mncheck/ext/cerberus/errors.py

# -*-: coding utf-8 -*-
""" This module contains the error-related constants and classes. """

from __future__ import absolute_import

from collections import defaultdict, namedtuple, MutableMapping
from copy import copy, deepcopy
from functools import wraps
from pprint import pformat

from cerberus.platform import PYTHON_VERSION
from cerberus.utils import compare_paths_lt, quote_string


ErrorDefinition = namedtuple('ErrorDefinition', 'code, rule')
"""
This class is used to define possible errors. Each distinguishable error is
defined by a *unique* error ``code`` as integer and the ``rule`` that can
cause it as string.
The instances' names do not contain a common prefix as they are supposed to be
referenced within the module namespace, e.g. ``errors.CUSTOM``.
"""


# custom
CUSTOM = ErrorDefinition(0x00, None)

# existence
DOCUMENT_MISSING = ErrorDefinition(0x01, None)  # issues/141
DOCUMENT_MISSING = "document is missing"
REQUIRED_FIELD = ErrorDefinition(0x02, 'required')
UNKNOWN_FIELD = ErrorDefinition(0x03, None)
DEPENDENCIES_FIELD = ErrorDefinition(0x04, 'dependencies')
DEPENDENCIES_FIELD_VALUE = ErrorDefinition(0x05, 'dependencies')
EXCLUDES_FIELD = ErrorDefinition(0x06, 'excludes')

# shape
DOCUMENT_FORMAT = ErrorDefinition(0x21, None)  # issues/141
DOCUMENT_FORMAT = "'{0}' is not a document, must be a dict"
EMPTY_NOT_ALLOWED = ErrorDefinition(0x22, 'empty')
NOT_NULLABLE = ErrorDefinition(0x23, 'nullable')
BAD_TYPE = ErrorDefinition(0x24, 'type')
BAD_TYPE_FOR_SCHEMA = ErrorDefinition(0x25, 'schema')
ITEMS_LENGTH = ErrorDefinition(0x26, 'items')
MIN_LENGTH = ErrorDefinition(0x27, 'minlength')
MAX_LENGTH = ErrorDefinition(0x28, 'maxlength')


# color
REGEX_MISMATCH = ErrorDefinition(0x41, 'regex')
MIN_VALUE = ErrorDefinition(0x42, 'min')
MAX_VALUE = ErrorDefinition(0x43, 'max')
UNALLOWED_VALUE = ErrorDefinition(0x44, 'allowed')
UNALLOWED_VALUES = ErrorDefinition(0x45, 'allowed')
FORBIDDEN_VALUE = ErrorDefinition(0x46, 'forbidden')
FORBIDDEN_VALUES = ErrorDefinition(0x47, 'forbidden')

# other
NORMALIZATION = ErrorDefinition(0x60, None)
COERCION_FAILED = ErrorDefinition(0x61, 'coerce')
RENAMING_FAILED = ErrorDefinition(0x62, 'rename_handler')
READONLY_FIELD = ErrorDefinition(0x63, 'readonly')
SETTING_DEFAULT_FAILED = ErrorDefinition(0x64, 'default_setter')

# groups
ERROR_GROUP = ErrorDefinition(0x80, None)
MAPPING_SCHEMA = ErrorDefinition(0x81, 'schema')
SEQUENCE_SCHEMA = ErrorDefinition(0x82, 'schema')
KEYSCHEMA = ErrorDefinition(0x83, 'keyschema')
VALUESCHEMA = ErrorDefinition(0x84, 'valueschema')
BAD_ITEMS = ErrorDefinition(0x8f, 'items')

LOGICAL = ErrorDefinition(0x90, None)
NONEOF = ErrorDefinition(0x91, 'noneof')
ONEOF = ErrorDefinition(0x92, 'oneof')
ANYOF = ErrorDefinition(0x93, 'anyof')
ALLOF = ErrorDefinition(0x94, 'allof')


""" SchemaError messages """

SCHEMA_ERROR_DEFINITION_TYPE = \
    "schema definition for field '{0}' must be a dict"
SCHEMA_ERROR_MISSING = "validation schema missing"


