from __future__ import annotations

from datetime import date
from enum import Enum
from typing import Literal
from pydantic import BaseModel, Field


class InstallmentType(str, Enum):
    equal = "equal"
    decreasing = "decreasing"


class OverpaymentEffect(str, Enum):
    shorten = "shorten"
    lower_payment = "lower_payment"


class GraceType(str, Enum):
    none = "none"
    interest_only = "interest_only"
    full = "full"


class RateChange(BaseModel):
    month: int = Field(ge=1, description="Miesiac od startu kredytu")
    annual_rate: float = Field(ge=0, le=30, description="Roczne oprocentowanie procentowo")


class Overpayment(BaseModel):
    month: int = Field(ge=1)
    amount: float = Field(gt=0)
    repeat: Literal["once", "monthly", "yearly"] = "once"
    until_month: int | None = Field(default=None, ge=1)
    commission_percent: float = Field(default=0, ge=0, le=20, description="Prowizja od nadplaty w procentach")
    commission_until_month: int | None = Field(default=None, ge=1, description="Ostatni miesiac naliczania prowizji od nadplaty")


class HistoricalMonth(BaseModel):
    month: int = Field(ge=1)
    annual_rate: float | None = Field(default=None, ge=0, le=30)
    grace_type: GraceType = GraceType.none
    overpayment: float = Field(default=0, ge=0)
    overpayment_commission_percent: float = Field(default=0, ge=0, le=20)
    note: str = ""


class SimulationRequest(BaseModel):
    principal: float = Field(gt=0)
    years: int = Field(default=25, ge=1, le=50)
    term_months: int | None = Field(default=None, ge=1, le=600, description="Okres kredytu w miesiacach")
    margin: float = Field(ge=0, le=20, default=2.0)
    base_rate: float = Field(ge=0, le=30, default=5.75)
    installment_type: InstallmentType = InstallmentType.equal
    overpayment_effect: OverpaymentEffect = OverpaymentEffect.shorten
    loan_start_date: date = Field(default_factory=date.today)
    due_day: int = Field(default=5, ge=1, le=28, description="Dzien splaty raty")
    move_due_date_to_business_day: bool = True
    overpayment_protection_months: int | None = Field(default=None, ge=1, description="Okres ochronny prowizji od nadplat w miesiacach")
    overpayment_protection_commission_percent: float = Field(default=0, ge=0, le=20, description="Domyslna prowizja od nadplat w okresie ochronnym")
    rate_changes: list[RateChange] = Field(default_factory=list)
    overpayments: list[Overpayment] = Field(default_factory=list)
    historical_months: list[HistoricalMonth] = Field(default_factory=list)


class ScheduleRow(BaseModel):
    month: int
    due_date: str
    days: int
    rate: float
    payment: float
    principal_part: float
    interest_part: float
    overpayment: float
    overpayment_fee: float
    remaining: float
    grace_type: GraceType = GraceType.none
    cumulative_interest: float
    cumulative_cost: float
    cumulative_overpayment: float


class Summary(BaseModel):
    months: int
    total_paid: float
    total_interest: float
    total_overpayment: float
    total_overpayment_fees: float
    interest_saved: float
    months_saved: int
    baseline_interest: float
    baseline_months: int
    average_payment: float
    max_payment: float
    payoff_date: str | None = None


class SimulationResponse(BaseModel):
    schedule: list[ScheduleRow]
    summary: Summary