8 files changed, 64 insertions, 24 deletions

diff --git a/crates/base_db/src/lib.rs b/crates/base_db/src/lib.rs
index 71e85c6ac..37a8432bd 100644
--- a/crates/base_db/src/lib.rs
+++ b/crates/base_db/src/lib.rs
@@ -96,7 +96,7 @@ pub trait FileLoader {
     /// `#[path = "C://no/way"]`
     fn resolve_path(&self, anchor: FileId, path: &str) -> Option<FileId>;
     fn relevant_crates(&self, file_id: FileId) -> Arc<FxHashSet<CrateId>>;
-    fn list_some_random_files_todo(&self, anchor: FileId) -> Vec<(FileId, String)>;
+    fn possible_sudmobules(&self, module_file: FileId) -> Vec<(FileId, String)>;
 }
 
 /// Database which stores all significant input facts: source code and project
@@ -166,8 +166,25 @@ impl<T: SourceDatabaseExt> FileLoader for FileLoaderDelegate<&'_ T> {
         self.0.source_root_crates(source_root)
     }
 
-    fn list_some_random_files_todo(&self, anchor: FileId) -> Vec<(FileId, String)> {
-        self.source_root(anchor).file_set.list_some_random_files_todo(anchor)
+    fn possible_sudmobules(&self, module_file: FileId) -> Vec<(FileId, String)> {
+        fn possible_sudmobules_opt(
+            module_files: &FileSet,
+            module_file: FileId,
+        ) -> Option<Vec<(FileId, String)>> {
+            // TODO kb resolve path thinks that the input is a file...
+            let directory_with_module_file = module_files.resolve_path(module_file, "/../")?;
+            let directory_with_applicable_modules =
+                match module_files.file_name_and_extension(module_file)? {
+                    ("mod", "rs") | ("lib", "rs") => Some(directory_with_module_file),
+                    (directory_with_module_name, "rs") => module_files
+                        .resolve_path(directory_with_module_file, directory_with_module_name),
+                    _ => None,
+                }?;
+            Some(module_files.list_files(directory_with_applicable_modules))
+        }
+
+        possible_sudmobules_opt(&self.source_root(module_file).file_set, module_file)
+            .unwrap_or_default()
     }
 }
 
diff --git a/crates/hir_def/src/test_db.rs b/crates/hir_def/src/test_db.rs
index 42a762936..a35ed4f3c 100644
--- a/crates/hir_def/src/test_db.rs
+++ b/crates/hir_def/src/test_db.rs
@@ -63,6 +63,9 @@ impl FileLoader for TestDB {
     fn relevant_crates(&self, file_id: FileId) -> Arc<FxHashSet<CrateId>> {
         FileLoaderDelegate(self).relevant_crates(file_id)
     }
+    fn possible_sudmobules(&self, module_file: FileId) -> Vec<(FileId, String)> {
+        FileLoaderDelegate(self).possible_sudmobules(module_file)
+    }
 }
 
 impl TestDB {
diff --git a/crates/hir_expand/src/test_db.rs b/crates/hir_expand/src/test_db.rs
index 86a5d867e..a0d1525b0 100644
--- a/crates/hir_expand/src/test_db.rs
+++ b/crates/hir_expand/src/test_db.rs
@@ -46,4 +46,7 @@ impl FileLoader for TestDB {
     fn relevant_crates(&self, file_id: FileId) -> Arc<FxHashSet<CrateId>> {
         FileLoaderDelegate(self).relevant_crates(file_id)
     }
+    fn possible_sudmobules(&self, module_file: FileId) -> Vec<(FileId, String)> {
+        FileLoaderDelegate(self).possible_sudmobules(module_file)
+    }
 }
diff --git a/crates/hir_ty/src/test_db.rs b/crates/hir_ty/src/test_db.rs
index 15b8435e9..6f61e7dfe 100644
--- a/crates/hir_ty/src/test_db.rs
+++ b/crates/hir_ty/src/test_db.rs
@@ -73,6 +73,9 @@ impl FileLoader for TestDB {
     fn relevant_crates(&self, file_id: FileId) -> Arc<FxHashSet<CrateId>> {
         FileLoaderDelegate(self).relevant_crates(file_id)
     }
+    fn possible_sudmobules(&self, module_file: FileId) -> Vec<(FileId, String)> {
+        FileLoaderDelegate(self).possible_sudmobules(module_file)
+    }
 }
 
