"""Shared base classes for Pydantic model implementations.

Provides Constraints, DataModelField, and BaseModelBase used by Pydantic v2 models.
"""

from __future__ import annotations

from abc import ABC
from functools import cached_property
from pathlib import Path
from typing import TYPE_CHECKING, Any, ClassVar, Optional

from pydantic import Field

from datamodel_code_generator import cached_path_exists
from datamodel_code_generator.imports import Import
from datamodel_code_generator.model import (
    ConstraintsBase,
    DataModel,
    DataModelFieldBase,
)
from datamodel_code_generator.model.base import UNDEFINED, repr_set_sorted
from datamodel_code_generator.types import UnionIntFloat, chain_as_tuple

# Defined here instead of importing from pydantic_v2.imports to avoid circular import
# (pydantic_base -> pydantic_v2.imports -> pydantic_v2/__init__ -> pydantic_v2.base_model -> pydantic_base)
IMPORT_ANYURL = Import.from_full_path("pydantic.AnyUrl")
IMPORT_FIELD = Import.from_full_path("pydantic.Field")

if TYPE_CHECKING:
    from collections import defaultdict

    from datamodel_code_generator.reference import Reference


class Constraints(ConstraintsBase):
    """Pydantic field constraints (gt, ge, lt, le, regex, etc.)."""

    gt: Optional[UnionIntFloat] = Field(None, alias="exclusiveMinimum")  # noqa: UP045
    ge: Optional[UnionIntFloat] = Field(None, alias="minimum")  # noqa: UP045
    lt: Optional[UnionIntFloat] = Field(None, alias="exclusiveMaximum")  # noqa: UP045
    le: Optional[UnionIntFloat] = Field(None, alias="maximum")  # noqa: UP045
    multiple_of: Optional[float] = Field(None, alias="multipleOf")  # noqa: UP045
    min_items: Optional[int] = Field(None, alias="minItems")  # noqa: UP045
    max_items: Optional[int] = Field(None, alias="maxItems")  # noqa: UP045
    min_length: Optional[int] = Field(None, alias="minLength")  # noqa: UP045
    max_length: Optional[int] = Field(None, alias="maxLength")  # noqa: UP045
    regex: Optional[str] = Field(None, alias="pattern")  # noqa: UP045


class DataModelField(DataModelFieldBase):
    """Field implementation for Pydantic models."""

    _EXCLUDE_FIELD_KEYS: ClassVar[set[str]] = {
        "alias",
        "default",
        "const",
        "gt",
        "ge",
        "lt",
        "le",
        "multiple_of",
        "min_items",
        "max_items",
        "min_length",
        "max_length",
        "regex",
    }
    _COMPARE_EXPRESSIONS: ClassVar[set[str]] = {"gt", "ge", "lt", "le"}
    constraints: Optional[Constraints] = None  # noqa: UP045
    _PARSE_METHOD: ClassVar[str] = "model_validate"

    @property
    def has_default_factory_in_field(self) -> bool:
        """Check if this field has a default_factory in Field() including computed ones."""
        return "default_factory" in self.extras or self.__dict__.get("_computed_default_factory") is not None

    @property
    def method(self) -> str | None:
        """Get the validation method name."""
        return self.validator

    @property
    def validator(self) -> str | None:
        """Get the validator name."""
        return None
        # TODO refactor this method for other validation logic

    @property
    def field(self) -> str | None:
        """For backwards compatibility."""
        if self.is_class_var:
            return None
        result = str(self)
        if (
            self.use_default_kwarg
            and not result.startswith("Field(...")
            and not result.startswith("Field(default_factory=")
        ):
            # Use `default=` for fields that have a default value so that type
            # checkers using @dataclass_transform can infer the field as
            # optional in __init__.
            result = result.replace("Field(", "Field(default=")
        if not result:
            return None
        return result

    def _get_strict_field_constraint_value(self, constraint: str, value: Any) -> Any:
        if value is None or constraint not in self._COMPARE_EXPRESSIONS:
            return value

        is_float_type = any(
            data_type.type == "float"
            or (data_type.strict and data_type.import_ and "Float" in data_type.import_.import_)
            for data_type in self.data_type.all_data_types
        )
        if is_float_type:
            return float(value)
        str_value = str(value)
        if "e" in str_value.lower():  # pragma: no cover
            # Scientific notation like 1e-08 - keep as float
            return float(value)
        if isinstance(value, int) and not isinstance(value, bool):
            return value
        return int(value)

    def _get_default_factory_for_optional_nested_model(self) -> str | None:
        """Get default_factory for optional nested Pydantic model fields.

