""" Base classes for Lint plugins and error handling """

import os
import sys
import logging
from copy import copy
import textwrap
import lxml.etree
import fcntl
import termios
import struct


def _ioctl_GWINSZ(fd):  # pylint: disable=C0103
    """ get a tuple of (height, width) giving the size of the window
    from the given file descriptor """
    try:
        return struct.unpack('hh', fcntl.ioctl(fd, termios.TIOCGWINSZ, '1234'))
    except:  # pylint: disable=W0702
        return None


def get_termsize():
    """ get a tuple of (width, height) giving the size of the terminal """
    if not sys.stdout.isatty():
        return None
    dims = _ioctl_GWINSZ(0) or _ioctl_GWINSZ(1) or _ioctl_GWINSZ(2)
    if not dims:
        try:
            fd = os.open(os.ctermid(), os.O_RDONLY)
            dims = _ioctl_GWINSZ(fd)
            os.close(fd)
        except:  # pylint: disable=W0702
            pass
    if not dims:
        try:
            dims = (os.environ['LINES'], os.environ['COLUMNS'])
        except KeyError:
            return None
    return int(dims[1]), int(dims[0])


class Plugin(object):
    """ Base class for all bcfg2-lint plugins """

    def __init__(self, config, errorhandler=None, files=None):
        """
        :param config: A :mod:`Bcfg2.Options` setup dict
        :type config: dict
        :param errorhandler: A :class:`Bcfg2.Server.Lint.ErrorHandler`
                             that will be used to handle lint errors.
                             If one is not provided, a new one will be
                             instantiated.
        :type errorhandler: Bcfg2.Server.Lint.ErrorHandler
        :param files: A list of files to run bcfg2-lint against.  (See
                      the bcfg2-lint ``--stdin`` option.)
        :type files: list of strings
        """

        #: The list of files that bcfg2-lint should be run against
        self.files = files

        #: The Bcfg2.Options setup dict
        self.config = config

        self.logger = logging.getLogger('bcfg2-lint')
        if errorhandler is None:
            #: The error handler
            self.errorhandler = ErrorHandler()
        else:
            self.errorhandler = errorhandler
        self.errorhandler.RegisterErrors(self.Errors())

    def Run(self):
        """ Run the plugin.  Must be overloaded by child classes. """
        raise NotImplementedError

    @classmethod
    def Errors(cls):
        """ Returns a dict of errors the plugin supplies, in a format
        suitable for passing to
        :func:`Bcfg2.Server.Lint.ErrorHandler.RegisterErrors`.

        Must be overloaded by child classes.

        :returns: dict
        """
        raise NotImplementedError

    def HandlesFile(self, fname):
        """ Returns True if the given file should be handled by the
        plugin according to :attr:`Bcfg2.Server.Lint.Plugin.files`,
        False otherwise. """
        return (self.files is None or
                fname in self.files or
                os.path.join(self.config['repo'], fname) in self.files or
                os.path.abspath(fname) in self.files or
                os.path.abspath(os.path.join(self.config['repo'],
                                             fname)) in self.files)

    def LintError(self, err, msg):
        """ Raise an error from the lint process.

        :param err: The name of the error being raised.  This name
                    must be a key in the dict returned by
                    :func:`Bcfg2.Server.Lint.Plugin.Errors`.
        :type err: string
        :param msg: The freeform message to display to the end user.
        :type msg: string
        """
        self.errorhandler.dispatch(err, msg)

    def RenderXML(self, element, keep_text=False):
        """ Render an XML element for error output.  This prefixes the
        line number and removes children for nicer display.

        :param element: The element to render
        :type element: lxml.etree._Element
        :param keep_text: Do not discard text content from the element
                          for display
        :type keep_text: boolean
        """
        xml = None
        if len(element) or element.text:
            el = copy(element)
            if el.text and not keep_text:
                el.text = '...'
            for child in el.iterchildren():
                el.remove(child)
            xml = lxml.etree.tostring(
                el,
                xml_declaration=False).decode("UTF-8").strip()
        else:
            xml = lxml.etree.tostring(
                element,
                xml_declaration=False).decode("UTF-8").strip()
        return "   line %s: %s" % (element.sourceline, xml)


class ErrorHandler(object):
    """ A class to handle errors for bcfg2-lint plugins """

    def __init__(self, errors=None):
        """
        :param config: An initial dict of errors to register
        :type config: dict
        """
        #: The number of errors passed to this error handler
        self.errors = 0

