aif-ng/aif/config/parser.py

276 lines
11 KiB
Python

import copy
import logging
import os
import re
##
import requests
from lxml import etree, objectify
_logger = logging.getLogger('config:{0}'.format(__name__))
class Config(object):
def __init__(self, xsd_path = None, *args, **kwargs):
self.xsd_path = None
self.tree = None
self.namespaced_tree = None
self.xml = None
self.namespaced_xml = None
self.raw = None
self.xsd = None
self.defaultsParser = None
self.obj = None
_logger.info('Instantiated {0}.'.format(type(self).__name__))
def main(self, validate = True, populate_defaults = True):
self.fetch()
self.parseRaw()
if populate_defaults:
self.populateDefaults()
if validate:
self.validate()
self.pythonize()
return(None)
def fetch(self): # Just a fail-safe; this is overridden by specific subclasses.
pass
return(None)
def getXSD(self, xsdpath = None):
if not xsdpath:
xsdpath = self.xsd_path
raw_xsd = None
base_url = None
if xsdpath:
_logger.debug('XSD path specified.')
orig_xsdpath = xsdpath
xsdpath = os.path.abspath(os.path.expanduser(xsdpath))
_logger.debug('Transformed XSD path: {0} => {1}'.format(orig_xsdpath, xsdpath))
if not os.path.isfile(xsdpath):
_logger.error('The specified XSD path {0} does not exist on the local filesystem.'.format(xsdpath))
raise ValueError('Specified XSD path does not exist')
with open(xsdpath, 'rb') as fh:
raw_xsd = fh.read()
base_url = os.path.split(xsdpath)[0]
else:
_logger.debug('No XSD path specified; getting it from the configuration file.')
xsi = self.xml.nsmap.get('xsi', 'http://www.w3.org/2001/XMLSchema-instance')
_logger.debug('xsi: {0}'.format(xsi))
schemaLocation = '{{{0}}}schemaLocation'.format(xsi)
schemaURL = self.xml.attrib.get(schemaLocation,
'https://schema.xml.r00t2.io/projects/aif.xsd')
_logger.debug('Detected schema map: {0}'.format(schemaURL))
split_url = schemaURL.split()
if len(split_url) == 2: # a properly defined schemaLocation
schemaURL = split_url[1]
else:
schemaURL = split_url[0] # a LAZY schemaLocation
_logger.info('Detected schema location: {0}'.format(schemaURL))
if schemaURL.startswith('file://'):
schemaURL = re.sub(r'^file://', r'', schemaURL)
_logger.debug('Fetching local file {0}'.format(schemaURL))
with open(schemaURL, 'rb') as fh:
raw_xsd = fh.read()
base_url = os.path.dirname(schemaURL)
else:
_logger.debug('Fetching remote file: {0}'.format(schemaURL))
req = requests.get(schemaURL)
if not req.ok:
_logger.error('Unable to fetch XSD.')
raise RuntimeError('Could not download XSD')
raw_xsd = req.content
base_url = os.path.split(req.url)[0] # This makes me feel dirty.
_logger.debug('Loaded XSD at {0} ({1} bytes).'.format(xsdpath, len(raw_xsd)))
_logger.debug('Parsed XML base URL: {0}'.format(base_url))
self.xsd = etree.XMLSchema(etree.XML(raw_xsd, base_url = base_url))
_logger.info('Rendered XSD.')
return(None)
def parseRaw(self, parser = None):
self.xml = etree.fromstring(self.raw, parser = parser)
_logger.debug('Generated xml.')
self.namespaced_xml = etree.fromstring(self.raw, parser = parser)
_logger.debug('Generated namespaced xml.')
self.tree = self.xml.getroottree()
_logger.debug('Generated tree.')
self.namespaced_tree = self.namespaced_xml.getroottree()
_logger.debug('Generated namespaced tree.')
self.tree.xinclude()
_logger.debug('Parsed XInclude for tree.')
self.namespaced_tree.xinclude()
_logger.debug('Parsed XInclude for namespaced tree.')
self.stripNS()
return(None)
def populateDefaults(self):
_logger.info('Populating missing values with defaults from XSD.')
if not self.xsd:
self.getXSD()
if not self.defaultsParser:
self.defaultsParser = etree.XMLParser(schema = self.xsd, attribute_defaults = True)
self.parseRaw(parser = self.defaultsParser)
return(None)
def pythonize(self, stripped = True, obj = 'tree'):
# https://bugs.launchpad.net/lxml/+bug/1850221
_logger.debug('Pythonizing to native objects')
strobj = self.toString(stripped = stripped, obj = obj)
self.obj = objectify.fromstring(strobj)
objectify.annotate(self.obj)
objectify.xsiannotate(self.obj)
return(None)
def removeDefaults(self):
_logger.info('Removing default values from missing values.')
self.parseRaw()
return(None)
def stripNS(self, obj = None):
_logger.debug('Stripping namespace.')
