# -*- coding: utf-8 -*-
#
# diffoscope: in-depth comparison of files, archives, and directories
#
# Copyright © 2016 Chris Lamb <lamby@debian.org>
#
# diffoscope is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# diffoscope is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with diffoscope.  If not, see <https://www.gnu.org/licenses/>.

import abc
import logging
import shlex
import subprocess

logger = logging.getLogger(__name__)


class Command(object, metaclass=abc.ABCMeta):
    MAX_STDERR_LINES = 50

    def __init__(self, path):
        self._path = path

    def start(self):
        logger.debug("Executing %s", ' '.join([shlex.quote(x) for x in self.cmdline()]))

        self._stdin = self.stdin()
        # "stdin" used to be a feeder but we didn't need the functionality so
        # it was simplified into the current form. it can be recovered from git
        # the extra functionality is needed in the future. alternatively,
        # consider using a shell pipeline ("sh -ec $script") to implement what
        # you need, because that involves much less code - like it or not (I
        # don't) shell is still the most readable option for composing processes
        self._process = subprocess.run(self.cmdline(),
                                       shell=False, close_fds=True,
                                       env=self.env(),
                                       stdin=self._stdin,
                                       stdout=subprocess.PIPE,
                                       stderr=subprocess.PIPE)

        self.stderr = self._read_stderr()

    @property
    def path(self):
        return self._path

    def stdin(self):
        return None

    @abc.abstractmethod
    def cmdline(self):
        raise NotImplementedError()

    def shell_cmdline(self):
        return ' '.join(map(lambda x: '{}' if x == self.path else shlex.quote(x), self.cmdline()))

    def env(self):
        return None  # inherit parent environment by default

    def filter(self, line):
        # Assume command output is utf-8 by default
        return line

    def poll(self):
        pass

    def terminate(self):
        pass

    def _read_stderr(self):
        buf = ""
        lines = self._process.stderr.splitlines(True)

        for index, line in enumerate(lines):
            if index >= Command.MAX_STDERR_LINES:
                break
            buf += line.decode('utf-8', errors='replace')

        if len(lines) > Command.MAX_STDERR_LINES:
            buf += '[ {} lines ignored ]\n'.format(
                len(lines) - Command.MAX_STDERR_LINES,
            )

        return buf

    @property
    def returncode(self):
        return self._process.returncode

    @property
    def stdout(self):
        return self._process.stdout.splitlines(True)
