# -*- coding: utf-8 -*-
"""
Base classes for writing management commands (named commands which can
be executed through ``django-admin`` or ``manage.py``).
"""
from __future__ import unicode_literals

import os
import sys
import warnings
from argparse import ArgumentParser
from optparse import OptionParser

import django
from django.core import checks
from django.core.management.color import color_style, no_style
from django.db import connections
from django.utils.deprecation import RemovedInDjango110Warning
from django.utils.encoding import force_str


class CommandError(Exception):
    """
    Exception class indicating a problem while executing a management
    command.

    If this exception is raised during the execution of a management
    command, it will be caught and turned into a nicely-printed error
    message to the appropriate output stream (i.e., stderr); as a
    result, raising this exception (with a sensible description of the
    error) is the preferred way to indicate that something has gone
    wrong in the execution of a command.
    """
    pass


class SystemCheckError(CommandError):
    """
    The system check framework detected unrecoverable errors.
    """
    pass


class CommandParser(ArgumentParser):
    """
    Customized ArgumentParser class to improve some error messages and prevent
    SystemExit in several occasions, as SystemExit is unacceptable when a
    command is called programmatically.
    """
    def __init__(self, cmd, **kwargs):
        self.cmd = cmd
        super(CommandParser, self).__init__(**kwargs)

    def parse_args(self, args=None, namespace=None):
        # Catch missing argument for a better error message
        if (hasattr(self.cmd, 'missing_args_message') and
                not (args or any(not arg.startswith('-') for arg in args))):
            self.error(self.cmd.missing_args_message)
        return super(CommandParser, self).parse_args(args, namespace)

    def error(self, message):
        if self.cmd._called_from_command_line:
            super(CommandParser, self).error(message)
        else:
            raise CommandError("Error: %s" % message)


def handle_default_options(options):
    """
    Include any default options that all commands should accept here
    so that ManagementUtility can handle them before searching for
    user commands.
    """
    if options.settings:
        os.environ['DJANGO_SETTINGS_MODULE'] = options.settings
    if options.pythonpath:
        sys.path.insert(0, options.pythonpath)


class OutputWrapper(object):
    """
    Wrapper around stdout/stderr
    """
    @property
    def style_func(self):
        return self._style_func

    @style_func.setter
    def style_func(self, style_func):
        if style_func and self.isatty():
            self._style_func = style_func
        else:
            self._style_func = lambda x: x

    def __init__(self, out, style_func=None, ending='\n'):
        self._out = out
        self.style_func = None
        self.ending = ending

    def __getattr__(self, name):
        return getattr(self._out, name)

    def isatty(self):
        return hasattr(self._out, 'isatty') and self._out.isatty()

    def write(self, msg, style_func=None, ending=None):
        ending = self.ending if ending is None else ending
        if ending and not msg.endswith(ending):
            msg += ending
        style_func = style_func or self.style_func
        self._out.write(force_str(style_func(msg)))


class BaseCommand(object):
    """
    The base class from which all management commands ultimately
    derive.

    Use this class if you want access to all of the mechanisms which
    parse the command-line arguments and work out what code to call in
    response; if you don't need to change any of that behavior,
    consider using one of the subclasses defined in this file.

    If you are interested in overriding/customizing various aspects of
    the command-parsing and -execution behavior, the normal flow works
    as follows:

    1. ``django-admin`` or ``manage.py`` loads the command class
       and calls its ``run_from_argv()`` method.

    2. The ``run_from_argv()`` method calls ``create_parser()`` to get
       an ``ArgumentParser`` for the arguments, parses them, performs
       any environment changes requested by options like
       ``pythonpath``, and then calls the ``execute()`` method,
       passing the parsed arguments.

    3. The ``execute()`` method attempts to carry out the command by
       calling the ``handle()`` method with the parsed arguments; any
       output produced by ``handle()`` will be printed to standard
       output and, if the command is intended to produce a block of
       SQL statements, will be wrapped in ``BEGIN`` and ``COMMIT``.

    4. If ``handle()`` or ``execute()`` raised any exception (e.g.
       ``CommandError``), ``run_from_argv()`` will  instead print an error
       message to ``stderr``.

    Thus, the ``handle()`` method is typically the starting point for
    subclasses; many built-in commands and command types either place
    all of their logic in ``handle()``, or perform some additional
    parsing work in ``handle()`` and then delegate from it to more
    specialized methods as needed.

    Several attributes affect behavior at various steps along the way:

    ``args``
        A string listing the arguments accepted by the command,
        suitable for use in help messages; e.g., a command which takes
        a list of application names might set this to '<app_label
        app_label ...>'.

    ``can_import_settings``
        A boolean indicating whether the command needs to be able to
        import Django settings; if ``True``, ``execute()`` will verify
        that this is possible before proceeding. Default value is
        ``True``.

    ``help``
        A short description of the command, which will be printed in
        help messages.

    ``option_list``
        This is the list of ``optparse`` options which will be fed
        into the command's ``OptionParser`` for parsing arguments.
        Deprecated and will be removed in Django 1.10.
        Use ``add_arguments`` instead.

    ``output_transaction``
        A boolean indicating whether the command outputs SQL
        statements; if ``True``, the output will automatically be
        wrapped with ``BEGIN;`` and ``COMMIT;``. Default value is
        ``False``.

    ``requires_system_checks``
        A boolean; if ``True``, entire Django project will be checked for errors
        prior to executing the command. Default value is ``True``.
        To validate an individual application's models
        rather than all applications' models, call
        ``self.check(app_configs)`` from ``handle()``, where ``app_configs``
        is the list of application's configuration provided by the
        app registry.

