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 = (
 222                         arg_type_name.__parameters__[0]
 223                         if len(arg_type_name.__parameters__)
 224                         else None
 225                     )
 226                     if type(value_type) is typing.TypeVar:
 227                         source.append("{}self.{} = [{}.from_json(o) for o in {} or []]".format(
 228                             INDENT * 2, arg_name, strcast(value_type), arg_name))
 229                     else:
 230                         source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 231                 elif issubclass(arg_type, typing.Mapping):
 232                     value_type = (
 233                         arg_type_name.__parameters__[1]
 234                         if len(arg_type_name.__parameters__) > 1
 235                         else None
 236                     )
 237                     if type(value_type) is typing.TypeVar:
 238                         source.append("{}self.{} = {{k: {}.from_json(v) for k, v in ({} or dict()).items()}}".format(
 239                             INDENT * 2, arg_name, strcast(value_type), arg_name))
 240                     else:
 241                         source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 242                 elif type(arg_type) is typing.TypeVar:
 243                     source.append("{}self.{} = {}.from_json({}) if {} else None".format(
 244                         INDENT * 2, arg_name, arg_type_name, arg_name, arg_name))
 245                 else:
 246                     source.append("{}self.{} = {}".format(INDENT * 2, arg_name, arg_name))
 247
 248         source = "\n".join(source)
 249         capture.write(source)
 250         capture.write("\n\n")
 251         co = compile(source, __name__, "exec")
 252         ns = _getns()
 253         exec(co, ns)
 254         cls = ns[name]
 255         classes[name] = cls
 256
 257
 258 def retspec(defs):
 259     # return specs
 260     # only return 1, so if there is more than one type
 261     # we need to include a union
 262     # In truth there is only 1 return
 263     # Error or the expected Type
 264     if not defs:
 265         return None
 266     rtypes = _registry.getObj(_types[defs])
 267     if not rtypes:
 268         return None
 269     if len(rtypes) > 1:
 270         return Union[tuple([strcast(r[1], True) for r in rtypes])]
 271     return strcast(rtypes[0][1], False)
 272
 273
 274 def return_type(defs):
 275     if not defs:
 276         return None
 277     rtypes = _registry.getObj(_types[defs])
 278     if not rtypes:
 279         return None
 280     if len(rtypes) > 1:
 281         for n, t in rtypes:
 282             if n == "Error":
 283                 continue
 284             return t
 285     return rtypes[0][1]
 286
 287
 288 def type_anno_func(func, defs, is_result=False):
 289     annos = {}
 290     if not defs:
 291         return func
 292     rtypes = _registry.getObj(_types[defs])
 293     if is_result:
 294         kn = "return"
 295         if not rtypes:
 296             annos[kn] = None
 297         elif len(rtypes) > 1:
 298             annos[kn] = Union[tuple([r[1] for r in rtypes])]
 299         else:
 300             annos[kn] = rtypes[0][1]
 301     else:
 302         for name, rtype in rtypes:
 303             name = name_to_py(name)
 304             annos[name] = rtype
 305     func.__annotations__.update(annos)
 306     return func
 307
 308
 309 def ReturnMapping(cls):
 310     # Annotate the method with a return Type
 311     # so the value can be cast
 312     def decorator(f):
 313         @functools.wraps(f)
 314         async def wrapper(*args, **kwargs):
 315             nonlocal cls
 316             reply = await f(*args, **kwargs)
 317             if cls is None:
 318                 return reply
 319             if 'error' in reply:
 320                 cls = classes['Error']
 321             if issubclass(cls, typing.Sequence):
 322                 result = []
 323                 item_cls = cls.__parameters__[0]
 324                 for item in reply:
 325                     result.append(item_cls.from_json(item))
 326             else:
 327                 result = cls.from_json(reply['response'])
 328
 329             return result
 330         return wrapper
 331     return decorator
 332
 333
 334 def makeFunc(cls, name, params, result, async=True):
 335     INDENT = "    "
 336     args = Args(params)
 337     assignments = []
 338     toschema = args.PyToSchemaMapping()
 339     for arg in args._get_arg_str(False, False):
 340         assignments.append("{}params[\'{}\'] = {}".format(INDENT,
 341                                                           toschema[arg],
 342                                                           arg))
 343     assignments = "\n".join(assignments)
 344     res = retspec(result)
 345     source = """
 346
 347 @ReturnMapping({rettype})
 348 {async}def {name}(self{argsep}{args}):
 349     '''
 350 {docstring}
 351     Returns -> {res}
 352     '''
 353     # map input types to rpc msg
