Moved Stats Service from Ghost

The functionality hasn't changed this has just moved the code
and updated the tests to provide better coverage

ghost/stats-service/.eslintrc.js

@@ -0,0 +1,6 @@
+module.exports = {
+    plugins: ['ghost'],
+    extends: [
+        'plugin:ghost/node'
+    ]
+};

ghost/stats-service/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2013-2022 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/stats-service/README.md

@@ -0,0 +1,41 @@
+# Stats
+
+Stats service
+
+## Install
+
+`npm install @tryghost/stats --save`
+
+or
+
+`yarn add @tryghost/stats`
+
+
+## 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) 2013-2022 Ghost Foundation - Released under the [MIT license](LICENSE).

ghost/stats-service/index.js

@@ -0,0 +1 @@
+module.exports = require('./lib/stats');

ghost/stats-service/lib/members.js

@@ -0,0 +1,165 @@
+const moment = require('moment');
+
+class MembersStatsService {
+    /**
+     * @param {object} deps
+     * @param {import('knex').Knex} deps.knex*/
+    constructor({knex}) {
+        this.knex = knex;
+    }
+
+    /**
+     * Get the current total members grouped by status
+     * @returns {Promise<TotalMembersByStatus>}
+     */
+    async getCount() {
+        const knex = this.knex;
+        const rows = await knex('members')
+            .select('status')
+            .select(knex.raw('COUNT(id) AS total'))
+            .groupBy('status');
+
+        const paidEvent = rows.find(c => c.status === 'paid');
+        const freeEvent = rows.find(c => c.status === 'free');
+        const compedEvent = rows.find(c => c.status === 'comped');
+
+        return {
+            paid: paidEvent ? paidEvent.total : 0,
+            free: freeEvent ? freeEvent.total : 0,
+            comped: compedEvent ? compedEvent.total : 0
+        };
+    }
+
+    /**
+     * Get the member deltas by status for all days, sorted ascending
+     * @returns {Promise<MemberStatusDelta[]>} The deltas of paid, free and comped users per day, sorted ascending
+     */
+    async fetchAllStatusDeltas() {
+        const knex = this.knex;
+        const rows = await knex('members_status_events')
+            .select(knex.raw('DATE(created_at) as date'))
+            .select(knex.raw(`SUM(
+                CASE WHEN to_status='paid' THEN 1
+                ELSE 0 END
+            ) as paid_subscribed`))
+            .select(knex.raw(`SUM(
+                CASE WHEN from_status='paid' THEN 1
+                ELSE 0 END
+            ) as paid_canceled`))
+            .select(knex.raw(`SUM(
+                CASE WHEN to_status='comped' THEN 1
+                WHEN from_status='comped' THEN -1
+                ELSE 0 END
+            ) as comped_delta`))
+            .select(knex.raw(`SUM(
+                CASE WHEN to_status='free' THEN 1
+                WHEN from_status='free' THEN -1
+                ELSE 0 END
+            ) as free_delta`))
+            .groupByRaw('DATE(created_at)')
+            .orderByRaw('DATE(created_at)');
+        return rows;
+    }
+
+    /**
+     * Returns a list of the total members by status for each day, including the paid deltas paid_subscribed and paid_canceled
+     * @returns {Promise<CountHistory>}
+     */
+    async getCountHistory() {
+        const rows = await this.fetchAllStatusDeltas();
+
+        // Fetch current total amounts and start counting from there
+        const totals = await this.getCount();
+        let {paid, free, comped} = totals;
+
+        // Get today in UTC (default timezone)
+        const today = moment().format('YYYY-MM-DD');
+
+        const cumulativeResults = [];
+
+        // Loop in reverse order (needed to have correct sorted result)
+        for (let i = rows.length - 1; i >= 0; i -= 1) {
+            const row = rows[i];
+
+            // Convert JSDates to YYYY-MM-DD (in UTC)
+            const date = moment(row.date).format('YYYY-MM-DD');
+            if (date > today) {
+                // Skip results that are in the future (fix for invalid events)
+                continue;
+            }
+            cumulativeResults.unshift({
+                date,
+                paid: Math.max(0, paid),
+                free: Math.max(0, free),
+                comped: Math.max(0, comped),
+
+                // Deltas
+                paid_subscribed: row.paid_subscribed,
+                paid_canceled: row.paid_canceled
+            });
+
+            // Update current counts
+            paid -= row.paid_subscribed - row.paid_canceled;
+            free -= row.free_delta;
+            comped -= row.comped_delta;
+        }
+
+        // Now also add the oldest day we have left over (this one will be zero, which is also needed as a data point for graphs)
+        const oldestDate = rows.length > 0 ? moment(rows[0].date).add(-1, 'days').format('YYYY-MM-DD') : today;
+
+        cumulativeResults.unshift({
+            date: oldestDate,
+            paid: Math.max(0, paid),
+            free: Math.max(0, free),
+            comped: Math.max(0, comped),
+
+            // Deltas
+            paid_subscribed: 0,
+            paid_canceled: 0
+        });
+
+        return {
+            data: cumulativeResults,
+            meta: {
+                totals
+            }
+        };
+    }
+}
+
+module.exports = MembersStatsService;
+
+/**
+ * @typedef MemberStatusDelta
+ * @type {Object}
+ * @property {Date} date
+ * @property {number} paid_subscribed Paid members that subscribed on this day
+ * @property {number} paid_canceled Paid members that canceled on this day
+ * @property {number} comped_delta Total net comped members on this day
+ * @property {number} free_delta Total net members on this day
+ */
+
+/**
+ * @typedef TotalMembersByStatus
+ * @type {Object}
+ * @property {number} paid Total paid members
+ * @property {number} free Total free members
+ * @property {number} comped Total comped members
+ */
+
+/**
+ * @typedef {Object} TotalMembersByStatusItem
+ * @property {string} date In YYYY-MM-DD format
+ * @property {number} paid Total paid members
+ * @property {number} free Total free members
+ * @property {number} comped Total comped members
+ * @property {number} paid_subscribed Paid members that subscribed on this day
+ * @property {number} paid_canceled Paid members that canceled on this day
+ */
+
+/**
+ * @typedef {Object} CountHistory
+ * @property {TotalMembersByStatusItem[]} data List of the total members by status for each day, including the paid deltas paid_subscribed and paid_canceled
+ * @property {Object} meta
+ * @property {TotalMembersByStatus} meta.totals
+ */

