from __future__ import annotations

import enum
from datetime import datetime
from typing import ClassVar, Optional

from sqlalchemy import Column, TIMESTAMP
from sqlalchemy import Enum as SAEnum
from sqlalchemy.sql import func
from sqlmodel import Field, SQLModel

from datatypes.epc.domain.epc import Epc
from domain.modelling.plan import Plan

# Calculator metrics are in kg CO₂/yr; the live ``plan`` columns are tonnes
# (legacy ``emissions_kg / 1000``). Convert on the way in.
_KG_PER_TONNE = 1000.0


class PlanType(enum.Enum):
    SOLAR_ECO4 = "solar_eco4"
    SOLAR_HHRSH_ECO4 = "solar_hhrsh_eco4"
    EMPTY_CAVITY_ECO = "empty_cavity_eco"
    PARTIAL_CAVITY_ECO = "partial_cavity_eco"
    EXTRACTION_ECO = "extraction_eco"


class PlanModel(SQLModel, table=True):
    """The single SQLModel definition of the live ``plan`` table (ADR-0017
    amendment). Full legacy column parity; out-of-cluster references
    (``portfolio_id`` / ``property_id`` / ``scenario_id``) are plain indexed
    ints, not FK constraints (mirror convention — the live FKs are owned by the
    Drizzle schema)."""

    __tablename__: ClassVar[str] = "plan"  # pyright: ignore[reportIncompatibleVariableOverride]

    id: Optional[int] = Field(default=None, primary_key=True)
    name: Optional[str] = Field(default="")
    portfolio_id: int
    property_id: int = Field(index=True)
    scenario_id: Optional[int] = Field(default=None)
    created_at: Optional[datetime] = Field(
        default=None,
        sa_column=Column(TIMESTAMP, nullable=False, server_default=func.now()),
    )
    is_default: bool = False

    valuation_increase_lower_bound: Optional[float] = Field(default=None)
    valuation_increase_upper_bound: Optional[float] = Field(default=None)
    valuation_increase_average: Optional[float] = Field(default=None)

    plan_type: Optional[PlanType] = Field(
        default=None,
        sa_column=Column(
            SAEnum(
                PlanType,
                name="plan_type",
                values_callable=lambda cls: [m.value for m in cls],  # pyright: ignore[reportUnknownLambdaType, reportUnknownMemberType, reportUnknownVariableType]
                create_type=False,
            ),
            nullable=True,
        ),
    )

    post_sap_points: Optional[float] = Field(default=None)
    post_epc_rating: Optional[Epc] = Field(
        default=None,
        sa_column=Column(SAEnum(Epc, name="epc"), nullable=True),
    )
    post_co2_emissions: Optional[float] = Field(default=None)  # tonnes/yr
    co2_savings: Optional[float] = Field(default=None)  # tonnes/yr
    post_energy_bill: Optional[float] = Field(default=None)  # £/yr
    energy_bill_savings: Optional[float] = Field(default=None)  # £/yr
    post_energy_consumption: Optional[float] = Field(default=None)  # kWh/yr
    energy_consumption_savings: Optional[float] = Field(default=None)  # kWh/yr
    valuation_post_retrofit: Optional[float] = Field(default=None)
    valuation_increase: Optional[float] = Field(default=None)
    cost_of_works: Optional[float] = Field(default=None)
    contingency_cost: Optional[float] = Field(default=None)

    @classmethod
    def from_domain(
        cls,
        plan: Plan,
        *,
        property_id: int,
        scenario_id: int,
        portfolio_id: int,
        is_default: bool,
    ) -> "PlanModel":
        return cls(
            portfolio_id=portfolio_id,
            property_id=property_id,
            scenario_id=scenario_id,
            is_default=is_default,
            post_sap_points=plan.post_sap_continuous,
            post_epc_rating=plan.post_epc_rating,
            post_co2_emissions=plan.post_retrofit.co2_kg_per_yr / _KG_PER_TONNE,
            co2_savings=plan.co2_savings_kg_per_yr / _KG_PER_TONNE,
            cost_of_works=plan.cost_of_works,
            contingency_cost=plan.contingency_cost,
            post_energy_bill=plan.post_energy_bill,
            energy_bill_savings=plan.energy_bill_savings,
            post_energy_consumption=plan.post_energy_consumption,
            energy_consumption_savings=plan.energy_consumption_savings,
            # Valuation Uplift £ forms (NULL when no Property Valuation is known;
            # the percentage is not persisted on the live plan columns — ADR-0018).
            valuation_increase_lower_bound=plan.valuation.lower_value,
            valuation_increase_upper_bound=plan.valuation.upper_value,
            valuation_increase_average=plan.valuation.average_value,
            valuation_post_retrofit=plan.valuation.post_retrofit_value,
            valuation_increase=plan.valuation.average_value,
        )