 354     params = dict()
 355     msg = dict(type='{cls.name}', request='{name}', version={cls.version}, params=params)
 356 {assignments}
 357     reply = {await}self.rpc(msg)
 358     return reply
 359
 360 """
 361
 362     fsource = source.format(async="async " if async else "",
 363                             name=name,
 364                             argsep=", " if args else "",
 365                             args=args,
 366                             res=res,
 367                             rettype=result.__name__ if result else None,
 368                             docstring=textwrap.indent(args.get_doc(), INDENT),
 369                             cls=cls,
 370                             assignments=assignments,
 371                             await="await " if async else "")
 372     ns = _getns()
 373     exec(fsource, ns)
 374     func = ns[name]
 375     return func, fsource
 376
 377
 378 def buildMethods(cls, capture):
 379     properties = cls.schema['properties']
 380     for methodname in sorted(properties):
 381         method, source = _buildMethod(cls, methodname)
 382         setattr(cls, methodname, method)
 383         capture.write(source, depth=1)
 384
 385
 386 def _buildMethod(cls, name):
 387     params = None
 388     result = None
 389     method = cls.schema['properties'][name]
 390     if 'properties' in method:
 391         prop = method['properties']
 392         spec = prop.get('Params')
 393         if spec:
 394             params = _types.get(spec['$ref'])
 395         spec = prop.get('Result')
 396         if spec:
 397             result = _types.get(spec['$ref'])
 398     return makeFunc(cls, name, params, result)
 399
 400
 401 def buildFacade(schema):
 402     cls = type(schema.name, (Type,), dict(name=schema.name,
 403                                           version=schema.version,
 404                                           schema=schema))
 405     source = """
 406 class {name}Facade(Type):
 407     name = '{name}'
 408     version = {version}
 409     schema = {schema}
 410     """.format(name=schema.name,
 411                version=schema.version,
 412                schema=textwrap.indent(pprint.pformat(schema), "    "))
 413     return cls, source
 414
 415
 416 class TypeEncoder(json.JSONEncoder):
 417     def default(self, obj):
 418         if isinstance(obj, Type):
 419             return obj.serialize()
 420         return json.JSONEncoder.default(self, obj)
 421
 422
 423 class Type:
 424     def connect(self, connection):
 425         self.connection = connection
 426
 427     async def rpc(self, msg):
 428         result = await self.connection.rpc(msg, encoder=TypeEncoder)
 429         return result
 430
 431     @classmethod
 432     def from_json(cls, data):
 433         if isinstance(data, str):
 434             data = json.loads(data)
 435         d = {}
 436         for k, v in (data or {}).items():
 437             d[cls._toPy.get(k, k)] = v
 438
 439         try:
 440             return cls(**d)
 441         except TypeError:
 442             print(cls)
 443             raise
 444
 445     def serialize(self):
 446         d = {}
 447         for attr, tgt in self._toSchema.items():
 448             d[tgt] = getattr(self, attr)
 449         return d
 450
 451     def to_json(self):
 452         return json.dumps(self.serialize())
 453
 454
 455 class Schema(dict):
 456     def __init__(self, schema):
 457         self.name = schema['Name']
 458         self.version = schema['Version']
 459         self.update(schema['Schema'])
 460
 461     @classmethod
 462     def referenceName(cls, ref):
 463         if ref.startswith("#/definitions/"):
 464             ref = ref.rsplit("/", 1)[-1]
 465         return ref
 466
 467     def resolveDefinition(self, ref):
 468         return self['definitions'][self.referenceName(ref)]
 469
 470     def deref(self, prop, name):
 471         if not isinstance(prop, dict):
 472             raise TypeError(prop)
 473         if "$ref" not in prop:
 474             return prop
 475
 476         target = self.resolveDefinition(prop["$ref"])
 477         return target
 478
 479     def buildDefinitions(self):
 480         # here we are building the types out
 481         # anything in definitions is a type
 482         # but these may contain references themselves
 483         # so we dfs to the bottom and build upwards
 484         # when a types is already in the registry
 485         defs = self.get('definitions')
 486         if not defs:
 487             return
 488         for d, data in defs.items():
 489             if d in _registry:
 490                 continue
 491             node = self.deref(data, d)
 492             kind = node.get("type")
 493             if kind == "object":
 494                 result = self.buildObject(node, d)
 495             elif kind == "array":
 496                 pass
 497             _registry.register(d, self.version, result)
 498             # XXX: This makes sure that the type gets added to the global
 499             # _types dict even if no other type in the schema has a ref
 500             # to it.
