script");',
            's.type = "text/javascript";',
            's.src = file;',
            's.onload = load_next;',
            'document.head.appendChild(s);',
            '} load_next(); })();'
        ].join('\n'));
        inject.forEach(key => {
            code.push(synth[key]);
        });
        return code.join('\n');
    }

    direct.forEach(file => {
        let cached = getCachedFile(file, path => {
            return minify(PATH.join(dir,file));
        });
        if (oversion) {
            cached = `self.debug_version='${oversion}';self.enable_service=${serviceWorker};` + cached;
        }
        code.push(cached);
    });

    inject.forEach(key => {
        code.push(synth[key]);
    });

    return code.join('');
}

function getCachedFile(file, fn) {
    let filePath = PATH.join(dir,file);
    let cachePath = cacheDir + PATH.sep + file
            .replace(/\//g,'_')
            .replace(/\\/g,'_')
            .replace(/:/g,'_'),
        cached = fileCache[filePath],
        now = time();

    if (cached) {
        if (now - cached.lastcheck > 60000) {
            let smod = lastmod(filePath),
                cmod = cached.mtime;

            if (!smod) {
                throw "missing source file";
            }
            if (smod > cmod) {
                cached = null;
            } else {
                cached.lastcheck = now;
            }
        }
    }

    if (!cached) {
        let smod = lastmod(filePath),
            cmod = lastmod(cachePath),
            cacheData;

        if (cmod >= smod || (forceUseCache && cmod)) {
            cacheData = fs.readFileSync(cachePath);
        } else {
            logger.log({update_cache:filePath});
            cacheData = fn(filePath);
            fs.writeFileSync(cachePath, cacheData);
        }

        if (wrap[file]) {
            // console.log('WRAP', filePath, cacheData.length);
            cacheData = wrap_module(cacheData, wrap[file]);
        }

        cached = {
            data: cacheData,
            mtime: cmod || now,
            lastcheck: now
        };

        fileCache[filePath] = cached;
    }

    // console.log('[*]', filePath, cached.data.length);
    return cached.data;
}

function minify(path) {
    let code = fs.readFileSync(path);
    let mini = uglify.minify(code.toString(), {
        compress: {
            merge_vars: false,
            unused: false
        }
    });
    if (mini.error) {
        console.trace(mini.error);
        throw mini.error;
    }
    return mini.code;
}

function quickReply(res, code, msg) {
    res.writeHead(code);
    res.end(msg+"\n");
}

function ifModifiedDate(req) {
    let ims = req.headers['if-modified-since'];
    if (ims) {
        // because sys time has a higher resolution than
        // seconds converted from IMS header. so give it
        // an extra second
        return new Date(ims).getTime() + 1000;
    }
    return 0;
}

function addCorsHeaders(req, res) {
    res.setHeader('Access-Control-Allow-Credentials', 'true');
    res.setHeader('Access-Control-Allow-Headers', 'X-Moto-Ajax, Content-Type');
    res.setHeader('Access-Control-Allow-Origin', req.headers['origin'] || '*');
    if (!crossOrigin) {
        res.setHeader("Cross-Origin-Opener-Policy", 'same-origin');
        res.setHeader("Cross-Origin-Embedder-Policy", 'require-corp');
    }
    res.setHeader("Allow", "GET,POST,OPTIONS");
}

// dispatch for path prefixs
function prepath(pre) {

    function handle(req, res, next) {
        pre.uid = pre.uid || guid();
        req.ppi = req.ppi || {};

        let path = req.app.path,
            key, fn, i = req.ppi[pre.uid] || 0;

        while (i < pre.length) {
            key = pre[i][0];
            fn = pre[i++][1];
            if (path.indexOf(key) === 0) {
                return fn(req, res, () => {
                    req.ppi[pre.uid] = i;
                    handle(req, res, next);
                });
            }
        }

        next();
    }

    return handle;
}

// dispatch full fixed paths
function fullpath(map) {
    return (req, res, next) => {
        let fn = map[req.app.path];
        if (fn) fn(req, res, next);
        else next();
    };
}

// dispatch full paths based on a prefix and a function map
function fixedmap(prefix, map) {
    return (req, res, next) => {
        let path = req.app.path;
        if (path.indexOf(prefix) != 0) return next();
        let fn = map[path.substring(prefix.length)];
        if (fn) fn(req, res, next);
        else next();
    };
}

// HTTP 307 redirect
function redir(path, type) {
    return (req, res, next) => http.redirect(res, path, type);
}

// mangle request path
function remap(path) {
    return (req, res, next) => {
        req.url = req.app.path = path;
        next();
    }
}

function cookieValue(cookie,key) {
    if (!cookie) return null;
    key = (key || "key") + "=";
    let kpos = cookie.lastIndexOf(key);
    if (kpos >= 0) {
        return cookie.substring(kpos+key.length).split(';')[0];
    } else {
        return null;
    }
}

function rewriteHtmlVersion(req, res, next) {
    if (["/kiri/","/mesh/","/meta/","/kiri/engine.html","/kiri/frame.html"].indexOf(req.app.path) >= 0) {
        addCorsHeaders(req, res);
        let real_write = res.write;
        let real_end = res.end;
        let mlen = '{{version}}'.length;
        let vstr = oversion || dversion || version;
        if (vstr.length < mlen) {
            vstr = vstr.padStart(mlen,0);
        } else if (vstr.length > mlen) {
            vstr = vstr.substring(0,mlen);
        }
        res.write = function() {
            arguments[0] = arguments[0].toString().replace(/{{version}}/g,vstr);
            real_write.apply(res, arguments);
        };
        res.end = function() {
            if (arguments[0]) {
                arguments[0] = arguments[0].toString().replace(/{{version}}/g,vstr);
            }
            real_end.apply(res, arguments);
        };
    }

    next();
}

module.exports = init;