"""前端和 AI 共用的只读查询协议；不接受 SQL、表名或任意表达式。"""
from typing import Literal
from pydantic import BaseModel, ConfigDict, Field, model_validator


class QueryFilter(BaseModel):
    model_config = ConfigDict(extra="forbid", allow_inf_nan=False)
    field: str = Field(min_length=1, max_length=40)
    op: Literal["eq", "contains", "gt", "ge", "lt", "le", "is_null", "not_null"] = "eq"
    value: str | int | float | None = None


class DataQuery(BaseModel):
    model_config = ConfigDict(extra="forbid", allow_inf_nan=False)
    module: Literal["students", "classes", "teachers", "advisors", "scores", "employment", "teacher_classes", "teacher_students"]
    filters: list[QueryFilter] = Field(default_factory=list, max_length=12)
    group_by: list[str] = Field(default_factory=list, max_length=3)
    aggregate: Literal["count", "avg", "sum", "min", "max"] | None = None
    aggregate_field: str | None = None
    having_min: float | None = None
    sort_by: str | None = None
    descending: bool = False
    page: int = Field(default=1, ge=1, le=100000)
    page_size: int = Field(default=10, ge=1, le=100)

    @model_validator(mode="after")
    def valid_aggregate(self):
        if not self.aggregate and (self.group_by or self.aggregate_field or self.having_min is not None):
            raise ValueError("分组、聚合字段和聚合筛选需要指定 aggregate")
        if self.aggregate and self.aggregate != "count" and not self.aggregate_field:
            raise ValueError("请指定需要统计的数值字段")
        if self.aggregate == "count" and self.aggregate_field:
            raise ValueError("count 统计记录数，无需 aggregate_field")
        return self