 501             getRefType(d)
 502
 503     def buildObject(self, node, name=None, d=0):
 504         # we don't need to build types recursively here
 505         # they are all in definitions already
 506         # we only want to include the type reference
 507         # which we can derive from the name
 508         struct = []
 509         add = struct.append
 510         props = node.get("properties")
 511         pprops = node.get("patternProperties")
 512         if props:
 513             # Sort these so the __init__ arg list for each Type remains
 514             # consistently ordered across regens of client.py
 515             for p in sorted(props):
 516                 prop = props[p]
 517                 if "$ref" in prop:
 518                     add((p, refType(prop)))
 519                 else:
 520                     kind = prop['type']
 521                     if kind == "array":
 522                         add((p, self.buildArray(prop, d + 1)))
 523                     elif kind == "object":
 524                         struct.extend(self.buildObject(prop, p, d + 1))
 525                     else:
 526                         add((p, objType(prop)))
 527         if pprops:
 528             if ".*" not in pprops:
 529                 raise ValueError(
 530                     "Cannot handle actual pattern in patternProperties %s" %
 531                     pprops)
 532             pprop = pprops[".*"]
 533             if "$ref" in pprop:
 534                 add((name, Mapping[str, refType(pprop)]))
 535                 return struct
 536             ppkind = pprop["type"]
 537             if ppkind == "array":
 538                 add((name, self.buildArray(pprop, d + 1)))
 539             else:
 540                 add((name, Mapping[str, SCHEMA_TO_PYTHON[ppkind]]))
 541
 542         if not struct and node.get('additionalProperties', False):
 543             add((name, Mapping[str, SCHEMA_TO_PYTHON['object']]))
 544
 545         return struct
 546
 547     def buildArray(self, obj, d=0):
 548         # return a sequence from an array in the schema
 549         if "$ref" in obj:
 550             return Sequence[refType(obj)]
 551         else:
 552             kind = obj.get("type")
 553             if kind and kind == "array":
 554                 items = obj['items']
 555                 return self.buildArray(items, d + 1)
 556             else:
 557                 return Sequence[objType(obj)]
 558
 559
 560 def _getns():
 561     ns = {'Type': Type,
 562           'typing': typing,
 563           'ReturnMapping': ReturnMapping
 564           }
 565     # Copy our types into the globals of the method
 566     for facade in _registry:
 567         ns[facade] = _registry.getObj(facade)
 568     return ns
 569
 570
 571
 572 def generate_facacdes(options):
 573     global classes
 574     schemas = json.loads(Path(options.schema).read_text("utf-8"))
 575     capture = codegen.CodeWriter()
 576     capture.write(textwrap.dedent("""\
 577         # DO NOT CHANGE THIS FILE! This file is auto-generated by facade.py.
 578         # Changes will be overwritten/lost when the file is regenerated.
 579
 580         from juju.client.facade import Type, ReturnMapping
 581
 582     """))
 583     schemas = [Schema(s) for s in schemas]
 584
 585     for schema in schemas:
 586         schema.buildDefinitions()
 587         buildTypes(schema, capture)
 588
 589     for schema in schemas:
 590         # TODO generate class now with a metaclass that takes the schema
 591         # the generated class has the right name and it in turn uses
 592         # the metaclass to populate cls
 593         cls, source = buildFacade(schema)
 594         capture.write(source)
 595         buildMethods(cls, capture)
 596         classes[schema.name] = cls
 597
 598     return capture
 599
 600 def setup():
 601     parser = argparse.ArgumentParser()
 602     parser.add_argument("-s", "--schema", default="schemas.json")
 603     parser.add_argument("-o", "--output", default="client.py")
 604     options = parser.parse_args()
 605     return options
 606
 607 def main():
 608     options = setup()
 609     capture = generate_facacdes(options)
 610     with open(options.output, "w") as fp:
 611         print(capture, file=fp)
 612
 613
 614
 615 if __name__ == '__main__':
 616     main()