ghost/stats-service/lib/mrr.js

@@ -0,0 +1,153 @@
+const moment = require('moment');
+
+class MrrStatsService {
+    /**
+     * @param {object} deps
+     * @param {import('knex').Knex} deps.knex
+     **/
+    constructor({knex}) {
+        this.knex = knex;
+    }
+
+    /**
+     * Get the current total MRR, grouped by currency (ascending order)
+     * @returns {Promise<MrrByCurrency[]>}
+     */
+    async getCurrentMrr() {
+        const knex = this.knex;
+        const rows = await knex('members_stripe_customers_subscriptions')
+            .select(knex.raw(`plan_currency as currency`))
+            .select(knex.raw(`SUM(mrr) AS mrr`))
+            .groupBy('plan_currency')
+            .orderBy('currency');
+
+        if (rows.length === 0) {
+            // Add a USD placeholder to always have at least one currency
+            rows.push({
+                currency: 'usd',
+                mrr: 0
+            });
+        }
+
+        return rows;
+    }
+
+    /**
+     * Get the MRR deltas for all days (from old to new), grouped by currency (ascending alphabetically)
+     * @returns {Promise<MrrDelta[]>} The deltas sorted from new to old
+     */
+    async fetchAllDeltas() {
+        const knex = this.knex;
+        const rows = await knex('members_paid_subscription_events')
+            .select('currency')
+            // In SQLite, DATE(created_at) would map to a string value, while DATE(created_at) would map to a JSDate object in MySQL
+            // That is why we need the cast here (to have some consistency)
+            .select(knex.raw('CAST(DATE(created_at) as CHAR) as date'))
+            .select(knex.raw(`SUM(mrr_delta) as delta`))
+            .groupByRaw('CAST(DATE(created_at) as CHAR), currency')
+            .orderByRaw('CAST(DATE(created_at) as CHAR), currency');
+        return rows;
+    }
+
+    /**
+     * Returns a list of the MRR history for each day and currency, including the current MRR per currency as meta data.
+     * The respons is in ascending date order, and currencies for the same date are always in ascending order.
+     * @returns {Promise<MrrHistory>}
+     */
+    async getHistory() {
+        // Fetch current total amounts and start counting from there
+        const totals = await this.getCurrentMrr();
+
+        const rows = await this.fetchAllDeltas();
+
+        // Get today in UTC (default timezone)
+        const today = moment().format('YYYY-MM-DD');
+
+        const results = [];
+
+        // Create a map of the totals by currency for fast lookup and editing
+
+        /** @type {Object.<string, number>}*/
+        const currentTotals = {};
+        for (const total of totals) {
+            currentTotals[total.currency] = total.mrr;
+        }
+
+        // Loop in reverse order (needed to have correct sorted result)
+        for (let i = rows.length - 1; i >= 0; i -= 1) {
+            const row = rows[i];
+
+            if (currentTotals[row.currency] === undefined) {
+                // Skip unexpected currencies that are not in the totals
+                continue;
+            }
+
+            // Convert JSDates to YYYY-MM-DD (in UTC)
+            const date = moment(row.date).format('YYYY-MM-DD');
+
+            if (date > today) {
+                // Skip results that are in the future for some reason
+                continue;
+            }
+
+            results.unshift({
+                date,
+                mrr: Math.max(0, currentTotals[row.currency]),
+                currency: row.currency
+            });
+
+            currentTotals[row.currency] -= row.delta;
+        }
+
+        // Now also add the oldest days we have left over and do not have deltas
+        const oldestDate = rows.length > 0 ? moment(rows[0].date).add(-1, 'days').format('YYYY-MM-DD') : today;
+
+        // Note that we also need to loop the totals in reverse order because we need to unshift
+        for (let i = totals.length - 1; i >= 0; i -= 1) {
+            const total = totals[i];
+            results.unshift({
+                date: oldestDate,
+                mrr: Math.max(0, currentTotals[total.currency]),
+                currency: total.currency
+            });
+        }
+
+        return {
+            data: results,
+            meta: {
+                totals
+            }
+        };
+    }
+}
+
+module.exports = MrrStatsService;
+
+/**
+ * @typedef MrrByCurrency
+ * @type {Object}
+ * @property {number} mrr
+ * @property {string} currency
+ */
+
+/**
+ * @typedef MrrDelta
+ * @type {Object}
+ * @property {Date} date
+ * @property {string} currency
+ * @property {number} delta MRR change on this day
+ */
+
+/**
+ * @typedef {Object} MrrRecord
+ * @property {string} date In YYYY-MM-DD format
+ * @property {string} currency
+ * @property {number} mrr MRR on this day
+ */
+
+/**
+ * @typedef {Object} MrrHistory
+ * @property {MrrRecord[]} data List of the total members by status for each day, including the paid deltas paid_subscribed and paid_canceled
+ * @property {Object} meta
+ * @property {MrrByCurrency[]} meta.totals
+ */

