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Diffstat (limited to 'src/leap/base/pluggableconfig.py')
| -rw-r--r-- | src/leap/base/pluggableconfig.py | 421 |
1 files changed, 421 insertions, 0 deletions
diff --git a/src/leap/base/pluggableconfig.py b/src/leap/base/pluggableconfig.py new file mode 100644 index 00000000..b8615ad8 --- /dev/null +++ b/src/leap/base/pluggableconfig.py @@ -0,0 +1,421 @@ +""" +generic configuration handlers +""" +import copy +import json +import logging +import os +import time +import urlparse + +import jsonschema + +logger = logging.getLogger(__name__) + + +__all__ = ['PluggableConfig', + 'adaptors', + 'types', + 'UnknownOptionException', + 'MissingValueException', + 'ConfigurationProviderException', + 'TypeCastException'] + +# exceptions + + +class UnknownOptionException(Exception): + """exception raised when a non-configuration + value is present in the configuration""" + + +class MissingValueException(Exception): + """exception raised when a required value is missing""" + + +class ConfigurationProviderException(Exception): + """exception raised when a configuration provider is missing, etc""" + + +class TypeCastException(Exception): + """exception raised when a + configuration item cannot be coerced to a type""" + + +class ConfigAdaptor(object): + """ + abstract base class for config adaotors for + serialization/deserialization and custom validation + and type casting. + """ + def read(self, filename): + raise NotImplementedError("abstract base class") + + def write(self, config, filename): + with open(filename, 'w') as f: + self._write(f, config) + + def _write(self, fp, config): + raise NotImplementedError("abstract base class") + + def validate(self, config, schema): + raise NotImplementedError("abstract base class") + + +adaptors = {} + + +class JSONSchemaEncoder(json.JSONEncoder): + """ + custom default encoder that + casts python objects to json objects for + the schema validation + """ + def default(self, obj): + if obj is str: + return 'string' + if obj is unicode: + return 'string' + if obj is int: + return 'integer' + if obj is list: + return 'array' + if obj is dict: + return 'object' + if obj is bool: + return 'boolean' + + +class JSONAdaptor(ConfigAdaptor): + indent = 2 + extensions = ['json'] + + def read(self, _from): + if isinstance(_from, file): + _from_string = _from.read() + if isinstance(_from, str): + _from_string = _from + return json.loads(_from_string) + + def _write(self, fp, config): + fp.write(json.dumps(config, + indent=self.indent, + sort_keys=True)) + + def validate(self, config, schema_obj): + schema_json = JSONSchemaEncoder().encode(schema_obj) + schema = json.loads(schema_json) + jsonschema.validate(config, schema) + + +adaptors['json'] = JSONAdaptor() + +# +# Adaptors +# +# Allow to apply a predefined set of types to the +# specs, so it checks the validity of formats and cast it +# to proper python types. + +# TODO: +# - multilingual object. +# - HTTPS uri + + +class DateType(object): + fmt = '%Y-%m-%d' + + def to_python(self, data): + return time.strptime(data, self.fmt) + + def get_prep_value(self, data): + return time.strftime(self.fmt, data) + + +class URIType(object): + + def to_python(self, data): + parsed = urlparse.urlparse(data) + if not parsed.scheme: + raise TypeCastException("uri %s has no schema" % data) + return parsed + + def get_prep_value(self, data): + return data.geturl() + + +class HTTPSURIType(object): + + def to_python(self, data): + parsed = urlparse.urlparse(data) + if not parsed.scheme: + raise TypeCastException("uri %s has no schema" % data) + if parsed.scheme != "https": + raise TypeCastException( + "uri %s does not has " + "https schema" % data) + return parsed + + def get_prep_value(self, data): + return data.geturl() + + +types = { + 'date': DateType(), + 'uri': URIType(), + 'https-uri': HTTPSURIType(), +} + + +class PluggableConfig(object): + + options = {} + + def __init__(self, + adaptors=adaptors, + types=types, + format=None): + + self.config = {} + self.adaptors = adaptors + self.types = types + self._format = format + + @property + def option_dict(self): + if hasattr(self, 'options') and isinstance(self.options, dict): + return self.options.get('properties', None) + + def items(self): + """ + act like an iterator + """ + if isinstance(self.option_dict, dict): + return self.option_dict.items() + return self.options + + def validate(self, config, format=None): + """ + validate config + """ + schema = self.options + if format is None: + format = self._format + + if format: + adaptor = self.get_adaptor(self._format) + adaptor.validate(config, schema) + else: + # we really should make format mandatory... + logger.error('no format passed to validate') + + # first round of validation is ok. + # now we proceed to cast types if any specified. + self.to_python(config) + + def to_python(self, config): + """ + cast types following first type and then format indications. + """ + unseen_options = [i for i in config if i not in self.option_dict] + if unseen_options: + raise UnknownOptionException( + "Unknown options: %s" % ', '.join(unseen_options)) + + for key, value in config.items(): + _type = self.option_dict[key].get('type') + if _type is None and 'default' in self.option_dict[key]: + _type = type(self.option_dict[key]['default']) + if _type is not None: + tocast = True + if not callable(_type) and isinstance(value, _type): + tocast = False + if tocast: + try: + config[key] = _type(value) + except BaseException, e: + raise TypeCastException( + "Could not coerce %s, %s, " + "to type %s: %s" % (key, value, _type.