# Copyright 2014-2016 Therp BV <http://therp.nl>
# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
# pylint: disable=consider-merging-classes-inherited
from odoo import api, fields, models, _
from odoo.exceptions import UserError
from ..identifier_adapter import IdentifierAdapter


class CleanupPurgeLineTable(models.TransientModel):
    _inherit = 'cleanup.purge.line'
    _name = 'cleanup.purge.line.table'
    _description = 'Purge tables wizard lines'

    wizard_id = fields.Many2one(
        'cleanup.purge.wizard.table', 'Purge Wizard', readonly=True)

    @api.multi
    def purge(self):
        """
        Unlink tables upon manual confirmation.
        """
        if self:
            objs = self
        else:
            objs = self.env['cleanup.purge.line.table']\
                .browse(self._context.get('active_ids'))
        tables = objs.mapped('name')
        for line in objs:
            if line.purged:
                continue

            # Retrieve constraints on the tables to be dropped
            # This query is referenced in numerous places
            # on the Internet but credits probably go to Tom Lane
            # in this post http://www.postgresql.org/\
            # message-id/22895.1226088573@sss.pgh.pa.us
            # Only using the constraint name and the source table,
            # but I'm leaving the rest in for easier debugging
            self.env.cr.execute(
                """
                SELECT conname, confrelid::regclass, af.attname AS fcol,
                    conrelid::regclass, a.attname AS col
                FROM pg_attribute af, pg_attribute a,
                    (SELECT conname, conrelid, confrelid,conkey[i] AS conkey,
                         confkey[i] AS confkey
                     FROM (select conname, conrelid, confrelid, conkey,
                       confkey, generate_series(1,array_upper(conkey,1)) AS i
                       FROM pg_constraint WHERE contype = 'f') ss) ss2
                WHERE af.attnum = confkey AND af.attrelid = confrelid AND
                a.attnum = conkey AND a.attrelid = conrelid
                AND confrelid::regclass = '%s'::regclass;
                """, (IdentifierAdapter(line.name, quote=False),))

            for constraint in self.env.cr.fetchall():
                if constraint[3] in tables:
                    self.logger.info(
                        'Dropping constraint %s on table %s (to be dropped)',
                        constraint[0], constraint[3])
                    self.env.cr.execute(
                        "ALTER TABLE %s DROP CONSTRAINT %s",
                        (
                            IdentifierAdapter(constraint[3]),
                            IdentifierAdapter(constraint[0])
                        ))

            self.logger.info(
                'Dropping table %s', line.name)
            self.env.cr.execute(
                "DROP TABLE %s", (IdentifierAdapter(line.name),))
            line.write({'purged': True})
        return True


class CleanupPurgeWizardTable(models.TransientModel):
    _inherit = 'cleanup.purge.wizard'
    _name = 'cleanup.purge.wizard.table'
    _description = 'Purge tables'

    @api.model
    def find(self):
        """
        Search for tables that cannot be instantiated.
        Ignore views for now.
        """
        known_tables = []
        for model in self.env['ir.model'].search([]):
            if model.model not in self.env:
                continue
            model_pool = self.env[model.model]
            known_tables.append(model_pool._table)
            known_tables += [
                column.relation
                for column in model_pool._fields.values()
                if column.type == 'many2many' and
                (column.compute is None or column.store)
                and column.relation
            ]

        self.env.cr.execute(
            """
            SELECT table_name FROM information_schema.tables
            WHERE table_schema = 'public' AND table_type = 'BASE TABLE'
            AND table_name NOT IN %s""", (tuple(known_tables),))

        res = [(0, 0, {'name': row[0]}) for row in self.env.cr.fetchall()]
        if not res:
            raise UserError(_('No orphaned tables found'))
        return res

    purge_line_ids = fields.One2many(
        'cleanup.purge.line.table', 'wizard_id', 'Tables to purge')