"""解析已登记的月度指导成本，不按名称或单位猜测。"""

from datetime import date
from decimal import Decimal, InvalidOperation

from sqlalchemy import func, select

from app.core.exceptions import BadRequestError
from app.models import PayrollInput, TPlusFact


def latest_guidance_facts(session, source):
    """只读取指定账套每个指导成本事实键的最新版本。"""
    ids = select(func.max(TPlusFact.id)).where(
        TPlusFact.source_database == source, TPlusFact.kind == "GUIDANCE"
    ).group_by(TPlusFact.fact_key)
    return {(fact.kind, fact.fact_key): fact for fact in session.scalars(select(TPlusFact).where(TPlusFact.id.in_(ids)))}


def resolve_guidance(facts, product_id, line_id, month, unit):
    """返回匹配状态和已封存事实；存在多条候选时不选择其中一条。"""
    candidates = [
        fact.data_json for (kind, _), fact in facts.items()
        if kind == "GUIDANCE"
        and fact.data_json.get("product_id") == product_id
        and fact.data_json.get("month") == month
        and (fact.data_json.get("basis") == "UNIT" or fact.data_json.get("shipment_line_id") == line_id)
    ]
    if not candidates:
        return "MISSING", None
    if len(candidates) != 1:
        return "AMBIGUOUS", None
    guidance = candidates[0]
    if guidance.get("unit") != unit:
        return "UNIT_MISMATCH", None
    if not guidance.get("is_finalized"):
        return "UNFINALIZED", None
    return "FINALIZED", guidance


def check_unit_guidance_conflicts(facts, product_id, month, unit, amount, frozen_shipments):
    """新增产品月度单价前检查重叠事实和全部相关的历史封存明细。"""
    if any(
        kind == "GUIDANCE" and fact.data_json.get("product_id") == product_id
        and fact.data_json.get("month") == month
        for (kind, _), fact in facts.items()
    ):
        raise BadRequestError("指导成本存在重叠记录，请先核对")

    try:
        expected = Decimal(str(amount))
        if not expected.is_finite() or expected < 0:
            raise ValueError
        for shipment in frozen_shipments:
            old = Decimal(str(shipment.get("unit_cost")))
            if not old.is_finite() or old < 0 or old != expected or shipment.get("unit") != unit:
                raise ValueError
    except (InvalidOperation, TypeError, ValueError):
        raise BadRequestError("已封存发货的成本或单位与指导价不一致，请先核对") from None


def frozen_guidance_shipments(session, source, product_id, month):
    """按不可变快照中的来源产品读取历史，不能依赖当前正式明细。"""
    query = (
        select(PayrollInput.data_json)
        .where(PayrollInput.source_database == source)
        .order_by(PayrollInput.id)
        .execution_options(yield_per=100)
    )
    for data in session.scalars(query):
        shipments = data.get("shipments") if isinstance(data, dict) else None
        if not isinstance(shipments, list):
            raise BadRequestError("已封存发货数据异常，请先核对")
        for shipment in shipments:
            if not isinstance(shipment, dict) or not shipment.get("line_id"):
                raise BadRequestError("已封存发货数据异常，请先核对")
            try:
                ship_date = date.fromisoformat(shipment["date"])
            except (KeyError, TypeError, ValueError):
                raise BadRequestError("已封存发货日期异常，请先核对") from None
            if ship_date.strftime("%Y-%m") != month:
                continue
            frozen_product = shipment.get("product_id")
            if frozen_product is None or str(frozen_product).strip() in ("", "None"):
                raise BadRequestError("已封存发货缺少来源产品身份，请先核对")
            if str(frozen_product) == str(product_id):
                yield shipment