use libgit2 to track PRs (#10)v0.2.0

* nix: don't depend on registry for nixpkgs input

* use libgit2 to track PRs

* nix: don't use ci devShell as defaul

* crates: bump serenity from `9ad74d4` to `0.12.2

* nix: fix cross compiled builds

* crates: split more from client

* bot-jobs: update remote refs more efficiently

* git-tracker: account for HEAD commits

* bot-config: use nixpkgs branches from environment

* bot-commands: don't display branches prs haven't landed in

* git-tracker: return false when commits aren't found

this is annoying as a hard error since it turns out github will report
garbage merge commit SHAs for PRs that *haven't* been merged yet. yay

* bot: improve docs in some places

* bot-client: display invite link on start

* bot-http: add TeawieClientExt

* bot-commands: add /about

* docs: update readme todos

* nix: enable StateDirectory in module

* crates: bump to 0.2.0

1 files changed, 77 insertions, 0 deletions

diff --git a/crates/bot-jobs/src/repo.rs b/crates/bot-jobs/src/repo.rs
new file mode 100644
index 0000000..4d3e214
--- /dev/null
+++ b/crates/bot-jobs/src/repo.rs
@@ -0,0 +1,77 @@
+use bot_consts::{NIXPKGS_REMOTE, NIXPKGS_URL};
+use bot_error::Error;
+
+use std::{io::Write, path::Path};
+
+use git2::{AutotagOption, FetchOptions, RemoteCallbacks, Repository};
+use log::{debug, info, trace, warn};
+
+pub const TTL_SECS: u64 = 60 * 5; // 5 minutes
+
+// much of this is shamelessly lifted from
+// https://github.com/rust-lang/git2-rs/blob/9a5c9706ff578c936be644dd1e8fe155bdc4d129/examples/pull.rs
+
+/// basic set of options for fetching from remotes
+fn fetch_options<'a>() -> FetchOptions<'a> {
+	let mut remote_callbacks = RemoteCallbacks::new();
+	remote_callbacks.transfer_progress(|progress| {
+		if progress.received_objects() == progress.total_objects() {
+			trace!(
+				"Resolving deltas {}/{}\r",
+				progress.indexed_deltas(),
+				progress.total_deltas()
+			);
+		} else {
+			trace!(
+				"Received {}/{} objects ({}) in {} bytes\r",
+				progress.received_objects(),
+				progress.total_objects(),
+				progress.indexed_objects(),
+				progress.received_bytes()
+			);
+		}
+		std::io::stdout().flush().ok();
+		true
+	});
+
+	let mut fetch_opts = FetchOptions::new();
+	fetch_opts.remote_callbacks(remote_callbacks);
+
+	fetch_opts
+}
+
+/// update the given branches in the [`repository`] using the nixpkgs remote
+fn update_branches_in(repository: &Repository, branches: &[String]) -> Result<(), Error> {
+	let mut remote = repository.find_remote(NIXPKGS_REMOTE)?;
+	// download all the refs
+	remote.download(branches, Some(&mut fetch_options()))?;
+	remote.disconnect()?;
+	// and (hopefully) update what they refer to for later
+	remote.update_tips(None, true, AutotagOption::Auto, None)?;
+
+	Ok(())
+}
+
+pub fn fetch_or_update_repository(path: &str, branches: &[String]) -> Result<(), Error> {
+	// Open our repository or clone it if it doesn't exist
+	let path = Path::new(path);
+	let repository = if path.exists() {
+		Repository::open(path)?
+	} else {
+		warn!(
+			"Couldn't find repository at {}! Cloning a fresh one from {NIXPKGS_URL}",
+			path.display()
+		);
+		Repository::clone(NIXPKGS_URL, path)?;
+		info!("Finished cloning to {}", path.display());
+
+		// bail early as we already have a fresh copy
+		return Ok(());
+	};
+
+	debug!("Updating repository at {}", path.display());
+	update_branches_in(&repository, branches)?;
+	debug!("Finished updating!");
+
+	Ok(())
+}