from collections.abc import Mapping, MutableMapping, Sequence
from urllib.parse import urlsplit
import itertools
import json
import re
import sys

# The files() API was added in Python 3.9.
if sys.version_info >= (3, 9):  # pragma: no cover
    import importlib.resources as resources
else:  # pragma: no cover
    import importlib_resources as resources


class URIDict(MutableMapping):
    """
    Dictionary which uses normalized URIs as keys.
    """

    def normalize(self, uri):
        return urlsplit(uri).geturl()

    def __init__(self, *args, **kwargs):
        self.store = dict()
        self.store.update(*args, **kwargs)

    def __getitem__(self, uri):
        return self.store[self.normalize(uri)]

    def __setitem__(self, uri, value):
        self.store[self.normalize(uri)] = value

    def __delitem__(self, uri):
        del self.store[self.normalize(uri)]

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

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

    def __repr__(self):
        return repr(self.store)


class Unset(object):
    """
    An as-of-yet unset attribute or unprovided default parameter.
    """

    def __repr__(self):
        return "<unset>"


def load_schema(name):
    """
    Load a schema from ./schemas/``name``.json and return it.
    """

    path = resources.files(__package__).joinpath(f"schemas/{name}.json")
    data = path.read_text(encoding="utf-8")
    return json.loads(data)


def format_as_index(container, indices):
    """
    Construct a single string containing indexing operations for the indices.

    For example for a container ``bar``, [1, 2, "foo"] -> bar[1][2]["foo"]

    Arguments:

        container (str):

            A word to use for the thing being indexed

        indices (sequence):

            The indices to format.
    """

    if not indices:
        return container
    return f"{container}[{']['.join(repr(index) for index in indices)}]"


def find_additional_properties(instance, schema):
    """
    Return the set of additional properties for the given ``instance``.

    Weeds out properties that should have been validated by ``properties`` and
    / or ``patternProperties``.

    Assumes ``instance`` is dict-like already.
    """

    properties = schema.get("properties", {})
    patterns = "|".join(schema.get("patternProperties", {}))
    for property in instance:
        if property not in properties:
            if patterns and re.search(patterns, property):
                continue
            yield property


def extras_msg(extras):
    """
    Create an error message for extra items or properties.
    """

    if len(extras) == 1:
        verb = "was"
    else:
        verb = "were"
    return ", ".join(repr(extra) for extra in extras), verb


def ensure_list(thing):
    """
    Wrap ``thing`` in a list if it's a single str.

    Otherwise, return it unchanged.
    """

    if isinstance(thing, str):
        return [thing]
    return thing


def _mapping_equal(one, two):
    """
    Check if two mappings are equal using the semantics of `equal`.
    """
    if len(one) != len(two):
        return False
    return all(
        key in two and equal(value, two[key])
        for key, value in one.items()
    )


def _sequence_equal(one, two):
    """
    Check if two sequences are equal using the semantics of `equal`.
    """
    if len(one) != len(two):
        return False
    return all(equal(i, j) for i, j in zip(one, two))


def equal(one, two):
    """
    Check if two things are equal evading some Python type hierarchy semantics.

    Specifically in JSON Schema, evade `bool` inheriting from `int`,
    recursing into sequences to do the same.
    """
    if isinstance(one, str) or isinstance(two, str):
        return one == two
    if isinstance(one, Sequence) and isinstance(two, Sequence):
        return _sequence_equal(one, two)
    if isinstance(one, Mapping) and isinstance(two, Mapping):
        return _mapping_equal(one, two)
    return unbool(one) == unbool(two)


def unbool(element, true=object(), false=object()):
    """
    A hack to make True and 1 and False and 0 unique for ``uniq``.
    """

    if element is True:
        return true
    elif element is False:
        return false
    return element


def uniq(container):
    """
    Check if all of a container's elements are unique.

