from __future__ import annotations

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 domain.modelling.measure_type import MeasureType
from domain.modelling.portfolio_goal import PortfolioGoal
from domain.modelling.scenario import Scenario


def _parse_exclusions(raw: Optional[str]) -> frozenset[MeasureType]:
    """Parse the live ``scenario.exclusions`` column — a Postgres text-array
    literal like ``{solar_pv,internal_wall_insulation}`` — into the excluded
    MeasureTypes. Each token must be an exact MeasureType value (no high-level
    category expansion); an unknown token is a data error and raises, matching
    the repo's strict-enum convention."""
    if not raw:
        return frozenset()
    inner = raw.strip()
    if inner.startswith("{") and inner.endswith("}"):
        inner = inner[1:-1]
    tokens = [token.strip().strip('"') for token in inner.split(",") if token.strip()]
    excluded: set[MeasureType] = set()
    for token in tokens:
        try:
            excluded.add(MeasureType(token))
        except ValueError as error:
            raise ValueError(
                f"scenario excludes unknown measure type {token!r}; the "
                f"exclusions column must hold exact MeasureType values"
            ) from error
    return frozenset(excluded)


class ScenarioModel(SQLModel, table=True):
    """The single SQLModel definition of the live ``scenario`` table (ADR-0017
    amendment). Full legacy column parity; ``goal`` is the ``PortfolioGoal``
    enum (legacy planning branches on it, so it must stay an enum — the stored
    string is the enum *value*, e.g. ``"Increasing EPC"``).

    Only ``goal`` / ``goal_value`` are required; everything else is nullable
    (mirror convention — the live NOT-NULLs are owned by the Drizzle schema),
    so the Modelling stage can construct the thin slice it uses while the legacy
    writers still supply the full row.
    """

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

    id: Optional[int] = Field(default=None, primary_key=True)
    name: Optional[str] = Field(default=None)
    created_at: Optional[datetime] = Field(
        default=None,
        sa_column=Column(TIMESTAMP, nullable=False, server_default=func.now()),
    )
    budget: Optional[float] = Field(default=None)
    portfolio_id: Optional[int] = Field(default=None)
    housing_type: Optional[str] = Field(default=None)
    goal: PortfolioGoal = Field(
        sa_column=Column(
            SAEnum(
                PortfolioGoal,
                values_callable=lambda cls: [m.value for m in cls],  # pyright: ignore[reportUnknownLambdaType, reportUnknownMemberType, reportUnknownVariableType]
                name="goal",
            ),
            nullable=False,
        )
    )
    goal_value: str
    trigger_file_path: Optional[str] = Field(default=None)
    already_installed_file_path: Optional[str] = Field(default=None)
    patches_file_path: Optional[str] = Field(default=None)
    non_invasive_recommendations_file_path: Optional[str] = Field(default=None)
    exclusions: Optional[str] = Field(default=None)
    multi_plan: bool = False
    is_default: bool = False

    # Portfolio-level aggregates stored against the Scenario.
    cost: Optional[float] = Field(default=None)
    contingency: Optional[float] = Field(default=None)
    funding: Optional[float] = Field(default=None)
    total_work_hours: Optional[float] = Field(default=None)
    energy_savings: Optional[float] = Field(default=None)
    co2_equivalent_savings: Optional[float] = Field(default=None)
    energy_cost_savings: Optional[float] = Field(default=None)
    epc_breakdown_pre_retrofit: Optional[str] = Field(default=None)
    epc_breakdown_post_retrofit: Optional[str] = Field(default=None)
    number_of_properties: Optional[int] = Field(default=None)
    n_units_to_retrofit: Optional[int] = Field(default=None)
    co2_per_unit_pre_retrofit: Optional[str] = Field(default=None)
    co2_per_unit_post_retrofit: Optional[str] = Field(default=None)
    energy_bill_per_unit_pre_retrofit: Optional[str] = Field(default=None)
    energy_bill_per_unit_post_retrofit: Optional[str] = Field(default=None)
    energy_consumption_per_unit_pre_retrofit: Optional[str] = Field(default=None)
    energy_consumption_per_unit_post_retrofit: Optional[str] = Field(default=None)
    valuation_improvement_per_unit: Optional[str] = Field(default=None)
    cost_per_unit: Optional[str] = Field(default=None)
    cost_per_co2_saved: Optional[str] = Field(default=None)
    cost_per_sap_point: Optional[str] = Field(default=None)
    valuation_return_on_investment: Optional[str] = Field(default=None)
    property_valuation_increase: Optional[float] = Field(default=None)
    labour_days: Optional[float] = Field(default=None)

    def to_domain(self) -> Scenario:
        if self.id is None:
            raise ValueError("scenario row has no id")
        return Scenario(
            id=self.id,
            goal=self.goal.value,
            goal_value=self.goal_value,
            budget=self.budget,
            is_default=self.is_default,
            exclusions=_parse_exclusions(self.exclusions),
        )