from decimal import Decimal

from app.domain.enums import Classification, Eligibility
from app.domain.models import ScoringModel
from app.scoring.mathutil import clamp


def classify_deal_score(score: Decimal, model: ScoringModel) -> str:
    for bound in model.classification_upper_bounds:
        if bound.inclusive and score <= bound.upper:
            return bound.label
        if not bound.inclusive and score < bound.upper:
            return bound.label
    return Classification.EXCEPTIONAL.value


def score_deal(product_score: Decimal, price_score: Decimal, model: ScoringModel) -> Decimal:
    return clamp(model.product_weight * product_score + model.price_weight * price_score)


def eligibility_from_parts(product: Eligibility, offer: Eligibility) -> Eligibility:
    if Eligibility.INELIGIBLE in {product, offer}:
        return Eligibility.INELIGIBLE
    if Eligibility.UNKNOWN in {product, offer}:
        return Eligibility.UNKNOWN
    return Eligibility.ELIGIBLE


def derive_eligible(overall: Eligibility) -> bool | None:
    if overall == Eligibility.ELIGIBLE:
        return True
    if overall == Eligibility.INELIGIBLE:
        return False
    return None


def classification_for(overall: Eligibility, deal_score: Decimal | None, model: ScoringModel) -> str:
    if overall == Eligibility.INELIGIBLE:
        return Classification.INELIGIBLE.value
    if overall == Eligibility.UNKNOWN or deal_score is None:
        return Classification.INSUFFICIENT_DATA.value
    return classify_deal_score(deal_score, model)