ghost/stats-service/lib/stats.js

@@ -0,0 +1,37 @@
+const MRRService = require('./mrr');
+const MembersService = require('./members');
+
+class StatsService {
+    /**
+     * @param {object} deps
+     * @param {MRRService} deps.mrr
+     * @param {MembersService} deps.members
+     **/
+    constructor(deps) {
+        this.mrr = deps.mrr;
+        this.members = deps.members;
+    }
+
+    async getMRRHistory() {
+        return this.mrr.getHistory();
+    }
+
+    async getMemberCountHistory() {
+        return this.members.getCountHistory();
+    }
+
+    /**
+     * @param {object} deps
+     * @param {import('knex').Knex} deps.knex
+     *
+     * @returns {StatsService}
+     **/
+    static create(deps) {
+        return new StatsService({
+            mrr: new MRRService(deps),
+            members: new MembersService(deps)
+        });
+    }
+}
+
+module.exports = StatsService;

ghost/stats-service/package.json

@@ -0,0 +1,38 @@
+{
+  "name": "@tryghost/stats",
+  "version": "0.0.0",
+  "repository": "https://github.com/TryGhost/Analytics/tree/main/packages/stats",
+  "author": "Ghost Foundation",
+  "license": "MIT",
+  "main": "index.js",
+  "scripts": {
+    "dev": "echo \"Implement me!\"",
+    "test": "NODE_ENV=testing c8 --all --check-coverage --reporter text --reporter cobertura mocha './test/**/*.test.js'",
+    "lint:code": "eslint *.js lib/ --ext .js --cache",
+    "lint": "yarn lint:code && yarn lint:test",
+    "lint:test": "eslint -c test/.eslintrc.js test/ --ext .js --cache",
+    "posttest": "yarn lint"
+  },
+  "files": [
+    "index.js",
+    "lib"
+  ],
+  "publishConfig": {
+    "access": "public"
+  },
+  "devDependencies": {
+    "@types/mocha": "^9.1.0",
+    "@types/node": "^17.0.25",
+    "@types/sinon": "^10.0.11",
+    "@vscode/sqlite3": "^5.0.8",
+    "c8": "7.11.2",
+    "knex": "^1.0.7",
+    "mocha": "9.2.2",
+    "should": "13.2.3",
+    "sinon": "13.0.2",
+    "typescript": "^4.6.3"
+  },
+  "dependencies": {
+    "moment": "^2.29.3"
+  }
+}

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

@@ -0,0 +1,6 @@
+module.exports = {
+    plugins: ['ghost'],
+    extends: [
+        'plugin:ghost/test'
+    ]
+};

