import os
import distutils
from setuptools import Command
from distutils.util import convert_path
from distutils import log
from distutils.errors import DistutilsOptionError

__all__ = ['config_file', 'edit_config', 'option_base', 'setopt']


def config_file(kind="local"):
    """Get the filename of the distutils, local, global, or per-user config

    `kind` must be one of "local", "global", or "user"
    """
    if kind=='local':
        return 'setup.cfg'
    if kind=='global':
        return os.path.join(
            os.path.dirname(distutils.__file__),'distutils.cfg'
        )
    if kind=='user':
        dot = os.name=='posix' and '.' or ''
        return os.path.expanduser(convert_path("~/%spydistutils.cfg" % dot))
    raise ValueError(
        "config_file() type must be 'local', 'global', or 'user'", kind
    )

def edit_config(filename, settings, dry_run=False):
    """Edit a configuration file to include `settings`

    `settings` is a dictionary of dictionaries or ``None`` values, keyed by
    command/section name.  A ``None`` value means to delete the entire section,
    while a dictionary lists settings to be changed or deleted in that section.
    A setting of ``None`` means to delete that setting.
    """
    from setuptools.compat import ConfigParser
    log.debug("Reading configuration from %s", filename)
    opts = ConfigParser.RawConfigParser()
    opts.read([filename])
    for section, options in settings.items():
        if options is None:
            log.info("Deleting section [%s] from %s", section, filename)
            opts.remove_section(section)
        else:
            if not opts.has_section(section):
                log.debug("Adding new section [%s] to %s", section, filename)
                opts.add_section(section)
            for option,value in options.items():
                if value is None:
                    log.debug(
                        "Deleting %s.%s from %s",
                        section, option, filename
                    )
                    opts.remove_option(section,option)
                    if not opts.options(section):
                        log.info("Deleting empty [%s] section from %s",
                            section, filename)
                        opts.remove_section(section)
                else:
                    log.debug(
                        "Setting %s.%s to %r in %s",
                        section, option, value, filename
                    )
                    opts.set(section,option,value)

    log.info("Writing %s", filename)
    if not dry_run:
        with open(filename, 'w') as f:
            opts.write(f)

class option_base(Command):
    """Abstract base class for commands that mess with config files"""

    user_options = [
        ('global-config', 'g',
            "save options to the site-wide distutils.cfg file"),
        ('user-config', 'u',
            "save options to the current user's pydistutils.cfg file"),
        ('filename=', 'f',
            "configuration file to use (default=setup.cfg)"),
    ]

    boolean_options = [
        'global-config', 'user-config',
    ]

    def initialize_options(self):
        self.global_config = None
        self.user_config = None
        self.filename = None

    def finalize_options(self):
        filenames = []
        if self.global_config:
            filenames.append(config_file('global'))
        if self.user_config:
            filenames.append(config_file('user'))
        if self.filename is not None:
            filenames.append(self.filename)
        if not filenames:
            filenames.append(config_file('local'))
        if len(filenames)>1:
            raise DistutilsOptionError(
                "Must specify only one configuration file option",
                filenames
            )
        self.filename, = filenames


class setopt(option_base):
    """Save command-line options to a file"""

    description = "set an option in setup.cfg or another config file"

    user_options = [
        ('command=', 'c', 'command to set an option for'),
        ('option=',  'o',  'option to set'),
        ('set-value=',   's', 'value of the option'),
        ('remove',   'r', 'remove (unset) the value'),
    ] + option_base.user_options

    boolean_options = option_base.boolean_options + ['remove']

    def initialize_options(self):
        option_base.initialize_options(self)
        self.command = None
        self.option = None
        self.set_value = None
        self.remove = None

    def finalize_options(self):
        option_base.finalize_options(self)
        if self.command is None or self.option is None:
            raise DistutilsOptionError("Must specify --command *and* --option")
        if self.set_value is None and not self.remove:
            raise DistutilsOptionError("Must specify --set-value or --remove")

    def run(self):
        edit_config(
            self.filename, {
                self.command: {self.option.replace('-','_'):self.set_value}
            },
            self.dry_run
        )
