#coding:utf-8
#
# id:           bugs.core_4488
# title:        Cursor references must always represent the CURRENT state of the record, without caching when this record is read
# decription:   
#                   See doc\\sql.extensions\\README.cursor_variables.txt:
#                   7) Reading from a cursor variable returns the current field values. That means an UPDATE (with
#                      WHERE CURRENT OF) also updates the fields for subsequent reads. And DELETE (with WHERE
#                      CURRENT OF) makes subsequent reads to return NULL.
#                
# tracker_id:   CORE-4488
# min_versions: ['3.0']
# versions:     3.0
# qmid:         None

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

# version: 3.0
# resources: None

substitutions_1 = [('=.*', '')]

init_script_1 = """
    recreate table t_source(id int, x int, y int, z int); commit;
    recreate table t_target(id int, x int, y int, z int); commit;
    insert into t_source values(1, 10, 100, 1000);
    insert into t_source values(2, 20, 200, 2000);
    insert into t_source values(3, 30, 300, 3000);
    commit;
"""

db_1 = db_factory(page_size=4096, sql_dialect=3, init=init_script_1)

test_script_1 = """
    --------------- 1 -----------------
    select '' as "old data of t_source:", (select count(*) from t_source) "rows in t_source", s.*
    from rdb$database b left join t_source s on 1=1;
    set term ^;
    execute block
    as
    begin
      for
      select
        id,
        x as x,
        y as y,
        z as z
      from t_source s
      as cursor cs
      do begin
        delete from t_source where current of cs; -- yes, we DELETE record BEFORE insert it's values because now they all are stored in cursor 'CS' variables
        insert into t_target values( cs.id, cs.x, cs.y, cs.z );
      end
    end
    ^ set term ;^
    select '' as "1. New data of t_source:", (select count(*) from t_source) "rows in t_source", s.*
    from rdb$database b left join t_source s on 1=1;
    select '' as "1. New data of t_target:", (select count(*) from t_target) "rows in t_target", t.*
    from rdb$database b left join t_target t on 1=1;
    rollback;
    
    --------------- 2 -----------------
    set term ^;
    execute block
    as
    begin
      for
      select
        id,
        x+1 as x,
        y+2 as y,
        z+3 as z
      from t_source s
      as cursor cs
      do begin
        delete from t_source where current of cs;
        insert into t_target values( cs.id, cs.x, cs.y, cs.z );
      end
    end
    ^ set term ;^
    
    select '' as "2. New data of t_source:", (select count(*) from t_source) "rows in t_source", s.*
    from rdb$database b left join t_source s on 1=1;
    select '' as "2. New data of t_target:", (select count(*) from t_target) "rows in t_target", t.*
    from rdb$database b left join t_target t on 1=1;
    
    rollback;
    
    --------------- 3 -----------------
    set term ^;
    execute block
    as
    begin
      for
      select
        id,
        x as x,
        y as y,
        z+1 as z
      from t_source s
      as cursor cs
      do begin
        update t_source set y=x, z=y, x=z where current of cs;
        insert into t_target values( cs.id, cs.x, cs.y, cs.z );
      end
    end
    ^ set term ;^
    
    select '' as "3. New data of t_source:", (select count(*) from t_source) "rows in t_source", s.*
    from rdb$database b left join t_source s on 1=1;
    select '' as "3. New data of t_target:", (select count(*) from t_target) "rows in t_target", t.*
    from rdb$database b left join t_target t on 1=1;
    
    rollback;
"""

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

expected_stdout_1 = """
    old data of t_source:      rows in t_source           ID            X            Y            Z
    ===================== ===================== ============ ============ ============ ============
                                              3            1           10          100         1000
                                              3            2           20          200         2000
                                              3            3           30          300         3000
    
    
    1. New data of t_source:      rows in t_source           ID            X            Y            Z
    ======================== ===================== ============ ============ ============ ============
                                                 0       <null>       <null>       <null>       <null>
    
    
    1. New data of t_target:      rows in t_target           ID            X            Y            Z
    ======================== ===================== ============ ============ ============ ============
                                                 3       <null>       <null>       <null>       <null>
                                                 3       <null>       <null>       <null>       <null>
                                                 3       <null>       <null>       <null>       <null>
    
    
    2. New data of t_source:      rows in t_source           ID            X            Y            Z
    ======================== ===================== ============ ============ ============ ============
                                                 0       <null>       <null>       <null>       <null>
    
    
    2. New data of t_target:      rows in t_target           ID            X            Y            Z
    ======================== ===================== ============ ============ ============ ============
                                                 3       <null>       <null>       <null>       <null>
                                                 3       <null>       <null>       <null>       <null>
                                                 3       <null>       <null>       <null>       <null>
    
    
    3. New data of t_source:      rows in t_source           ID            X            Y            Z
    ======================== ===================== ============ ============ ============ ============
                                                 3            1         1000           10          100
                                                 3            2         2000           20          200
                                                 3            3         3000           30          300
    
    
    3. New data of t_target:      rows in t_target           ID            X            Y            Z
    ======================== ===================== ============ ============ ============ ============
                                                 3            1         1000           10          101
                                                 3            2         2000           20          201
                                                 3            3         3000           30          301
"""

@pytest.mark.version('>=3.0')
def test_1(act_1: Action):
    act_1.expected_stdout = expected_stdout_1
    act_1.execute()
    assert act_1.clean_stdout == act_1.clean_expected_stdout