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:
 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         args = Args(kind)
 192         if name in classes:
 193             continue
 194         source = ["""
 195 class {}(Type):
 196     _toSchema = {}
 197     _toPy = {}
 198     def __init__(self{}{}):
 199         '''
 200 {}
 201         '''""".format(
 202             name,
 203             args.PyToSchemaMapping(),
 204             args.SchemaToPyMapping(),
 205             ", " if args else "",
 206             args.as_kwargs(),
 207             textwrap.indent(args.get_doc(), INDENT * 2))
 208                   ]
 209         assignments = args._get_arg_str(False, False)
 210
 211         if not args:
 212             source.append("{}pass".format(INDENT * 2))
 213         else:
 214             for arg in args:
 215                 arg_name = name_to_py(arg[0])
 216                 arg_type = arg[1]
 217                 arg_type_name = strcast(arg_type)
 218                 if arg_type in basic_types:
 219                     source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 220                 elif issubclass(arg_type, typing.Sequence):
 221                     value_type = arg_type_name.__parameters__[0]
 222                     if type(value_type) is typing.TypeVar:
 223                         source.append("{}self.{} = [{}.from_json(o) for o in {} or []]".format(
 224                             INDENT * 2, arg_name, strcast(value_type), arg_name))
 225                     else:
 226                         source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 227                 elif issubclass(arg_type, typing.Mapping):
 228                     value_type = arg_type_name.__parameters__[1]
 229                     if type(value_type) is typing.TypeVar:
 230                         source.append("{}self.{} = {{k: {}.from_json(v) for k, v in ({} or dict()).items()}}".format(
 231                             INDENT * 2, arg_name, strcast(value_type), arg_name))
 232                     else:
 233                         source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 234                 elif type(arg_type) is typing.TypeVar:
 235                     source.append("{}self.{} = {}.from_json({}) if {} else None".format(
 236                         INDENT * 2, arg_name, arg_type_name, arg_name, arg_name))
 237                 else:
 238                     source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 239
 240         source = "\n".join(source)
 241         capture.write(source)
 242         capture.write("\n\n")
 243         co = compile(source, __name__, "exec")
 244         ns = _getns()
 245         exec(co, ns)
 246         cls = ns[name]
 247         classes[name] = cls
 248
 249
 250 def retspec(defs):
 251     # return specs
 252     # only return 1, so if there is more than one type
 253     # we need to include a union
 254     # In truth there is only 1 return
 255     # Error or the expected Type
 256     if not defs:
 257         return None
 258     rtypes = _registry.getObj(_types[defs])
 259     if not rtypes:
 260         return None
 261     if len(rtypes) > 1:
 262         return Union[tuple([strcast(r[1], True) for r in rtypes])]
 263     return strcast(rtypes[0][1], False)
 264
 265
 266 def return_type(defs):
 267     if not defs:
 268         return None
 269     rtypes = _registry.getObj(_types[defs])
 270     if not rtypes:
 271         return None
 272     if len(rtypes) > 1:
 273         for n, t in rtypes:
 274             if n == "Error":
 275                 continue
 276             return t
 277     return rtypes[0][1]
 278
 279
 280 def type_anno_func(func, defs, is_result=False):
 281     annos = {}
 282     if not defs:
 283         return func
 284     rtypes = _registry.getObj(_types[defs])
 285     if is_result:
 286         kn = "return"
 287         if not rtypes:
 288             annos[kn] = None
 289         elif len(rtypes) > 1:
 290             annos[kn] = Union[tuple([r[1] for r in rtypes])]
 291         else:
 292             annos[kn] = rtypes[0][1]
 293     else:
 294         for name, rtype in rtypes:
 295             name = name_to_py(name)
 296             annos[name] = rtype
 297     func.__annotations__.update(annos)
 298     return func
 299
 300
 301 def ReturnMapping(cls):
 302     # Annotate the method with a return Type
 303     # so the value can be cast
 304     def decorator(f):
 305         @functools.wraps(f)
 306         async def wrapper(*args, **kwargs):
 307             nonlocal cls
 308             reply = await f(*args, **kwargs)
 309             if cls is None:
 310                 return reply
 311             if 'Error' in reply:
 312                 cls = classes['Error']
 313             if issubclass(cls, typing.Sequence):
 314                 result = []
 315                 item_cls = cls.__parameters__[0]
 316                 for item in reply:
 317                     result.append(item_cls.from_json(item))
 318             else:
 319                 result = cls.from_json(reply['Response'])
 320
 321             return result
 322         return wrapper
 323     return decorator
 324
 325
 326 def makeFunc(cls, name, params, result, async=True):
 327     INDENT = "    "
 328     args = Args(params)
 329     assignments = []
 330     toschema = args.PyToSchemaMapping()
 331     for arg in args._get_arg_str(False, False):
 332         assignments.append("{}params[\'{}\'] = {}".format(INDENT,
