import sqlalchemy
import config, constants, util

def textclause_repr(self):
    return 'text(%r)' % self.text

def table_repr(self):
    data = {
        'name': self.name,
        'columns': constants.NLTAB.join([repr(cl) for cl in self.columns]),
        'constraints': constants.NLTAB.join(
            [repr(cn) for cn in self.constraints
            if not isinstance(cn, sqlalchemy.PrimaryKeyConstraint)]),
        'index': '',
        'schema': self.schema != None and ",\n%sschema='%s'" % (constants.TAB, self.schema) or '',
        }

    if data['constraints']:
        data['constraints'] = '\n%s%s,' % (constants.TAB, data['constraints'])

    if data['columns']:
        data['columns'] = '\n%s%s' % (constants.TAB, data['columns'])

    return util.as_out_str(constants.TABLE % data)

def _repr_coltype_as(coltype, as_type):
    """repr a Type instance as a super type."""

    specimen = object.__new__(as_type)
    specimen.__dict__ = coltype.__dict__
    return repr(specimen)

def column_repr(self):
    kwarg = []
    if self.key != self.name:
        kwarg.append( 'key')

    if hasattr(self, 'primary_key'):
        kwarg.append( 'primary_key')

    if not self.nullable:
        kwarg.append( 'nullable')
    if self.onupdate:
        kwarg.append( 'onupdate')
    #issue: 
    #http://www.sqlalchemy.org/trac/wiki/06Migration#AnImportantExpressionLanguageGotcha
    if self.default is not None:
        kwarg.append( 'default')
    elif self.server_default:
        self.default = self.server_default.arg
        kwarg.append( 'default')

    ks = ', '.join('%s=%r' % (k, getattr(self, k)) for k in kwarg )

    name = self.name

    if not hasattr(config, 'options') and config.options.generictypes:
        coltype = repr(self.type)
    elif type(self.type).__module__ == 'sqlalchemy.types':
        coltype = repr(self.type)
    else:
        # Try to 'cast' this column type to a cross-platform type
        # from sqlalchemy.types, dropping any database-specific type
        # arguments.
        for base in type(self.type).__mro__:
            if (base.__module__ == 'sqlalchemy.types' and
                base.__name__ in sqlalchemy.__all__):
                coltype = _repr_coltype_as(self.type, base)
                break
        # FIXME: if a dialect has a non-standard type that does not
        # derive from an ANSI type, there's no choice but to ignore
        # generic-types and output the exact type. However, import
        # headers have already been output and lack the required
        # dialect import.
        else:
            coltype = repr(self.type)

    data = {'name': self.name,
            'type': coltype,
            'constraints': ', '.join([repr(cn) for cn in self.constraints]),
            'args': ks and ks or '',
            }

    if data['constraints']:
        data['constraints'] = ', ' + data['constraints']
    if data['args']:
        data['args'] = ', ' + data['args']

    return util.as_out_str(constants.COLUMN % data)

def foreignkeyconstraint_repr(self):
    data = {'name': repr(self.name),
            'names': repr([x.parent.name for x in self.elements]),
            'specs': repr([x._get_colspec() for x in self.elements])
            }
    return util.as_out_str(constants.FOREIGN_KEY % data)

def index_repr(index):
    cols = []
    for column in index.columns:
        # FIXME: still punting on the issue of unicode table names
        if util.is_python_identifier(column.name):
            cols.append('%s.c.%s' % (column.table.name, column.name))
        else:
            cols.append('%s.c[%r]' % (column.table.name, column.name))

    data = {'name': repr(index.name),
            'columns': ', '.join(cols),
            'unique': repr(index.unique),
            }
    return util.as_out_str(constants.INDEX % data)

def check_constraint_repr(cc):
    data = {'sqltext': cc.sqltext}
    return util.as_out_str(constants.CHECK_CONSTRAINT % data)

def monkey_patch_sa():
    sqlalchemy.sql.expression._TextClause.__repr__ = textclause_repr
    sqlalchemy.schema.Table.__repr__ = table_repr
    sqlalchemy.schema.Column.__repr__ = column_repr
    sqlalchemy.schema.ForeignKeyConstraint.__repr__ = foreignkeyconstraint_repr
    sqlalchemy.schema.Index.__repr__ = index_repr
    sqlalchemy.schema.CheckConstraint.__repr__ = check_constraint_repr