import atexit
import os
import sqlite3

class FakeError:
    pass

def table_exists(conn, table):
    sql = 'PRAGMA TABLE_INFO(%s) ' % table
    cur = conn.execute(sql)
    row = cur.fetchone()
    return row is not None

def row_count(conn, table):
    cur = conn.execute('SELECT COUNT(*) FROM %s' % table)
    row = cur.fetchone()
    return row[0]

def index_exists(conn, table):
    sql = 'PRAGMA INDEX_INFO(%s) ' % table
    cur = conn.execute(sql)
    row = cur.fetchone()
    return row is not None

def column_exists(conn, table, column):
    sql = 'PRAGMA TABLE_INFO(%s) ' % table
    cur = conn.execute(sql)
    for row in cur:
        if row[1] == column:
            return True
    return False

def create_temp_database():
    filename = os.tempnam('/tmp', 'test') + '.db'
    #print "using filename", filename
    conn = sqlite3.connect(filename)
    atexit.register(os.remove, filename)
    conn.execute('CREATE TABLE foo (id INTEGER)')
    conn.commit()
    assert table_exists(conn, 'foo')
    return conn

def test_dml():
    ''' check basic dml is transactional '''
    conn = create_temp_database()
    conn.execute('INSERT INTO foo VALUES (1)')
    conn.rollback()
    assert row_count(conn, 'foo') == 0

def test_table_create():
    ''' check that table create is transactional '''
    conn = create_temp_database()
    conn.execute('INSERT INTO foo VALUES (1)')
    conn.execute('CREATE TABLE bar (id INTEGER)')
    assert table_exists(conn, 'bar')
    conn.execute('INSERT INTO bar VALUES (1)')
    conn.rollback()
    assert not table_exists(conn, 'bar')

def test_index_create():
    ''' check that index create is transactional '''
    conn = create_temp_database()
    conn.execute('INSERT INTO foo VALUES (1)')
    conn.execute('CREATE INDEX foo_by_id ON foo (id)')
    assert index_exists(conn, 'foo_by_id')
    conn.execute('INSERT INTO foo VALUES (2)')
    conn.rollback()
    assert not index_exists(conn, 'foo_by_id')


def test_column_add():
    ''' check that column add is transactional '''
    conn = create_temp_database()
    conn.execute('INSERT INTO foo VALUES (1)')
    conn.execute('ALTER TABLE foo ADD COLUMN stuff INTEGER')
    assert column_exists(conn, 'foo', 'stuff')
    conn.execute('INSERT INTO foo VALUES (2, 3)')
    conn.rollback()
    assert not column_exists(conn, 'foo', 'stuff')

def test_rename():
    ''' check that table rename is transactional '''
    conn = create_temp_database()
    conn.execute('INSERT INTO foo VALUES (1)')
    conn.execute('ALTER TABLE foo RENAME TO bar')
    assert not table_exists(conn, 'foo')
    assert table_exists(conn, 'bar')
    conn.rollback()
    assert table_exists(conn, 'foo')
    assert not table_exists(conn, 'bar')

def test_drop_table():
    ''' check that table drop is transactional '''
    conn = create_temp_database()
    conn.execute('INSERT INTO foo VALUES (1)')
    conn.execute('DROP TABLE foo')
    assert not table_exists(conn, 'foo')
    conn.rollback()
    assert table_exists(conn, 'foo')

def test_drop_index():
    ''' check that index drop is transactional '''
    conn = create_temp_database()
    conn.execute('CREATE INDEX foo_by_id ON foo (id)')
    conn.execute('INSERT INTO foo VALUES (1)')
    conn.commit()
    assert index_exists(conn, 'foo_by_id')
    conn.execute('DROP INDEX foo_by_id')
    assert not index_exists(conn, 'foo_by_id')
    conn.rollback()
    assert index_exists(conn, 'foo_by_id')