""" The properties plugin maps property files into client metadata
instances. """

import os
import re
import sys
import copy
import logging
import lxml.etree
import Bcfg2.Server.Plugin
from Bcfg2.Server.Plugin import PluginExecutionError
try:
    import Bcfg2.Encryption
    HAS_CRYPTO = True
except ImportError:
    HAS_CRYPTO = False

try:
    import json
    # py2.4 json library is structured differently
    json.loads  # pylint: disable=W0104
    HAS_JSON = True
except (ImportError, AttributeError):
    try:
        import simplejson as json
        HAS_JSON = True
    except ImportError:
        HAS_JSON = False

try:
    import yaml
    HAS_YAML = True
except ImportError:
    HAS_YAML = False

LOGGER = logging.getLogger(__name__)

SETUP = None


class PropertyFile(object):
    """ Base Properties file handler """

    def __init__(self, name):
        """
        :param name: The filename of this properties file.

        .. automethod:: _write
        """
        self.name = name

    def write(self):
        """ Write the data in this data structure back to the property
        file. This public method performs checking to ensure that
        writing is possible and then calls :func:`_write`. """
        if not SETUP.cfp.getboolean("properties", "writes_enabled",
                                    default=True):
            msg = "Properties files write-back is disabled in the " + \
                "configuration"
            LOGGER.error(msg)
            raise PluginExecutionError(msg)
        try:
            self.validate_data()
        except PluginExecutionError:
            msg = "Cannot write %s: %s" % (self.name, sys.exc_info()[1])
            LOGGER.error(msg)
            raise PluginExecutionError(msg)
        try:
            return self._write()
        except IOError:
            err = sys.exc_info()[1]
            msg = "Failed to write %s: %s" % (self.name, err)
            LOGGER.error(msg)
            raise PluginExecutionError(msg)

    def _write(self):
        """ Write the data in this data structure back to the property
        file. """
        raise NotImplementedError

    def validate_data(self):
        """ Verify that the data in this file is valid. """
        raise NotImplementedError

    def get_additional_data(self, metadata):  # pylint: disable=W0613
        """ Get file data for inclusion in client metadata. """
        return copy.copy(self)


class JSONPropertyFile(Bcfg2.Server.Plugin.FileBacked, PropertyFile):
    """ Handle JSON Properties files. """

    def __init__(self, name, fam=None):
        Bcfg2.Server.Plugin.FileBacked.__init__(self, name, fam=fam)
        PropertyFile.__init__(self, name)
        self.json = None
    __init__.__doc__ = Bcfg2.Server.Plugin.FileBacked.__init__.__doc__

    def Index(self):
        try:
            self.json = json.loads(self.data)
        except ValueError:
            err = sys.exc_info()[1]
            raise PluginExecutionError("Could not load JSON data from %s: %s" %
                                       (self.name, err))
    Index.__doc__ = Bcfg2.Server.Plugin.FileBacked.Index.__doc__

    def _write(self):
        json.dump(self.json, open(self.name, 'wb'))
        return True
    _write.__doc__ = PropertyFile._write.__doc__

    def validate_data(self):
        try:
            json.dumps(self.json)
        except:
            err = sys.exc_info()[1]
            raise PluginExecutionError("Data for %s cannot be dumped to JSON: "
                                       "%s" % (self.name, err))
    validate_data.__doc__ = PropertyFile.validate_data.__doc__

    def __str__(self):
        return str(self.json)

    def __repr__(self):
        return repr(self.json)


class YAMLPropertyFile(Bcfg2.Server.Plugin.FileBacked, PropertyFile):
    """ Handle YAML Properties files. """

    def __init__(self, name, fam=None):
        Bcfg2.Server.Plugin.FileBacked.__init__(self, name, fam=fam)
        PropertyFile.__init__(self, name)
        self.yaml = None
    __init__.__doc__ = Bcfg2.Server.Plugin.FileBacked.__init__.__doc__

    def Index(self):
        try:
            self.yaml = yaml.load(self.data)
        except yaml.YAMLError:
            err = sys.exc_info()[1]
            raise PluginExecutionError("Could not load YAML data from %s: %s" %
                                       (self.name, err))
    Index.__doc__ = Bcfg2.Server.Plugin.FileBacked.Index.__doc__

    def _write(self):
        yaml.dump(self.yaml, open(self.name, 'wb'))
        return True
    _write.__doc__ = PropertyFile._write.__doc__

    def validate_data(self):
        try:
            yaml.dump(self.yaml)
        except yaml.YAMLError:
            err = sys.exc_info()[1]
            raise PluginExecutionError("Data for %s cannot be dumped to YAML: "
                                       "%s" % (self.name, err))
    validate_data.__doc__ = PropertyFile.validate_data.__doc__

    def __str__(self):
        return str(self.yaml)

    def __repr__(self):
        return repr(self.yaml)


class XMLPropertyFile(Bcfg2.Server.Plugin.StructFile, PropertyFile):
    """ Handle XML Properties files. """

    def __init__(self, name, fam=None, should_monitor=False):
        Bcfg2.Server.Plugin.StructFile.__init__(self, name, fam=fam,
                                                should_monitor=should_monitor)
        PropertyFile.__init__(self, name)

    def _write(self):
        open(self.name, "wb").write(
            lxml.etree.tostring(self.xdata,
                                xml_declaration=False,
                                pretty_print=True).decode('UTF-8'))
        return True

