import importlib.util
from pathlib import Path
import sqlite3
import tempfile
import unittest

spec = importlib.util.spec_from_file_location("migration", Path(__file__).with_name("migrate_user_links.py"))
migration = importlib.util.module_from_spec(spec)
spec.loader.exec_module(migration)


class MigrationTest(unittest.TestCase):
    def test_dry_run_idempotent_migration_and_rename(self):
        with tempfile.TemporaryDirectory() as temporary:
            path = Path(temporary) / "test.db"
            with sqlite3.connect(path) as db:
                db.executescript("""
                    CREATE TABLE User(id INTEGER PRIMARY KEY, username TEXT);
                    CREATE TABLE sub_bind(key TEXT PRIMARY KEY, user TEXT, subscription_account_id INTEGER);
                    CREATE TABLE sub_update_record(id INTEGER PRIMARY KEY, user TEXT, location TEXT);
                    INSERT INTO User VALUES(1,'old-name');
                    INSERT INTO sub_bind VALUES('example-key','old-name',2);
                    INSERT INTO sub_update_record VALUES(10,'old-name','unknown');
                    INSERT INTO sub_update_record VALUES(11,'old-name','unknown');
                """)
            before = path.read_bytes()
            self.assertEqual(2, len(migration.migrate(path)["schema_changes"]))
            self.assertEqual(before, path.read_bytes())
            self.assertEqual(0, migration.migrate(path, True)["unresolved_bindings"])
            self.assertEqual([], migration.migrate(path, True)["schema_changes"])
            with sqlite3.connect(path) as db:
                db.execute("update User set username='new-name' where id=1")
                self.assertEqual((1,), db.execute("select user_id from sub_bind").fetchone())
                # A slow first lookup must not overwrite the second request's row.
                db.execute("update sub_update_record set location='first-location' where id=10")
                self.assertEqual(("unknown",), db.execute("select location from sub_update_record where id=11").fetchone())

    def test_ambiguous_names_fail_without_modifying_database(self):
        with tempfile.TemporaryDirectory() as temporary:
            path = Path(temporary) / "test.db"
            with sqlite3.connect(path) as db:
                db.executescript("""
                    CREATE TABLE User(id INTEGER PRIMARY KEY, username TEXT);
                    CREATE TABLE sub_bind(user TEXT);
                    CREATE TABLE sub_update_record(user TEXT);
                    INSERT INTO User VALUES(1,'same'),(2,'same');
                """)
            before = path.read_bytes()
            with self.assertRaises(ValueError):
                migration.migrate(path, True)
            self.assertEqual(before, path.read_bytes())


if __name__ == "__main__":
    unittest.main()