# https://stackoverflow.com/questions/30232031/how-can-i-strip-namespaces-out-of-an-lxml-tree/30233635#30233635
xpathq = "descendant-or-self::*[namespace-uri()!='']"
if not obj:
_logger.debug('No XML object selected; using instance\'s xml and tree.')
for x in (self.tree, self.xml):
for e in x.xpath(xpathq):
e.tag = etree.QName(e).localname
elif isinstance(obj, (etree._Element, etree._ElementTree)):
_logger.debug('XML object provided: {0}'.format(etree.tostring(obj, with_tail = False).decode('utf-8')))
obj = copy.deepcopy(obj)
for e in obj.xpath(xpathq):
e.tag = etree.QName(e).localname
return(obj)
else:
_logger.error('A non-XML object was provided.')
raise ValueError('Did not know how to parse obj parameter')
return(None)
def toString(self, stripped = False, obj = None):
if isinstance(obj, (etree._Element, etree._ElementTree)):
_logger.debug('Converting an XML object to a string')
if stripped:
_logger.debug('Stripping before stringifying.')
obj = self.stripNS(obj)
elif obj in ('tree', None):
if not stripped:
_logger.debug('Converting the instance\'s namespaced tree to a string.')
obj = self.namespaced_tree
else:
_logger.debug('Converting the instance\'s stripped tree to a string.')
obj = self.tree
elif obj == 'xml':
if not stripped:
_logger.debug('Converting instance\'s namespaced XML to a string')
obj = self.namespaced_xml
else:
_logger.debug('Converting instance\'s stripped XML to a string')
obj = self.xml
else:
_logger.error(('obj parameter must be "tree", "xml", or of type '
'lxml.etree._Element or lxml.etree._ElementTree'))
raise TypeError('Invalid obj type')
obj = copy.deepcopy(obj)
strxml = etree.tostring(obj,
encoding = 'utf-8',
xml_declaration = True,
pretty_print = True,
with_tail = True,
inclusive_ns_prefixes = True)
_logger.debug('Rendered string output successfully.')
return(strxml)
def validate(self):
if not self.xsd:
self.getXSD()
_logger.debug('Checking validation against namespaced tree.')
self.xsd.assertValid(self.namespaced_tree)
return(None)
class LocalFile(Config):
def __init__(self, path, xsd_path = None, *args, **kwargs):
super().__init__(xsd_path = xsd_path, *args, **kwargs)
self.type = 'local'
self.source = path
def fetch(self):
orig_src = self.source
self.source = os.path.abspath(os.path.expanduser(self.source))
_logger.debug('Canonized path: {0} => {1}'.format(orig_src, self.source))
if not os.path.isfile(self.source):
_logger.error('Config at {0} not found.'.format(self.source))
raise ValueError('Config file does not exist'.format(self.source))
with open(self.source, 'rb') as fh:
self.raw = fh.read()
_logger.debug('Fetched configuration ({0} bytes).'.format(len(self.raw)))
return(None)
class RemoteFile(Config):
def __init__(self, uri, xsd_path = None, *args, **kwargs):
super().__init__(*args, **kwargs)
self.type = 'remote'
self.source = uri
def fetch(self):
r = requests.get(self.source)
if not r.ok():
_logger.error('Could not fetch {0}'.format(self.source))
raise RuntimeError('Could not download XML')
self.raw = r.content
_logger.debug('Fetched configuration ({0} bytes).'.format(len(self.raw)))
return(None)
class ConfigStr(Config):
def __init__(self, rawxml, xsd_path = None, *args, **kwargs):
super().__init__(*args, **kwargs)
self.type = 'raw_str'
self.source = rawxml
def fetch(self):
self.raw = self.source.encode('utf-8')
_logger.debug('Raw configuration (str) passed in ({0} bytes); converted to bytes.'.format(len(self.raw)))
return(None)
class ConfigBin(Config):
def __init__(self, rawbinaryxml, xsd_path = None, *args, **kwargs):
super().__init__(*args, **kwargs)
self.type = 'raw_bin'
self.source = rawbinaryxml
def fetch(self):
self.raw = self.source
_logger.debug('Raw configuration (binary) passed in ({0} bytes); converted to bytes.'.format(len(self.raw)))
return(None)
detector = {'raw': (re.compile(r'^\s*(?P<xml><(\?xml|aif)\s+.*)\s*$', re.DOTALL | re.MULTILINE), ConfigStr),
'remote': (re.compile(r'^(?P<uri>(?P<scheme>(https?|ftps?)://)(?P<path>.*))\s*$'), RemoteFile),
'local': (re.compile(r'^(file://)?(?P<path>(/?[^/]+)+/?)$'), LocalFile)}
def getConfig(cfg_ref, validate = True, populate_defaults = True, xsd_path = None):
cfgobj = None
# This is kind of gross.
for configtype, (pattern, configClass) in detector.items():
try:
if pattern.search(cfg_ref):
cfgobj = configClass(cfg_ref, xsd_path = xsd_path)
_logger.info('Config detected as {0}.'.format(configtype))
break
except TypeError:
ptrn = re.compile(detector['raw'][0].pattern.encode('utf-8'))
if not ptrn.search(cfg_ref):
_logger.error('Could not detect which configuration type was passed.')
raise ValueError('Unexpected/unparseable cfg_ref.')
else:
_logger.info('Config detected as ConfigBin.')
cfgobj = ConfigBin(cfg_ref, xsd_path = xsd_path)
break
if cfgobj:
_logger.info('Parsing configuration.')
cfgobj.main(validate = validate, populate_defaults = populate_defaults)
return(cfgobj)