meta-file.js

// Copyright (c) 2015 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

'use strict';

var readJSON = require('read-json');
var fs = require('graceful-fs');
var setImmediate = require('timers').setImmediate;

module.exports = MetaFile;

function MetaFile(opts) {
    if (!(this instanceof MetaFile)) {
        return new MetaFile(opts);
    }

    var self = this;

    self.fileName = opts.fileName;

    self._lastDate = null;
    self._remotes = null;
    self._version = null;
    self._shasums = null;
}

MetaFile.prototype.readFile = function readFile(cb) {
    var self = this;

    readJSON(self.fileName, onFile);

    function onFile(err, meta) {
        if (err && err.code === 'ENOENT') {
            self._remotes = {};
            return cb(null);
        } else if (err) {
            if (err.constructor.name === 'SyntaxError') {
                err.message = 'Corrupt meta.json file: ' + err.message;
            }
            return cb(err);
        }

        self._remotes = meta.remotes;
        self._version = meta.version;
        self._lastDate = new Date(meta.time || Date.now());
        self._shasums = meta.shasums;

        cb(null);
    }
};

MetaFile.prototype.getSha = function getSha(directoryName) {
    var self = this;
    var remote = self._remotes[directoryName];

    if (!remote) {
        return null;
    }

    return remote.sha;
};

MetaFile.prototype.getShasums = function getShasums(directoryName) {
    var self = this;
    var remote = self._remotes[directoryName];

    if (!remote) {
        return null;
    }

    return remote.shasums;
};

MetaFile.prototype._updateVersion = function version(opts) {
    opts = opts || {};
    var self = this;
    var newDate = opts.time ? new Date(opts.time) : new Date();
    if (+newDate > +self._lastDate) {
        self._lastDate = newDate;
    }
};

MetaFile.prototype.updateRecord =
function updateRecord(directoryName, opts, callback) {
    opts = opts || {};
    var self = this;

    self._updateVersion(opts);

    self._remotes[directoryName] = {
        time: opts.time ? opts.time : self._lastDate.toISOString(),
        version: opts.version ? opts.version : self._lastDate.getTime(),
        sha: opts.sha,
        shasums: opts.shasums
    };

    self.save(callback);
};

MetaFile.prototype.getRecord = function getRecord(service) {
    var self = this;
    return self._remotes[service];
};

MetaFile.prototype.publish = function publish(opts, callback) {
    opts = opts || {};
    var self = this;
    self._updateVersion(opts);
    self._shasums = opts.shasums || {};
    self.save(callback);
};

// a lock should be set that delays this if updateRecord is in progress
MetaFile.prototype.getDependencies = function getDependencies(callback) {
    var self = this;

    setImmediate(function onSetImmediate() {
        callback(null, self._remotes);
    });
};

MetaFile.prototype.toJSON = function toJSON() {
    var self = this;
    var date = self._lastDate;

    var json = {};

    // date will only exist for the registry meta.json file and should
    // be the date of the most recently updated file.
    // Services should have a different field to indicate what version
    // of the monorepo to install from. TODO: what name?
    if (date) {
        json.time = date.toISOString();
        // "version" is a poor choice for a name here. It really should
        // be something like mtime. i.e. last time a new thrift definition
        // was published.
        json.version = date.getTime();
    }

    if (self._shasums) {
        json.shasums = self._shasums;
    }

    if (self._remotes) { // sort remotes to simplify diffs / reviews
        json.remotes = sortObject(self._remotes);
    }

    return json;
};

// sort object properties by their names in lexicographical order
function sortObject(unsorted) {
    var sorted = {};
    Object.keys(unsorted).sort().forEach(function forEachSort(key) {
        sorted[key] = unsorted[key];
    });
    return sorted;
}

MetaFile.prototype.toJSONString = function toJSONString() {
    var self = this;
    return JSON.stringify(self.toJSON(), null, 4) + '\n';
};

MetaFile.prototype.save = function save(callback) {
    var self = this;
    fs.writeFile(self.fileName, self.toJSONString(), 'utf8', callback);
};

MetaFile.prototype.time = function time() {
    var self = this;
    return self._lastDate;
};