from __future__ import annotations

from datetime import date, datetime
from enum import Enum
from typing import TYPE_CHECKING, List

from sqlalchemy import (
    Date,
    DateTime,
    Enum as SQLEnum,
    ForeignKey,
    Integer,
    Numeric,
    String,
    Text,
)
from sqlalchemy.orm import Mapped, mapped_column, relationship
from sqlalchemy.sql import func

from config.database import Base
from .metadata import ResourceType

if TYPE_CHECKING:  # pragma: no cover
    from .financial_input import FinancialInput
    from .project import Project
    from .simulation_parameter import SimulationParameter


class ScenarioStatus(str, Enum):
    """Lifecycle states for project scenarios."""

    DRAFT = "draft"
    ACTIVE = "active"
    ARCHIVED = "archived"


class Scenario(Base):
    """A specific configuration of assumptions for a project."""

    __tablename__ = "scenarios"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    project_id: Mapped[int] = mapped_column(
        ForeignKey("projects.id", ondelete="CASCADE"), nullable=False, index=True
    )
    name: Mapped[str] = mapped_column(String(255), nullable=False)
    description: Mapped[str | None] = mapped_column(Text, nullable=True)
    status: Mapped[ScenarioStatus] = mapped_column(
        SQLEnum(ScenarioStatus), nullable=False, default=ScenarioStatus.DRAFT
    )
    start_date: Mapped[date | None] = mapped_column(Date, nullable=True)
    end_date: Mapped[date | None] = mapped_column(Date, nullable=True)
    discount_rate: Mapped[float | None] = mapped_column(Numeric(5, 2), nullable=True)
    currency: Mapped[str | None] = mapped_column(String(3), nullable=True)
    primary_resource: Mapped[ResourceType | None] = mapped_column(
        SQLEnum(ResourceType), nullable=True
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now()
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now()
    )

    project: Mapped["Project"] = relationship("Project", back_populates="scenarios")
    financial_inputs: Mapped[List["FinancialInput"]] = relationship(
        "FinancialInput",
        back_populates="scenario",
        cascade="all, delete-orphan",
        passive_deletes=True,
    )
    simulation_parameters: Mapped[List["SimulationParameter"]] = relationship(
        "SimulationParameter",
        back_populates="scenario",
        cascade="all, delete-orphan",
        passive_deletes=True,
    )

    def __repr__(self) -> str:  # pragma: no cover
        return f"Scenario(id={self.id!r}, name={self.name!r}, project_id={self.project_id!r})"