#
# This file is distributed under the MIT License. See LICENSE.md for details.
#

import copy
from abc import ABC
from typing import Dict, List

from .definition import Definition
from .enum import EnumDefinition
from .reference import ReferenceDefinition
from .sequence import SequenceDefinition
from .upcastable import UpcastableDefinition

# TODO: we should return the fields in a stable order (in all_fields, all_optional_fields, etc)


def is_enum(resolved_type):
    return isinstance(resolved_type, EnumDefinition)


class StructField(ABC):
    def __init__(self, *, name, doc=None, optional=False, const=False, is_guid=False):
        self.name = name
        self.doc = doc
        self.optional = optional
        self.const = const
        self.is_guid = is_guid
        self.resolved_type = None

    @staticmethod
    def from_yaml(source_dict: Dict):
        if source_dict.get("type"):
            return SimpleStructField(**source_dict)

        if source_dict.get("sequence"):
            sequence_def = source_dict["sequence"]
            args = copy.copy(source_dict)
            del args["sequence"]
            args.update(
                {
                    "sequence_type": sequence_def["type"],
                    "element_type": sequence_def["elementType"],
                    "upcastable": sequence_def.get("upcastable", False),
                }
            )
            return SequenceStructField(**args)

        if source_dict.get("reference"):
            reference = source_dict["reference"]
            args = copy.copy(source_dict)
            del args["reference"]
            args.update(
                {
                    "pointee_type": reference["pointeeType"],
                    "root_type": reference["rootType"],
                }
            )
            return ReferenceStructField(**args)

        raise ValueError("Invalid struct field")

    def resolve_references(self, schema):
        raise NotImplementedError()


class UpcastableStructField(StructField):
    def __init__(self, underlying):
        super().__init__(
            name=underlying.name,
            doc=underlying.doc,
            optional=underlying.optional,
            const=underlying.const,
            is_guid=underlying.is_guid,
        )
        self.underlying = underlying

    def resolve_references(self, schema):
        self.underlying.resolve_references(schema)
        self.resolved_type = UpcastableDefinition(self.underlying.resolved_type)
        assert self.resolved_type


class SimpleStructField(StructField):
    def __init__(
        self,
        *,
        name,
        type,  # noqa: A002
        doc=None,
        optional=False,
        const=False,
        upcastable=False,
        is_guid=False,
    ):
        super().__init__(name=name, doc=doc, optional=optional, const=const, is_guid=is_guid)
        self.type = type
        self.upcastable = upcastable

    def resolve_references(self, schema):
        self.resolved_type = schema.get_definition_for(self.type)
        if self.upcastable:
            self.resolved_type = UpcastableDefinition(self.resolved_type)
        assert self.resolved_type


class SequenceStructField(StructField):
    def __init__(
        self,
        *,
        name,
        sequence_type,
        element_type,
        upcastable=False,
        doc=None,
        optional=False,
        const=False,
    ):
        super().__init__(name=name, doc=doc, optional=optional, const=const)
        self.sequence_type = sequence_type
        self.element_type = element_type
        self.upcastable = upcastable
        self.resolved_element_type = None

    def resolve_references(self, schema):
        self.resolved_element_type = schema.get_definition_for(self.element_type)
        if self.upcastable:
            self.resolved_element_type = UpcastableDefinition(self.resolved_element_type)
        self.resolved_type = SequenceDefinition(self.sequence_type, self.resolved_element_type)


class ReferenceStructField(StructField):
    def __init__(self, *, name, pointee_type, root_type, doc=None, optional=False, const=False):
        super().__init__(name=name, doc=doc, optional=optional, const=const)
        self.pointee_type = pointee_type
        self.root_type = root_type

    def resolve_references(self, schema):
        resolved_pointee_type = schema.get_definition_for(self.pointee_type)
        resolved_root_type = schema.get_definition_for(self.root_type)
        self.resolved_type = ReferenceDefinition(resolved_pointee_type, resolved_root_type)


class StructDefinition(Definition):
    def __init__(
        self,
        *,
        name,
        fields,
        inherits=None,
        doc=None,
        abstract=False,
        _key=None,
    ):
        super().__init__(False, name)

        self.doc = doc
        # Names of types on which this definition depends on.
        # Not necessarily names defined by the user
        self.autogenerated = False

        self.fields: List[StructField] = fields
        self.abstract = abstract
        self._key = _key
        self._inherits = inherits

        # These fields will be populated by resolve_references()
        self.inherits = None
        self._key_kind_index = None
        # Type containing the key fields (might be self or a base class)
        self.key_definition = None
        # None, "simple" or "composite"
        self.keytype = None
        self.key_fields: List[SimpleStructField] = []
        self.emit_full_constructor = None
        self.children: List[StructDefinition] = []
        self._refs_resolved = False

    def resolve_references(self, schema):
        if self._refs_resolved:
            return

        if self._inherits:
            self.inherits = schema.get_definition_for(self._inherits)
            self.dependencies.add(self._inherits)

        for field in self.fields:
            field.resolve_references(schema)

            if isinstance(field, SimpleStructField):
                self.dependencies.add(field.type)
            elif isinstance(field, SequenceStructField):
                self.dependencies.add(field.element_type)
            elif isinstance(field, ReferenceStructField):
                self.dependencies.add(field.pointee_type)
                # TODO: if we add this dependency we generate circular dependencies
                # self.dependencies.add(field.root_type)  # noqa: E800
            else:
                raise ValueError()

        if self._key:
            self.key_definition = self

        elif self.inherits and self.inherits._key:
            # TODO: support indirect inheritance
            self.key_definition = self.inherits

        # TODO: mark key fields as const
        if self.key_definition:
            for key_field_index, key_field_name in enumerate(self.key_definition._key):
                key_field = next(f for f in self.key_definition.fields if f.name == key_field_name)
                assert isinstance(key_field, SimpleStructField)
                self.key_fields.append(key_field)

                if key_field.name == "Kind":
                    assert self._key_kind_index is None, "Multiple kind fields in the key"
                    self._key_kind_index = key_field_index

            if len(self.key_definition.key_fields) == 0:
                self.keytype = None
            elif len(self.key_definition.key_fields) == 1:
                self.keytype = "simple"
            else:
                self.keytype = "composite"

        self._refs_resolved = True

        key_fields_names = {f.name for f in self.key_fields}
        all_field_names = {f.name for f in self.all_fields}
        self.emit_full_constructor = key_fields_names != all_field_names

        if (self.inherits or self.abstract) and self.keytype:
            assert self._key_kind_index is not None, "A polymorphic type without kind in the key"

    @staticmethod
    def from_dict(source_dict: Dict):
        args = {
            "name": source_dict["name"],
            "doc": source_dict.get("doc"),
            "fields": [StructField.from_yaml(d) for d in source_dict["fields"]],
            "_key": source_dict.get("key"),
            "inherits": source_dict.get("inherits"),
            "abstract": source_dict.get("abstract", False),
        }
        return StructDefinition(**args)

    @property
    def optional_fields(self):
        for field in self.fields:
            if field.optional:
                yield field

    @property
    def required_fields(self):
        for field in self.fields:
            if not field.optional:
                yield field

    @property
    def all_optional_fields(self):
        for field in self.all_fields:
            if field.optional:
                yield field

    @property
    def all_required_fields(self):
        for field in self.all_fields:
            if not field.optional:
                yield field

    @property
    def all_fields(self):
        if not self._refs_resolved:
            raise RuntimeError("all_fields not available before resolving references")
        if self.inherits:
            yield from self.inherits.fields
        yield from self.fields