import os
import logging
from twisted.internet import defer, threads
from lbrynet import conf
from lbrynet.database.storage import SQLiteStorage
from lbrynet.daemon.Component import Component

log = logging.getLogger(__name__)

# settings must be initialized before this file is imported

DATABASE_COMPONENT = "database"


class DatabaseComponent(Component):
    component_name = DATABASE_COMPONENT
    storage = None

    @staticmethod
    def get_db_dir():
        return conf.settings['data_dir']

    @staticmethod
    def get_download_directory():
        return conf.settings['download_directory']

    @staticmethod
    def get_blobfile_dir():
        return conf.settings['BLOBFILES_DIR']

    @staticmethod
    def get_current_db_revision():
        return 7

    @staticmethod
    def get_revision_filename():
        return conf.settings.get_db_revision_filename()

    @staticmethod
    def _write_db_revision_file(version_num):
        with open(conf.settings.get_db_revision_filename(), mode='w') as db_revision:
            db_revision.write(str(version_num))

    @classmethod
    @defer.inlineCallbacks
    def setup(cls):
        # check directories exist, create them if they don't
        log.info("Loading databases")
        if not os.path.exists(cls.get_download_directory()):
            os.mkdir(cls.get_download_directory())
        if not os.path.exists(cls.get_db_dir()):
            os.mkdir(cls.get_db_dir())
            cls._write_db_revision_file(cls.get_current_db_revision())
            log.debug("Created the db revision file: %s", cls.get_revision_filename())
        if not os.path.exists(cls.get_blobfile_dir()):
            os.mkdir(cls.get_blobfile_dir())
            log.debug("Created the blobfile directory: %s", str(cls.get_blobfile_dir()))
        if not os.path.exists(cls.get_revision_filename()):
            log.warning("db_revision file not found. Creating it")
            cls._write_db_revision_file(cls.get_current_db_revision())

        # check the db migration and run any needed migrations
        migrated = False
        with open(cls.get_revision_filename(), "r") as revision_read_handle:
            old_revision = int(revision_read_handle.read().strip())

        if old_revision > cls.get_current_db_revision():
            raise Exception('This version of lbrynet is not compatible with the database\n'
                            'Your database is revision %i, expected %i' %
                            (old_revision, cls.get_current_db_revision()))
        if old_revision < cls.get_current_db_revision():
            from lbrynet.database.migrator import dbmigrator
            log.info("Upgrading your databases (revision %i to %i)", old_revision, cls.get_current_db_revision())
            yield threads.deferToThread(
                dbmigrator.migrate_db, cls.get_db_dir(), old_revision, cls.get_current_db_revision()
            )
            cls._write_db_revision_file(cls.get_current_db_revision())
            log.info("Finished upgrading the databases.")
            migrated = True

        # start SQLiteStorage
        cls.storage = SQLiteStorage(cls.get_db_dir())
        yield cls.storage.setup()
        defer.returnValue(migrated)

    @classmethod
    @defer.inlineCallbacks
    def stop(cls):
        yield cls.storage.stop()