juju/client/facade.py

   1 import argparse
   2 import builtins
   3 import functools
   4 import json
   5 import keyword
   6 from pathlib import Path
   7 import pprint
   8 import textwrap
   9 from typing import Sequence, Mapping, TypeVar, Any, Union
  10 import typing
  11
  12 from . import codegen
  13
  14 _marker = object()
  15
  16 # Map basic types to Python's typing with a callable
  17 SCHEMA_TO_PYTHON = {
  18     'string': str,
  19     'integer': int,
  20     'float': float,
  21     'number': float,
  22     'boolean': bool,
  23     'object': Any,
  24 }
  25
  26
  27 class KindRegistry(dict):
  28     def register(self, name, version, obj):
  29         self[name] = {version: {
  30             "object": obj,
  31         }}
  32
  33     def lookup(self, name, version=None):
  34         """If version is omitted, max version is used"""
  35         versions = self.get(name)
  36         if not versions:
  37             return None
  38         if version:
  39             return versions[version]
  40         return versions[max(versions)]
  41
  42     def getObj(self, name, version=None):
  43         result = self.lookup(name, version)
  44         if result:
  45             obj = result["object"]
  46             return obj
  47         return None
  48
  49
  50 class TypeRegistry(dict):
  51     def get(self, name):
  52         # Two way mapping
  53         refname = Schema.referenceName(name)
  54         if refname not in self:
  55             result = TypeVar(refname)
  56             self[refname] = result
  57             self[result] = refname
  58
  59         return self[refname]
  60
  61 _types = TypeRegistry()
  62 _registry = KindRegistry()
  63 classes = {}
  64
  65
  66 def booler(v):
  67     if isinstance(v, str):
  68         if v == "false":
  69             return False
  70     return bool(v)
  71
  72
  73 def getRefType(ref):
  74     return _types.get(ref)
  75
  76
  77 def refType(obj):
  78     return getRefType(obj["$ref"])
  79
  80
  81 def objType(obj):
  82     kind = obj.get('type')
  83     if not kind:
  84         raise ValueError("%s has no type" % obj)
  85     result = SCHEMA_TO_PYTHON.get(kind)
  86     if not result:
  87         raise ValueError("%s has type %s" % (obj, kind))
  88     return result
  89
  90
  91 basic_types = [str, bool, int, float]
  92
  93
  94 def name_to_py(name):
  95     result = name.replace("-", "_")
  96     result = result.lower()
  97     if keyword.iskeyword(result) or result in dir(builtins):
  98         result += "_"
  99     return result
 100
 101
 102 def strcast(kind, keep_builtins=False):
 103     if issubclass(kind, typing.GenericMeta):
 104         return str(kind)[1:]
 105     if str(kind).startswith('~'):
 106         return str(kind)[1:]
 107     if (kind in basic_types or
 108             type(kind) in basic_types) and keep_builtins is False:
 109         return kind.__name__
 110     return kind
 111
 112
 113 class Args(list):
 114     def __init__(self, defs):
 115         self.defs = defs
 116         if defs:
 117             rtypes = _registry.getObj(_types[defs])
 118             if len(rtypes) == 1:
 119                 if not self.do_explode(rtypes[0][1]):
 120                     for name, rtype in rtypes:
 121                         self.append((name, rtype))
 122             else:
 123                 for name, rtype in rtypes:
 124                     self.append((name, rtype))
 125
 126     def do_explode(self, kind):
 127         if kind in basic_types or type(kind) is typing.TypeVar:
 128             return False
 129         if not issubclass(kind, (typing.Sequence,
 130                                  typing.Mapping)):
 131             self.clear()
 132             self.extend(Args(kind))
 133             return True
 134         return False
 135
 136     def PyToSchemaMapping(self):
 137         m = {}
 138         for n, rt in self:
 139             m[name_to_py(n)] = n
 140         return m
 141
 142     def SchemaToPyMapping(self):
 143         m = {}
 144         for n, tr in self:
 145             m[n] = name_to_py(n)
 146         return m
 147
 148     def _format(self, name, rtype, typed=True):
 149         if typed:
 150             return "{} : {}".format(
 151                 name_to_py(name),
