Stub out a command sorta like rostar unpack

src/cli/unpack.rs

@@ -0,0 +1,65 @@
+use std::{io::BufReader, path::PathBuf};
+
+use anyhow::bail;
+use clap::Parser;
+use fs_err::File;
+use rbx_dom_weak::{Instance, WeakDom};
+
+use crate::{Project, ProjectNode};
+
+use super::resolve_path;
+
+/// Unpack a Roblox place file into an existing Rojo project.
+#[derive(Debug, Parser)]
+pub struct UnpackCommand {
+    /// Path to the project to unpack. Defaults to the current directory.
+    #[clap(long, default_value = "")]
+    pub project: PathBuf,
+
+    /// Path to the place to unpack from.
+    pub place: PathBuf,
+}
+
+impl UnpackCommand {
+    pub fn run(self) -> anyhow::Result<()> {
+        let project_path = resolve_path(&self.project);
+        let project = match Project::load_fuzzy(&project_path)? {
+            Some(project) => project,
+            None => bail!("No project file was found; rojo unpack requires a project file."),
+        };
+
+        let place_ext = self
+            .place
+            .extension()
+            .and_then(|ext| ext.to_str())
+            .map(|ext| ext.to_lowercase());
+
+        let file = BufReader::new(File::open(&self.place)?);
+
+        let dom = match place_ext.as_deref() {
+            Some("rbxl") => rbx_binary::from_reader(file)?,
+            Some("rbxlx") => rbx_xml::from_reader_default(file)?,
+            Some(_) | None => bail!("Place files must end in .rbxl or .rbxlx"),
+        };
+
+        let context = Context { project, dom };
+        context.unpack();
+
+        Ok(())
+    }
+}
+
+struct Context {
+    project: Project,
+    dom: WeakDom,
+}
+
+impl Context {
+    fn unpack(&self) {
+        self.unpack_node(&self.project.tree, self.dom.root());
+    }
+
+    fn unpack_node(&self, node: &ProjectNode, instance: &Instance) {
+        // TODO
+    }
+}