    ``leave_locale_alone``
        A boolean indicating whether the locale set in settings should be
        preserved during the execution of the command instead of translations
        being deactivated.

        Default value is ``False``.

        Make sure you know what you are doing if you decide to change the value
        of this option in your custom command if it creates database content
        that is locale-sensitive and such content shouldn't contain any
        translations (like it happens e.g. with django.contrib.auth
        permissions) as activating any locale might cause unintended effects.

        This option can't be False when the can_import_settings option is set
        to False too because attempting to deactivate translations needs access
        to settings. This condition will generate a CommandError.
    """
    # Metadata about this command.
    option_list = ()
    help = ''
    args = ''

    # Configuration shortcuts that alter various logic.
    _called_from_command_line = False
    can_import_settings = True
    output_transaction = False  # Whether to wrap the output in a "BEGIN; COMMIT;"
    leave_locale_alone = False
    requires_system_checks = True

    def __init__(self, stdout=None, stderr=None, no_color=False):
        self.stdout = OutputWrapper(stdout or sys.stdout)
        self.stderr = OutputWrapper(stderr or sys.stderr)
        if no_color:
            self.style = no_style()
        else:
            self.style = color_style()
            self.stderr.style_func = self.style.ERROR

    @property
    def use_argparse(self):
        return not bool(self.option_list)

    def get_version(self):
        """
        Return the Django version, which should be correct for all built-in
        Django commands. User-supplied commands can override this method to
        return their own version.
        """
        return django.get_version()

    def usage(self, subcommand):
        """
        Return a brief description of how to use this command, by
        default from the attribute ``self.help``.
        """
        usage = '%%prog %s [options] %s' % (subcommand, self.args)
        if self.help:
            return '%s\n\n%s' % (usage, self.help)
        else:
            return usage

    def create_parser(self, prog_name, subcommand):
        """
        Create and return the ``ArgumentParser`` which will be used to
        parse the arguments to this command.
        """
        if not self.use_argparse:
            def store_as_int(option, opt_str, value, parser):
                setattr(parser.values, option.dest, int(value))

            # Backwards compatibility: use deprecated optparse module
            warnings.warn("OptionParser usage for Django management commands "
                          "is deprecated, use ArgumentParser instead",
                          RemovedInDjango110Warning, stacklevel=3)
            parser = OptionParser(prog=prog_name,
                                usage=self.usage(subcommand),
                                version=self.get_version())
            parser.add_option('-v', '--verbosity', action='callback', dest='verbosity', default=1,
                type='choice', choices=['0', '1', '2', '3'], callback=store_as_int,
                help='Verbosity level; 0=minimal output, 1=normal output, 2=verbose output, 3=very verbose output')
            parser.add_option('--settings',
                help=(
                    'The Python path to a settings module, e.g. '
                    '"myproject.settings.main". If this isn\'t provided, the '
                    'DJANGO_SETTINGS_MODULE environment variable will be used.'
                ),
            )
            parser.add_option('--pythonpath',
                help='A directory to add to the Python path, e.g. "/home/djangoprojects/myproject".'),
            parser.add_option('--traceback', action='store_true',
                help='Raise on CommandError exceptions')
            parser.add_option('--no-color', action='store_true', dest='no_color', default=False,
                help="Don't colorize the command output.")
            for opt in self.option_list:
                parser.add_option(opt)
        else:
            parser = CommandParser(self, prog="%s %s" % (os.path.basename(prog_name), subcommand),
                description=self.help or None)
            parser.add_argument('--version', action='version', version=self.get_version())
            parser.add_argument('-v', '--verbosity', action='store', dest='verbosity', default='1',
                type=int, choices=[0, 1, 2, 3],
                help='Verbosity level; 0=minimal output, 1=normal output, 2=verbose output, 3=very verbose output')
            parser.add_argument('--settings',
                help=(
                    'The Python path to a settings module, e.g. '
                    '"myproject.settings.main". If this isn\'t provided, the '
                    'DJANGO_SETTINGS_MODULE environment variable will be used.'
                ),
            )
            parser.add_argument('--pythonpath',
                help='A directory to add to the Python path, e.g. "/home/djangoprojects/myproject".')
            parser.add_argument('--traceback', action='store_true',
                help='Raise on CommandError exceptions')
            parser.add_argument('--no-color', action='store_true', dest='no_color', default=False,
                help="Don't colorize the command output.")
            if self.args:
                # Keep compatibility and always accept positional arguments, like optparse when args is set
                parser.add_argument('args', nargs='*')
            self.add_arguments(parser)
        return parser

    def add_arguments(self, parser):
        """
        Entry point for subclassed commands to add custom arguments.
        """
        pass

    def print_help(self, prog_name, subcommand):
        """
        Print the help message for this command, derived from
        ``self.usage()``.
        """
        parser = self.create_parser(prog_name, subcommand)
        parser.print_help()

    def run_from_argv(self, argv):
        """
        Set up any environment changes requested (e.g., Python path
        and Django settings), then run this command. If the
        command raises a ``CommandError``, intercept it and print it sensibly
        to stderr. If the ``--traceback`` option is present or the raised
        ``Exception`` is not ``CommandError``, raise it.
        """
        self._called_from_command_line = True
        parser = self.create_parser(argv[0], argv[1])

        if self.use_argparse:
            options = parser.parse_args(argv[2:])
            cmd_options = vars(options)
            # Move positional args out of options to mimic legacy optparse
            args = cmd_options.pop('args', ())
        else:
            options, args = parser.parse_args(argv[2:])
            cmd_options = vars(options)