bookings: Fix get_wallet_balance that would sum all deposits

And by "all", I mean all deposits. Of all users. Which made for a
substantial wallet balance...

src/pcapi/alembic/versions/514dfbeddddf_fix_get_wallet_balance.py

@@ -0,0 +1,56 @@
+"""Update `check_booking`
+
+Revision ID: 514dfbeddddf
+Revises: 0867450b4c30
+Create Date: 2021-02-08 10:58:14.217608
+
+"""
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision = "514dfbeddddf"
+down_revision = "0867450b4c30"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.execute(
+        """
+    CREATE OR REPLACE FUNCTION get_wallet_balance(user_id BIGINT, only_used_bookings BOOLEAN)
+    RETURNS NUMERIC(10,2) AS $$
+    DECLARE
+        sum_deposits NUMERIC ;
+        sum_bookings NUMERIC ;
+    BEGIN
+        SELECT COALESCE(SUM(amount), 0)
+        INTO sum_deposits
+        FROM deposit
+        WHERE "userId"=user_id
+        AND ("expirationDate" > now() OR "expirationDate" IS NULL);
+
+        CASE
+            only_used_bookings
+        WHEN true THEN
+            SELECT COALESCE(SUM(amount * quantity), 0)
+            INTO sum_bookings
+            FROM booking
+            WHERE "userId"=user_id AND NOT "isCancelled" AND "isUsed" = true;
+        WHEN false THEN
+            SELECT COALESCE(SUM(amount * quantity), 0)
+            INTO sum_bookings
+            FROM booking
+            WHERE "userId"=user_id AND NOT "isCancelled";
+        END CASE;
+
+        RETURN (sum_deposits - sum_bookings);
+    END; $$
+    LANGUAGE plpgsql;
+        """
+    )
+
+
+def downgrade():
+    # No downgrade, since the previous version of the SQL function has a huge bug.
+    pass

src/pcapi/core/bookings/models.py

@@ -143,7 +143,7 @@ def isConfirmed(self):
         INTO sum_deposits
         FROM deposit
         WHERE "userId"=user_id
-        AND "expirationDate" > now() OR "expirationDate" IS NULL;
+        AND ("expirationDate" > now() OR "expirationDate" IS NULL);
 
         CASE
             only_used_bookings