feat(rustup): Add rustup as a backend

Adds rustup as a backend for pacdef. Only works on
components listed for now.

Signed-off-by: innocentzero <isfarulhaque@proton.me>

crates/pacdef_core/src/backend/actual/mod.rs

@@ -5,3 +5,4 @@ pub mod debian;
 pub mod flatpak;
 pub mod python;
 pub mod rust;
+pub mod rustup;

crates/pacdef_core/src/backend/actual/rustup.rs

@@ -0,0 +1,69 @@
+use crate::backend::backend_trait::{Backend, Switches, Text};
+use crate::backend::macros::impl_backend_constants;
+use crate::{Group, Package};
+use anyhow::Context;
+use core::panic;
+use std::collections::HashSet;
+use std::process::Command;
+
+#[derive(Debug, Clone)]
+pub struct Rustup {
+    pub(crate) packages: HashSet<Package>,
+}
+
+const BINARY: Text = "rustup";
+const SECTION: Text = "rustup";
+
+const SWITCHES_INSTALL: Switches = &["component", "add"];
+const SWITCHES_INFO: Switches = &["component", "list", "--installed"];
+const SWITCHES_MAKE_DEPENDENCY: Switches = &[];
+const SWITCHES_NOCONFIRM: Switches = &[];
+const SWITCHES_REMOVE: Switches = &["component", "remove"];
+
+const SUPPORTS_AS_DEPENDENCY: bool = false;
+
+impl Backend for Rustup {
+    impl_backend_constants!();
+
+    fn get_all_installed_packages(&self) -> anyhow::Result<HashSet<Package>> {
+        let mut cmd = Command::new(self.get_binary());
+        let packages: HashSet<Package> = run_rustup_command(&mut cmd, SWITCHES_INFO)
+            .context("Getting installed components")?
+            .iter()
+            .map(|name| ["component/", name].join("").into())
+            .collect();
+        Ok(packages)
+    }
+
+    fn get_explicitly_installed_packages(&self) -> anyhow::Result<HashSet<Package>> {
+        self.get_all_installed_packages()
+            .context("Getting all installed packages")
+    }
+
+    fn make_dependency(&self, _: &[Package]) -> anyhow::Result<std::process::ExitStatus> {
+        panic!("Not supported by {}", BINARY)
+    }
+}
+
+fn run_rustup_command(cmd: &mut Command, args: &[&str]) -> Result<Vec<String>, anyhow::Error> {
+    cmd.args(args);
+    let output = String::from_utf8(cmd.output()?.stdout)?;
+    let mut val = Vec::new();
+    for i in output.lines() {
+        let mut it = i.splitn(3, "-");
+        let component = it.next().expect("Component name is empty!");
+        match component {
+            "cargo" | "rustfmt" | "clippy" | "miri" | "rls" | "rustc" => {
+                val.push(component.to_string());
+            }
+            _ => {
+                val.push(
+                    component.to_string()
+                        + "-"
+                        + it.next().expect("No such component is managed by rustup"),
+                );
+            }
+        }
+    }
+    Ok(val)
+}