"""Behaviour of the Postgres-backed PlanRepository: persisting a Plan and its
Plan Measures to the live ``plan`` / ``recommendation`` tables (ADR-0017).

The Plan is the parent; each selected Plan Measure is a ``recommendation`` row
linked by the new ``plan_id`` FK. A re-run INSERTs a fresh Plan and keeps the
prior one as history (no cascade delete); when the new Plan is the default it
demotes prior default Plans for the (property, scenario) to ``is_default=False``
(ADR-0012). CO₂ is stored in tonnes (calculator kg ÷ 1000) to match the live
column contract.
"""

from __future__ import annotations

from sqlalchemy import Engine
from sqlmodel import Session, col, select

from datatypes.epc.domain.epc import Epc
from domain.modelling.measure_type import MeasureType
from domain.modelling.scoring.package_scorer import Score
from domain.modelling.plan import Plan, PlanMeasure
from domain.modelling.recommendation import Cost
from domain.modelling.scoring.scoring import MeasureImpact
from infrastructure.postgres.modelling import PlanModel, RecommendationModel
from repositories.plan.plan_postgres_repository import PlanPostgresRepository


def _plan() -> Plan:
    measures: tuple[PlanMeasure, ...] = (
        PlanMeasure(
            measure_type=MeasureType.CAVITY_WALL_INSULATION,
            description="Cavity wall insulation",
            cost=Cost(total=1000.0, contingency_rate=0.10),
            impact=MeasureImpact(
                sap_points=8.0,
                co2_savings_kg_per_yr=500.0,
                energy_savings_kwh_per_yr=2000.0,
            ),
            kwh_savings=1500.0,
            energy_cost_savings=300.0,
        ),
    )
    return Plan(
        measures=measures,
        baseline=Score(
            sap_continuous=40.0,
            co2_kg_per_yr=4000.0,
            primary_energy_kwh_per_yr=20000.0,
        ),
        post_retrofit=Score(
            sap_continuous=70.0,
            co2_kg_per_yr=3500.0,
            primary_energy_kwh_per_yr=18000.0,
        ),
    )


def test_save_persists_plan_and_its_measures_with_tonnes_and_band(
    db_engine: Engine,
) -> None:
    # Act
    with Session(db_engine) as session:
        plan_id: int = PlanPostgresRepository(session).save(
            _plan(), property_id=10, scenario_id=7, portfolio_id=1, is_default=True
        )
        session.commit()

    # Assert
    with Session(db_engine) as session:
        plan_row = session.get(PlanModel, plan_id)
        rec_rows = session.exec(
            select(RecommendationModel).where(
                col(RecommendationModel.plan_id) == plan_id
            )
        ).all()

    assert plan_row is not None
    assert plan_row.property_id == 10
    assert plan_row.scenario_id == 7
    assert plan_row.portfolio_id == 1
    assert plan_row.is_default is True
    assert plan_row.post_sap_points is not None
    assert plan_row.post_co2_emissions is not None
    assert plan_row.co2_savings is not None
    assert plan_row.cost_of_works is not None
    assert plan_row.contingency_cost is not None
    assert abs(plan_row.post_sap_points - 70.0) <= 1e-9
    assert plan_row.post_epc_rating is Epc.C  # SAP 70 → band C
    assert abs(plan_row.post_co2_emissions - 3.5) <= 1e-9  # tonnes
    assert abs(plan_row.co2_savings - 0.5) <= 1e-9  # (4000-3500)/1000
    assert abs(plan_row.cost_of_works - 1000.0) <= 1e-9
    assert abs(plan_row.contingency_cost - 100.0) <= 1e-9  # 1000 * 0.10

    assert len(rec_rows) == 1
    rec = rec_rows[0]
    assert rec.estimated_cost is not None
    assert rec.sap_points is not None
    assert rec.co2_equivalent_savings is not None
    assert rec.type == "cavity_wall_insulation"
    assert rec.measure_type == "cavity_wall_insulation"
    assert rec.description == "Cavity wall insulation"
    assert abs(rec.estimated_cost - 1000.0) <= 1e-9
    assert abs(rec.sap_points - 8.0) <= 1e-9
    assert abs(rec.co2_equivalent_savings - 0.5) <= 1e-9  # tonnes
    assert rec.kwh_savings is not None
    assert rec.energy_cost_savings is not None
    assert abs(rec.kwh_savings - 1500.0) <= 1e-9  # delivered kWh saved/yr
    assert abs(rec.energy_cost_savings - 300.0) <= 1e-9  # £/yr saved
    assert rec.default is True
    assert rec.already_installed is False


