# coding=utf-8

from __future__ import (
    absolute_import,
    division,
    print_function,
    unicode_literals,
)

from core import logger, main_db
from core.utils import backup_versioned_file

MIN_DB_VERSION = 1  # oldest db version we support migrating from
MAX_DB_VERSION = 2


def backup_database(version):
    logger.info('Backing up database before upgrade')
    if not backup_versioned_file(main_db.db_filename(), version):
        logger.log_error_and_exit('Database backup failed, abort upgrading database')
    else:
        logger.info('Proceeding with upgrade')


# ======================
# = Main DB Migrations =
# ======================
# Add new migrations at the bottom of the list; subclass the previous migration.

class InitialSchema(main_db.SchemaUpgrade):
    def test(self):
        no_update = False
        if self.has_table('db_version'):
            cur_db_version = self.check_db_version()
            no_update = not cur_db_version < MAX_DB_VERSION
        return no_update

    def execute(self):
        if not self.has_table('downloads') and not self.has_table('db_version'):
            queries = [
                'CREATE TABLE db_version (db_version INTEGER);',
                'CREATE TABLE downloads (input_directory TEXT, input_name TEXT, input_hash TEXT, input_id TEXT, client_agent TEXT, status INTEGER, last_update NUMERIC, CONSTRAINT pk_downloadID PRIMARY KEY (input_directory, input_name));',
                'INSERT INTO db_version (db_version) VALUES (2);',
            ]
            for query in queries:
                self.connection.action(query)

        else:
            cur_db_version = self.check_db_version()

            if cur_db_version < MIN_DB_VERSION:
                logger.log_error_and_exit(u'Your database version ({current}) is too old to migrate '
                                          u'from what this version of nzbToMedia supports ({min}).'
                                          u'\nPlease remove nzbtomedia.db file to begin fresh.'.format
                                          (current=cur_db_version, min=MIN_DB_VERSION))

            if cur_db_version > MAX_DB_VERSION:
                logger.log_error_and_exit(u'Your database version ({current}) has been incremented '
                                          u'past what this version of nzbToMedia supports ({max}).'
                                          u'\nIf you have used other forks of nzbToMedia, your database '
                                          u'may be unusable due to their modifications.'.format
                                          (current=cur_db_version, max=MAX_DB_VERSION))
            if cur_db_version < MAX_DB_VERSION:  # We need to upgrade.
                queries = [
                    'CREATE TABLE downloads2 (input_directory TEXT, input_name TEXT, input_hash TEXT, input_id TEXT, client_agent TEXT, status INTEGER, last_update NUMERIC, CONSTRAINT pk_downloadID PRIMARY KEY (input_directory, input_name));',
                    'INSERT INTO downloads2 SELECT * FROM downloads;',
                    'DROP TABLE IF EXISTS downloads;',
                    'ALTER TABLE downloads2 RENAME TO downloads;',
                    'INSERT INTO db_version (db_version) VALUES (2);',
                ]
                for query in queries:
                    self.connection.action(query)