 impl TestDB {
diff --git a/crates/ide/src/completion/completion_context.rs b/crates/ide/src/completion/completion_context.rs
index 4d8b3670b..cbfc77a46 100644
--- a/crates/ide/src/completion/completion_context.rs
+++ b/crates/ide/src/completion/completion_context.rs
@@ -120,11 +120,10 @@ impl<'a> CompletionContext<'a> {
                     if !matches!(definition_source.value, ModuleSource::SourceFile(_)) {
                         return None;
                     }
-                    let definition_source_file = definition_source.file_id.original_file(db);
-
-                    // TODO kb for all possible candidates
-                    let zz = db.list_some_random_files_todo(definition_source_file);
-                    dbg!(zz);
+                    let module_definition_source_file = definition_source.file_id.original_file(db);
+                    let mod_declaration_candidates =
+                        db.possible_sudmobules(module_definition_source_file);
+                    dbg!(mod_declaration_candidates);
                     // TODO kb exlude existing children from the candidates
                     let existing_children = current_module.children(db).collect::<Vec<_>>();
                     dbg!(existing_children);
diff --git a/crates/ide_db/src/lib.rs b/crates/ide_db/src/lib.rs
index f3197cc39..dc1d2b9fe 100644
--- a/crates/ide_db/src/lib.rs
+++ b/crates/ide_db/src/lib.rs
@@ -74,8 +74,8 @@ impl FileLoader for RootDatabase {
     fn relevant_crates(&self, file_id: FileId) -> Arc<FxHashSet<CrateId>> {
         FileLoaderDelegate(self).relevant_crates(file_id)
     }
-    fn list_some_random_files_todo(&self, anchor: FileId) -> Vec<(FileId, String)> {
-        FileLoaderDelegate(self).list_some_random_files_todo(anchor)
+    fn possible_sudmobules(&self, module_file: FileId) -> Vec<(FileId, String)> {
+        FileLoaderDelegate(self).possible_sudmobules(module_file)
     }
 }
 
diff --git a/crates/vfs/src/file_set.rs b/crates/vfs/src/file_set.rs
index 8bce17bc0..0caddc3bc 100644
--- a/crates/vfs/src/file_set.rs
+++ b/crates/vfs/src/file_set.rs
@@ -20,15 +20,24 @@ impl FileSet {
         self.files.len()
     }
     pub fn resolve_path(&self, anchor: FileId, path: &str) -> Option<FileId> {
-        let mut base = self.paths[&anchor].clone();
+        let mut base = dbg!(self.paths[&anchor].clone());
         base.pop();
-        let path = base.join(path)?;
+        let path = dbg!(base).join(dbg!(path))?;
         self.files.get(&path).copied()
     }
-    pub fn list_some_random_files_todo(&self, anchor: FileId) -> Vec<(FileId, String)> {
-        let anchor_path = self.paths[&anchor].clone();
+
+    pub fn file_name_and_extension(&self, file: FileId) -> Option<(&str, &str)> {
+        self.paths[&file].file_name_and_extension()
+    }
+
+    pub fn list_files(&self, directory: FileId) -> Vec<(FileId, String)> {
+        // TODO kb determine the ways to list all applicable files
+        // Maybe leave list directory here only and the move the rest of the logic into the database impl?
+        // cache results in Salsa?
+
+        dbg!(directory);
         /*
-        [crates/vfs/src/file_set.rs:30] anchor_path = "/Users/someonetoignore/Downloads/tmp_dir/zzzz/src/lib.rs"
+        [crates/vfs/src/file_set.rs:30] directory = "/Users/someonetoignore/Downloads/tmp_dir/zzzz/src/"
         [crates/vfs/src/file_set.rs:31] self.files.keys() = [
             "/Users/someonetoignore/Downloads/tmp_dir/zzzz/src/test_mod_1/test_mod_2/test_mod_3.rs",
             "/Users/someonetoignore/Downloads/tmp_dir/zzzz/src/test_mod_1/test_mod_2.rs",
@@ -38,15 +47,6 @@ impl FileSet {
             "/Users/someonetoignore/Downloads/tmp_dir/zzzz/src/test_mod_3.rs",
         ]
         */
-
-        // TODO kb determine the ways to list all applicable files
-        // Maybe leave list directory here only and the move the rest of the logic into the database impl?
-
-        // Need to get the following things:
-        // * name of the anchor_path file (file_name, validate that it's a file!)
-        // * list of all files in the file's contai/ning directory (file_dir)
-        // * list of all files in `file_dir/file_name` or just `file_dir/`, for lib.rs or mod.rs
-        // * consider special case for /src/bin/foo.rs as a mod<|> source
         Vec::new()
     }
     pub fn insert(&mut self, file_id: FileId, path: VfsPath) {
diff --git a/crates/vfs/src/vfs_path.rs b/crates/vfs/src/vfs_path.rs
index 944a702df..7b965bb4c 100644
--- a/crates/vfs/src/vfs_path.rs
+++ b/crates/vfs/src/vfs_path.rs
@@ -49,6 +49,16 @@ impl VfsPath {
         }
     }
 
+    pub fn file_name_and_extension(&self) -> Option<(&str, &str)> {
+        match &self.0 {
+            VfsPathRepr::PathBuf(p) => p
+                .file_stem()
+                .zip(p.extension())
+                .and_then(|(name, extension)| Some((name.to_str()?, extension.to_str()?))),
+            VfsPathRepr::VirtualPath(p) => p.file_name_and_extension(),
+        }
+    }
+
     // Don't make this `pub`
     pub(crate) fn encode(&self, buf: &mut Vec<u8>) {
         let tag = match &self.0 {
@@ -268,4 +278,9 @@ impl VirtualPath {
         res.0 = format!("{}/{}", res.0, path);
         Some(res)
     }
+
+    pub fn file_name_and_extension(&self) -> Option<(&str, &str)> {
+        // TODO kb check if is a file
+        Some(("test_mod_1", "rs"))
+    }
 }