Added limit service initial commit

- This provides some basic functionality and error message generation for adding host-based limits in Ghost
- It is a first-pass, needs unit tests etc

ghost/limit-service/.eslintrc.js

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+module.exports = {
+    plugins: ['ghost'],
+    extends: [
+        'plugin:ghost/node'
+    ]
+};

ghost/limit-service/LICENSE

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+MIT License
+
+Copyright (c) 2013-2021 Ghost Foundation
+
+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.

ghost/limit-service/README.md

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+# Limit Service
+
+## Install
+
+`npm install @tryghost/limit-service --save`
+
+or
+
+`yarn add @tryghost/limit-service`
+
+
+## Usage
+
+
+## Develop
+
+This is a mono repository, managed with [lerna](https://lernajs.io/).
+
+Follow the instructions for the top-level repo.
+1. `git clone` this repo & `cd` into it as usual
+2. Run `yarn` to install top-level dependencies.
+
+
+## Run
+
+- `yarn dev`
+
+
+## Test
+
+- `yarn lint` run just eslint
+- `yarn test` run lint and tests
+
+
+
+
+# Copyright & License 
+
+Copyright (c) 2013-2021 Ghost Foundation - Released under the [MIT license](LICENSE).

ghost/limit-service/lib/config.js

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+module.exports = {
+    members: {
+        currentCountQuery: async (db) => {
+            let result = await db.knex('members').count('id', {as: 'count'}).first();
+            return result.count;
+        }
+    },
+    staff: {
+        currentCountQuery: async (db) => {
+            let result = await db.knex('users')
+                .count('users.id', {as: 'count'})
+                .leftJoin('roles_users', 'users.id', 'roles_users.user_id')
+                .leftJoin('roles', 'roles_users.role_id', 'roles.id')
+                .whereNot('roles.name', 'Contributor').andWhereNot('users.status', 'inactive').first();
+
+            return result.count;
+        }
+    },
+    custom_integrations: {
+        currentCountQuery: async (db) => {
+            let result = await db.knex('integrations').count('id', {as: 'count'}).whereNotIn('type', ['internal', 'builtin']).first();
+            return result.count;
+        }
+    },
+    custom_themes: {}
+};

ghost/limit-service/lib/limit-service.js

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+const errors = require('@tryghost/errors');
+const {MaxLimit, FlagLimit} = require('./limit');
+const config = require('./config');
+const _ = require('lodash');
+
+class LimitService {
+    constructor() {
+        this.limits = {};
+    }
+
+    loadLimits({limits, helpLink, db}) {
+        Object.keys(limits).forEach((name) => {
+            if (config[name]) {
+                let limitConfig = _.merge({}, limits[name], config[name]);
+
+                if (_.has(limitConfig, 'max')) {
+                    this.limits[name] = new MaxLimit({name: name, config: limitConfig, helpLink, db});
+                } else {
+                    this.limits[name] = new FlagLimit({name: name, config: limitConfig, helpLink});
+                }
+            }
+        });
+    }
+
+    isLimited(limitName) {
+        return !!this.limits[limitName];
+    }
+
+    async checkIsOverLimit(limitName) {
+        if (!this.isLimited(limitName)) {
+            return;
+        }
+
+        try {
+            await this.limits[limitName].errorIfIsOverLimit();
+            return false;
+        } catch (error) {
+            if (error instanceof errors.HostLimitError) {
+                return true;
+            }
+        }
+    }
+
+    async checkWouldGoOverLimit(limitName) {
+        if (!this.isLimited(limitName)) {
+            return;
+        }
+
+        try {
+            await this.limits[limitName].errorIfWouldGoOverLimit();
+            return false;
+        } catch (error) {
+            if (error instanceof errors.HostLimitError) {
+                return true;
+            }
+        }
+    }
+
+    async errorIfIsOverLimit(limitName) {
+        if (!this.isLimited(limitName)) {
+            return;
+        }
+
+        await this.limits[limitName].errorIfIsOverLimit();
+    }
+
+    async errorIfWouldGoOverLimit(limitName) {
+        if (!this.isLimited(limitName)) {
+            return;
+        }
+
+        await this.limits[limitName].errorIfWouldGoOverLimit();
+    }
+}
+
+module.exports = LimitService;