__name__, e)) + _format = self.option_dict[key].get('format', None) + _ftype = self.types.get(_format, None) + if _ftype: + try: + config[key] = _ftype.to_python(value) + except BaseException, e: + raise TypeCastException( + "Could not coerce %s, %s, " + "to format %s: %s" % (key, value, + _ftype.__class__.__name__, + e)) + + return config + + def prep_value(self, config): + """ + the inverse of to_python method, + called just before serialization + """ + for key, value in config.items(): + _format = self.option_dict[key].get('format', None) + _ftype = self.types.get(_format, None) + if _ftype and hasattr(_ftype, 'get_prep_value'): + try: + config[key] = _ftype.get_prep_value(value) + except BaseException, e: + raise TypeCastException( + "Could not serialize %s, %s, " + "by format %s: %s" % (key, value, + _ftype.__class__.__name__, + e)) + else: + config[key] = value + return config + + # methods for adding configuration + + def get_default_values(self): + """ + return a config options from configuration defaults + """ + defaults = {} + for key, value in self.items(): + if 'default' in value: + defaults[key] = value['default'] + return copy.deepcopy(defaults) + + def get_adaptor(self, format): + """ + get specified format adaptor or + guess for a given filename + """ + adaptor = self.adaptors.get(format, None) + if adaptor: + return adaptor + + # not registered in adaptors dict, let's try all + for adaptor in self.adaptors.values(): + if format in adaptor.extensions: + return adaptor + + def filename2format(self, filename): + extension = os.path.splitext(filename)[-1] + return extension.lstrip('.') or None + + def serialize(self, filename, format=None, full=False): + if not format: + format = self._format + if not format: + format = self.filename2format(filename) + if not format: + raise Exception('Please specify a format') + # TODO: more specific exception type + + adaptor = self.get_adaptor(format) + if not adaptor: + raise Exception("Adaptor not found for format: %s" % format) + + config = copy.deepcopy(self.config) + serializable = self.prep_value(config) + adaptor.write(serializable, filename) + + def deserialize(self, string=None, fromfile=None, format=None): + """ + load configuration from a file or string + """ + + def _try_deserialize(): + if fromfile: + with open(fromfile, 'r') as f: + content = adaptor.read(f) + elif string: + content = adaptor.read(string) + return content + + # XXX cleanup this! + + if fromfile: + assert os.path.exists(fromfile) + if not format: + format = self.filename2format(fromfile) + + if not format: + format = self._format + if format: + adaptor = self.get_adaptor(format) + else: + adaptor = None + + if adaptor: + content = _try_deserialize() + return content + + # no adaptor, let's try rest of adaptors + + adaptors = self.adaptors[:] + + if format: + adaptors.sort( + key=lambda x: int( + format in x.extensions), + reverse=True) + + for adaptor in adaptors: + content = _try_deserialize() + return content + + def load(self, *args, **kwargs): + """ + load from string or file + if no string of fromfile option is given, + it will attempt to load from defaults + defined in the schema. + """ + string = args[0] if args else None + fromfile = kwargs.get("fromfile", None) + content = None + + # start with defaults, so we can + # have partial values applied. + content = self.get_default_values() + if string and isinstance(string, str): + content = self.deserialize(string) + + if not string and fromfile is not None: + #import ipdb;ipdb.set_trace() + content = self.deserialize(fromfile=fromfile) + + if not content: + logger.error('no content could be loaded') + # XXX raise! + return + + # lazy evaluation until first level of nesting + # to allow lambdas with context-dependant info + # like os.path.expanduser + for k, v in content.iteritems(): + if callable(v): + content[k] = v() + + self.validate(content) + self.config = content + return True + + +def testmain(): + from tests import test_validation as t + import pprint + + config = PluggableConfig(_format="json") + properties = copy.deepcopy(t.sample_spec) + + config.options = properties + config.load(fromfile='data.json') + + print 'config' + pprint.pprint(config.config) + + config.serialize('/tmp/testserial.json') + +if __name__ == "__main__": + testmain() |