chore: script to import user tracks to another user (#759)

## Goal

Help Robert (and other users) import his playlists to his new account.

## Important

- the list of playlists of the destination user will be overwritten
   => existing tracks (if any) on that profile may end up in old playlists.
- on each imported track, the number of plays, reposts and likes will be reset to zero.

## Usage in development

```sh
$ . ./env-vars-testing-local.sh
$ node scripts/import-from-prod.js adrien # imports 21 tracks from openwhyd.com/adrien --> local id: 4d94501d1f78ac091dbc9b4d
$ node scripts/import-posts.js 4d94501d1f78ac091dbc9b4d 000000000000000000000002 # copy to local id: 000000000000000000000002
```

## Usage in production

```sh
$ . env-vars-local.sh
$ node scripts/import-posts.js 5f0f0d701125f9d3afca1bcc 6591c8dd0890c870388d2508 # imports all posts from https://openwhyd.org/u/5f0f0d701125f9d3afca1bcc
```

env-vars-testing-local.sh

@@ -1,3 +1,4 @@
 . ./env-vars-testing.sh
 . ./.env-local # helpful to store secrets, e.g. credentials for auth0 development tenant
 export MONGODB_PORT=27117
+export URL_PREFIX="http://localhost:8080"

scripts/import-posts.js

@@ -0,0 +1,118 @@
+// @ts-check
+
+// Import tracks from a user into another openwhyd account.
+//
+// IMPORTANT:
+// - the list of playlists of the destination user will be overwritten
+//   => existing tracks (if any) on that profile may end up in old playlists.
+// - on each imported track, the number of plays, reposts and likes will be reset to zero.
+//
+// Usage in production:
+//   $ . env-vars-local.sh
+//   $ node scripts/import-posts.js 5f0f0d701125f9d3afca1bcc 6591c8dd0890c870388d2508 # imports all posts from https://openwhyd.org/u/5f0f0d701125f9d3afca1bcc
+
+const assert = require('node:assert');
+const request = require('request');
+const mongodb = require('mongodb');
+
+const ObjectId = (id) => new mongodb.ObjectId(id);
+
+// Parameters
+const fromUserId = process.argv[2];
+const toUserId = process.argv[3];
+assert.ok(
+  fromUserId && toUserId,
+  'Usage: $ node scripts/import-posts.js <from_user_id> <to_user_id>',
+);
+
+// Environment
+const {
+  URL_PREFIX,
+  MONGODB_HOST,
+  MONGODB_PORT,
+  MONGODB_DATABASE,
+  MONGODB_USER,
+  MONGODB_PASS,
+} = process.env;
+const authStr =
+  MONGODB_USER && MONGODB_PASS
+    ? encodeURIComponent(MONGODB_USER) +
+      ':' +
+      encodeURIComponent(MONGODB_PASS) +
+      '@'
+    : '';
+const url = `mongodb://${authStr}${MONGODB_HOST}:${MONGODB_PORT}`;
+const dbName = MONGODB_DATABASE;
+
+const connectToDb = ({ url, dbName }) => {
+  const client = new mongodb.MongoClient(url);
+  return { db: client.db(dbName), client };
+};
+
+const fetchUserProfile = ({ userId }) =>
+  new Promise((resolve, reject) => {
+    const url = `${URL_PREFIX}/api/user/${userId}?format=json`;
+    console.warn(`fetching profile from ${url} ...`);
+    request(url, (err, _, body) =>
+      err ? reject(err) : resolve(JSON.parse(body)),
+    );
+  });
+
+const updateUser = ({ db, user }) => {
+  const { _id, ...userData } = user;
+  return db
+    .collection('user')
+    .updateOne({ _id: ObjectId(_id) }, { $set: { ...userData } });
+};
+
+/** Returns list of posts, from most recent to oldest */
+const fetchUserPosts = ({ userId }) =>
+  new Promise((resolve, reject) => {
+    const limit = 99999999;
+    const url = `${URL_PREFIX}/u/${userId}?format=json&limit=${limit}`;
+    console.warn(`fetching posts from ${url} ...`);
+    request(url, (err, _, body) =>
+      err
+        ? reject(err)
+        : resolve({
+            posts: JSON.parse(body),
+          }),
+    );
+  });
+
+const insertPosts = ({ db, posts, postOverrides }) => {
+  const postsToImport = posts
+    .reverse() // _id will be regenerated chronologically => sort posts from oldest to most recent
+    .map(({ _id, ...post }) => ({
+      ...post,
+      nbP: 0,
+      nbR: 0,
+      lov: [],
+      ...postOverrides, // may include uId and uNm
+    }));
+  return db.collection('post').insertMany(postsToImport);
+};
+
+(async () => {
+  console.warn(`connecting to ${MONGODB_HOST}:${MONGODB_PORT}/${dbName} ...`);
+  const { db, client } = await connectToDb({ url, dbName });
+  const { pl } = await fetchUserProfile({ userId: fromUserId });
+  const { name: toUserName } = await fetchUserProfile({ userId: toUserId });
+  console.warn(
+    `about to import posts of ${pl.length} playlists, from user ${fromUserId} to ${toUserId} (${toUserName})`,
+  );
+  await new Promise((resolve) => setTimeout(resolve, 5000)); // give user some time to Ctrl-C
+  await updateUser({ db, user: { _id: toUserId, pl } });
+  const { posts } = await fetchUserPosts({ userId: fromUserId });
+  console.warn(`inserting ${posts.length} posts...`);
+  await insertPosts({
+    db,
+    posts,
+    postOverrides: { uId: toUserId, uNm: toUserName },
+  });
+  client.close();
+  console.warn(`✅ ${posts.length} posts imported to ${toUserId}`);
+})().catch((err) => {
+  console.error(err);
+  process.exit(1);
+});