api: Add go files

I know this is a huge commit, but I can't be bothered to check
this in part by part.

api/owner_login_test.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestOwnerLoginBasics(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	if _, err := ownerLogin("test@example.com", "hunter2"); err == nil {
+		t.Errorf("expected error not found when logging in without creating an account")
+		return
+	}
+
+	ownerNew("test@example.com", "Test", "hunter2")
+
+	if _, err := ownerLogin("test@example.com", "hunter2"); err != nil {
+		t.Errorf("unexpected error when logging in: %v", err)
+		return
+	}
+
+	if _, err := ownerLogin("test@example.com", "h******"); err == nil {
+		t.Errorf("expected error not found when given wrong password")
+		return
+	}
+
+	if session, err := ownerLogin("test@example.com", "hunter2"); session == "" {
+		t.Errorf("empty session on successful login: %v", err)
+		return
+	}
+}
+
+func TestOwnerLoginEmpty(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	if _, err := ownerLogin("test@example.com", ""); err == nil {
+		t.Errorf("expected error not found when passing empty password")
+		return
+	}
+
+	ownerNew("test@example.com", "Test", "hunter2")
+
+	if _, err := ownerLogin("test@example.com", ""); err == nil {
+		t.Errorf("expected error not found when passing empty password")
+		return
+	}
+}