"""Slice 3 — generation-calibrated PV overshading (ADR-0026).

Google's `yearlyEnergyDcKwh` per segment already encodes real orientation,
tilt and shading from imagery. Dividing its AC equivalent by SAP's own
unshaded annual output (0.8 × kWp × S) cancels orientation/tilt and isolates
the effective overshading factor ZPV, which snaps to the RdSAP bucket
{1:1.0, 2:0.8, 3:0.5, 4:0.35}.
"""

import json
from pathlib import Path
from typing import Any

from domain.modelling.generators.solar_recommendation import (
    overshading_code_from_zpv,
    segment_overshading_code,
)
from domain.modelling.solar_potential import SolarPotential, SolarRoofSegment
from domain.sap10_calculator.rdsap.cert_to_inputs import (
    pv_annual_solar_radiation_kwh_per_m2,
)

_FIXTURE: Path = (
    Path(__file__).resolve().parent
    / "fixtures"
    / "google_building_insights_001431.json"
)
_DC_TO_AC_RATE = 0.955
_SAP_PV_PERFORMANCE_FACTOR = 0.8


def _insights() -> dict[str, Any]:
    with _FIXTURE.open(encoding="utf-8") as handle:
        data: dict[str, Any] = json.load(handle)
    return data


def test_overshading_cutpoints_snap_to_rdsap_buckets() -> None:
    # Arrange / Act / Assert — ADR-0026 midpoints: ≥0.90→1, 0.65–0.90→2,
    # 0.425–0.65→3, <0.425→4, and ZPV>1 clamps to 1.
    assert overshading_code_from_zpv(1.20) == 1
    assert overshading_code_from_zpv(0.90) == 1
    assert overshading_code_from_zpv(0.89) == 2
    assert overshading_code_from_zpv(0.65) == 2
    assert overshading_code_from_zpv(0.64) == 3
    assert overshading_code_from_zpv(0.425) == 3
    assert overshading_code_from_zpv(0.42) == 4
    assert overshading_code_from_zpv(0.10) == 4


def _segment_with_zpv(target_zpv: float) -> SolarRoofSegment:
    """A south-facing 30°-tilt 2 kWp segment whose Google generation is set so
    its back-solved overshading factor is ``target_zpv``."""
    orientation, pitch_code, panels, capacity = 5, 2, 5, 400.0  # 5 × 400 W = 2 kWp
    kwp = panels * capacity / 1000
    s = pv_annual_solar_radiation_kwh_per_m2(orientation, pitch_code)
    g_ac = _SAP_PV_PERFORMANCE_FACTOR * kwp * s * target_zpv
    yearly_dc = g_ac / _DC_TO_AC_RATE
    return SolarRoofSegment(
        segment_index=0,
        panels_count=panels,
        azimuth_degrees=180.0,  # S → octant 5
        pitch_degrees=30.0,  # → code 2
        yearly_energy_dc_kwh=yearly_dc,
    )


def test_segment_overshading_recovers_each_bucket() -> None:
    # Arrange / Act / Assert — a segment dialled to each bucket midpoint
    capacity = 400.0
    assert segment_overshading_code(_segment_with_zpv(1.0), capacity) == 1
    assert segment_overshading_code(_segment_with_zpv(0.8), capacity) == 2
    assert segment_overshading_code(_segment_with_zpv(0.5), capacity) == 3
    assert segment_overshading_code(_segment_with_zpv(0.35), capacity) == 4


def test_real_example_segments_are_unshaded() -> None:
    # Arrange
    potential = SolarPotential.from_building_insights(_insights())
    largest = potential.configurations[-1]

    # Act
    codes = {
        segment_overshading_code(seg, potential.panel_capacity_watts)
        for seg in largest.segments
    }

    # Assert — a clear London roof: every plane back-solves to ZPV > 1 → code 1
    assert codes == {1}