"""
Data providers that iterate over a source that is not in memory
or not in a file.
"""
import gzip
import logging
import subprocess
import tempfile
from urllib.parse import (
    urlencode,
    urlparse,
)
from urllib.request import urlopen

from galaxy.util import DEFAULT_SOCKET_TIMEOUT
from . import (
    base,
    line
)

_TODO = """
YAGNI: ftp, image, cryptos, sockets
job queue
admin: admin server log rgx/stats, ps aux
"""

log = logging.getLogger(__name__)


# ----------------------------------------------------------------------------- server subprocess / external prog
class SubprocessDataProvider(base.DataProvider):
    """
    Data provider that uses the output from an intermediate program and
    subprocess as its data source.
    """
    # TODO: need better ways of checking returncode, stderr for errors and raising

    def __init__(self, *args, **kwargs):
        """
        :param args: the list of strings used to build commands.
        :type args: variadic function args
        """
        self.exit_code = None
        command_list = args
        self.popen = self.subprocess(*command_list, **kwargs)
        # TODO:?? not communicate()?
        super().__init__(self.popen.stdout)
        self.exit_code = self.popen.poll()

    # NOTE: there's little protection here v. sending a ';' and a dangerous command here
    # but...we're all adults here, right? ...RIGHT?!
    def subprocess(self, *command_list, **kwargs):
        """
        :param args: the list of strings used as commands.
        :type args: variadic function args
        """
        try:
            # how expensive is this?
            popen = subprocess.Popen(command_list, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
            log.info(f'opened subrocess ({str(command_list)}), PID: {str(popen.pid)}')

        except OSError as os_err:
            command_str = ' '.join(self.command)
            raise OSError(' '.join((str(os_err), ':', command_str)))

        return popen

    def __exit__(self, *args):
        # poll the subrocess for an exit code
        self.exit_code = self.popen.poll()
        log.info(f'{str(self)}.__exit__, exit_code: {str(self.exit_code)}')
        return super().__exit__(*args)

    def __str__(self):
        # provide the pid and current return code
        source_str = ''
        if hasattr(self, 'popen'):
            source_str = f'{str(self.popen.pid)}:{str(self.popen.poll())}'
        return f'{self.__class__.__name__}({str(source_str)})'


class RegexSubprocessDataProvider(line.RegexLineDataProvider):
    """
    RegexLineDataProvider that uses a SubprocessDataProvider as its data source.
    """
    # this is a conv. class and not really all that necc...

    def __init__(self, *args, **kwargs):
        # using subprocess as proxy data source in filtered line prov.
        subproc_provider = SubprocessDataProvider(*args)
        super().__init__(subproc_provider, **kwargs)


# ----------------------------------------------------------------------------- other apis
class URLDataProvider(base.DataProvider):
    """
    Data provider that uses the contents of a URL for its data source.

    This can be piped through other providers (column, map, genome region, etc.).
    """
    VALID_METHODS = ('GET', 'POST')

    def __init__(self, url, method='GET', data=None, **kwargs):
        """
        :param url: the base URL to open.
        :param method: the HTTP method to use.
            Optional: defaults to 'GET'
        :param data: any data to pass (either in query for 'GET'
            or as post data with 'POST')
        :type data: dict
        """
        self.url = url
        self.method = method

        self.data = data or {}
        encoded_data = urlencode(self.data)

        scheme = urlparse(url).scheme
        assert scheme in ('http', 'https', 'ftp'), f'Invalid URL scheme: {scheme}'

        if method == 'GET':
            self.url += f'?{encoded_data}'
            opened = urlopen(url, timeout=DEFAULT_SOCKET_TIMEOUT)
        elif method == 'POST':
            opened = urlopen(url, encoded_data, timeout=DEFAULT_SOCKET_TIMEOUT)
        else:
            raise ValueError(f'Not a valid method: {method}')

        super().__init__(opened, **kwargs)
        # NOTE: the request object is now accessible as self.source

    def __enter__(self):
        pass

    def __exit__(self, *args):
        self.source.close()


# ----------------------------------------------------------------------------- generic compression
class GzipDataProvider(base.DataProvider):
    """
    Data provider that uses g(un)zip on a file as its source.

    This can be piped through other providers (column, map, genome region, etc.).
    """

    def __init__(self, source, **kwargs):
        unzipped = gzip.GzipFile(source, 'rb')
        super().__init__(unzipped, **kwargs)
        # NOTE: the GzipFile is now accessible in self.source


# ----------------------------------------------------------------------------- intermediate tempfile
class TempfileDataProvider(base.DataProvider):
    """
    Writes the data from the given source to a temp file, allowing
    it to be used as a source where a file_name is needed (e.g. as a parameter
    to a command line tool: samtools view -t <this_provider.source.file_name>)
    """

    def __init__(self, source, **kwargs):
        # TODO:
        raise NotImplementedError()
        # write the file here
        # self.create_file
        # super(TempfileDataProvider, self).__init__(self.tmp_file, **kwargs)

    def create_file(self):
        self.tmp_file = tempfile.NamedTemporaryFile()
        return self.tmp_file

    def write_to_file(self):
        parent_gen = super().__iter__()
        with open(self.tmp_file, 'w') as open_file:
            for datum in parent_gen:
                open_file.write(f"{datum}\n")