 152                 strcast(rtype)
 153             )
 154         else:
 155             return name_to_py(name)
 156
 157     def _get_arg_str(self, typed=False, joined=", "):
 158         if self:
 159             parts = []
 160             for item in self:
 161                 parts.append(self._format(item[0], item[1], typed))
 162             if joined:
 163                 return joined.join(parts)
 164             return parts
 165         return ''
 166
 167     def as_kwargs(self):
 168         if self:
 169             parts = []
 170             for item in self:
 171                 parts.append('{}=None'.format(name_to_py(item[0])))
 172             return ', '.join(parts)
 173         return ''
 174
 175     def typed(self):
 176         return self._get_arg_str(True)
 177
 178     def __str__(self):
 179         return self._get_arg_str(False)
 180
 181     def get_doc(self):
 182         return self._get_arg_str(True, "\n")
 183
 184
 185 def buildTypes(schema, capture):
 186     global classes
 187     INDENT = "    "
 188     for kind in sorted((k for k in _types if not isinstance(k, str)),
 189                        key=lambda x: str(x)):
 190         name = _types[kind]
 191         if name in classes:
 192             continue
 193         args = Args(kind)
 194         source = ["""
 195 class {}(Type):
 196     _toSchema = {}
 197     _toPy = {}
 198     def __init__(self{}{}):
 199         '''
 200 {}
 201         '''""".format(
 202             name,
 203             # pprint these to get stable ordering across regens
 204             pprint.pformat(args.PyToSchemaMapping(), width=999),
 205             pprint.pformat(args.SchemaToPyMapping(), width=999),
 206             ", " if args else "",
 207             args.as_kwargs(),
 208             textwrap.indent(args.get_doc(), INDENT * 2))
 209                   ]
 210         assignments = args._get_arg_str(False, False)
 211
 212         if not args:
 213             source.append("{}pass".format(INDENT * 2))
 214         else:
 215             for arg in args:
 216                 arg_name = name_to_py(arg[0])
 217                 arg_type = arg[1]
 218                 arg_type_name = strcast(arg_type)
 219                 if arg_type in basic_types:
 220                     source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 221                 elif issubclass(arg_type, typing.Sequence):
 222                     value_type = (
 223                         arg_type_name.__parameters__[0]
 224                         if len(arg_type_name.__parameters__)
 225                         else None
 226                     )
 227                     if type(value_type) is typing.TypeVar:
 228                         source.append("{}self.{} = [{}.from_json(o) for o in {} or []]".format(
 229                             INDENT * 2, arg_name, strcast(value_type), arg_name))
 230                     else:
 231                         source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 232                 elif issubclass(arg_type, typing.Mapping):
 233                     value_type = (
 234                         arg_type_name.__parameters__[1]
 235                         if len(arg_type_name.__parameters__) > 1
 236                         else None
 237                     )
 238                     if type(value_type) is typing.TypeVar:
 239                         source.append("{}self.{} = {{k: {}.from_json(v) for k, v in ({} or dict()).items()}}".format(
 240                             INDENT * 2, arg_name, strcast(value_type), arg_name))
 241                     else:
 242                         source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 243                 elif type(arg_type) is typing.TypeVar:
 244                     source.append("{}self.{} = {}.from_json({}) if {} else None".format(
 245                         INDENT * 2, arg_name, arg_type_name, arg_name, arg_name))
 246                 else:
 247                     source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 248
 249         source = "\n".join(source)
 250         capture.write(source)
 251         capture.write("\n\n")
 252         co = compile(source, __name__, "exec")
 253         ns = _getns()
 254         exec(co, ns)
 255         cls = ns[name]
