Try to work on build some more.

crates/core/src/package.rs

@@ -1,8 +1,10 @@
 use std::hash::Hash;
 use std::path::{Path, PathBuf};
 
+use fs::expand_files;
 use serde::{Deserialize, Serialize};
 
+use crate::class::Class;
 use crate::prey::{F_PREY_LOCK, F_PREY_TOML, Prey, PreyLock};
 
 /// Hashing is only based off the Prey.
@@ -15,6 +17,8 @@ pub struct PackageHandler {
 }
 
 impl PackageHandler {
+    const DIR_JAVA: &str = "java/";
+
     pub fn new<P: AsRef<Path>>(package_root: P, target_dir: P) -> crate::Result<Self> {
         let package_root = package_root.as_ref().to_path_buf();
 
@@ -26,8 +30,6 @@ impl PackageHandler {
         })
     }
 
-    pub fn update_class_cache(&self) {}
-
     pub fn entry_point(&self) -> PathBuf {
         self.prey.entry_point()
     }
@@ -39,6 +41,34 @@ impl PackageHandler {
     pub fn version(&self) -> semver::Version {
         self.prey.version()
     }
+
+    pub fn get_update_targets(&mut self) -> crate::Result<Vec<&mut Class>> {
+        let mut targets = vec![];
+
+        if self.prey_lock.is_none() {
+            // Try to pass a reference to the class so that there's mutability of the object
+            // available at the workspace level instead of parsing all the way down the
+            // tree. How I do this, idk. My brain is friend from a few days of JS.
+
+            self.prey_lock = Some(PreyLock::from(expand_files(Self::DIR_JAVA)?));
+            return Ok(self
+                .prey_lock
+                .clone()
+                .unwrap()
+                .classes
+                .iter()
+                .map(|mut *class| &mut class)
+                .collect());
+        }
+
+        for mut tracked in self.prey_lock.unwrap().classes {
+            if !tracked.is_updated()? {
+                targets.push(&mut tracked);
+            }
+        }
+
+        Ok(targets)
+    }
 }
 
 impl Hash for PackageHandler {