"""Batch EPC write path — save_batch() correctness and safety tests.

Guards the four user stories from #1348:
  1. FK mis-wiring regression: building-part IDs must not be crossed between
     properties in the same save_batch() call.
  2. save()/save_batch() parity: the single-property delegation path is loss-free.
  3. Batch idempotency: a second save_batch() with the same requests replaces,
     not duplicates.
  4. Source isolation: lodged and predicted slots coexist after separate
     save_batch() calls on the same property IDs.
"""

from __future__ import annotations

import json
from dataclasses import replace
from pathlib import Path
from typing import Any

from sqlalchemy import Engine
from sqlmodel import Session

from datatypes.epc.domain.epc_property_data import EpcPropertyData
from datatypes.epc.domain.mapper import EpcPropertyDataMapper
from repositories.epc.epc_postgres_repository import EpcPostgresRepository, EpcSaveRequest

_JSON_SAMPLES = Path(__file__).resolve().parents[3] / "backend/epc_api/json_samples"


def _load_epc(schema_dir: str = "RdSAP-Schema-21.0.0") -> EpcPropertyData:
    raw: dict[str, Any] = json.loads(
        (_JSON_SAMPLES / schema_dir / "epc.json").read_text()
    )
    return EpcPropertyDataMapper.from_api_response(raw)


def _with_floor_areas(epc: EpcPropertyData, areas_m2: list[float]) -> EpcPropertyData:
    """Replace the building parts with variants that have a single floor dimension
    carrying the given total_floor_area_m2 — making them easy to distinguish after
    a round-trip without changing anything else about the EPC."""
    template_bp = epc.sap_building_parts[0]
    template_dim = template_bp.sap_floor_dimensions[0]
    new_parts = [
        replace(template_bp, sap_floor_dimensions=[replace(template_dim, total_floor_area_m2=a)])
        for a in areas_m2
    ]
    return replace(epc, sap_building_parts=new_parts)


# ---------------------------------------------------------------------------
# Tracer bullet: single-request save_batch() is loss-free vs save()
# ---------------------------------------------------------------------------

def test_single_request_save_batch_matches_save(db_engine: Engine) -> None:
    # Arrange
    epc = _load_epc()

    with Session(db_engine) as session:
        repo = EpcPostgresRepository(session)
        epc_id_via_save = repo.save(epc, property_id=1001)
        epc_id_via_batch = repo.save_batch([EpcSaveRequest(epc, property_id=1002)])[0]
        session.commit()

    # Act
    with Session(db_engine) as session:
        repo = EpcPostgresRepository(session)
        via_save = repo.get(epc_id_via_save)
        via_batch = repo.get(epc_id_via_batch)

    # Assert — both paths reconstruct the original exactly.
    assert via_save == epc
    assert via_batch == epc


# ---------------------------------------------------------------------------
# FK mis-wiring regression: building-part IDs must not be crossed
# ---------------------------------------------------------------------------

def test_multi_property_building_part_ids_are_not_crossed(db_engine: Engine) -> None:
    # Arrange — property A has 2 parts with distinctive areas; B has 1 with a
    # third distinctive area. If part IDs are mis-wired the floor-dimension FK
    # rows end up under the wrong property.
    base = _load_epc()
    epc_a = _with_floor_areas(base, [10.0, 20.0])
    epc_b = _with_floor_areas(base, [99.0])

    with Session(db_engine) as session:
        repo = EpcPostgresRepository(session)
        repo.save_batch([
            EpcSaveRequest(epc_a, property_id=2001),
            EpcSaveRequest(epc_b, property_id=2002),
        ])
        session.commit()

    # Act
    with Session(db_engine) as session:
        repo = EpcPostgresRepository(session)
        reloaded_a = repo.get_for_property(2001)
        reloaded_b = repo.get_for_property(2002)

    # Assert — each property's building parts carry its own floor areas.
    assert reloaded_a is not None
    assert reloaded_b is not None
    areas_a = sorted(
        dim.total_floor_area_m2
        for part in reloaded_a.sap_building_parts
        for dim in part.sap_floor_dimensions
    )
    areas_b = sorted(
        dim.total_floor_area_m2
        for part in reloaded_b.sap_building_parts
        for dim in part.sap_floor_dimensions
    )
    assert areas_a == [10.0, 20.0]
    assert areas_b == [99.0]


# ---------------------------------------------------------------------------
# Idempotency: second save_batch() replaces, not duplicates
# ---------------------------------------------------------------------------

def test_save_batch_is_idempotent(db_engine: Engine) -> None:
    # Arrange
    epc = _load_epc()
    requests = [EpcSaveRequest(epc, property_id=3001)]

    with Session(db_engine) as session:
        EpcPostgresRepository(session).save_batch(requests)
        session.commit()

    # Act — re-save the same batch.
    with Session(db_engine) as session:
        EpcPostgresRepository(session).save_batch(requests)
        session.commit()

    # Assert — exactly one EPC survives (no duplicate rows).
    with Session(db_engine) as session:
        result = EpcPostgresRepository(session).get_for_property(3001)

    assert result == epc


# ---------------------------------------------------------------------------
# Source isolation: lodged and predicted slots survive separate batch saves
# ---------------------------------------------------------------------------

def test_lodged_and_predicted_batch_slots_are_independent(db_engine: Engine) -> None:
    # Arrange — two properties each get a lodged EPC and then a predicted EPC
    # via separate save_batch() calls.
    epc = _load_epc()
    property_ids = [4001, 4002]

    with Session(db_engine) as session:
        repo = EpcPostgresRepository(session)
        repo.save_batch([EpcSaveRequest(epc, property_id=pid, source="lodged") for pid in property_ids])
        repo.save_batch([EpcSaveRequest(epc, property_id=pid, source="predicted") for pid in property_ids])
        session.commit()

    # Act
    with Session(db_engine) as session:
        repo = EpcPostgresRepository(session)
        lodged = repo.get_for_properties(property_ids)
        predicted = repo.get_predicted_for_properties(property_ids)

    # Assert — both slots are populated for both properties.
    assert lodged == {4001: epc, 4002: epc}
    assert predicted == {4001: epc, 4002: epc}