import sys
from collections import defaultdict
from typing import Any, Callable, Dict, List, Optional, Set, Type

from xsdata.exceptions import XmlContextError
from xsdata.formats.bindings import T
from xsdata.formats.dataclass.compat import class_types
from xsdata.formats.dataclass.models.builders import XmlMetaBuilder
from xsdata.formats.dataclass.models.elements import XmlMeta
from xsdata.models.enums import DataType
from xsdata.utils.constants import return_input


class XmlContext:
    """
    The service provider for binding operations' metadata.

    :param element_name_generator: Default element name generator
    :param attribute_name_generator: Default attribute name generator
    :param class_type: Default class type `dataclasses`
    :param models_package: Restrict auto locate to a specific package
    """

    __slots__ = (
        "element_name_generator",
        "attribute_name_generator",
        "class_type",
        "cache",
        "xsi_cache",
        "sys_modules",
        "models_package",
    )

    def __init__(
        self,
        element_name_generator: Callable = return_input,
        attribute_name_generator: Callable = return_input,
        class_type: str = "dataclasses",
        models_package: Optional[str] = None,
    ):
        self.element_name_generator = element_name_generator
        self.attribute_name_generator = attribute_name_generator
        self.class_type = class_types.get_type(class_type)

        self.cache: Dict[Type, XmlMeta] = {}
        self.xsi_cache: Dict[str, List[Type]] = defaultdict(list)
        self.models_package = models_package
        self.sys_modules = 0

    def reset(self):
        self.cache.clear()
        self.xsi_cache.clear()
        self.sys_modules = 0

    def get_builder(
        self, globalns: Optional[Dict[str, Callable]] = None
    ) -> XmlMetaBuilder:
        return XmlMetaBuilder(
            class_type=self.class_type,
            element_name_generator=self.element_name_generator,
            attribute_name_generator=self.attribute_name_generator,
            globalns=globalns,
        )

    def fetch(
        self,
        clazz: Type,
        parent_ns: Optional[str] = None,
        xsi_type: Optional[str] = None,
    ) -> XmlMeta:
        """
        Fetch the model metadata of the given dataclass type, namespace and xsi
        type.

        :param clazz: The requested dataclass type
        :param parent_ns: The inherited parent namespace
        :param xsi_type: if present it means that the given clazz is
            derived and the lookup procedure needs to check and match a
            dataclass model to the qualified name instead
        """
        meta = self.build(clazz, parent_ns)
        subclass = None
        if xsi_type and meta.target_qname != xsi_type:
            subclass = self.find_subclass(clazz, xsi_type)

        return self.build(subclass, parent_ns) if subclass else meta

    def build_xsi_cache(self):
        """Index all imported dataclasses by their xsi:type qualified name."""
        if len(sys.modules) == self.sys_modules:
            return

        self.xsi_cache.clear()
        builder = self.get_builder()
        for clazz in self.get_subclasses(object):
            if self.is_binding_model(clazz):
                meta = builder.build_class_meta(clazz)

                if meta.target_qname:
                    self.xsi_cache[meta.target_qname].append(clazz)

        self.sys_modules = len(sys.modules)

    def is_binding_model(self, clazz: Type[T]) -> bool:
        if not self.class_type.is_model(clazz):
            return False

        return not self.models_package or (
            hasattr(clazz, "__module__")
            and isinstance(clazz.__module__, str)
            and clazz.__module__.startswith(self.models_package)
        )

    def find_types(self, qname: str) -> List[Type[T]]:
        """
        Find all classes that match the given xsi:type qname.

        - Ignores native schema types, xs:string, xs:float, xs:int, ...
        - Rebuild cache if new modules were imported since last run

        :param qname: Qualified name
        """
        if not DataType.from_qname(qname):
            self.build_xsi_cache()
            if qname in self.xsi_cache:
                return self.xsi_cache[qname]

        return []

    def find_type(self, qname: str) -> Optional[Type[T]]:
        """
        Return the most recently imported class that matches the given xsi:type
        qname.

        :param qname: Qualified name
        """
        types: List[Type] = self.find_types(qname)
        return types[-1] if types else None

    def find_type_by_fields(self, field_names: Set[str]) -> Optional[Type[T]]:
        """
        Find a dataclass from all the imported modules that matches the given
        list of field names.

        :param field_names: A unique list of field names
        """

        def get_field_diff(clazz: Type) -> int:
            meta = self.cache[clazz]
            local_names = {var.local_name for var in meta.get_all_vars()}
            return len(local_names - field_names)

        self.build_xsi_cache()
        choices = [
            (clazz, get_field_diff(clazz))
            for types in self.xsi_cache.values()
            for clazz in types
            if self.local_names_match(field_names, clazz)
        ]

        choices.sort(key=lambda x: (x[1], x[0].__name__))
        return choices[0][0] if len(choices) > 0 else None

    def find_subclass(self, clazz: Type, qname: str) -> Optional[Type]:
        """
        Compare all classes that match the given xsi:type qname and return the
        first one that is either a subclass or shares the same parent class as
        the original class.

        :param clazz: The search dataclass type
        :param qname: Qualified name
        """
        types: List[Type] = self.find_types(qname)
        for tp in types:
            # Why would an xml node with have an xsi:type that points
            # to parent class is beyond me but it happens, let's protect
            # against that scenario <node xsi:type="nodeAbstract" />
            if issubclass(clazz, tp):
                continue

            for tp_mro in tp.__mro__:
                if tp_mro is not object and tp_mro in clazz.__mro__:
                    return tp

        return None

    def build(
        self,
        clazz: Type,
        parent_ns: Optional[str] = None,
        globalns: Optional[Dict[str, Callable]] = None,
    ) -> XmlMeta:
        """
        Fetch from cache or build the binding metadata for the given class and
        parent namespace.

        :param clazz: A dataclass type
        :param parent_ns: The inherited parent namespace
        """
        if clazz not in self.cache:
            builder = self.get_builder(globalns)
            self.cache[clazz] = builder.build(clazz, parent_ns)
        return self.cache[clazz]

    def build_recursive(self, clazz: Type, parent_ns: Optional[str] = None):
        """Build the binding metadata for the given class and all of its
        dependencies."""
        if clazz not in self.cache:
            meta = self.build(clazz, parent_ns)
            for var in meta.get_all_vars():
                types = var.element_types if var.elements else var.types
                for tp in types:
                    if self.class_type.is_model(tp):
                        self.build_recursive(tp, meta.namespace)

    def local_names_match(self, names: Set[str], clazz: Type) -> bool:
        try:
            meta = self.build(clazz)
            local_names = {var.local_name for var in meta.get_all_vars()}
            return not names.difference(local_names)
        except (XmlContextError, NameError, TypeError):
            # The dataclass includes unsupported typing annotations
            # Let's remove it from xsi_cache
            builder = self.get_builder()
            target_qname = builder.build_class_meta(clazz).target_qname
            if target_qname and target_qname in self.xsi_cache:
                self.xsi_cache[target_qname].remove(clazz)

            return False

    @classmethod
    def is_derived(cls, obj: Any, clazz: Type) -> bool:
        """
        Return whether the given obj is derived from the given dataclass type.

        :param obj: A dataclass instance
        :param clazz: A dataclass type
        """
        if obj is None:
            return False

        if isinstance(obj, clazz):
            return True

        return any(x is not object and isinstance(obj, x) for x in clazz.__bases__)

    @classmethod
    def get_subclasses(cls, clazz: Type):
        try:
            for subclass in clazz.__subclasses__():
                yield from cls.get_subclasses(subclass)
                yield subclass
        except TypeError:
            pass