        Returns the class name if the field type references a BaseModel,
        otherwise returns None.
        """
        for data_type in self.data_type.data_types or (self.data_type,):
            if data_type.is_dict:
                continue
            if data_type.reference and isinstance(data_type.reference.source, BaseModelBase):
                return data_type.alias or data_type.reference.source.class_name
        return None

    def _process_data_in_str(self, data: dict[str, Any]) -> None:  # pragma: no cover
        if self.const:
            data["const"] = True

        if self.use_frozen_field and self.read_only:
            data["allow_mutation"] = False

    def _process_annotated_field_arguments(self, field_arguments: list[str]) -> list[str]:  # noqa: PLR6301  # pragma: no cover
        return field_arguments

    def __str__(self) -> str:  # noqa: PLR0912
        """Return Field() call with all constraints and metadata."""
        data: dict[str, Any] = {k: v for k, v in self.extras.items() if k not in self._EXCLUDE_FIELD_KEYS}
        if self.alias:
            data["alias"] = self.alias
        has_type_constraints = self.data_type.kwargs is not None and len(self.data_type.kwargs) > 0
        if (
            self.constraints is not None
            and not self.self_reference()
            and not (self.data_type.strict and has_type_constraints)
        ):
            data = {
                **data,
                **(
                    {}
                    if any(d.import_ == IMPORT_ANYURL for d in self.data_type.all_data_types)
                    else {
                        k: self._get_strict_field_constraint_value(k, v)
                        for k, v in self.constraints.model_dump(exclude_unset=True).items()
                    }
                ),
            }

        if self.use_field_description:
            data.pop("description", None)  # Description is part of field docstring

        self._process_data_in_str(data)

        discriminator = data.pop("discriminator", None)
        if discriminator:
            if isinstance(discriminator, str):
                data["discriminator"] = discriminator
            elif isinstance(discriminator, dict):  # pragma: no cover
                data["discriminator"] = discriminator["propertyName"]

        if (self.required and not self.has_default) or (
            self.default is not UNDEFINED and self.default is not None and "default_factory" not in data
        ):
            default_factory = None
        else:
            default_factory = data.pop("default_factory", None)

        if (
            default_factory is None
            and self.use_default_factory_for_optional_nested_models
            and not self.required
            and (self.default is None or self.default is UNDEFINED)
        ):
            default_factory = self._get_default_factory_for_optional_nested_model()

        self.__dict__["_computed_default_factory"] = default_factory

        field_arguments = sorted(f"{k}={v!r}" for k, v in data.items() if v is not None)

        if not field_arguments and not default_factory:
            if self.nullable and self.required:
                return "Field(...)"  # Field() is for mypy
            return ""

        if default_factory:
            field_arguments = [f"default_factory={default_factory}", *field_arguments]

        if self.use_annotated:
            field_arguments = self._process_annotated_field_arguments(field_arguments)
        elif self.required and not default_factory and not self.extras.get("validate_default"):
            field_arguments = ["...", *field_arguments]
        elif not default_factory:
            default_repr = repr_set_sorted(self.default) if isinstance(self.default, set) else repr(self.default)
            field_arguments = [default_repr, *field_arguments]

        if self.is_class_var:
            if self.default is UNDEFINED:  # pragma: no cover
                return ""
            return repr_set_sorted(self.default) if isinstance(self.default, set) else repr(self.default)

        return f"Field({', '.join(field_arguments)})"

    @property
    def is_class_var(self) -> bool:
        """Check if this field is a ClassVar."""
        return self.extras.get("x-is-classvar") is True

    @property
    def type_hint(self) -> str:
        """Get the type hint including ClassVar if applicable."""
        if self.is_class_var:
            return f"ClassVar[{super().type_hint}]"
        return super().type_hint

    @property
    def annotated(self) -> str | None:
        """Get the Annotated type hint if use_annotated is enabled."""
        if not self.use_annotated or not str(self) or self.is_class_var:
            return None
        return f"Annotated[{self.type_hint}, {self!s}]"

    @property
    def imports(self) -> tuple[Import, ...]:
        """Get all required imports including Field if needed."""
        if self.field:
            return chain_as_tuple(super().imports, (IMPORT_FIELD,))
        return super().imports


class BaseModelBase(DataModel, ABC):
    """Abstract base class for Pydantic BaseModel implementations."""

    REQUIRES_RUNTIME_IMPORTS_WITH_RUFF_CHECK: ClassVar[bool] = True

    def __init__(  # noqa: PLR0913
        self,
        *,
        reference: Reference,
        fields: list[DataModelFieldBase],
        decorators: list[str] | None = None,
        base_classes: list[Reference] | None = None,
        custom_base_class: str | list[str] | None = None,
        custom_template_dir: Path | None = None,
        extra_template_data: defaultdict[str, Any] | None = None,
        path: Path | None = None,
        description: str | None = None,
        default: Any = UNDEFINED,
        nullable: bool = False,
        keyword_only: bool = False,
        treat_dot_as_module: bool | None = None,
    ) -> None:
        """Initialize the BaseModel with fields and configuration."""
        methods: list[str] = [field.method for field in fields if field.method]

        super().__init__(
            fields=fields,
            reference=reference,
            decorators=decorators,
            base_classes=base_classes,
            custom_base_class=custom_base_class,
            custom_template_dir=custom_template_dir,
            extra_template_data=extra_template_data,
            methods=methods,
            path=path,
            description=description,
            default=default,
            nullable=nullable,
            keyword_only=keyword_only,
            treat_dot_as_module=treat_dot_as_module,
        )

    @cached_property
    def template_file_path(self) -> Path:
        """Get the template file path with backward compatibility support."""
        # This property is for Backward compatibility
        # Current version supports '{custom_template_dir}/BaseModel.jinja'
        # But, Future version will support only '{custom_template_dir}/pydantic/BaseModel.jinja'
        if self._custom_template_dir is not None:
            custom_template_file_path = self._custom_template_dir / Path(self.TEMPLATE_FILE_PATH).name
            if cached_path_exists(custom_template_file_path):
                return custom_template_file_path
        return super().template_file_path