ghost/stats-service/test/lib/members.test.js

@@ -0,0 +1,373 @@
+const MembersStatsService = require('../../lib/members');
+const knex = require('knex').default;
+const assert = require('assert');
+const moment = require('moment');
+const sinon = require('sinon');
+
+describe('MembersStatsService', function () {
+    describe('getCountHistory', function () {
+        /** @type {MembersStatsService} */
+        let membersStatsService;
+
+        /**
+         * @type {MembersStatsService.TotalMembersByStatus}
+         */
+        const currentCounts = {paid: 0, free: 0, comped: 0};
+        /**
+         * @type {MembersStatsService.MemberStatusDelta[]}
+         */
+        let events = [];
+
+        const today = '2000-01-10';
+        const tomorrow = '2000-01-11';
+        const yesterday = '2000-01-09';
+        const dayBeforeYesterday = '2000-01-08';
+        const twoDaysBeforeYesterday = '2000-01-07';
+
+        /** @type {Date} */
+        let todayDate;
+        /** @type {Date} */
+        let tomorrowDate;
+        /** @type {Date} */
+        let yesterdayDate;
+        /** @type {Date} */
+        let dayBeforeYesterdayDate;
+
+        after(function () {
+            sinon.restore();
+        });
+
+        /** @type {import('knex').Knex} */
+        let db;
+
+        before(function () {
+            todayDate = moment(today).toDate();
+            tomorrowDate = moment(tomorrow).toDate();
+            yesterdayDate = moment(yesterday).toDate();
+            dayBeforeYesterdayDate = moment(dayBeforeYesterday).toDate();
+            sinon.useFakeTimers(todayDate.getTime());
+            membersStatsService = new MembersStatsService({knex: knex({client: 'sqlite3', connection: {filename: ':memory:'}})});
+        });
+
+        beforeEach(async function () {
+            db = knex({client: 'sqlite3', connection: {filename: ':memory:'}, useNullAsDefault: true});
+            membersStatsService = new MembersStatsService({knex: db});
+
+            await db.schema.createTable('members_status_events', function (table) {
+                table.string('from_status');
+                table.string('to_status');
+                table.date('created_at');
+            });
+
+            await db.schema.createTable('members', function (table) {
+                table.string('id');
+                table.string('status');
+            });
+        });
+
+        async function setupDB() {
+            const paidMembers = Array.from({length: currentCounts.paid}).map(() => ({
+                id: 'id',
+                status: 'paid'
+            }));
+            const freeMembers = Array.from({length: currentCounts.free}).map(() => ({
+                id: 'id',
+                status: 'free'
+            }));
+            const compedMembers = Array.from({length: currentCounts.comped}).map(() => ({
+                id: 'id',
+                status: 'comped'
+            }));
+
+            await db('members').insert(paidMembers.concat(freeMembers, compedMembers));
+
+            /**
+             * @typedef {object} StatusEvent
+             * @prop {string} created_at
+             * @prop {string|null} from_status
+             * @prop {string|null} to_status
+             **/
+
+            /**
+             * @param {string} status
+             * @param {number} number
+             * @param {Date} date
+             * @returns {StatusEvent[]}
+             **/
+            function generateEvents(status, number, date) {
+                return Array.from({length: Math.abs(number)}).map(() => ({
+                    created_at: date.toISOString(),
+                    from_status: number > 0 ? null : status,
+                    to_status: number < 0 ? null : status
+                }));
+            }
+
+            const toInsert = events.reduce((/** @type {StatusEvent[]} */memo, event) => {
+                const paidSubscribed = generateEvents('paid', event.paid_subscribed, event.date);
+                const paidCanceled = generateEvents('paid', -event.paid_canceled, event.date);
+                const freeSubscribed = generateEvents('free', event.free_delta, event.date);
+                const compedSubscribed = generateEvents('comped', event.comped_delta, event.date);
+                return memo.concat(paidSubscribed, paidCanceled, freeSubscribed, compedSubscribed);
+            }, []);
+
+            if (toInsert.length) {
+                await db('members_status_events').insert(toInsert);
+            }
+        }
+
+        it('Always returns at least one value', async function () {
+            // No status events
+            events = [];
+            currentCounts.paid = 1;
+            currentCounts.free = 2;
+            currentCounts.comped = 3;
+
+            await setupDB();
+
+            const {data: results, meta} = await membersStatsService.getCountHistory();
+            assert(results.length === 1, 'Should have one result');
+            assert.deepEqual(results[0], {
+                date: today,
+                paid: 1,
+                free: 2,
+                comped: 3,
+                paid_subscribed: 0,
+                paid_canceled: 0
+            });
+            assert.deepEqual(meta.totals, currentCounts);
+        });
+
+        it('Passes paid_subscribers and paid_canceled', async function () {
+            // Update faked status events
+            events = [
+                {
+                    date: todayDate,
+                    paid_subscribed: 4,
+                    paid_canceled: 3,
+                    free_delta: 2,
+                    comped_delta: 3
+                }
+            ];
+
+            // Update current faked counts
+            currentCounts.paid = 1;
+            currentCounts.free = 2;
+            currentCounts.comped = 3;
+
+            await setupDB();
+
+            const {data: results, meta} = await membersStatsService.getCountHistory();
+            assert.deepEqual(results, [
+                {
+                    date: yesterday,
+                    paid: 0,
+                    free: 0,
+                    comped: 0,
+                    paid_subscribed: 0,
+                    paid_canceled: 0
+                },
+                {
+                    date: today,
+                    paid: 1,
+                    free: 2,
+                    comped: 3,
+                    paid_subscribed: 4,