 333                                                           toschema[arg],
 334                                                           arg))
 335     assignments = "\n".join(assignments)
 336     res = retspec(result)
 337     source = """
 338
 339 @ReturnMapping({rettype})
 340 {async}def {name}(self{argsep}{args}):
 341     '''
 342 {docstring}
 343     Returns -> {res}
 344     '''
 345     # map input types to rpc msg
 346     params = dict()
 347     msg = dict(Type='{cls.name}', Request='{name}', Version={cls.version}, Params=params)
 348 {assignments}
 349     reply = {await}self.rpc(msg)
 350     return reply
 351
 352 """
 353
 354     fsource = source.format(async="async " if async else "",
 355                             name=name,
 356                             argsep=", " if args else "",
 357                             args=args,
 358                             res=res,
 359                             rettype=result.__name__ if result else None,
 360                             docstring=textwrap.indent(args.get_doc(), INDENT),
 361                             cls=cls,
 362                             assignments=assignments,
 363                             await="await " if async else "")
 364     ns = _getns()
 365     exec(fsource, ns)
 366     func = ns[name]
 367     return func, fsource
 368
 369
 370 def buildMethods(cls, capture):
 371     properties = cls.schema['properties']
 372     for methodname in sorted(properties):
 373         method, source = _buildMethod(cls, methodname)
 374         setattr(cls, methodname, method)
 375         capture.write(source, depth=1)
 376
 377
 378 def _buildMethod(cls, name):
 379     params = None
 380     result = None
 381     method = cls.schema['properties'][name]
 382     if 'properties' in method:
 383         prop = method['properties']
 384         spec = prop.get('Params')
 385         if spec:
 386             params = _types.get(spec['$ref'])
 387         spec = prop.get('Result')
 388         if spec:
 389             result = _types.get(spec['$ref'])
 390     return makeFunc(cls, name, params, result)
 391
 392
 393 def buildFacade(schema):
 394     cls = type(schema.name, (Type,), dict(name=schema.name,
 395                                           version=schema.version,
 396                                           schema=schema))
 397     source = """
 398 class {name}Facade(Type):
 399     name = '{name}'
 400     version = {version}
 401     schema = {schema}
 402     """.format(name=schema.name,
 403                version=schema.version,
 404                schema=textwrap.indent(pprint.pformat(schema), "    "))
 405     return cls, source
 406
 407
 408 class TypeEncoder(json.JSONEncoder):
 409     def default(self, obj):
 410         if isinstance(obj, Type):
 411             return obj.serialize()
 412         return json.JSONEncoder.default(self, obj)
 413
 414
 415 class Type:
 416     def connect(self, connection):
 417         self.connection = connection
 418
 419     async def rpc(self, msg):
 420         result = await self.connection.rpc(msg, encoder=TypeEncoder)
 421         return result
 422
 423     @classmethod
 424     def from_json(cls, data):
 425         if isinstance(data, str):
 426             data = json.loads(data)
 427         d = {}
 428         for k, v in (data or {}).items():
 429             d[cls._toPy.get(k, k)] = v
 430
 431         try:
 432             return cls(**d)
 433         except TypeError:
 434             print(cls)
 435             raise
 436
 437     def serialize(self):
 438         d = {}
 439         for attr, tgt in self._toSchema.items():
 440             d[tgt] = getattr(self, attr)
 441         return d
 442
 443     def to_json(self):
 444         return json.dumps(self.serialize())
 445
 446
 447 class Schema(dict):
 448     def __init__(self, schema):
 449         self.name = schema['Name']
 450         self.version = schema['Version']
 451         self.update(schema['Schema'])
 452
 453     @classmethod
 454     def referenceName(cls, ref):
 455         if ref.startswith("#/definitions/"):
 456             ref = ref.rsplit("/", 1)[-1]
 457         return ref
 458
 459     def resolveDefinition(self, ref):
 460         return self['definitions'][self.referenceName(ref)]
 461
 462     def deref(self, prop, name):
 463         if not isinstance(prop, dict):
 464             raise TypeError(prop)
 465         if "$ref" not in prop:
 466             return prop
 467
 468         target = self.resolveDefinition(prop["$ref"])
 469         return target
 470
 471     def buildDefinitions(self):
 472         # here we are building the types out
 473         # anything in definitions is a type
 474         # but these may contain references themselves
 475         # so we dfs to the bottom and build upwards
 476         # when a types is already in the registry
 477         defs = self.get('definitions')
 478         if not defs:
 479             return
 480         for d, data in defs.items():
 481             if d in _registry:
 482                 continue
 483             node = self.deref(data, d)
 484             kind = node.get("type")
 485             if kind == "object":
 486                 result = self.buildObject(node, d)
 487             elif kind == "array":
 488                 pass
 489             _registry.register(d, self.version, result)
 490             # XXX: This makes sure that the type gets added to the global
 491             # _types dict even if no other type in the schema has a ref
 492             # to it.
