# standard imports
import logging

# external imports
from hexathon import (
        to_int as hex_to_int,
        strip_0x,
        )

logg = logging.getLogger(__name__)


class ChainsyncerSettings:

    def __init__(self):
        self.o = {}
        self.get = self.o.get


    def process_sync_backend(self, config):
        self.o['SYNCER_BACKEND'] = config.get('SYNCER_BACKEND')


    def process_sync_range(self, config):
        o = self.o['SYNCER_INTERFACE'].block_latest()
        r = self.o['RPC'].do(o)
        block_offset = int(strip_0x(r), 16) + 1
        logg.info('network block height at startup is {}'.format(block_offset))

        keep_alive = False
        session_block_offset = 0
        block_limit = 0
        until = 0

        if config.true('_HEAD'):
            self.o['SYNCER_OFFSET'] = block_offset
            self.o['SYNCER_LIMIT'] = -1
            return

        session_block_offset = int(config.get('SYNCER_OFFSET'))
        until = int(config.get('SYNCER_LIMIT'))

        if until > 0:
            if until <= session_block_offset:
                raise ValueError('sync termination block number must be later than offset ({} >= {})'.format(session_block_offset, until))
            block_limit = until
        elif until == -1:
            keep_alive = True

        if session_block_offset == -1:
            session_block_offset = block_offset
        elif config.true('_KEEP_ALIVE'):
            block_limit = -1
        else:
            if block_limit == 0:
                block_limit = block_offset
    
        self.o['SYNCER_OFFSET'] = session_block_offset
        self.o['SYNCER_LIMIT'] = block_limit