lsp: Add code action to add missing imports

blueprintcompiler/language/types.py

@@ -55,7 +55,16 @@ class TypeName(AstNode):
     @validate("namespace")
     def gir_ns_exists(self):
         if not self.tokens["extern"]:
-            self.root.gir.validate_ns(self.tokens["namespace"])
+            try:
+                self.root.gir.validate_ns(self.tokens["namespace"])
+            except CompileError as e:
+                ns = self.tokens["namespace"]
+                e.actions = [
+                    self.root.import_code_action(n, version)
+                    for n, version in gir.get_available_namespaces()
+                    if n == ns
+                ]
+                raise e
 
     @validate()
     def deprecated(self) -> None:

blueprintcompiler/language/ui.py

@@ -99,6 +99,18 @@ class UI(AstNode):
             and self.template.class_name.glib_type_name == id
         )
 
+    def import_code_action(self, ns: str, version: str) -> CodeAction:
+        if len(self.children[Import]):
+            pos = self.children[Import][-1].range.end
+        else:
+            pos = self.children[GtkDirective][0].range.end
+
+        return CodeAction(
+            f"Import {ns} {version}",
+            f"\nusing {ns} {version};",
+            Range(pos, pos, self.group.text),
+        )
+
     @context(ScopeCtx)
     def scope_ctx(self) -> ScopeCtx:
         return ScopeCtx(node=self)