 256         classes[name] = cls
 257
 258
 259 def retspec(defs):
 260     # return specs
 261     # only return 1, so if there is more than one type
 262     # we need to include a union
 263     # In truth there is only 1 return
 264     # Error or the expected Type
 265     if not defs:
 266         return None
 267     rtypes = _registry.getObj(_types[defs])
 268     if not rtypes:
 269         return None
 270     if len(rtypes) > 1:
 271         return Union[tuple([strcast(r[1], True) for r in rtypes])]
 272     return strcast(rtypes[0][1], False)
 273
 274
 275 def return_type(defs):
 276     if not defs:
 277         return None
 278     rtypes = _registry.getObj(_types[defs])
 279     if not rtypes:
 280         return None
 281     if len(rtypes) > 1:
 282         for n, t in rtypes:
 283             if n == "Error":
 284                 continue
 285             return t
 286     return rtypes[0][1]
 287
 288
 289 def type_anno_func(func, defs, is_result=False):
 290     annos = {}
 291     if not defs:
 292         return func
 293     rtypes = _registry.getObj(_types[defs])
 294     if is_result:
 295         kn = "return"
 296         if not rtypes:
 297             annos[kn] = None
 298         elif len(rtypes) > 1:
 299             annos[kn] = Union[tuple([r[1] for r in rtypes])]
 300         else:
 301             annos[kn] = rtypes[0][1]
 302     else:
 303         for name, rtype in rtypes:
 304             name = name_to_py(name)
 305             annos[name] = rtype
 306     func.__annotations__.update(annos)
 307     return func
 308
 309
 310 def ReturnMapping(cls):
 311     # Annotate the method with a return Type
 312     # so the value can be cast
 313     def decorator(f):
 314         @functools.wraps(f)
 315         async def wrapper(*args, **kwargs):
 316             nonlocal cls
 317             reply = await f(*args, **kwargs)
 318             if cls is None:
 319                 return reply
 320             if 'error' in reply:
 321                 cls = classes['Error']
 322             if issubclass(cls, typing.Sequence):
 323                 result = []
 324                 item_cls = cls.__parameters__[0]
 325                 for item in reply:
 326                     result.append(item_cls.from_json(item))
 327                     """
 328                     if 'error' in item:
 329                         cls = classes['Error']
 330                     else:
 331                         cls = item_cls
 332                     result.append(cls.from_json(item))
 333                     """
 334             else:
 335                 result = cls.from_json(reply['response'])
 336
 337             return result
 338         return wrapper
 339     return decorator
 340
 341
 342 def makeFunc(cls, name, params, result, async=True):
 343     INDENT = "    "
 344     args = Args(params)
 345     assignments = []
 346     toschema = args.PyToSchemaMapping()
 347     for arg in args._get_arg_str(False, False):
 348         assignments.append("{}_params[\'{}\'] = {}".format(INDENT,
 349                                                            toschema[arg],
 350                                                            arg))
 351     assignments = "\n".join(assignments)
 352     res = retspec(result)
 353     source = """
 354
 355 @ReturnMapping({rettype})
 356 {async}def {name}(self{argsep}{args}):
 357     '''
 358 {docstring}
 359     Returns -> {res}
 360     '''
 361     # map input types to rpc msg
 362     _params = dict()
 363     msg = dict(type='{cls.name}', request='{name}', version={cls.version}, params=_params)
 364 {assignments}
 365     reply = {await}self.rpc(msg)
 366     return reply
 367
 368 """
 369
 370     fsource = source.format(async="async " if async else "",
 371                             name=name,
 372                             argsep=", " if args else "",
 373                             args=args,
 374                             res=res,
 375                             rettype=result.__name__ if result else None,
 376                             docstring=textwrap.indent(args.get_doc(), INDENT),
 377                             cls=cls,
 378                             assignments=assignments,
 379                             await="await " if async else "")