def test_save_persists_null_per_measure_savings_when_unbilled(
    db_engine: Engine,
) -> None:
    # Arrange — a Plan Measure whose per-measure bills were never derived.
    measure = PlanMeasure(
        measure_type=MeasureType.LOFT_INSULATION,
        description="Loft insulation",
        cost=Cost(total=500.0, contingency_rate=0.20),
        impact=MeasureImpact(
            sap_points=3.0, co2_savings_kg_per_yr=200.0, energy_savings_kwh_per_yr=800.0
        ),
    )
    plan = Plan(
        measures=(measure,),
        baseline=Score(
            sap_continuous=40.0, co2_kg_per_yr=4000.0, primary_energy_kwh_per_yr=20000.0
        ),
        post_retrofit=Score(
            sap_continuous=45.0, co2_kg_per_yr=3800.0, primary_energy_kwh_per_yr=19000.0
        ),
    )

    # Act
    with Session(db_engine) as session:
        plan_id: int = PlanPostgresRepository(session).save(
            plan, property_id=11, scenario_id=7, portfolio_id=1, is_default=True
        )
        session.commit()

    # Assert — the savings columns persist as NULL (ADR-0014 amendment)
    with Session(db_engine) as session:
        rec_rows = session.exec(
            select(RecommendationModel).where(col(RecommendationModel.plan_id) == plan_id)
        ).all()
    assert len(rec_rows) == 1
    assert rec_rows[0].kwh_savings is None
    assert rec_rows[0].energy_cost_savings is None


def test_rerun_keeps_history_and_demotes_the_prior_default_plan(
    db_engine: Engine,
) -> None:
    # Arrange — first (default) run
    with Session(db_engine) as session:
        first_id = PlanPostgresRepository(session).save(
            _plan(), property_id=10, scenario_id=7, portfolio_id=1, is_default=True
        )
        session.commit()

    # Act — re-run the same (property, scenario) as the default
    with Session(db_engine) as session:
        second_id = PlanPostgresRepository(session).save(
            _plan(), property_id=10, scenario_id=7, portfolio_id=1, is_default=True
        )
        session.commit()

    # Assert — the prior Plan is kept as history (no delete), and only the new
    # Plan is the default; exactly one Plan for the pair stays is_default=True.
    with Session(db_engine) as session:
        plan_rows = session.exec(
            select(PlanModel).where(col(PlanModel.property_id) == 10)
        ).all()
        by_id = {p.id: p for p in plan_rows}

    assert len(plan_rows) == 2
    assert first_id != second_id
    assert by_id[first_id].is_default is False  # demoted
    assert by_id[second_id].is_default is True  # the current default
    assert sum(1 for p in plan_rows if p.is_default) == 1


def test_rerun_as_non_default_does_not_demote_the_prior_default(
    db_engine: Engine,
) -> None:
    # Arrange — a default Plan exists
    with Session(db_engine) as session:
        first_id = PlanPostgresRepository(session).save(
            _plan(), property_id=12, scenario_id=7, portfolio_id=1, is_default=True
        )
        session.commit()

    # Act — re-run as NON-default (e.g. a non-default scenario); no demotion runs
    with Session(db_engine) as session:
        PlanPostgresRepository(session).save(
            _plan(), property_id=12, scenario_id=7, portfolio_id=1, is_default=False
        )
        session.commit()

    # Assert — the prior default is untouched (we only demote when saving a default)
    with Session(db_engine) as session:
        plan_rows = session.exec(
            select(PlanModel).where(col(PlanModel.property_id) == 12)
        ).all()
        by_id = {p.id: p for p in plan_rows}

    assert len(plan_rows) == 2
    assert by_id[first_id].is_default is True