+                    paid_canceled: 3
+                }
+            ]);
+            assert.deepEqual(meta.totals, currentCounts);
+        });
+
+        it('Correctly resolves deltas', async function () {
+            // Update faked status events
+            events = [
+                {
+                    date: yesterdayDate,
+                    paid_subscribed: 2,
+                    paid_canceled: 1,
+                    free_delta: 0,
+                    comped_delta: 0
+                },
+                {
+                    date: todayDate,
+                    paid_subscribed: 4,
+                    paid_canceled: 3,
+                    free_delta: 2,
+                    comped_delta: 3
+                }
+            ];
+
+            // Update current faked counts
+            currentCounts.paid = 2;
+            currentCounts.free = 3;
+            currentCounts.comped = 4;
+
+            await setupDB();
+
+            const {data: results, meta} = await membersStatsService.getCountHistory();
+            assert.deepEqual(results, [
+                {
+                    date: dayBeforeYesterday,
+                    paid: 0,
+                    free: 1,
+                    comped: 1,
+                    paid_subscribed: 0,
+                    paid_canceled: 0
+                },
+                {
+                    date: yesterday,
+                    paid: 1,
+                    free: 1,
+                    comped: 1,
+                    paid_subscribed: 2,
+                    paid_canceled: 1
+                },
+                {
+                    date: today,
+                    paid: 2,
+                    free: 3,
+                    comped: 4,
+                    paid_subscribed: 4,
+                    paid_canceled: 3
+                }
+            ]);
+            assert.deepEqual(meta.totals, currentCounts);
+        });
+
+        it('Correctly handles negative numbers', async function () {
+            // Update faked status events
+            events = [
+                {
+                    date: dayBeforeYesterdayDate,
+                    paid_subscribed: 2,
+                    paid_canceled: 1,
+                    free_delta: 2,
+                    comped_delta: 10
+                },
+                {
+                    date: yesterdayDate,
+                    paid_subscribed: 2,
+                    paid_canceled: 1,
+                    free_delta: -100,
+                    comped_delta: 0
+                },
+                {
+                    date: todayDate,
+                    paid_subscribed: 4,
+                    paid_canceled: 3,
+                    free_delta: 100,
+                    comped_delta: 3
+                }
+            ];
+
+            // Update current faked counts
+            currentCounts.paid = 2;
+            currentCounts.free = 3;
+            currentCounts.comped = 4;
+
+            await setupDB();
+
+            const {data: results, meta} = await membersStatsService.getCountHistory();
+            assert.deepEqual(results, [
+                {
+                    date: twoDaysBeforeYesterday,
+                    paid: 0,
+                    free: 1,
+                    comped: 0,
+                    paid_subscribed: 0,
+                    paid_canceled: 0
+                },
+                {
+                    date: dayBeforeYesterday,
+                    paid: 0,
+                    // note that this shouldn't be 100 (which is also what we test here):
+                    free: 3,
+                    comped: 1,
+                    paid_subscribed: 2,
+                    paid_canceled: 1
+                },
+                {
+                    date: yesterday,
+                    paid: 1,
+                    // never return negative numbers, this is in fact -997:
+                    free: 0,
+                    comped: 1,
+                    paid_subscribed: 2,
+                    paid_canceled: 1
+                },
+                {
+                    date: today,
+                    paid: 2,
+                    free: 3,
+                    comped: 4,
+                    paid_subscribed: 4,
+                    paid_canceled: 3
+                }
+            ]);
+            assert.deepEqual(meta.totals, currentCounts);
+        });
+
+        it('Ignores events in the future', async function () {
+            // Update faked status events
+            events = [
+                {
+                    date: yesterdayDate,
+                    paid_subscribed: 1,
+                    paid_canceled: 0,
+                    free_delta: 1,
+                    comped_delta: 0
+                },
+                {
+                    date: todayDate,
+                    paid_subscribed: 4,
+                    paid_canceled: 3,
+                    free_delta: 2,
+                    comped_delta: 3
+                },
+                {
+                    date: tomorrowDate,
+                    paid_subscribed: 10,
+                    paid_canceled: 5,
+                    free_delta: 8,
+                    comped_delta: 9
+                }
+            ];
+
+            // Update current faked counts
+            currentCounts.paid = 1;
+            currentCounts.free = 2;
+            currentCounts.comped = 3;
+
+            await setupDB();
+
+            const {data: results, meta} = await membersStatsService.getCountHistory();
+            assert.deepEqual(results, [
+                {
+                    date: dayBeforeYesterday,
+                    paid: 0,
+                    free: 0,
+                    comped: 0,
+                    paid_subscribed: 0,
+                    paid_canceled: 0
+                },
+                {
+                    date: yesterday,
+                    paid: 0,
+                    free: 0,
+                    comped: 0,
+                    paid_subscribed: 1,
+                    paid_canceled: 0
+                },
+                {
+                    date: today,
+                    paid: 1,
+                    free: 2,
+                    comped: 3,
+                    paid_subscribed: 4,
+                    paid_canceled: 3
+                }
+            ]);
+            assert.deepEqual(meta.totals, currentCounts);
+        });
+    });
+});

