from typing import List

from src.domain.entities.legal_charges import LegalChargesRule
from src.domain.interfaces.legal_charges_repository import LegalChargesRepositoryInterface
from src.core.exceptions import ValidationError

_VALID_CONDITIONS = {"loan_amount_less_than", "loan_amount_more_than"}


class SaveLegalChargesUseCase:
    """Upsert legal-charges rules for a set of merchant categories.

    Rules:
    - At least one rule must be provided.
    - condition must be one of the two allowed values.
    - net_loan_amount and legal_charges must both be non-negative integers.
    - Duplicate category_ids in the same request are rejected.
    """

    def __init__(self, repo: LegalChargesRepositoryInterface) -> None:
        self.repo = repo

    def execute(
        self,
        rules: List[LegalChargesRule],
        user_id: int,
    ) -> List[LegalChargesRule]:
        if not rules:
            raise ValidationError("At least one rule must be provided.")

        seen_categories: set = set()
        for rule in rules:
            if rule.condition not in _VALID_CONDITIONS:
                raise ValidationError(
                    f"Invalid condition '{rule.condition}' for category_id={rule.category_id}. "
                    f"Must be one of: {sorted(_VALID_CONDITIONS)}."
                )
            if rule.net_loan_amount < 0:
                raise ValidationError(
                    f"net_loan_amount for category_id={rule.category_id} must be non-negative."
                )
            if rule.legal_charges < 0:
                raise ValidationError(
                    f"legal_charges for category_id={rule.category_id} must be non-negative."
                )
            if rule.category_id in seen_categories:
                raise ValidationError(
                    f"Duplicate category_id={rule.category_id} in request."
                )
            seen_categories.add(rule.category_id)

        return self.repo.upsert_all(rules=rules, user_id=user_id)