        #: The number of warnings passed to this error handler
        self.warnings = 0

        self.logger = logging.getLogger('bcfg2-lint')

        termsize = get_termsize()
        if termsize is not None and termsize[0] > 0:
            twrap = textwrap.TextWrapper(initial_indent="  ",
                                         subsequent_indent="  ",
                                         width=termsize[0])
            #: A function to wrap text to the width of the terminal
            self._wrapper = twrap.wrap
        else:
            self._wrapper = lambda s: [s]

        #: A dict of registered errors
        self.errortypes = dict()
        if errors is not None:
            self.RegisterErrors(dict(errors.items()))

    def RegisterErrors(self, errors):
        """ Register a dict of errors that a plugin may raise.  The
        keys of the dict are short strings that describe each error;
        the values are the default error handling for that error
        ("error", "warning", or "silent").

        :param errors: The error dict
        :type errors: dict
        """
        for err, action in errors.items():
            if err not in self.errortypes:
                if "warn" in action:
                    self.errortypes[err] = self.warn
                elif "err" in action:
                    self.errortypes[err] = self.error
                else:
                    self.errortypes[err] = self.debug

    def dispatch(self, err, msg):
        """ Dispatch an error to the correct handler.

        :param err: The name of the error being raised.  This name
                    must be a key in
                    :attr:`Bcfg2.Server.Lint.ErrorHandler.errortypes`,
                    the dict of registered errors.
        :type err: string
        :param msg: The freeform message to display to the end user.
        :type msg: string
        """
        if err in self.errortypes:
            self.errortypes[err](msg)
            self.logger.debug("    (%s)" % err)
        else:
            # assume that it's an error, but complain
            self.error(msg)
            self.logger.warning("Unknown error %s" % err)

    def error(self, msg):
        """ Log an error condition.

        :param msg: The freeform message to display to the end user.
        :type msg: string
        """
        self.errors += 1
        self._log(msg, self.logger.error, prefix="ERROR: ")

    def warn(self, msg):
        """ Log a warning condition.

        :param msg: The freeform message to display to the end user.
        :type msg: string
        """
        self.warnings += 1
        self._log(msg, self.logger.warning, prefix="WARNING: ")

    def debug(self, msg):
        """ Log a silent/debug condition.

        :param msg: The freeform message to display to the end user.
        :type msg: string
        """
        self._log(msg, self.logger.debug)

    def _log(self, msg, logfunc, prefix=""):
        """ Generic log function that logs a message with the given
        function after wrapping it for the terminal width. """
        # a message may itself consist of multiple lines.  wrap() will
        # elide them all into a single paragraph, which we don't want.
        # so we split the message into its paragraphs and wrap each
        # paragraph individually.  this means, unfortunately, that we
        # lose textwrap's built-in initial indent functionality,
        # because we want to only treat the very first line of the
        # first paragraph specially.  so we do some silliness.
        rawlines = msg.splitlines()
        firstline = True
        for rawline in rawlines:
            lines = self._wrapper(rawline)
            for line in lines:
                if firstline:
                    logfunc(prefix + line.lstrip())
                    firstline = False
                else:
                    logfunc(line)


class ServerlessPlugin(Plugin):
    """ Base class for bcfg2-lint plugins that are run before the
    server starts up (i.e., plugins that check things that may prevent
    the server from starting up). """
    pass


class ServerPlugin(Plugin):
    """ Base class for bcfg2-lint plugins that check things that
    require the running Bcfg2 server. """

    def __init__(self, core, config, errorhandler=None, files=None):
        """
        :param core: The Bcfg2 server core
        :type core: Bcfg2.Server.Core.BaseCore
        :param config: A :mod:`Bcfg2.Options` setup dict
        :type config: dict
        :param errorhandler: A :class:`Bcfg2.Server.Lint.ErrorHandler`
                             that will be used to handle lint errors.
                             If one is not provided, a new one will be
                             instantiated.
        :type errorhandler: Bcfg2.Server.Lint.ErrorHandler
        :param files: A list of files to run bcfg2-lint against.  (See
                      the bcfg2-lint ``--stdin`` option.)
        :type files: list of strings
        """
        Plugin.__init__(self, config, errorhandler=errorhandler, files=files)

        #: The server core
        self.core = core
        self.logger = self.core.logger

        #: The metadata plugin
        self.metadata = self.core.metadata