ghost/stats-service/test/lib/mrr.test.js

@@ -0,0 +1,386 @@
+const MrrStatsService = require('../../lib/mrr');
+const moment = require('moment');
+const sinon = require('sinon');
+const knex = require('knex').default;
+require('should');
+
+describe('MrrStatsService', function () {
+    describe('getHistory', function () {
+        /** @type {MrrStatsService} */
+        let mrrStatsService;
+
+        const today = '2000-01-10';
+        const tomorrow = '2000-01-11';
+        const yesterday = '2000-01-09';
+        const dayBeforeYesterday = '2000-01-08';
+        const twoDaysBeforeYesterday = '2000-01-07';
+
+        after(function () {
+            sinon.restore();
+        });
+
+        /** @type {import('knex').Knex} */
+        let db;
+
+        before(function () {
+            const todayDate = moment(today).toDate();
+            sinon.useFakeTimers(todayDate.getTime());
+        });
+
+        beforeEach(async function () {
+            db = knex({client: 'sqlite3', connection: {filename: ':memory:'}, useNullAsDefault: true});
+            mrrStatsService = new MrrStatsService({knex: db});
+
+            await db.schema.createTable('members_paid_subscription_events', function (table) {
+                table.string('currency');
+                table.string('mrr_delta');
+                table.date('created_at');
+            });
+
+            await db.schema.createTable('members_stripe_customers_subscriptions', function (table) {
+                table.string('plan_currency');
+                table.string('mrr');
+            });
+        });
+
+        it('Handles no data', async function () {
+            const {data: results, meta} = await mrrStatsService.getHistory();
+            results.length.should.eql(1);
+
+            // Note that currencies should always be sorted ascending, so EUR should be first.
+            results[0].should.eql({
+                date: today,
+                mrr: 0,
+                currency: 'usd'
+            });
+            meta.totals.should.eql([
+                {
+                    mrr: 0,
+                    currency: 'usd'
+                }
+            ]);
+        });
+
+        it('Always returns at least one value', async function () {
+            await db('members_stripe_customers_subscriptions').insert([{
+                plan_currency: 'usd',
+                mrr: 1
+            }, {
+                plan_currency: 'eur',
+                mrr: 2
+            }]);
+
+            const {data: results, meta} = await mrrStatsService.getHistory();
+            results.length.should.eql(2);
+
+            // Note that currencies should always be sorted ascending, so EUR should be first.
+            results[0].should.eql({
+                date: today,
+                mrr: 2,
+                currency: 'eur'
+            });
+            results[1].should.eql({
+                date: today,
+                mrr: 1,
+                currency: 'usd'
+            });
+            meta.totals.should.eql([
+                {
+                    mrr: 2,
+                    currency: 'eur'
+                },
+                {
+                    mrr: 1,
+                    currency: 'usd'
+                }
+            ]);
+        });
+
+        it('Does not substract delta of first event', async function () {
+            await db('members_stripe_customers_subscriptions').insert([{
+                plan_currency: 'usd',
+                mrr: 5
+            }]);
+            await db('members_paid_subscription_events').insert([{
+                created_at: today,
+                mrr_delta: 5,
+                currency: 'usd'
+            }]);
+
+            const {data: results, meta} = await mrrStatsService.getHistory();
+            results.length.should.eql(2);
+            results[0].should.eql({
+                date: yesterday,
+                mrr: 0,
+                currency: 'usd'
+            });
+            results[1].should.eql({
+                date: today,
+                mrr: 5,
+                currency: 'usd'
+            });
+            meta.totals.should.eql([
+                {
+                    mrr: 5,
+                    currency: 'usd'
+                }
+            ]);
+        });
+
+        it('Correctly calculates deltas', async function () {
+            await db('members_paid_subscription_events').insert([{
+                created_at: yesterday,
+                mrr_delta: 2,
+                currency: 'usd'
+            },
+            {
+                created_at: today,
+                mrr_delta: 5,
+                currency: 'usd'
+            }]);
+
+            await db('members_stripe_customers_subscriptions').insert([{
+                plan_currency: 'usd',
+                mrr: 2
+            }, {
+                plan_currency: 'usd',
+                mrr: 5
+            }]);
+
+            const {data: results, meta} = await mrrStatsService.getHistory();
+            results.length.should.eql(3);
+            results[0].should.eql({
+                date: dayBeforeYesterday,
+                mrr: 0,
+                currency: 'usd'
+            });
+            results[1].should.eql({
+                date: yesterday,
+                mrr: 2,
+                currency: 'usd'
+            });
+            results[2].should.eql({
+                date: today,
+                mrr: 7,
+                currency: 'usd'
+            });
+            meta.totals.should.eql([
+                {
+                    mrr: 7,
+                    currency: 'usd'
+                }
+            ]);
+        });
+
+        it('Correctly calculates deltas for multiple currencies', async function () {
+            await db('members_paid_subscription_events').insert([
+                {
+                    created_at: yesterday,
+                    mrr_delta: 200,
+                    currency: 'eur'
+                },
+                {
+                    created_at: yesterday,
+                    mrr_delta: 2,
+                    currency: 'usd'
+                },
+                {
+                    created_at: today,
