from datetime import date, datetime
from decimal import Decimal

from pydantic import BaseModel, ConfigDict, Field, model_validator

from app.models.expense import ExpenseCategory, ServiceType


class FuelEntryBase(BaseModel):
    entry_date: date
    odometer: int
    liters: Decimal
    price_per_liter: Decimal
    total_cost: Decimal | None = None
    station: str | None = None
    fuel_brand: str | None = None
    is_full_tank: bool = True
    notes: str | None = None

    @model_validator(mode="after")
    def fill_total_cost(self) -> "FuelEntryBase":
        if self.total_cost is None:
            self.total_cost = self.liters * self.price_per_liter
        return self


class FuelEntryCreate(FuelEntryBase):
    car_id: int


class FuelEntryUpdate(BaseModel):
    entry_date: date | None = None
    odometer: int | None = None
    liters: Decimal | None = None
    price_per_liter: Decimal | None = None
    total_cost: Decimal | None = None
    station: str | None = None
    fuel_brand: str | None = None
    is_full_tank: bool | None = None
    notes: str | None = None


class FuelEntryRead(FuelEntryBase):
    id: int
    car_id: int
    total_cost: Decimal
    created_at: datetime

    model_config = ConfigDict(from_attributes=True)


class ServiceEntryBase(BaseModel):
    entry_date: date
    odometer: int | None = None
    service_type: ServiceType
    title: str
    category: str | None = None
    vendor: str | None = None
    total_cost: Decimal
    next_due_date: date | None = None
    next_due_odometer: int | None = None
    notes: str | None = None


class ServiceEntryCreate(ServiceEntryBase):
    car_id: int


class ServiceEntryUpdate(BaseModel):
    entry_date: date | None = None
    odometer: int | None = None
    service_type: ServiceType | None = None
    title: str | None = None
    category: str | None = None
    vendor: str | None = None
    total_cost: Decimal | None = None
    next_due_date: date | None = None
    next_due_odometer: int | None = None
    notes: str | None = None


class ServiceEntryRead(ServiceEntryBase):
    id: int
    car_id: int
    created_at: datetime

    model_config = ConfigDict(from_attributes=True)


class ExpenseEntryBase(BaseModel):
    entry_date: date
    category: ExpenseCategory
    title: str
    vendor: str | None = None
    total_cost: Decimal
    currency: str = "RUB"
    odometer: int | None = None
    period_start: date | None = None
    period_end: date | None = None
    period_months: int | None = None
    is_recurring: bool = False
    notes: str | None = None

    @model_validator(mode="after")
    def validate_period(self) -> "ExpenseEntryBase":
        if self.period_months is not None and self.period_months < 1:
            raise ValueError("period_months must be positive")
        if self.period_start and self.period_end and self.period_end < self.period_start:
            raise ValueError("period_end must be after period_start")
        return self


class ExpenseEntryCreate(ExpenseEntryBase):
    car_id: int


class ExpenseEntryUpdate(BaseModel):
    entry_date: date | None = None
    category: ExpenseCategory | None = None
    title: str | None = None
    vendor: str | None = None
    total_cost: Decimal | None = None
    currency: str | None = None
    odometer: int | None = None
    period_start: date | None = None
    period_end: date | None = None
    period_months: int | None = None
    is_recurring: bool | None = None
    notes: str | None = None


class ExpenseEntryRead(ExpenseEntryBase):
    id: int
    car_id: int
    created_at: datetime

    model_config = ConfigDict(from_attributes=True)


class OwnershipCategoryBreakdown(BaseModel):
    category: str
    total_cost: Decimal
    entries_count: int


class OwnershipStats(BaseModel):
    car_id: int
    date_from: date
    date_to: date
    fuel_cost: Decimal
    service_cost: Decimal
    total_cost: Decimal
    expenses_cost: Decimal = Decimal("0")
    recurring_costs: Decimal = Decimal("0")
    one_time_costs: Decimal = Decimal("0")
    forecast_next_month: Decimal = Decimal("0")
    depreciation_cost: Decimal = Decimal("0")
    cost_per_month: Decimal = Decimal("0")
    cost_by_category: dict[str, Decimal] = Field(default_factory=dict)
    categories: list[OwnershipCategoryBreakdown] = Field(default_factory=list)
    liters: Decimal
    distance_km: int
    avg_consumption_l_per_100km: float | None
    cost_per_km: float | None
    fuel_entries_count: int
    service_entries_count: int


class OdometerPrediction(BaseModel):
    car_id: int
    samples: int
    current_odometer: int | None
    predicted_today: int | None
    predicted_30_days: int | None
    avg_km_per_day: float | None
    avg_km_per_month: float | None
    current_price_per_liter: float | None = None
    predicted_price_per_liter_30_days: float | None = None
    avg_price_per_liter: float | None = None
    price_samples: int = 0
    price_confidence: float = 0
    confidence: float
    insight: str