""" Error representations """


class ValidationError(object):
    """ A simple class to store and query basic error information. """
    def __init__(self, document_path, schema_path, code, rule, constraint,
                 value, info):
        self.document_path = document_path
        """ The path to the field within the document that caused the error.
            Type: :class:`tuple` """
        self.schema_path = schema_path
        """ The path to the rule within the schema that caused the error.
            Type: :class:`tuple` """
        self.code = code
        """ The error's identifier code. Type: :class:`int` """
        self.rule = rule
        """ The rule that failed. Type: `string` """
        self.constraint = constraint
        """ The constraint that failed. """
        self.value = value
        """ The value that failed. """
        self.info = info
        """ May hold additional information about the error.
            Type: :class:`tuple` """

    def __eq__(self, other):
        """ Assumes the errors relate to the same document and schema. """
        return hash(self) == hash(other)

    def __hash__(self):
        """ Expects that all other properties are transitively determined. """
        return hash(self.document_path) ^ hash(self.schema_path) \
            ^ hash(self.code)

    def __lt__(self, other):
        if self.document_path != other.document_path:
            return compare_paths_lt(self.document_path, other.document_path)
        else:
            return compare_paths_lt(self.schema_path, other.schema_path)

    def __repr__(self):
        return "{class_name} @ {memptr} ( " \
               "document_path={document_path}," \
               "schema_path={schema_path}," \
               "code={code}," \
               "constraint={constraint}," \
               "value={value}," \
               "info={info} )"\
               .format(class_name=self.__class__.__name__, memptr=hex(id(self)),  # noqa: E501
                       document_path=self.document_path,
                       schema_path=self.schema_path,
                       code=hex(self.code),
                       constraint=quote_string(self.constraint),
                       value=quote_string(self.value),
                       info=self.info)

    @property
    def child_errors(self):
        """
        A list that contains the individual errors of a bulk validation error.
        """
        return self.info[0] if self.is_group_error else None

    @property
    def definitions_errors(self):
        """ Dictionary with errors of an *of-rule mapped to the index of the
            definition it occurred in. Returns :obj:`None` if not applicable.
            """
        if not self.is_logic_error:
            return None

        result = defaultdict(list)
        for error in self.child_errors:
            i = error.schema_path[len(self.schema_path)]
            result[i].append(error)
        return result

    @property
    def field(self):
        """ Field of the contextual mapping, possibly :obj:`None`. """
        if self.document_path:
            return self.document_path[-1]
        else:
            return None

    @property
    def is_group_error(self):
        """ ``True`` for errors of bulk validations. """
        return bool(self.code & ERROR_GROUP.code)

    @property
    def is_logic_error(self):
        """ ``True`` for validation errors against different schemas with
            *of-rules. """
        return bool(self.code & LOGICAL.code - ERROR_GROUP.code)

    @property
    def is_normalization_error(self):
        """ ``True`` for normalization errors. """
        return bool(self.code & NORMALIZATION.code)


class ErrorList(list):
    """ A list for :class:`~cerberus.errors.ValidationError` instances that
        can be queried with the ``in`` keyword for a particular
        :class:`~cerberus.errors.ErrorDefinition`. """
    def __contains__(self, error_definition):
        for code in (x.code for x in self):
            if code == error_definition.code:
                return True
        return False


class ErrorTreeNode(MutableMapping):
    __slots__ = ('descendants', 'errors', 'parent_node', 'path', 'tree_root')

    def __init__(self, path, parent_node):
        self.parent_node = parent_node
        self.tree_root = self.parent_node.tree_root
        self.path = path[:self.parent_node.depth + 1]
        self.errors = ErrorList()
        self.descendants = {}

    def __add__(self, error):
        self.add(error)
        return self

    def __contains__(self, item):
        if isinstance(item, ErrorDefinition):
            return item in self.errors
        else:
            return item in self.descendants

    def __delitem__(self, key):
        del self.descendants[key]

    def __iter__(self):
        return iter(self.errors)

    def __getitem__(self, item):
        if isinstance(item, ErrorDefinition):
            for error in self.errors:
                if item.code == error.code:
                    return error
        else:
            return self.descendants.get(item)

    def __len__(self):
        return len(self.errors)

    def __repr__(self):
        return self.__str__()

    def __setitem__(self, key, value):
        self.descendants[key] = value

    def __str__(self):
        return str(self.errors) + ',' + str(self.descendants)

    @property
    def depth(self):
        return len(self.path)

    @property
    def tree_type(self):
        return self.tree_root.tree_type

    def add(self, error):
        error_path = self._path_of_(error)

        key = error_path[self.depth]
        if key not in self.descendants:
            self[key] = ErrorTreeNode(error_path, self)

        if len(error_path) == self.depth + 1:
            self[key].errors.append(error)
            self[key].errors.sort()
            if error.is_group_error:
                for child_error in error.child_errors:
                    self.tree_root += child_error
        else:
            self[key] += error

    def _path_of_(self, error):
        return getattr(error, self.tree_type + '_path')


class ErrorTree(ErrorTreeNode):
    """ Base class for :class:`~cerberus.errors.DocumentErrorTree` and
        :class:`~cerberus.errors.SchemaErrorTree`. """
    def __init__(self, errors=[]):
        self.parent_node = None
        self.tree_root = self
        self.path = ()
        self.errors = ErrorList()
        self.descendants = {}
        for error in errors:
            self += error

    def add(self, error):
        """ Add an error to the tree.