+                    mrr_delta: 800,
+                    currency: 'eur'
+                },
+                {
+                    created_at: today,
+                    mrr_delta: 5,
+                    currency: 'usd'
+                }
+            ]);
+
+            await db('members_stripe_customers_subscriptions').insert([{
+                plan_currency: 'eur',
+                mrr: 200
+            }, {
+                plan_currency: 'usd',
+                mrr: 2
+            }, {
+                plan_currency: 'eur',
+                mrr: 800
+            }, {
+                plan_currency: 'usd',
+                mrr: 5
+            }, {
+                plan_currency: 'eur',
+                mrr: 200
+            }]);
+
+            const {data: results, meta} = await mrrStatsService.getHistory();
+            results.length.should.eql(6);
+            results[0].should.eql({
+                date: dayBeforeYesterday,
+                mrr: 200,
+                currency: 'eur'
+            });
+            results[1].should.eql({
+                date: dayBeforeYesterday,
+                mrr: 0,
+                currency: 'usd'
+            });
+            results[2].should.eql({
+                date: yesterday,
+                mrr: 400,
+                currency: 'eur'
+            });
+            results[3].should.eql({
+                date: yesterday,
+                mrr: 2,
+                currency: 'usd'
+            });
+            results[4].should.eql({
+                date: today,
+                mrr: 1200,
+                currency: 'eur'
+            });
+            results[5].should.eql({
+                date: today,
+                mrr: 7,
+                currency: 'usd'
+            });
+            meta.totals.should.eql([
+                {
+                    mrr: 1200,
+                    currency: 'eur'
+                },
+                {
+                    mrr: 7,
+                    currency: 'usd'
+                }
+            ]);
+        });
+
+        it('Ignores invalid currencies in deltas', async function () {
+            await db('members_paid_subscription_events').insert({
+                created_at: today,
+                mrr_delta: 200,
+                currency: 'abc'
+            });
+
+            await db('members_stripe_customers_subscriptions').insert({
+                plan_currency: 'usd',
+                mrr: 7
+            });
+
+            const {data: results, meta} = await mrrStatsService.getHistory();
+            results.length.should.eql(1);
+            results[0].should.eql({
+                date: yesterday,
+                mrr: 7,
+                currency: 'usd'
+            });
+            meta.totals.should.eql([
+                {
+                    mrr: 7,
+                    currency: 'usd'
+                }
+            ]);
+        });
+
+        it('Ignores events in the future', async function () {
+            await db('members_paid_subscription_events').insert([
+                {
+                    created_at: yesterday,
+                    mrr_delta: 2,
+                    currency: 'usd'
+                },
+                {
+                    created_at: today,
+                    mrr_delta: 5,
+                    currency: 'usd'
+                },
+                {
+                    created_at: tomorrow,
+                    mrr_delta: 10,
+                    currency: 'usd'
+                }
+            ]);
+
+            await db('members_stripe_customers_subscriptions').insert({plan_currency: 'usd', mrr: 7});
+
+            const {data: results, meta} = await mrrStatsService.getHistory();
+            results.length.should.eql(3);
+            results[0].should.eql({
+                date: dayBeforeYesterday,
+                mrr: 0,
+                currency: 'usd'
+            });
+            results[1].should.eql({
+                date: yesterday,
+                mrr: 2,
+                currency: 'usd'
+            });
+            results[2].should.eql({
+                date: today,
+                mrr: 7,
+                currency: 'usd'
+            });
+            meta.totals.should.eql([
+                {
+                    mrr: 7,
+                    currency: 'usd'
+                }
+            ]);
+        });
+
+        it('Correctly handles negative total MRR', async function () {
+            await db('members_paid_subscription_events').insert([
+                {
+                    created_at: dayBeforeYesterday,
+                    mrr_delta: 2,
+                    currency: 'usd'
+                },
+                {
+                    created_at: yesterday,
+                    mrr_delta: -1000,
+                    currency: 'usd'
+                },
+                {
+                    created_at: today,
+                    mrr_delta: 1000,
+                    currency: 'usd'
+                }
+            ]);
+
+            await db('members_stripe_customers_subscriptions').insert({plan_currency: 'usd', mrr: 7});
+
+            const {data: results, meta} = await mrrStatsService.getHistory();
+            results.length.should.eql(4);
+            results[0].should.eql({
+                date: twoDaysBeforeYesterday,
+                mrr: 5,
+                currency: 'usd'
+            });
+            results[1].should.eql({
+                date: dayBeforeYesterday,
+                // We are mainly testing that this should not be 1000!
+                mrr: 7,
+                currency: 'usd'
+            });
+            results[2].should.eql({
+                date: yesterday,
+                // Should never be shown negative (in fact it is -993 here)
+                mrr: 0,
+                currency: 'usd'
+            });
+            results[3].should.eql({
+                date: today,
+                mrr: 7,
+                currency: 'usd'
+            });
+            meta.totals.should.eql([
+                {
+                    mrr: 7,
+                    currency: 'usd'
+                }
+            ]);
+        });
+    });
+});

