import datetime
import re

##################################
## supported dbtype: sqlite, mysql
dbtype = 'sqlite'

__all__ = [
    "dbtype", "rand", "create", 
    "dtstr", "dtobj", "dtnorm", "dtback", ]
#################

def doReplace(rstr, replacers):
    '''
    Intrinsic method, replaces some stuff in 'create'
    '''
    for (what, tofor) in replacers[dbtype]:
        rstr = rstr.replace(what, tofor)
    return rstr
    
def rand():
    '''
    Correct sql name of random number generator
    '''
    if dbtype == "sqlite":
        return "random()"
    else:
        return "rand()"

def create(tablename, initstr):
    '''
    SQL "CREATE TABLE tablename (field, field, field)" abstraction.
      - tablename -- name of table to be created
      - initstr -- comma-separated string of field declaration
    Returns string ready for execution in sql console.
    
    Useful shortcuts:
      - __ID__ -- primary key
      - INT -- integer value (like int(10))
      - TEXT -- text field
    
    All indexes encountered are removed for sqlite.
      
    Example:
    >>> create( 'users', '__ID__, name varchar(1), active INT, about TEXT' )
    '''
    replacers = {
        'sqlite':
            [('_ID_', 'id integer primary key default null'),
             ('INT',  'integer'), 
             ('TEXT', 'varchar(65535)'), 
             ('FINAL', ''), ],
        'mysql':
            [('_ID_', 'id int(10) unsigned primary key NOT NULL auto_increment'),
             ('INT',  'int(10)'),
             ('TEXT', 'text'), 
             ('FINAL', 'default charset=utf8'), ],
    }
    if dbtype == "sqlite":
      initstr = re.sub(r',(\s|\n)*index\s*\((.|\n)*$',"",initstr)
    return 'CREATE TABLE %s (%s) %s' % \
        (tablename,
         doReplace(initstr, replacers),
         doReplace('FINAL', replacers))

def dtstr(dt):
    '''
    Converts datetime to iso format string: 
    was it sqlite-string representation or datetime -- don't matter.
    
    Example:
    >>> import datetime
    >>> dtstr(datetime.datetime.now())
    >>> dtstr('2008-01-08 00:00:12')
    '''
    if type(dt) == datetime.datetime:
        return dt.isoformat()
    else:
        return dt


def dtobj(dt):
    '''
    Converts datetime to "datetime.datetime" object:
    was it sqlite-string representation or datetime -- don't matter.
    
    Example:
    >>> import datetime
    >>> dtobj(datetime.datetime.now())
    >>> dtobj('2008-01-08 00:00:12')
    '''
    if type(dt) == datetime.datetime:
        return dt
    else:
        return datetime.datetime.strptime(dt[:19], "%Y-%m-%d %H:%M:%S")
  

dtnorm = dtstr
dtback = dtobj