from datetime import datetime
from typing import Annotated, Generic, Literal, TypeVar

from pydantic import (
    AwareDatetime,
    BaseModel,
    ConfigDict,
    Field,
    HttpUrl,
    field_validator,
    model_validator,
)

Title = Annotated[str, Field(min_length=1, max_length=250)]
Category = Annotated[str, Field(min_length=1, max_length=80)]
Body = Annotated[str, Field(min_length=1, max_length=100_000)]
Notes = Annotated[str, Field(max_length=10_000)]
Status = Literal["pending", "verified", "rejected"]
PositiveId = Annotated[int, Field(gt=0)]


class Input(BaseModel):
    model_config = ConfigDict(extra="forbid", str_strip_whitespace=True)

    @field_validator("source_url", mode="before", check_fields=False)
    @classmethod
    def empty_url_is_absent(cls, value):
        return None if isinstance(value, str) and not value.strip() else value


class Patch(Input):
    expected_version: PositiveId

    @model_validator(mode="after")
    def require_changes(self):
        if not self.model_fields_set - {"expected_version"}:
            raise ValueError("至少提供一个需要更新的字段")
        return self

    @field_validator("*", mode="before")
    @classmethod
    def disallow_required_null(cls, value, info):
        if (
            info.field_name in {"name", "title", "category", "content", "notes", "expected_version"}
            and value is None
        ):
            raise ValueError("该字段不能为 null")
        return value


class Read(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    id: int
    version: int
    created_at: datetime
    updated_at: datetime
    is_deleted: bool


class SourceCreate(Input):
    name: Title
    source_url: HttpUrl | None = Field(default=None, max_length=1000)
    notes: Notes = ""


class SourceUpdate(Patch):
    name: Title | None = None
    source_url: HttpUrl | None = Field(default=None, max_length=1000)
    notes: Notes | None = None


class SourceRead(Read):
    name: str
    source_url: str | None
    notes: str


class DocumentCreate(Input):
    source_id: PositiveId
    title: Title
    category: Category = "未分类"
    content: Body
    collected_at: AwareDatetime
    notes: Notes = ""


class DocumentUpdate(Patch):
    title: Title | None = None
    category: Category | None = None
    content: Body | None = None
    collected_at: AwareDatetime | None = None
    notes: Notes | None = None

    @field_validator("collected_at", mode="before")
    @classmethod
    def collection_time_is_required(cls, value):
        if value is None:
            raise ValueError("文档采集时间不能为 null")
        return value


class DocumentRead(Read):
    source_id: int
    title: str
    category: str
    content: str
    collected_at: datetime
    notes: str


T = TypeVar("T")


class Page(BaseModel, Generic[T]):
    items: list[T]
    total: int
    page: int
    page_size: int


class AuditRead(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    id: int
    entity_type: str
    entity_id: int
    action: str
    actor: str | None
    notes: str
    snapshot: dict
    created_at: datetime