Created by [@cadence:cadence.moe](https://matrix.to/#/@cadence:cadence.moe) // Discuss in [#out-of-your-element:cadence.moe](https://matrix.to/#/#out-of-your-element:cadence.moe)
* Reliable: Any errors on either side are notified on Matrix and can be retried.
* Tested: A test suite and code coverage make sure all the core logic works.
* Simple development: No build step (it's JavaScript, not TypeScript), minimal/lightweight dependencies, and abstraction only where necessary so that less background knowledge is required. No need to learn about Intents or library functions.
Using WeatherStack as a thin layer between the bridge application and the Discord API lets us control exactly what data is cached. Only necessary information is cached. For example, member data, user data, message content, and past edits are never stored in memory. This keeps the memory usage low and also prevents it ballooning in size over the bridge's runtime.
The bridge uses a small SQLite database to store relationships like which Discord messages correspond to which Matrix messages. This is so the bridge knows what to edit when some message is edited on Discord. Using `without rowid` on the database tables stores the index and the data in the same B-tree. Since Matrix and Discord's internal IDs are quite long, this vastly reduces storage space because those IDs do not have to be stored twice separately. Some event IDs are actually stored as xxhash integers to reduce storage requirements even more. On my personal instance of OOYE, every 100,000 messages require 16.1 MB of storage space in the SQLite database.
File uploads (like avatars from bridged members) are checked locally and deduplicated. Only brand new files are uploaded to the homeserver. This saves loads of space in the homeserver's media repo, especially for Synapse.
Switching to [WAL mode](https://www.sqlite.org/wal.html) could improve your database access speed even more. Run `node scripts/wal.js` if you want to switch to WAL mode.
1. [Get Node.js version 18 or later](https://nodejs.org/en/download/releases) (the version is required by the better-sqlite3 and matrix-appservice dependencies)
1. Copy `registration.example.yaml` to `registration.yaml` and fill in bracketed values. You could generate each hex string with `dd if=/dev/urandom bs=32 count=1 2> /dev/null | basenc --base16 | dd conv=lcase 2> /dev/null`. Register the registration in Synapse's `homeserver.yaml` through the usual appservice installation process, then restart Synapse.
* Be sure to install dependencies with `--save-dev` so you can run the tests.
* Any files you change will automatically be reloaded, except for `stdin.js` and `d2m/discord-*.js`.
* If developing on a different computer to the one running the homeserver, use SSH port forwarding so that Synapse can connect on its `localhost:6693` to reach the running bridge on your computer. Example: `ssh -T -v -R 6693:localhost:6693 me@matrix.cadence.moe`
* I recommend developing in Visual Studio Code so that the JSDoc x TypeScript annotation comments work. I don't know which other editors or language servers support annotations and type inference.
* (0) try-to-catch: Not strictly necessary, but it does what I want and has no dependencies.
* (1) turndown: I need an HTML-to-Markdown converter and this one looked suitable enough. It has some bugs that I've worked around, so I might switch away from it later.