 380     ns = _getns()
 381     exec(fsource, ns)
 382     func = ns[name]
 383     return func, fsource
 384
 385
 386 def buildMethods(cls, capture):
 387     properties = cls.schema['properties']
 388     for methodname in sorted(properties):
 389         method, source = _buildMethod(cls, methodname)
 390         setattr(cls, methodname, method)
 391         capture.write(source, depth=1)
 392
 393
 394 def _buildMethod(cls, name):
 395     params = None
 396     result = None
 397     method = cls.schema['properties'][name]
 398     if 'properties' in method:
 399         prop = method['properties']
 400         spec = prop.get('Params')
 401         if spec:
 402             params = _types.get(spec['$ref'])
 403         spec = prop.get('Result')
 404         if spec:
 405             result = _types.get(spec['$ref'])
 406     return makeFunc(cls, name, params, result)
 407
 408
 409 def buildFacade(schema):
 410     cls = type(schema.name, (Type,), dict(name=schema.name,
 411                                           version=schema.version,
 412                                           schema=schema))
 413     source = """
 414 class {name}Facade(Type):
 415     name = '{name}'
 416     version = {version}
 417     schema = {schema}
 418     """.format(name=schema.name,
 419                version=schema.version,
 420                schema=textwrap.indent(pprint.pformat(schema), "    "))
 421     return cls, source
 422
 423
 424 class TypeEncoder(json.JSONEncoder):
 425     def default(self, obj):
 426         if isinstance(obj, Type):
 427             return obj.serialize()
 428         return json.JSONEncoder.default(self, obj)
 429
 430
 431 class Type:
 432     def connect(self, connection):
 433         self.connection = connection
 434
 435     async def rpc(self, msg):
 436         result = await self.connection.rpc(msg, encoder=TypeEncoder)
 437         return result
 438
 439     @classmethod
 440     def from_json(cls, data):
 441         if isinstance(data, str):
 442             data = json.loads(data)
 443         d = {}
 444         for k, v in (data or {}).items():
 445             d[cls._toPy.get(k, k)] = v
 446
 447         try:
 448             return cls(**d)
 449         except TypeError:
 450             raise
 451
 452     def serialize(self):
 453         d = {}
 454         for attr, tgt in self._toSchema.items():
 455             d[tgt] = getattr(self, attr)
 456         return d
 457
 458     def to_json(self):
 459         return json.dumps(self.serialize())
 460
 461
 462 class Schema(dict):
 463     def __init__(self, schema):
 464         self.name = schema['Name']
 465         self.version = schema['Version']
 466         self.update(schema['Schema'])
 467
 468     @classmethod
 469     def referenceName(cls, ref):
 470         if ref.startswith("#/definitions/"):
 471             ref = ref.rsplit("/", 1)[-1]
 472         return ref
 473
 474     def resolveDefinition(self, ref):
 475         return self['definitions'][self.referenceName(ref)]
 476
 477     def deref(self, prop, name):
 478         if not isinstance(prop, dict):
 479             raise TypeError(prop)
 480         if "$ref" not in prop:
 481             return prop
 482
 483         target = self.resolveDefinition(prop["$ref"])
 484         return target
 485
 486     def buildDefinitions(self):
 487         # here we are building the types out
 488         # anything in definitions is a type
 489         # but these may contain references themselves
 490         # so we dfs to the bottom and build upwards
 491         # when a types is already in the registry
 492         defs = self.get('definitions')
 493         if not defs:
 494             return
 495         for d, data in defs.items():
 496             if d in _registry:
 497                 continue
 498             node = self.deref(data, d)
 499             kind = node.get("type")
 500             if kind == "object":
 501                 result = self.buildObject(node, d)
 502             elif kind == "array":
 503                 pass
 504             _registry.register(d, self.version, result)
 505             # XXX: This makes sure that the type gets added to the global
 506             # _types dict even if no other type in the schema has a ref
 507             # to it.
