session: handle removed linked account

If a user creates a session linked to an account, but later deletes that
account using the `litcli accounts remove` command, the KVDB session
will still contain the account ID of the removed account.

During the KVDB to SQL migration, the accounts migration runs before the
sessions migration. Since the deleted account no longer exists, it
cannot be migrated. As a result, the migrated SQL session cannot link to
the now non-existent account in the SQL store.

In such cases, we will migrate the session and not link to any account
in the SQL session.

Author: ViktorT-11

session/sql_migration.go

@@ -13,6 +13,7 @@ import (
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightninglabs/lightning-terminal/accounts"
 	"github.com/lightninglabs/lightning-terminal/db/sqlc"
+	"github.com/lightningnetwork/lnd/fn"
 	"github.com/lightningnetwork/lnd/sqldb"
 	"github.com/pmezard/go-difflib/difflib"
 	"go.etcd.io/bbolt"
@@ -196,6 +197,7 @@ func migrateSessionsToSQLAndValidate(ctx context.Context,
 		overrideSessionTimeZone(kvSession)
 		overrideSessionTimeZone(migratedSession)
 		overrideMacaroonRecipe(kvSession, migratedSession)
+		overrideRemovedAccount(kvSession, migratedSession)
 
 		if !reflect.DeepEqual(kvSession, migratedSession) {
 			diff := difflib.UnifiedDiff{
@@ -245,7 +247,17 @@ func migrateSingleSessionToSQL(ctx context.Context,
 		var acctDBID int64
 		acctDBID, err = tx.GetAccountIDByAlias(ctx, acctAlias)
 		if errors.Is(err, sql.ErrNoRows) {
-			err = accounts.ErrAccNotFound
+			// If we can't find the account in the SQL store, it
+			// most likely means that the user deleted the account
+			// with the "litcli accounts remove" command after the
+			// session was created. We therefore can't link the
+			// SQL session to the account, and we therefore just
+			// leave the acctID as sql.Null
+			log.Warnf("Unable to find account %v in SQL store, "+
+				"skipping linking session %x to account",
+				acctAlias, session.ID)
+			err = nil
+
 			return
 		} else if err != nil {
 			return
@@ -495,3 +507,26 @@ func overrideMacaroonRecipe(kvSession *Session, migratedSession *Session) {
 		}
 	}
 }
+
+// overrideRemovedAccount modifies the kvSession to remove the account ID if the
+// migrated session does not have an account ID, while the kvSession has one.
+// This happens when the account was not found in the SQL store during the
+// migration, which can occur if the account was deleted after the session
+// was created.
+func overrideRemovedAccount(kvSession *Session, migratedSession *Session) {
+	kvSession.AccountID = fn.ElimOption(
+		migratedSession.AccountID,
+
+		// If the migrated session does not have a linked account, we
+		// also remove it from the kv session.
+		func() fn.Option[accounts.AccountID] {
+			return fn.None[accounts.AccountID]()
+		},
+
+		// If the migrated session has a linked account, we keep the
+		// account on the kv session.
+		func(id accounts.AccountID) fn.Option[accounts.AccountID] {
+			return kvSession.AccountID
+		},
+	)
+}

session/sql_migration_test.go

@@ -76,6 +76,11 @@ func TestSessionsStoreMigration(t *testing.T) {
 			// kvSession has such a recipe stored.
 			overrideMacaroonRecipe(kvSession, sqlSession)
 
+			// We also need to override the account ID if the
+			// kvSession has an account ID set, while the SQL
+			// session doesn't.
+			overrideRemovedAccount(kvSession, sqlSession)
+
 			assertEqualSessions(t, kvSession, sqlSession)
 		}
 
@@ -314,6 +319,51 @@ func TestSessionsStoreMigration(t *testing.T) {
 				return getBoltStoreSessions(t, store)
 			},
 		},
+		{
+			name: "one session with a deleted linked account",
+			populateDB: func(t *testing.T, store *BoltStore,
+				acctStore accounts.Store) []*Session {
+
+				// Create an account with balance
+				acct, err := acctStore.NewAccount(
+					ctx, 1234, time.Now().Add(time.Hour),
+					"",
+				)
+				require.NoError(t, err)
+				require.False(t, acct.HasExpired())
+
+				// For now, we manually add the account caveat
+				// for bbolt compatibility.
+				accountCaveat := checkers.Condition(
+					macaroons.CondLndCustom,
+					fmt.Sprintf("%s %x",
+						accounts.CondAccount,
+						acct.ID[:],
+					),
+				)
+
+				sessCaveats := []macaroon.Caveat{
+					{
+						Id: []byte(accountCaveat),
+					},
+				}
+
+				_, err = store.NewSession(
+					ctx, "test", TypeMacaroonAccount,
+					time.Unix(1000, 0), "",
+					WithAccount(acct.ID),
+					WithMacaroonRecipe(sessCaveats, nil),
+				)
+				require.NoError(t, err)
+
+				// Now delete the account, which represents
+				// that the user ran "litcli accounts remove".
+				err = acctStore.RemoveAccount(ctx, acct.ID)
+				require.NoError(t, err)
+
+				return getBoltStoreSessions(t, store)
+			},
+		},
 		{
 			name: "linked session",
 			populateDB: func(t *testing.T, store *BoltStore,
@@ -664,6 +714,16 @@ func randomizedSessions(t *testing.T, kvStore *BoltStore,
 			}
 		}
 
+		// When an account is set, we also remove the account in 50% of
+		// the cases. This simulates that the user ran "litcli accounts
+		// remove" after creating the session.
+		activeSess.AccountID.WhenSome(func(id accounts.AccountID) {
+			if rand.Intn(2) == 0 {
+				err = accountsStore.RemoveAccount(ctx, id)
+			}
+		})
+		require.NoError(t, err)
+
 		// Finally, we shift the active session to a random state.
 		// As the state we set may be a state that's no longer set
 		// through the current code base, or be an illegal state