Add basic config handling

1 files changed, 473 insertions, 0 deletions

diff --git a/src/leap/config/pluggableconfig.py b/src/leap/config/pluggableconfig.py
new file mode 100644
index 00000000..64aa05cc
--- /dev/null
+++ b/src/leap/config/pluggableconfig.py
@@ -0,0 +1,473 @@
+# -*- coding: utf-8 -*-
+# pluggableconfig.py
+# Copyright (C) 2013 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+generic configuration handlers
+"""
+import copy
+import json
+import logging
+import os
+import time
+import urlparse
+
+import jsonschema
+
+#from leap.base.util.translations import LEAPTranslatable
+
+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:
+# - 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 TranslatableType(object):
+    """
+    a type that casts to LEAPTranslatable objects.
+    Used for labels we get from providers and stuff.
+    """
+
+    def to_python(self, data):
+        # TODO: add translatable
+        return data#LEAPTranslatable(data)
+
+    # needed? we already have an extended dict...
+    #def get_prep_value(self, data):
+        #return dict(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.geturl()
+
+    def get_prep_value(self, data):
+        return data
+
+
+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.geturl()
+
+    def get_prep_value(self, data):
+        return data
+
+
+types = {
+    'date': DateType(),
+    'uri': URIType(),
+    'https-uri': HTTPSURIType(),
+    'translatable': TranslatableType(),
+}
+
+
+class PluggableConfig(object):
+
+    options = {}
+
+    def __init__(self,
+                 adaptors=adaptors,
+                 types=types,
+                 format=None):
+
+        self.config = {}
+        self.adaptors = adaptors
+        self.types = types
+        self._format = format
+        self.mtime = None
+        self.dirty = False
+
+    @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)
+
+        if self.mtime:
+            self.touch_mtime(filename)
+
+    def touch_mtime(self, filename):
+        mtime = self.mtime
+        os.utime(filename, (mtime, mtime))
+
+    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 set_dirty(self):
+        self.dirty = True
+
+    def is_dirty(self):
+        return self.dirty
+
+    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)
+        mtime = kwargs.pop("mtime", None)
+        self.mtime = mtime
+        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():  # pragma: no cover
+
+    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()