        :param error: :class:`~cerberus.errors.ValidationError`
        """
        if not self._path_of_(error):
            self.errors.append(error)
            self.errors.sort()
        else:
            super(ErrorTree, self).add(error)

    def fetch_errors_from(self, path):
        """ Returns all errors for a particular path.

        :param path: :class:`tuple` of :term:`hashable` s.
        :rtype: :class:`~cerberus.errors.ErrorList`
        """
        node = self.fetch_node_from(path)
        if node is not None:
            return node.errors
        else:
            return ErrorList()

    def fetch_node_from(self, path):
        """ Returns a node for a path.

        :param path: Tuple of :term:`hashable` s.
        :rtype: :class:`~cerberus.errors.ErrorTreeNode` or :obj:`None`
        """
        context = self
        for key in path:
            context = context[key]
            if context is None:
                break
        return context


class DocumentErrorTree(ErrorTree):
    """ Implements a dict-like class to query errors by indexes following the
        structure of a validated document. """
    tree_type = 'document'


class SchemaErrorTree(ErrorTree):
    """ Implements a dict-like class to query errors by indexes following the
        structure of the used schema. """
    tree_type = 'schema'


class BaseErrorHandler(object):
    """ Base class for all error handlers.
        Subclasses are identified as error-handlers with an instance-test. """
    def __init__(self, *args, **kwargs):
        """ Optionally initialize a new instance. """
        pass

    def __call__(self, errors):
        """ Returns errors in a handler-specific format.

        :param errors: An object containing the errors.
        :type errors: :term:`iterable` of
                      :class:`~cerberus.errors.ValidationError` instances or a
                      :class:`~cerberus.Validator` instance
        """
        raise NotImplementedError

    def __iter__(self):
        """ Be a superhero and implement an iterator over errors. """
        raise NotImplementedError

    def add(self, error):
        """ Add an error to the errors' container object of a handler.

        :param error: The error to add.
        :type error: :class:`~cerberus.errors.ValidationError`
        """
        raise NotImplementedError

    def emit(self, error):
        """ Optionally emits an error in the handler's format to a stream.
            Or light a LED, or even shut down a power plant.

        :param error: The error to emit.
        :type error: :class:`~cerberus.errors.ValidationError`
        """
        pass

    def end(self, validator):
        """ Gets called when a validation ends.

        :param validator: The calling validator.
        :type validator: :class:`~cerberus.Validator` """
        pass

    def extend(self, errors):
        """ Adds all errors to the handler's container object.

        :param errors: The errors to add.
        :type errors: :term:`iterable` of
                      :class:`~cerberus.errors.ValidationError` instances
        """
        for error in errors:
            self.add(error)

    def start(self, validator):
        """ Gets called when a validation starts.

        :param validator: The calling validator.
        :type validator: :class:`~cerberus.Validator`
        """
        pass


class ToyErrorHandler(BaseErrorHandler):
    def __call__(self, *args, **kwargs):
        raise RuntimeError('This is not supposed to happen.')

    def clear(self):
        pass


def encode_unicode(f):
    """Cerberus error messages expect regular binary strings.
    If unicode is used in a ValidationError message can't be printed.

    This decorator ensures that if legacy Python is used unicode
    strings are encoded before passing to a function.
    """
    @wraps(f)
    def wrapped(obj, error):

        def _encode(value):
            """Helper encoding unicode strings into binary utf-8"""
            if isinstance(value, unicode):  # noqa: F821
                return value.encode('utf-8')
            return value

        error = copy(error)
        error.document_path = _encode(error.document_path)
        error.schema_path = _encode(error.schema_path)
        error.constraint = _encode(error.constraint)
        error.value = _encode(error.value)
        error.info = _encode(error.info)
        return f(obj, error)

    return wrapped if PYTHON_VERSION < 3 else f


class BasicErrorHandler(BaseErrorHandler):
    """ Models cerberus' legacy. Returns a :class:`dict`. When mangled
        through :class:`str` a pretty-formatted representation of that
        tree is returned.
    """
    messages = {0x00: "{0}",

                0x01: "document is missing",
                0x02: "required field",
                0x03: "unknown field",
                0x04: "field '{0}' is required",
                0x05: "depends on these values: {constraint}",
                0x06: "{0} must not be present with '{field}'",

                0x21: "'{0}' is not a document, must be a dict",
                0x22: "empty values not allowed",
                0x23: "null value not allowed",
                0x24: "must be of {constraint} type",
                0x25: "must be of dict type",
                0x26: "length of list should be {constraint}, it is {0}",
                0x27: "min length is {constraint}",
                0x28: "max length is {constraint}",

                0x41: "value does not match regex '{constraint}'",
                0x42: "min value is {constraint}",
                0x43: "max value is {constraint}",
                0x44: "unallowed value {value}",
                0x45: "unallowed values {0}",
                0x46: "unallowed value {value}",
                0x47: "unallowed values {0}",