ghost/stats-service/test/lib/stats.test.js

@@ -0,0 +1,10 @@
+const StatsService = require('../../lib/stats');
+const knex = require('knex').default;
+const assert = require('assert');
+
+describe('StatsService', function () {
+    it('Exposes a create factory', function () {
+        const service = StatsService.create({knex: knex({client: 'sqlite3', connection: {filename: ':memory:'}})});
+        assert(service instanceof StatsService);
+    });
+});

ghost/stats-service/tsconfig.json

@@ -0,0 +1,101 @@
+{
+  "compilerOptions": {
+    /* Visit https://aka.ms/tsconfig.json to read more about this file */
+
+    /* Projects */
+    // "incremental": true,                              /* Enable incremental compilation */
+    // "composite": true,                                /* Enable constraints that allow a TypeScript project to be used with project references. */
+    // "tsBuildInfoFile": "./",                          /* Specify the folder for .tsbuildinfo incremental compilation files. */
+    // "disableSourceOfProjectReferenceRedirect": true,  /* Disable preferring source files instead of declaration files when referencing composite projects */
+    // "disableSolutionSearching": true,                 /* Opt a project out of multi-project reference checking when editing. */
+    // "disableReferencedProjectLoad": true,             /* Reduce the number of projects loaded automatically by TypeScript. */
+
+    /* Language and Environment */
+    "target": "es2016",                                  /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
+    // "lib": [],                                        /* Specify a set of bundled library declaration files that describe the target runtime environment. */
+    // "jsx": "preserve",                                /* Specify what JSX code is generated. */
+    // "experimentalDecorators": true,                   /* Enable experimental support for TC39 stage 2 draft decorators. */
+    // "emitDecoratorMetadata": true,                    /* Emit design-type metadata for decorated declarations in source files. */
+    // "jsxFactory": "",                                 /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h' */
+    // "jsxFragmentFactory": "",                         /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
+    // "jsxImportSource": "",                            /* Specify module specifier used to import the JSX factory functions when using `jsx: react-jsx*`.` */
+    // "reactNamespace": "",                             /* Specify the object invoked for `createElement`. This only applies when targeting `react` JSX emit. */
+    // "noLib": true,                                    /* Disable including any library files, including the default lib.d.ts. */
+    // "useDefineForClassFields": true,                  /* Emit ECMAScript-standard-compliant class fields. */
+
+    /* Modules */
+    "module": "commonjs",                                /* Specify what module code is generated. */
+    // "rootDir": "./",                                  /* Specify the root folder within your source files. */
+    // "moduleResolution": "node",                       /* Specify how TypeScript looks up a file from a given module specifier. */
+    // "baseUrl": "./",                                  /* Specify the base directory to resolve non-relative module names. */
+    // "paths": {},                                      /* Specify a set of entries that re-map imports to additional lookup locations. */
+    // "rootDirs": [],                                   /* Allow multiple folders to be treated as one when resolving modules. */
+    // "typeRoots": [],                                  /* Specify multiple folders that act like `./node_modules/@types`. */
+    // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
+    // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
+    // "resolveJsonModule": true,                        /* Enable importing .json files */
+    // "noResolve": true,                                /* Disallow `import`s, `require`s or `<reference>`s from expanding the number of files TypeScript should add to a project. */
+
+    /* JavaScript Support */
+    "allowJs": true,                                  /* Allow JavaScript files to be a part of your program. Use the `checkJS` option to get errors from these files. */
+    "checkJs": true,                                  /* Enable error reporting in type-checked JavaScript files. */
+    // "maxNodeModuleJsDepth": 1,                        /* Specify the maximum folder depth used for checking JavaScript files from `node_modules`. Only applicable with `allowJs`. */
+
+    /* Emit */
+    // "declaration": true,                              /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
+    // "declarationMap": true,                           /* Create sourcemaps for d.ts files. */
+    // "emitDeclarationOnly": true,                      /* Only output d.ts files and not JavaScript files. */
+    // "sourceMap": true,                                /* Create source map files for emitted JavaScript files. */
+    // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If `declaration` is true, also designates a file that bundles all .d.ts output. */
+    // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
+    // "removeComments": true,                           /* Disable emitting comments. */
+    "noEmit": true,                                   /* Disable emitting files from a compilation. */
+    // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
+    // "importsNotUsedAsValues": "remove",               /* Specify emit/checking behavior for imports that are only used for types */
+    // "downlevelIteration": true,                       /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
+    // "sourceRoot": "",                                 /* Specify the root path for debuggers to find the reference source code. */
+    // "mapRoot": "",                                    /* Specify the location where debugger should locate map files instead of generated locations. */
+    // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
+    // "inlineSources": true,                            /* Include source code in the sourcemaps inside the emitted JavaScript. */
+    // "emitBOM": true,                                  /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
+    // "newLine": "crlf",                                /* Set the newline character for emitting files. */
+    // "stripInternal": true,                            /* Disable emitting declarations that have `@internal` in their JSDoc comments. */
+    // "noEmitHelpers": true,                            /* Disable generating custom helper functions like `__extends` in compiled output. */
+    // "noEmitOnError": true,                            /* Disable emitting files if any type checking errors are reported. */
+    // "preserveConstEnums": true,                       /* Disable erasing `const enum` declarations in generated code. */
+    // "declarationDir": "./",                           /* Specify the output directory for generated declaration files. */
+    // "preserveValueImports": true,                     /* Preserve unused imported values in the JavaScript output that would otherwise be removed. */
+
+    /* Interop Constraints */
+    // "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
+    // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
+    "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */
+    // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
+    "forceConsistentCasingInFileNames": true,            /* Ensure that casing is correct in imports. */
+
+    /* Type Checking */
+    "strict": true,                                      /* Enable all strict type-checking options. */
+    // "noImplicitAny": true,                            /* Enable error reporting for expressions and declarations with an implied `any` type.. */
+    // "strictNullChecks": true,                         /* When type checking, take into account `null` and `undefined`. */
+    // "strictFunctionTypes": true,                      /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */
+    // "strictBindCallApply": true,                      /* Check that the arguments for `bind`, `call`, and `apply` methods match the original function. */
+    // "strictPropertyInitialization": true,             /* Check for class properties that are declared but not set in the constructor. */
+    // "noImplicitThis": true,                           /* Enable error reporting when `this` is given the type `any`. */
+    // "useUnknownInCatchVariables": true,               /* Type catch clause variables as 'unknown' instead of 'any'. */
+    // "alwaysStrict": true,                             /* Ensure 'use strict' is always emitted. */
+    // "noUnusedLocals": true,                           /* Enable error reporting when a local variables aren't read. */
+    // "noUnusedParameters": true,                       /* Raise an error when a function parameter isn't read */
+    // "exactOptionalPropertyTypes": true,               /* Interpret optional property types as written, rather than adding 'undefined'. */
+    // "noImplicitReturns": true,                        /* Enable error reporting for codepaths that do not explicitly return in a function. */
+    // "noFallthroughCasesInSwitch": true,               /* Enable error reporting for fallthrough cases in switch statements. */
+    // "noUncheckedIndexedAccess": true,                 /* Include 'undefined' in index signature results */
+    // "noImplicitOverride": true,                       /* Ensure overriding members in derived classes are marked with an override modifier. */
+    // "noPropertyAccessFromIndexSignature": true,       /* Enforces using indexed accessors for keys declared using an indexed type */
+    // "allowUnusedLabels": true,                        /* Disable error reporting for unused labels. */
+    // "allowUnreachableCode": true,                     /* Disable error reporting for unreachable code. */
+
+    /* Completeness */
+    // "skipDefaultLibCheck": true,                      /* Skip type checking .d.ts files that are included with TypeScript. */
+    "skipLibCheck": true                                 /* Skip type checking all .d.ts files. */
+  }
+}