from pydantic import BaseModel, ConfigDict, Field, field_validator

ALLOWED_KNOWLEDGE_COLLECTIONS = frozenset({
    "fin_faq_collection",
    "fin_product_collection",
    "fin_policy_collection",
})


class KnowledgeQuery(BaseModel):
    model_config = ConfigDict(extra="forbid", frozen=True)

    query: str = Field(min_length=1, max_length=2000)
    intents: tuple[str, ...] = Field(min_length=1, max_length=4)
    top_k: int = Field(default=5, ge=1, le=20)

    @field_validator("query")
    @classmethod
    def query_must_not_be_blank(cls, value: str) -> str:
        if not value.strip():
            raise ValueError("query must not be blank")
        return value


class KnowledgeHit(BaseModel):
    model_config = ConfigDict(extra="forbid", frozen=True)

    knowledge_id: str
    collection: str
    snippet: str
    title: str | None = None
    answer: str | None = None
    score: float | None = Field(default=None, ge=0, le=1)
    version: str | None = None


class KnowledgeSearchResult(BaseModel):
    model_config = ConfigDict(extra="forbid", frozen=True)

    hits: tuple[KnowledgeHit, ...] = ()
    degraded: bool = False
    degradation_reason: str | None = None
    searched_collections: tuple[str, ...] = ()