                0x61: "field '{field}' cannot be coerced: {0}",
                0x62: "field '{field}' cannot be renamed: {0}",
                0x63: "field is read-only",
                0x64: "default value for '{field}' cannot be set: {0}",

                0x81: "mapping doesn't validate subschema: {0}",
                0x82: "one or more sequence-items don't validate: {0}",
                0x83: "one or more keys of a mapping  don't validate: {0}",
                0x84: "one or more values in a mapping don't validate: {0}",
                0x85: "one or more sequence-items don't validate: {0}",

                0x91: "one or more definitions validate",
                0x92: "none or more than one rule validate",
                0x93: "no definitions validate",
                0x94: "one or more definitions don't validate"
                }

    def __init__(self, tree=None):
        self.tree = {} if tree is None else tree

    def __call__(self, errors=None):
        if errors is not None:
            self.clear()
            self.extend(errors)
        return self.pretty_tree

    def __str__(self):
        return pformat(self.pretty_tree)

    @property
    def pretty_tree(self):
        pretty = deepcopy(self.tree)
        for field in pretty:
            self._purge_empty_dicts(pretty[field])
        return pretty

    @encode_unicode
    def add(self, error):
        # Make sure the original error is not altered with
        # error paths specific to the handler.
        error = deepcopy(error)

        self._rewrite_error_path(error)

        if error.is_logic_error:
            self._insert_logic_error(error)
        elif error.is_group_error:
            self._insert_group_error(error)
        elif error.code in self.messages:
            self._insert_error(error.document_path,
                               self._format_message(error.field, error))

    def clear(self):
        self.tree = {}

    def start(self, validator):
        self.clear()

    def _format_message(self, field, error):
        return self.messages[error.code].format(
            *error.info, constraint=error.constraint,
            field=field, value=error.value)

    def _insert_error(self, path, node):
        """ Adds an error or sub-tree to :attr:tree.

        :param path: Path to the error.
        :type path: Tuple of strings and integers.
        :param node: An error message or a sub-tree.
        :type node: String or dictionary.
        """
        field = path[0]
        if len(path) == 1:
            if field in self.tree:
                subtree = self.tree[field].pop()
                self.tree[field] += [node, subtree]
            else:
                self.tree[field] = [node, {}]
        elif len(path) >= 1:
            if field not in self.tree:
                self.tree[field] = [{}]
            subtree = self.tree[field][-1]

            if subtree:
                new = self.__class__(tree=copy(subtree))
            else:
                new = self.__class__()
            new._insert_error(path[1:], node)
            subtree.update(new.tree)

    def _insert_group_error(self, error):
        for child_error in error.child_errors:
            if child_error.is_logic_error:
                self._insert_logic_error(child_error)
            elif child_error.is_group_error:
                self._insert_group_error(child_error)
            else:
                self._insert_error(child_error.document_path,
                                   self._format_message(child_error.field,
                                                        child_error))

    def _insert_logic_error(self, error):
        field = error.field
        self._insert_error(error.document_path,
                           self._format_message(field, error))

        for definition_errors in error.definitions_errors.values():
            for child_error in definition_errors:
                if child_error.is_logic_error:
                    self._insert_logic_error(child_error)
                elif child_error.is_group_error:
                    self._insert_group_error(child_error)
                else:
                    self._insert_error(child_error.document_path,
                                       self._format_message(field, child_error))

    def _purge_empty_dicts(self, error_list):
        subtree = error_list[-1]
        if not error_list[-1]:
            error_list.pop()
        else:
            for key in subtree:
                self._purge_empty_dicts(subtree[key])

    def _rewrite_error_path(self, error, offset=0):
        """
        Recursively rewrites the error path to correctly represent logic errors
        """
        if error.is_logic_error:
            self._rewrite_logic_error_path(error, offset)
        elif error.is_group_error:
            self._rewrite_group_error_path(error, offset)

    def _rewrite_group_error_path(self, error, offset=0):
        child_start = len(error.document_path) - offset

        for child_error in error.child_errors:
            relative_path = child_error.document_path[child_start:]
            child_error.document_path = error.document_path + relative_path

            self._rewrite_error_path(child_error, offset)

    def _rewrite_logic_error_path(self, error, offset=0):
        child_start = len(error.document_path) - offset

        for i, definition_errors in error.definitions_errors.items():
            if not definition_errors:
                continue

            nodename = '%s definition %s' % (error.rule, i)
            path = error.document_path + (nodename,)

            for child_error in definition_errors:
                rel_path = child_error.document_path[child_start:]
                child_error.document_path = path + rel_path

                self._rewrite_error_path(child_error, offset + 1)


class SchemaErrorHandler(BasicErrorHandler):
    messages = BasicErrorHandler.messages.copy()
    messages[0x03] = "unknown rule"