    Tries to rely on the container being recursively sortable, or otherwise
    falls back on (slow) brute force.
    """
    try:
        sort = sorted(unbool(i) for i in container)
        sliced = itertools.islice(sort, 1, None)

        for i, j in zip(sort, sliced):
            return not _sequence_equal(i, j)

    except (NotImplementedError, TypeError):
        seen = []
        for e in container:
            e = unbool(e)

            for i in seen:
                if equal(i, e):
                    return False

            seen.append(e)
    return True


def find_evaluated_item_indexes_by_schema(validator, instance, schema):
    """
    Get all indexes of items that get evaluated under the current schema

    Covers all keywords related to unevaluatedItems: items, prefixItems, if,
    then, else, contains, unevaluatedItems, allOf, oneOf, anyOf
    """
    if validator.is_type(schema, "boolean"):
        return []
    evaluated_indexes = []

    if "items" in schema:
        return list(range(0, len(instance)))

    if "$ref" in schema:
        scope, resolved = validator.resolver.resolve(schema["$ref"])
        validator.resolver.push_scope(scope)

        try:
            evaluated_indexes += find_evaluated_item_indexes_by_schema(
                validator, instance, resolved)
        finally:
            validator.resolver.pop_scope()

    if "prefixItems" in schema:
        evaluated_indexes += list(range(0, len(schema["prefixItems"])))

    if "if" in schema:
        if validator.evolve(schema=schema["if"]).is_valid(instance):
            evaluated_indexes += find_evaluated_item_indexes_by_schema(
                validator, instance, schema["if"],
            )
            if "then" in schema:
                evaluated_indexes += find_evaluated_item_indexes_by_schema(
                    validator, instance, schema["then"],
                )
        else:
            if "else" in schema:
                evaluated_indexes += find_evaluated_item_indexes_by_schema(
                    validator, instance, schema["else"],
                )

    for keyword in ["contains", "unevaluatedItems"]:
        if keyword in schema:
            for k, v in enumerate(instance):
                if validator.evolve(schema=schema[keyword]).is_valid(v):
                    evaluated_indexes.append(k)

    for keyword in ["allOf", "oneOf", "anyOf"]:
        if keyword in schema:
            for subschema in schema[keyword]:
                errs = list(validator.descend(instance, subschema))
                if not errs:
                    evaluated_indexes += find_evaluated_item_indexes_by_schema(
                        validator, instance, subschema,
                    )

    return evaluated_indexes


def find_evaluated_property_keys_by_schema(validator, instance, schema):
    """
    Get all keys of items that get evaluated under the current schema

    Covers all keywords related to unevaluatedProperties: properties,
    additionalProperties, unevaluatedProperties, patternProperties,
    dependentSchemas, allOf, oneOf, anyOf, if, then, else
    """
    if validator.is_type(schema, "boolean"):
        return []
    evaluated_keys = []

    if "$ref" in schema:
        scope, resolved = validator.resolver.resolve(schema["$ref"])
        validator.resolver.push_scope(scope)

        try:
            evaluated_keys += find_evaluated_property_keys_by_schema(
                validator, instance, resolved,
            )
        finally:
            validator.resolver.pop_scope()

    for keyword in [
        "properties", "additionalProperties", "unevaluatedProperties",
    ]:
        if keyword in schema:
            if validator.is_type(schema[keyword], "boolean"):
                for property, value in instance.items():
                    if validator.evolve(schema=schema[keyword]).is_valid(
                        {property: value},
                    ):
                        evaluated_keys.append(property)

            if validator.is_type(schema[keyword], "object"):
                for property, subschema in schema[keyword].items():
                    if property in instance and validator.evolve(
                        schema=subschema,
                    ).is_valid(instance[property]):
                        evaluated_keys.append(property)

    if "patternProperties" in schema:
        for property, value in instance.items():
            for pattern, _ in schema["patternProperties"].items():
                if re.search(pattern, property) and validator.evolve(
                    schema=schema["patternProperties"],
                ).is_valid({property: value}):
                    evaluated_keys.append(property)

    if "dependentSchemas" in schema:
        for property, subschema in schema["dependentSchemas"].items():
            if property not in instance:
                continue
            evaluated_keys += find_evaluated_property_keys_by_schema(
                validator, instance, subschema,
            )

    for keyword in ["allOf", "oneOf", "anyOf"]:
        if keyword in schema:
            for subschema in schema[keyword]:
                errs = list(validator.descend(instance, subschema))
                if not errs:
                    evaluated_keys += find_evaluated_property_keys_by_schema(
                        validator, instance, subschema,
                    )

    if "if" in schema:
        if validator.evolve(schema=schema["if"]).is_valid(instance):
            evaluated_keys += find_evaluated_property_keys_by_schema(
                validator, instance, schema["if"],
            )
            if "then" in schema:
                evaluated_keys += find_evaluated_property_keys_by_schema(
                    validator, instance, schema["then"],
                )
        else:
            if "else" in schema:
                evaluated_keys += find_evaluated_property_keys_by_schema(
                    validator, instance, schema["else"],
                )

    return evaluated_keys