ghost/limit-service/lib/limit.js

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+const errors = require('@tryghost/errors');
+const _ = require('lodash');
+
+_.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
+
+class Limit {
+    constructor({name, error, helpLink, db}) {
+        this.name = name;
+        this.error = error;
+        this.helpLink = helpLink;
+        this.db = db;
+    }
+
+    generateError() {
+        let errorObj = {
+            errorDetails: {
+                name: this.name
+            }
+        };
+
+        if (this.helpLink) {
+            errorObj.help = this.helpLink;
+        }
+
+        return errorObj;
+    }
+}
+
+class MaxLimit extends Limit {
+    constructor({name, config, helpLink, db}) {
+        super({name, error: config.error || '', helpLink, db});
+
+        if (!config.currentCountQuery) {
+            throw new errors.IncorrectUsageError('Attempted to setup a max limit without a current count query');
+        }
+
+        this.currentCountQueryFn = config.currentCountQuery;
+        this.max = config.max;
+        this.fallbackMessage = `This action would exceed the ${_.lowerCase(this.name)} limit on your current plan.`;
+    }
+
+    generateError(count) {
+        let errorObj = super.generateError();
+        let max = this.max;
+
+        errorObj.message = this.fallbackMessage;
+
+        if (this.error) {
+            try {
+                errorObj.message = _.template(this.error)({max, count});
+            } catch (e) {
+                errorObj.message = this.fallbackMessage;
+            }
+        }
+
+        errorObj.errorDetails.limit = max;
+        errorObj.errorDetails.total = count;
+
+        return new errors.HostLimitError(errorObj);
+    }
+
+    async currentCountQuery() {
+        return await this.currentCountQueryFn(this.db);
+    }
+
+    async errorIfWouldGoOverLimit() {
+        let currentCount = await this.currentCountQuery(this.db);
+        if ((currentCount + 1) > this.max) {
+            throw this.generateError(currentCount);
+        }
+    }
+    async errorIfIsOverLimit() {
+        let currentCount = await this.currentCountQuery(this.db);
+        if (currentCount > this.max) {
+            throw this.generateError(currentCount);
+        }
+    }
+}
+
+class FlagLimit extends Limit {
+    constructor({name, config, helpLink, db}) {
+        super({name, error: config.error || '', helpLink, db});
+
+        this.disabled = config.disabled;
+        this.fallbackMessage = `Your plan does not support ${_.lowerCase(this.name)}. Please upgrade to enable ${_.lowerCase(this.name)}.`;
+    }
+
+    generateError() {
+        let errorObj = super.generateError();
+
+        if (this.error) {
+            errorObj.message = this.error;
+        } else {
+            errorObj.message = this.fallbackMessage;
+        }
+
+        return new errors.HostLimitError(errorObj);
+    }
+
+    /**
+     * Flag limits are on/off so using a feature is always over the limit
+     */
+    async errorIfWouldGoOverLimit() {
+        if (this.disabled) {
+            throw this.generateError();
+        }
+    }
+
+    /**
+     * Flag limits are on/off so we can't be over the limit
+     */
+    async errorIfIsOverLimit() {
+        return;
+    }
+}
+
+module.exports = {
+    MaxLimit,
+    FlagLimit
+};

ghost/limit-service/package.json

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+{
+  "name": "@tryghost/limit-service",
+  "version": "0.0.0",
+  "repository": "https://github.com/TryGhost/Utils/tree/master/packages/limit-service",
+  "author": "Ghost Foundation",
+  "license": "MIT",
+  "main": "./lib/limit-service.js",
+  "exports": "./lib/limit-service.js",
+  "scripts": {
+    "dev": "echo \"Implement me!\"",
+    "test": "NODE_ENV=testing mocha './test/**/*.test.js'",
+    "lint": "eslint . --ext .js --cache",
+    "posttest": "yarn lint"
+  },
+  "files": [
+    "index.js",
+    "lib"
+  ],
+  "publishConfig": {
+    "access": "public"
+  },
+  "devDependencies": {
+    "mocha": "8.3.0",
+    "should": "13.2.3",
+    "sinon": "9.2.4"
+  },
+  "dependencies": {
+    "lodash": "^4.17.21"
+  }
+}

ghost/limit-service/test/.eslintrc.js

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+module.exports = {
+    plugins: ['ghost'],
+    extends: [
+        'plugin:ghost/test'
+    ]
+};

ghost/limit-service/test/hello.test.js

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+// Switch these lines once there are useful utils
+// const testUtils = require('./utils');
+require('./utils');
+
+describe('Hello world', function () {
+    it('Runs a test', function () {
+        // TODO: Write me!
+        'hello'.should.eql('hello');
+    });
+});

ghost/limit-service/test/utils/assertions.js

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+/**
+ * Custom Should Assertions
+ *
+ * Add any custom assertions to this file.
+ */
+
+// Example Assertion
+// should.Assertion.add('ExampleAssertion', function () {
+//     this.params = {operator: 'to be a valid Example Assertion'};
+//     this.obj.should.be.an.Object;
+// });

ghost/limit-service/test/utils/index.js

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+/**
+ * Test Utilities
+ *
+ * Shared utils for writing tests
+ */
+
+// Require overrides - these add globals for tests
+require('./overrides');
+
+// Require assertions - adds custom should assertions
+require('./assertions');

ghost/limit-service/test/utils/overrides.js

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+// This file is required before any test is run
+
+// Taken from the should wiki, this is how to make should global
+// Should is a global in our eslint test config
+global.should = require('should').noConflict();
+should.extend();
+
+// Sinon is a simple case
+// Sinon is a global in our eslint test config
+global.sinon = require('sinon');