 508             getRefType(d)
 509
 510     def buildObject(self, node, name=None, d=0):
 511         # we don't need to build types recursively here
 512         # they are all in definitions already
 513         # we only want to include the type reference
 514         # which we can derive from the name
 515         struct = []
 516         add = struct.append
 517         props = node.get("properties")
 518         pprops = node.get("patternProperties")
 519         if props:
 520             # Sort these so the __init__ arg list for each Type remains
 521             # consistently ordered across regens of client.py
 522             for p in sorted(props):
 523                 prop = props[p]
 524                 if "$ref" in prop:
 525                     add((p, refType(prop)))
 526                 else:
 527                     kind = prop['type']
 528                     if kind == "array":
 529                         add((p, self.buildArray(prop, d + 1)))
 530                     elif kind == "object":
 531                         struct.extend(self.buildObject(prop, p, d + 1))
 532                     else:
 533                         add((p, objType(prop)))
 534         if pprops:
 535             if ".*" not in pprops:
 536                 raise ValueError(
 537                     "Cannot handle actual pattern in patternProperties %s" %
 538                     pprops)
 539             pprop = pprops[".*"]
 540             if "$ref" in pprop:
 541                 add((name, Mapping[str, refType(pprop)]))
 542                 return struct
 543             ppkind = pprop["type"]
 544             if ppkind == "array":
 545                 add((name, self.buildArray(pprop, d + 1)))
 546             else:
 547                 add((name, Mapping[str, SCHEMA_TO_PYTHON[ppkind]]))
 548
 549         if not struct and node.get('additionalProperties', False):
 550             add((name, Mapping[str, SCHEMA_TO_PYTHON['object']]))
 551
 552         return struct
 553
 554     def buildArray(self, obj, d=0):
 555         # return a sequence from an array in the schema
 556         if "$ref" in obj:
 557             return Sequence[refType(obj)]
 558         else:
 559             kind = obj.get("type")
 560             if kind and kind == "array":
 561                 items = obj['items']
 562                 return self.buildArray(items, d + 1)
 563             else:
 564                 return Sequence[objType(obj)]
 565
 566
 567 def _getns():
 568     ns = {'Type': Type,
 569           'typing': typing,
 570           'ReturnMapping': ReturnMapping
 571           }
 572     # Copy our types into the globals of the method
 573     for facade in _registry:
 574         ns[facade] = _registry.getObj(facade)
 575     return ns
 576
 577
 578
 579 def generate_facacdes(options):
 580     global classes
 581     schemas = json.loads(Path(options.schema).read_text("utf-8"))
 582     capture = codegen.CodeWriter()
 583     capture.write(textwrap.dedent("""\
 584         # DO NOT CHANGE THIS FILE! This file is auto-generated by facade.py.
 585         # Changes will be overwritten/lost when the file is regenerated.
 586
 587         from juju.client.facade import Type, ReturnMapping
 588
 589     """))
 590     schemas = [Schema(s) for s in schemas]
 591
 592     for schema in schemas:
 593         schema.buildDefinitions()
 594         buildTypes(schema, capture)
 595
 596     for schema in schemas:
 597         # TODO generate class now with a metaclass that takes the schema
 598         # the generated class has the right name and it in turn uses
 599         # the metaclass to populate cls
 600         cls, source = buildFacade(schema)
 601         capture.write(source)
 602         buildMethods(cls, capture)
 603         classes[schema.name] = cls
 604
 605     return capture
 606
 607 def setup():
 608     parser = argparse.ArgumentParser()
 609     parser.add_argument("-s", "--schema", default="schemas.json")
 610     parser.add_argument("-o", "--output", default="client.py")
 611     options = parser.parse_args()
 612     return options
 613
 614 def main():
 615     options = setup()
 616     capture = generate_facacdes(options)
 617     with open(options.output, "w") as fp:
 618         print(capture, file=fp)
 619
 620
 621
 622 if __name__ == '__main__':
 623     main()