# -*- coding: utf-8 -*-
###############################################################################
#
#    Copyright (C) 2001-2014 Micronaet SRL (<http://www.micronaet.it>).
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as published
#    by the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
###############################################################################
import os
import sys
import logging
import openerp
import openerp.netsvc as netsvc
import openerp.addons.decimal_precision as dp
from openerp.osv import fields, osv, expression, orm
from datetime import datetime, timedelta
from dateutil.relativedelta import relativedelta
from openerp import SUPERUSER_ID, api
from openerp import tools
from openerp.tools.translate import _
from openerp.tools.float_utils import float_round as round
from openerp.tools import (DEFAULT_SERVER_DATE_FORMAT, 
    DEFAULT_SERVER_DATETIME_FORMAT, 
    DATETIME_FORMATS_MAP, 
    float_compare)


_logger = logging.getLogger(__name__)

class AccountInvoice(orm.Model):
    """ Model name: AccountInvoice
    """    
    _inherit = 'account.invoice'

    def check_invoice(self, lines):
        ''' Check line if tax is present
        '''
        no_tax = 0
        for line in lines:
            if not line.invoice_line_tax_id:
                no_tax += 1                    
        return no_tax

    def action_date_assign(self, cr, uid, ids, context=None):
        ''' Override state action for trigger invoice_open
        '''
        res = super(AccountInvoice, self).action_date_assign(
            cr, uid, ids, context=context)
        
        # Check vat
        if self.check_invoice(
                self.browse(cr, uid, ids, context=context)[0].invoice_line):
            raise osv.except_osv(
                _('VAT check!'), 
                _('One or more line with VAT not present!')    )        
        return res    
        
    
# vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:

# -*- coding: utf-8 -*-
###############################################################################
#
#    Copyright (C) 2001-2014 Micronaet SRL (<http://www.micronaet.it>).
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as published
#    by the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
###############################################################################
import os
import sys
import logging
import openerp
import openerp.netsvc as netsvc
import openerp.addons.decimal_precision as dp
from openerp.osv import fields, osv, expression, orm
from datetime import datetime, timedelta
from dateutil.relativedelta import relativedelta
from openerp import SUPERUSER_ID, api
from openerp import tools
from openerp.tools.translate import _
from openerp.tools.float_utils import float_round as round
from openerp.tools import (DEFAULT_SERVER_DATE_FORMAT, 
    DEFAULT_SERVER_DATETIME_FORMAT, 
    DATETIME_FORMATS_MAP, 
    float_compare)


_logger = logging.getLogger(__name__)

class AccountInvoice(orm.Model):
    """ Model name: AccountInvoice
    """    
    _inherit = 'account.invoice'

    def check_invoice(self, lines):
        ''' Check line if tax is present
        '''
        no_tax = 0
        for line in lines:
            if not line.invoice_line_tax_id or len(
                    line.invoice_line_tax_id) > 1: 
                no_tax += 1                    
        return no_tax

    def action_date_assign(self, cr, uid, ids, context=None):
        ''' Override state action for trigger invoice_open
        '''
        res = super(AccountInvoice, self).action_date_assign(
            cr, uid, ids, context=context)
        
        # Check vat
        if self.check_invoice(
                self.browse(cr, uid, ids, context=context)[0].invoice_line):
            raise osv.except_osv(
                _('VAT check!'), 
                _('One or more line with VAT not present (or more than 1)!'))
        return res    
        
    
# vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:

Check also multi vat in line!!!