    def validate_data(self):
        """ ensure that the data in this object validates against the
        XML schema for this property file (if a schema exists) """
        schemafile = self.name.replace(".xml", ".xsd")
        if os.path.exists(schemafile):
            try:
                schema = lxml.etree.XMLSchema(file=schemafile)
            except lxml.etree.XMLSchemaParseError:
                err = sys.exc_info()[1]
                raise PluginExecutionError("Failed to process schema for %s: "
                                           "%s" % (self.name, err))
        else:
            # no schema exists
            return True

        if not schema.validate(self.xdata):
            raise PluginExecutionError("Data for %s fails to validate; run "
                                       "bcfg2-lint for more details" %
                                       self.name)
        else:
            return True

    def Index(self):
        Bcfg2.Server.Plugin.StructFile.Index(self)
        if HAS_CRYPTO:
            for el in self.xdata.xpath("//*[@encrypted]"):
                try:
                    el.text = self._decrypt(el).encode('ascii',
                                                       'xmlcharrefreplace')
                except UnicodeDecodeError:
                    self.logger.info("Properties: Decrypted %s to gibberish, "
                                     "skipping" % el.tag)
                except Bcfg2.Encryption.EVPError:
                    strict = self.xdata.get(
                        "decrypt",
                        SETUP.cfp.get(Bcfg2.Encryption.CFG_SECTION, "decrypt",
                                      default="strict")) == "strict"
                    msg = "Properties: Failed to decrypt %s element in %s" % \
                          (el.tag, self.name)
                    if strict:
                        raise PluginExecutionError(msg)
                    else:
                        self.logger.debug(msg)

    def _decrypt(self, element):
        """ Decrypt a single encrypted properties file element """
        if not element.text or not element.text.strip():
            return
        passes = Bcfg2.Encryption.get_passphrases(SETUP)
        try:
            passphrase = passes[element.get("encrypted")]
            try:
                return Bcfg2.Encryption.ssl_decrypt(
                    element.text, passphrase,
                    algorithm=Bcfg2.Encryption.get_algorithm(SETUP))
            except Bcfg2.Encryption.EVPError:
                # error is raised below
                pass
        except KeyError:
            # bruteforce_decrypt raises an EVPError with a sensible
            # error message, so we just let it propagate up the stack
            return Bcfg2.Encryption.bruteforce_decrypt(
                element.text, passphrases=passes.values(),
                algorithm=Bcfg2.Encryption.get_algorithm(SETUP))
        raise Bcfg2.Encryption.EVPError("Failed to decrypt")

    def get_additional_data(self, metadata):
        if SETUP.cfp.getboolean("properties", "automatch", default=False):
            default_automatch = "true"
        else:
            default_automatch = "false"

        if self.xdata.get("automatch", default_automatch).lower() == "true":
            return self.XMLMatch(metadata)
        else:
            return copy.copy(self)

    def __str__(self):
        return str(self.xdata)

    def __repr__(self):
        return repr(self.xdata)


class Properties(Bcfg2.Server.Plugin.Plugin,
                 Bcfg2.Server.Plugin.Connector,
                 Bcfg2.Server.Plugin.DirectoryBacked):
    """ The properties plugin maps property files into client metadata
    instances. """

    #: Extensions that are understood by Properties.
    extensions = ["xml"]
    if HAS_JSON:
        extensions.append("json")
    if HAS_YAML:
        extensions.extend(["yaml", "yml"])

    #: Only track and include files whose names and paths match this
    #: regex.  Created on-the-fly based on which libraries are
    #: installed (and thus which data formats are supported).
    #: Candidates are ``.xml`` (always supported), ``.json``,
    #: ``.yaml``, and ``.yml``.
    patterns = re.compile(r'.*\.%s$' % '|'.join(extensions))

    #: Ignore XML schema (``.xsd``) files
    ignore = re.compile(r'.*\.xsd$')

    def __init__(self, core, datastore):
        global SETUP  # pylint: disable=W0603
        Bcfg2.Server.Plugin.Plugin.__init__(self, core, datastore)
        Bcfg2.Server.Plugin.Connector.__init__(self)
        Bcfg2.Server.Plugin.DirectoryBacked.__init__(self, self.data, core.fam)
        SETUP = core.setup

        #: Instead of creating children of this object with a static
        #: object, we use :func:`property_dispatcher` to create a
        #: child of the appropriate subclass of :class:`PropertyFile`
        self.__child__ = self.property_dispatcher
    __init__.__doc__ = Bcfg2.Server.Plugin.Plugin.__init__.__doc__

    def property_dispatcher(self, fname, fam):
        """ Dispatch an event on a Properties file to the
        appropriate object.

        :param fname: The name of the file that received the event
        :type fname: string
        :param fam: The file monitor the event was received by
        :type fam: Bcfg2.Server.FileMonitor.FileMonitor
        :returns: An object of the appropriate subclass of
                  :class:`PropertyFile`
        """
        if fname.endswith(".xml"):
            return XMLPropertyFile(fname, fam)
        elif HAS_JSON and fname.endswith(".json"):
            return JSONPropertyFile(fname, fam)
        elif HAS_YAML and (fname.endswith(".yaml") or fname.endswith(".yml")):
            return YAMLPropertyFile(fname, fam)
        else:
            raise Bcfg2.Server.Plugin.PluginExecutionError(
                "Properties: Unknown extension %s" % fname)

    def get_additional_data(self, metadata):
        rv = dict()
        for fname, pfile in self.entries.items():
            rv[fname] = pfile.get_additional_data(metadata)
        return rv
    get_additional_data.__doc__ = \
        Bcfg2.Server.Plugin.Connector.get_additional_data.__doc__