From 0d3591702345aefe9751bb50c00fb0230c60c48a Mon Sep 17 00:00:00 2001
From: Evan Goode <mail@evangoo.de>
Date: Mon, 23 Dec 2024 21:57:35 -0500
Subject: [PATCH] db: fix 3->4 migration of empty DB

---
 db.go           |  6 ++++--
 db_test.go      | 16 ++++++++++++++++
 sql/3-empty.sql | 10 ++++++++++
 3 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 sql/3-empty.sql

diff --git a/db.go b/db.go
index 4529f07..5e6df3a 100644
--- a/db.go
+++ b/db.go
@@ -335,8 +335,10 @@ func Migrate(config *Config, dbPath mo.Option[string], db *gorm.DB, alreadyExist
 				user.Players = append(user.Players, player)
 				users = append(users, user)
 			}
-			if err := tx.Session(&gorm.Session{FullSaveAssociations: true}).Save(&users).Error; err != nil {
-				return err
+			if len(users) > 0 {
+				if err := tx.Session(&gorm.Session{FullSaveAssociations: true}).Save(&users).Error; err != nil {
+					return err
+				}
 			}
 			userVersion += 1
 		}
diff --git a/db_test.go b/db_test.go
index 560c7d6..0a9c685 100644
--- a/db_test.go
+++ b/db_test.go
@@ -42,6 +42,7 @@ func TestDB(t *testing.T) {
 	t.Run("Test 2->3 migration", ts.testMigrate2To3)
 	t.Run("Test 3->4 migration", ts.testMigrate3To4)
 	t.Run("Test 3->4 migration, username/player name collision", ts.testMigrate3To4Collision)
+	t.Run("Test 3->4 migration, empty database", ts.testMigrate3To4Empty)
 	t.Run("Test backwards migration", ts.testMigrateBackwards)
 }
 
@@ -145,6 +146,21 @@ func (ts *TestSuite) testMigrate3To4Collision(t *testing.T) {
 	assert.Equal(t, "qux", v4qux.Players[0].Name)
 }
 
+func (ts *TestSuite) testMigrate3To4Empty(t *testing.T) {
+	db := ts.getFreshDatabase(t)
+
+	query, err := os.ReadFile("sql/3-empty.sql")
+	assert.Nil(t, err)
+	assert.Nil(t, db.Exec(string(query)).Error)
+
+	var users []User
+	assert.Nil(t, db.Find(&users).Error)
+	assert.Equal(t, 0, len(users))
+
+	err = Migrate(ts.Config, mo.None[string](), db, true, 4)
+	assert.Nil(t, err)
+}
+
 func (ts *TestSuite) testMigrateBackwards(t *testing.T) {
 	db := ts.getFreshDatabase(t)
 
diff --git a/sql/3-empty.sql b/sql/3-empty.sql
new file mode 100644
index 0000000..f7fd8d2
--- /dev/null
+++ b/sql/3-empty.sql
@@ -0,0 +1,10 @@
+PRAGMA user_version=3;
+PRAGMA foreign_keys=OFF;
+BEGIN TRANSACTION;
+CREATE TABLE `users` (`is_admin` numeric,`is_locked` numeric,`uuid` text,`username` text NOT NULL UNIQUE,`password_salt` blob NOT NULL,`password_hash` blob NOT NULL,`server_id` text,`player_name` text collate nocase NOT NULL UNIQUE,`offline_uuid` text NOT NULL,`fallback_player` text,`preferred_language` text,`browser_token` text,`api_token` text,`skin_hash` text,`skin_model` text,`cape_hash` text,`created_at` datetime,`name_last_changed_at` datetime,PRIMARY KEY (`uuid`));
+CREATE TABLE `clients` (`uuid` text,`client_token` text,`version` integer,`user_uuid` text,PRIMARY KEY (`uuid`),CONSTRAINT `fk_users_clients` FOREIGN KEY (`user_uuid`) REFERENCES `users`(`uuid`));
+CREATE TABLE `invites` (`code` text,`created_at` datetime,PRIMARY KEY (`code`));
+CREATE INDEX `idx_users_cape_hash` ON `users`(`cape_hash`);
+CREATE INDEX `idx_users_skin_hash` ON `users`(`skin_hash`);
+CREATE INDEX `idx_users_browser_token` ON `users`(`browser_token`);
+COMMIT;