feat: scaffold files service

migrations/002_access_functions.up.sql

@@ -0,0 +1,48 @@
+CREATE OR REPLACE FUNCTION has_node_access(p_node_id UUID, p_user_id UUID)
+RETURNS BOOLEAN
+LANGUAGE sql
+STABLE
+AS $$
+WITH RECURSIVE ancestors AS (
+    SELECT id, parent_id FROM files_nodes WHERE id = p_node_id AND deleted_at IS NULL
+    UNION ALL
+    SELECT p.id, p.parent_id
+      FROM files_nodes p
+      JOIN ancestors a ON a.parent_id = p.id
+     WHERE p.deleted_at IS NULL
+)
+SELECT EXISTS (
+    SELECT 1
+      FROM ancestors a
+      JOIN files_access fa ON fa.node_id = a.id
+     WHERE fa.user_id = p_user_id
+);
+$$;
+
+CREATE OR REPLACE FUNCTION effective_node_access(p_node_id UUID, p_user_id UUID, p_subordinate_ids TEXT[])
+RETURNS TEXT
+LANGUAGE sql
+STABLE
+AS $$
+WITH RECURSIVE ancestors AS (
+    SELECT id, parent_id, owner_user_id FROM files_nodes WHERE id = p_node_id AND deleted_at IS NULL
+    UNION ALL
+    SELECT p.id, p.parent_id, p.owner_user_id
+      FROM files_nodes p
+      JOIN ancestors a ON a.parent_id = p.id
+     WHERE p.deleted_at IS NULL
+),
+direct_access AS (
+    SELECT fa.access_level
+      FROM ancestors a
+      JOIN files_access fa ON fa.node_id = a.id
+     WHERE fa.user_id = p_user_id
+)
+SELECT CASE
+    WHEN EXISTS (SELECT 1 FROM files_nodes n WHERE n.id = p_node_id AND n.owner_user_id = p_user_id AND n.deleted_at IS NULL) THEN 'edit'
+    WHEN EXISTS (SELECT 1 FROM files_nodes n WHERE n.id = p_node_id AND n.owner_user_id::text = ANY(p_subordinate_ids) AND n.deleted_at IS NULL) THEN 'view'
+    WHEN EXISTS (SELECT 1 FROM direct_access WHERE access_level = 'edit') THEN 'edit'
+    WHEN EXISTS (SELECT 1 FROM direct_access) THEN 'view'
+    ELSE ''
+END;
+$$;