# -*- coding: utf-8 -*-
##############################################################################
#
#    OpenERP, Open Source Management Solution
#    This module copyright (C) 2014 Therp BV (<http://therp.nl>).
#
#    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/>.
#
##############################################################################

from openerp.osv import orm, fields
from openerp.tools.translate import _


class CleanupPurgeLineColumn(orm.TransientModel):
    _inherit = 'cleanup.purge.line'
    _name = 'cleanup.purge.line.column'

    _columns = {
        'model_id': fields.many2one(
            'ir.model', 'Model',
            required=True, ondelete='CASCADE'),
        'wizard_id': fields.many2one(
            'cleanup.purge.wizard.column', 'Purge Wizard', readonly=True),
        }

    def purge(self, cr, uid, ids, context=None):
        """
        Unlink columns upon manual confirmation.
        """
        for line in self.browse(cr, uid, ids, context=context):
            if line.purged:
                continue

            model_pool = self.pool[line.model_id.model]

            # Check whether the column actually still exists.
            # Inheritance such as stock.picking.in from stock.picking
            # can lead to double attempts at removal
            cr.execute(
                'SELECT count(attname) FROM pg_attribute '
                'WHERE attrelid = '
                '( SELECT oid FROM pg_class WHERE relname = %s ) '
                'AND attname = %s',
                (model_pool._table, line.name));
            if not cr.fetchone()[0]:
                continue

            self.logger.info(
                'Dropping column %s from table %s',
                line.name, model_pool._table)
            cr.execute(
                """
                ALTER TABLE "%s" DROP COLUMN "%s"
                """ % (model_pool._table, line.name))
            line.write({'purged': True})
            cr.commit()
        return True

class CleanupPurgeWizardColumn(orm.TransientModel):
    _inherit = 'cleanup.purge.wizard'
    _name = 'cleanup.purge.wizard.column'

    # List of known columns in use without corresponding fields
    # Format: {table: [fields]}
    blacklist = {
        'wkf_instance': ['uid'], # lp:1277899
        }

    def default_get(self, cr, uid, fields, context=None):
        res = super(CleanupPurgeWizardColumn, self).default_get(
            cr, uid, fields, context=context)
        if 'name' in fields:
            res['name'] = _('Purge columns')
        return res

    def get_orphaned_columns(self, cr, uid, model_pool, context=None):
        """
        From openobject-server/openerp/osv/orm.py
        Iterate on the database columns to identify columns
        of fields which have been removed
        """
        columns = [
            c for c in model_pool._columns
            if not (isinstance(model_pool._columns[c], fields.function)
                    and not model_pool._columns[c].store)]
        columns += orm.MAGIC_COLUMNS
        columns += self.blacklist.get(model_pool._table, [])

        cr.execute("SELECT a.attname"
                   "  FROM pg_class c, pg_attribute a"
                   " WHERE c.relname=%s"
                   "   AND c.oid=a.attrelid"
                   "   AND a.attisdropped=%s"
                   "   AND pg_catalog.format_type(a.atttypid, a.atttypmod)"
                   "        NOT IN ('cid', 'tid', 'oid', 'xid')"
                   "   AND a.attname NOT IN %s",
                   (model_pool._table, False, tuple(columns))),
        return [column[0] for column in cr.fetchall()]

    def find(self, cr, uid, context=None):
        """
        Search for columns that are not in the corresponding model.
        """
        res = []
        model_pool = self.pool['ir.model']
        model_ids = model_pool.search(cr, uid, [], context=context)
        line_pool = self.pool['cleanup.purge.line.column']
        for model in model_pool.browse(cr, uid, model_ids, context=context):
            model_pool = self.pool.get(model.model)
            if not model_pool or not model_pool._auto:
                continue
            for column in self.get_orphaned_columns(
                    cr, uid, model_pool, context=context):
                res.append((0, 0, {
                            'name': column,
                            'model_id': model.id}))
        if not res:
            raise orm.except_orm(
                _('Nothing to do'),
                _('No orphaned columns found'))
        return res

    _columns = {
        'purge_line_ids': fields.one2many(
            'cleanup.purge.line.column',
            'wizard_id', 'Columns to purge'),
        }