import logging
import os

from copy import deepcopy
from twisted.internet import defer
from twisted.internet.task import LoopingCall

from lbrynet.core.Error import InsufficientFundsError, KeyFeeAboveMaxAllowed
from lbrynet.core.StreamDescriptor import download_sd_blob
from lbrynet.metadata.Fee import FeeValidator
from lbrynet.lbryfilemanager.EncryptedFileDownloader import ManagedEncryptedFileDownloaderFactory
from lbrynet import conf

INITIALIZING_CODE = 'initializing'
DOWNLOAD_METADATA_CODE = 'downloading_metadata'
DOWNLOAD_TIMEOUT_CODE = 'timeout'
DOWNLOAD_RUNNING_CODE = 'running'
DOWNLOAD_STOPPED_CODE = 'stopped'
STREAM_STAGES = [
    (INITIALIZING_CODE, 'Initializing...'),
    (DOWNLOAD_METADATA_CODE, 'Downloading metadata'),
    (DOWNLOAD_RUNNING_CODE, 'Started stream'),
    (DOWNLOAD_STOPPED_CODE, 'Paused stream'),
    (DOWNLOAD_TIMEOUT_CODE, 'Stream timed out')
]


log = logging.getLogger(__name__)


class GetStream(object):
    def __init__(self, sd_identifier, session, wallet,
                 lbry_file_manager, exchange_rate_manager,
                 max_key_fee, data_rate=0.5, timeout=None,
                 download_directory=None, file_name=None):
        if timeout is None:
            timeout = conf.settings.download_timeout
        self.wallet = wallet
        self.resolved_name = None
        self.description = None
        self.fee = None
        self.data_rate = data_rate
        self.file_name = file_name
        self.session = session
        self.exchange_rate_manager = exchange_rate_manager
        self.payment_rate_manager = self.session.payment_rate_manager
        self.lbry_file_manager = lbry_file_manager
        self.sd_identifier = sd_identifier
        self.stream_hash = None
        self.max_key_fee = max_key_fee
        self.stream_info = None
        self.stream_info_manager = None
        self.d = defer.Deferred(None)
        self.timeout = timeout
        self.timeout_counter = 0
        self.download_directory = download_directory
        self.download_path = None
        self.downloader = None
        self.finished = defer.Deferred(None)
        self.checker = LoopingCall(self.check_status)
        self.code = STREAM_STAGES[0]

    def check_status(self):
        self.timeout_counter += 1

        # TODO: Why is this the stopping condition for the finished callback?
        if self.download_path:
            self.checker.stop()
            self.finished.callback((True, self.stream_hash, self.download_path))

        elif self.timeout_counter >= self.timeout:
            log.info("Timeout downloading lbry://%s" % self.resolved_name)
            self.checker.stop()
            self.d.cancel()
            self.code = STREAM_STAGES[4]
            self.finished.callback((False, None, None))

    def _convert_max_fee(self):
        max_fee = FeeValidator(self.max_key_fee)
        if max_fee.currency_symbol == "LBC":
            return max_fee.amount
        return self.exchange_rate_manager.to_lbc(self.max_key_fee).amount

    def start(self, stream_info, name):
        def _cause_timeout(err):
            log.info('Cancelling download')
            self.timeout_counter = self.timeout * 2

        def _set_status(x, status):
            log.info("Download lbry://%s status changed to %s" % (self.resolved_name, status))
            self.code = next(s for s in STREAM_STAGES if s[0] == status)
            return x

        def get_downloader_factory(metadata):
            for factory in metadata.factories:
                if isinstance(factory, ManagedEncryptedFileDownloaderFactory):
                    return factory, metadata
            raise Exception('No suitable factory was found in {}'.format(metadata.factories))

        def make_downloader(args):
            factory, metadata = args
            return factory.make_downloader(metadata,
                                           [self.data_rate, True],
                                           self.payment_rate_manager,
                                           download_directory=self.download_directory,
                                           file_name=self.file_name)

        self.resolved_name = name
        self.stream_info = deepcopy(stream_info)
        self.description = self.stream_info['description']
        self.stream_hash = self.stream_info['sources']['lbry_sd_hash']

        if 'fee' in self.stream_info:
            self.fee = FeeValidator(self.stream_info['fee'])
            max_key_fee = self._convert_max_fee()
            converted_fee = self.exchange_rate_manager.to_lbc(self.fee).amount
            if converted_fee > self.wallet.wallet_balance:
                log.warning("Insufficient funds to download lbry://%s", self.resolved_name)
                return defer.fail(InsufficientFundsError())
            if converted_fee > max_key_fee:
                log.warning(
                    "Key fee %f above limit of %f didn't download lbry://%s",
                    converted_fee, max_key_fee, self.resolved_name)
                return defer.fail(KeyFeeAboveMaxAllowed())
            log.info(
                "Key fee %f below limit of %f, downloading lbry://%s",
                converted_fee, max_key_fee, self.resolved_name)

        self.checker.start(1)

        self.d.addCallback(lambda _: _set_status(None, DOWNLOAD_METADATA_CODE))
        self.d.addCallback(lambda _: download_sd_blob(
            self.session, self.stream_hash, self.payment_rate_manager))
        self.d.addCallback(self.sd_identifier.get_metadata_for_sd_blob)
        self.d.addCallback(lambda r: _set_status(r, DOWNLOAD_RUNNING_CODE))
        self.d.addCallback(get_downloader_factory)
        self.d.addCallback(make_downloader)
        self.d.addCallbacks(self._start_download, _cause_timeout)
        self.d.callback(None)

        return self.finished

    def _start_download(self, downloader):
        log.info('Starting download for %s', self.resolved_name)
        self.downloader = downloader
        self.download_path = os.path.join(downloader.download_directory, downloader.file_name)

        d = self._pay_key_fee()
        d.addCallback(lambda _: log.info(
            "Downloading %s --> %s", self.stream_hash, self.downloader.file_name))
        d.addCallback(lambda _: self.downloader.start())

    def _pay_key_fee(self):
        if self.fee is not None:
            fee_lbc = self.exchange_rate_manager.to_lbc(self.fee).amount
            reserved_points = self.wallet.reserve_points(self.fee.address, fee_lbc)
            if reserved_points is None:
                return defer.fail(InsufficientFundsError())
            return self.wallet.send_points_to_address(reserved_points, fee_lbc)
        return defer.succeed(None)