from copy import deepcopy

from cashflow_model import FinancialModel, ForecastScenario
from engine.forecast import ForecastService


class ScenarioError(Exception):
    pass


DEFAULT_SCENARIOS = {
    "baseline": ForecastScenario(
        name="baseline",
        income_multiplier=1.0,
        expense_multiplier=1.0,
        growth_multiplier=1.0,
        description="Базовый сценарий без изменений",
    ),
    "optimistic": ForecastScenario(
        name="optimistic",
        income_multiplier=1.15,
        expense_multiplier=0.95,
        growth_multiplier=1.2,
        description="Оптимистичный: доход +15%, расход -5%, рост активов +20%",
    ),
    "pessimistic": ForecastScenario(
        name="pessimistic",
        income_multiplier=0.85,
        expense_multiplier=1.1,
        growth_multiplier=0.8,
        description="Пессимистичный: доход -15%, расход +10%, рост активов -20%",
    ),
}


class ScenarioService:
    def __init__(self, model: FinancialModel):
        self.model = deepcopy(model)

    def apply(self, scenario: ForecastScenario, months: int = 12) -> dict:
        model = deepcopy(self.model)

        for t in model.transactions:
            if t.amount > 0:
                t.amount *= scenario.income_multiplier
            else:
                t.amount *= scenario.expense_multiplier

        for r in model.recurring:
            if r.category == "income":
                r.amount *= scenario.income_multiplier
            else:
                r.amount *= scenario.expense_multiplier

        for a in model.assets:
            a.growth_rate *= scenario.growth_multiplier

        service = ForecastService(model)
        result = service.summary(months)
        result["scenario"] = scenario.name
        result["scenario_description"] = scenario.description
        return result

    def compare(self, months: int = 12) -> dict:
        results = {}
        for name, scenario in DEFAULT_SCENARIOS.items():
            results[name] = self.apply(scenario, months)
        return results

    def what_if(
        self,
        income_mult: float = 1.0,
        expense_mult: float = 1.0,
        growth_mult: float = 1.0,
        months: int = 12,
    ) -> dict:
        scenario = ForecastScenario(
            name="what-if",
            income_multiplier=income_mult,
            expense_multiplier=expense_mult,
            growth_multiplier=growth_mult,
            description=(
                f"What-if: income x{income_mult}, "
                f"expense x{expense_mult}, growth x{growth_mult}"
            ),
        )
        return self.apply(scenario, months)