#coding:utf-8
#
# id:           functional.session.alter_session_reset_decfloat
# title:        
#                   ALTER SESSION RESET: DECFLOAT parameters must be returned to default values
#                
# decription:   
#                  Test issue from CORE-5832 about ALTER SESSION RESET:
#                  "DECFLOAT parameters (BIND, TRAP and ROUND) must be reset to default values".
#               
#                  We change all three specified parameters and evaluate some expressions.
#                  Then we run RESET SESSION and evaluate the same expressions. 
#                  Results must differ for all of them.
#               
#                  NOTE-1.
#                      FDB driver 2.0.1 does not support DEFCFLOAT datatype (at least version 2.0.1),
#                      so test type must be ISQL.
#               
#                  NOTE-2. *** SET AUTODDL OFF REQUIRED ***
#                      Following is detailed explanation of this note:
#                      ========
#                          Default ISQL behaviour is to start always *TWO* transactions (for DML and second for DDL)
#                          after previous commit / rollback and before *ANY* further satement is to be executed, except
#                          those which control ISQL itself (e.g. 'SET TERM'; 'IN ...'; 'SET BAIL' etc).
#                          So, even when statement <S> has nothing to change, ISQL will start TWO transactions
#                          just before executing <S>.
#                          This means that these transactions will start even if want to run 'ALTER SESSION RESET'.
#                          This, in turn, makes one of them (which must perform DDL) be 'active and NOT current'
#                          from ALTER SESSION point of view (which is run within DML transaction).
#               
#                          According to description given in CORE-5832, ALTER SESSION throws error isc_ses_reset_err
#                          "if any open transaction exist in current conneciton, *except of current transaction* and
#                          prepared 2PC transactions which is allowed and ignored by this check".
#               
#                          So, we have to prohibit 'autostart' of DDL-transaction because otherwise ALTER SESSION will
#                          throw: "SQLSTATE = 01002 / Cannot reset user session / -There are open transactions (2 active)".
#                          This is done by 'SET AUTODDL OFF' statement at the beginning of this test script.
#                      ========
#               
#                  Thanks to Vlad for explanations (discussed 18.01.2021).
#                  Checked on 4.0.0.2307 SS/CS.
#                
# tracker_id:   
# min_versions: ['4.0.0']
# versions:     4.0
# qmid:         None

import pytest
from firebird.qa import db_factory, isql_act, Action

# version: 4.0
# resources: None

substitutions_1 = [('^((?!(sqltype|before_reset|after_reset)).)*$', ''), ('[ \t]+', ' '), ('.*alias.*', '')]

init_script_1 = """"""

db_1 = db_factory(sql_dialect=3, init=init_script_1)

test_script_1 = """

    recreate table test(a decfloat, b decfloat, c decfloat);
    insert into test(a,b,c) values(1608.90, 5.00, 100.00);
    commit;

    set list on;
    set autoddl off;
    commit;

    set bind of decfloat to smallint;
    set decfloat traps to;
    set decfloat round ceiling;

    set sqlda_display on;
    select cast(1234.5678 as decfloat(16)) as "before_reset: check datatype" from rdb$database;
    set sqlda_display off;

    -- Should issue: Infinity
    select 1/1e-9999 as "before_reset: check division result" from rdb$database;


    select a * b / c as "before_reset: check round result" from test;

    --------------------
    alter session reset;
    --------------------

    set sqlda_display on;
    select cast(1234.5678 as decfloat(16)) as "after_reset: check datatype" from rdb$database;
    set sqlda_display off;

    -- Should issue:
    -- Statement failed, SQLSTATE = 22012
    -- Decimal float divide by zero.  The code attempted to divide a DECFLOAT value by zero.
    select 1/1e-9999 "after_reset: check division result" from rdb$database;

    select a * b / c as "after_reset: check round result" from test;

"""

act_1 = isql_act('db_1', test_script_1, substitutions=substitutions_1)

expected_stdout_1 = """
    01: sqltype: 500 SHORT scale: 0 subtype: 0 len: 2
    before_reset: check datatype    1235
    
    before_reset: check division result 0
    
    before_reset: check round result 81
    
    01: sqltype: 32760 DECFLOAT(16) scale: 0 subtype: 0 len: 8
    after_reset: check datatype                   1234.5678

    after_reset: check round result                                     80.445
"""
expected_stderr_1 = """
    Statement failed, SQLSTATE = 22012
    Decimal float divide by zero.  The code attempted to divide a DECFLOAT value by zero.
"""

@pytest.mark.version('>=4.0')
def test_1(act_1: Action):
    act_1.expected_stdout = expected_stdout_1
    act_1.expected_stderr = expected_stderr_1
    act_1.execute()
    assert act_1.clean_stderr == act_1.clean_expected_stderr

    assert act_1.clean_stdout == act_1.clean_expected_stdout