from datetime import datetime, timezone
from typing import Literal
from uuid import UUID

from pydantic import BaseModel, ConfigDict, Field, field_validator, model_validator

from app.schemas.catalog import Input


class BuildIndex(Input):
    chunk_size: int = Field(500, ge=100, le=2000)
    overlap: int = Field(80, ge=0, le=1000)

    @model_validator(mode="after")
    def bounded_overlap(self):
        if self.overlap > self.chunk_size // 2:
            raise ValueError("重叠不得超过切分长度的一半")
        return self


class PublishIndex(Input):
    expected_generation: int = Field(ge=0)


class IndexConfig(BuildIndex):
    splitter: Literal["unicode-window-v1"]


class ChunkProvenance(BaseModel):
    knowledge_id: int
    knowledge_version: int
    document_id: int | None
    document_version: int | None
    source_id: int | None
    source_version: int | None
    source_name: str | None
    source_url: str
    title: str
    category: str


class TimestampRead(BaseModel):
    model_config = ConfigDict(from_attributes=True)

    @field_validator("created_at", "published_at", check_fields=False)
    @classmethod
    def utc_timestamp(cls, value):
        return value.astimezone(timezone.utc) if value is not None else None


class IndexRead(TimestampRead):
    id: UUID
    status: Literal["ready", "published", "superseded"]
    config: IndexConfig
    corpus_fingerprint: str
    catalog_revision: int
    item_count: int
    chunk_count: int
    created_by: int
    created_at: datetime
    published_at: datetime | None


class ActiveIndex(BaseModel):
    generation: int
    catalog_revision: int
    is_current: bool
    active_version: IndexRead | None


class ChunkRead(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    id: UUID
    index_version_id: UUID
    knowledge_id: int
    ordinal: int
    start_offset: int
    end_offset: int
    text: str
    text_sha256: str
    provenance: ChunkProvenance


class PublicationRead(TimestampRead):
    generation: int
    previous_version_id: UUID | None
    version_id: UUID
    actor_id: int
    published_at: datetime