 493             getRefType(d)
 494
 495     def buildObject(self, node, name=None, d=0):
 496         # we don't need to build types recursively here
 497         # they are all in definitions already
 498         # we only want to include the type reference
 499         # which we can derive from the name
 500         struct = []
 501         add = struct.append
 502         props = node.get("properties")
 503         pprops = node.get("patternProperties")
 504         if props:
 505             # Sort these so the __init__ arg list for each Type remains
 506             # consistently ordered across regens of client.py
 507             for p in sorted(props):
 508                 prop = props[p]
 509                 if "$ref" in prop:
 510                     add((p, refType(prop)))
 511                 else:
 512                     kind = prop['type']
 513                     if kind == "array":
 514                         add((p, self.buildArray(prop, d + 1)))
 515                     elif kind == "object":
 516                         struct.extend(self.buildObject(prop, p, d + 1))
 517                     else:
 518                         add((p, objType(prop)))
 519         if pprops:
 520             if ".*" not in pprops:
 521                 raise ValueError(
 522                     "Cannot handle actual pattern in patternProperties %s" %
 523                     pprops)
 524             pprop = pprops[".*"]
 525             if "$ref" in pprop:
 526                 add((name, Mapping[str, refType(pprop)]))
 527                 return struct
 528             ppkind = pprop["type"]
 529             if ppkind == "array":
 530                 add((name, self.buildArray(pprop, d + 1)))
 531             else:
 532                 add((name, Mapping[str, SCHEMA_TO_PYTHON[ppkind]]))
 533
 534         if not struct and node.get('additionalProperties', False):
 535             add((name, Mapping[str, SCHEMA_TO_PYTHON['object']]))
 536
 537         return struct
 538
 539     def buildArray(self, obj, d=0):
 540         # return a sequence from an array in the schema
 541         if "$ref" in obj:
 542             return Sequence[refType(obj)]
 543         else:
 544             kind = obj.get("type")
 545             if kind and kind == "array":
 546                 items = obj['items']
 547                 return self.buildArray(items, d + 1)
 548             else:
 549                 return Sequence[objType(obj)]
 550
 551
 552 def _getns():
 553     ns = {'Type': Type,
 554           'typing': typing,
 555           'ReturnMapping': ReturnMapping
 556           }
 557     # Copy our types into the globals of the method
 558     for facade in _registry:
 559         ns[facade] = _registry.getObj(facade)
 560     return ns
 561
 562
 563
 564 def generate_facacdes(options):
 565     global classes
 566     schemas = json.loads(Path(options.schema).read_text("utf-8"))
 567     capture = codegen.CodeWriter()
 568     capture.write(textwrap.dedent("""\
 569         # DO NOT CHANGE THIS FILE! This file is auto-generated by facade.py.
 570         # Changes will be overwritten/lost when the file is regenerated.
 571
 572         from juju.client.facade import Type, ReturnMapping
 573
 574     """))
 575     schemas = [Schema(s) for s in schemas]
 576
 577     for schema in schemas:
 578         schema.buildDefinitions()
 579         buildTypes(schema, capture)
 580
 581     for schema in schemas:
 582         # TODO generate class now with a metaclass that takes the schema
 583         # the generated class has the right name and it in turn uses
 584         # the metaclass to populate cls
 585         cls, source = buildFacade(schema)
 586         capture.write(source)
 587         buildMethods(cls, capture)
 588         classes[schema.name] = cls
 589
 590     return capture
 591
 592 def setup():
 593     parser = argparse.ArgumentParser()
 594     parser.add_argument("-s", "--schema", default="schemas.json")
 595     parser.add_argument("-o", "--output", default="client.py")
 596     options = parser.parse_args()
 597     return options
 598
 599 def main():
 600     options = setup()
 601     capture = generate_facacdes(options)
 602     with open(options.output, "w") as fp:
 603         print(capture, file=fp)
 604
 605
 606
 607 if __name__ == '__main__':
 608     main()