"""Tests for loading, cleaning and aligning the two price series."""

from __future__ import annotations

from pathlib import Path

import numpy as np
import openpyxl
import pandas as pd
import pytest

from battery_dispatch.config import BatterySpec
from battery_dispatch.data import (
    HALF_HOURLY_SHEET,
    HOURLY_SHEET,
    build_markets,
    load_prices,
    slice_whole_days,
)
from battery_dispatch.markets import MARKET_1, MARKET_2

REPO_ROOT = Path(__file__).resolve().parents[1]
PRICE_FILE = REPO_ROOT / "data" / "Attachment 2.xlsx"
SPEC_FILE = REPO_ROOT / "data" / "Attachment 1.xlsx"

requires_data = pytest.mark.skipif(
    not PRICE_FILE.exists(), reason="Attachment 2.xlsx not present"
)


def write_workbook(
    path: Path,
    half_hourly: list[tuple],
    hourly: list[tuple],
) -> Path:
    """Build a miniature Attachment 2 with the same sheet names and layout."""
    workbook = openpyxl.Workbook()
    sheet = workbook.active
    sheet.title = HALF_HOURLY_SHEET
    sheet.append([None, "Market 1 Price [£/MWh]"])
    for row in half_hourly:
        sheet.append(list(row))

    second = workbook.create_sheet(HOURLY_SHEET)
    second.append([None, "Market 2 Price [£/MWh]"])
    for row in hourly:
        second.append(list(row))

    workbook.save(path)
    return path


def synthetic_day(tmp_path: Path, trailing_blanks: int = 0) -> Path:
    """One clean day: 48 half-hours and 24 hours, plus optional blank rows."""
    half_hourly = [
        (pd.Timestamp("2018-01-01") + pd.Timedelta(minutes=30 * i), float(i))
        for i in range(48)
    ]
    hourly = [
        (pd.Timestamp("2018-01-01") + pd.Timedelta(hours=h), 100.0 + h)
        for h in range(24)
    ]
    hourly += [(None, None)] * trailing_blanks
    return write_workbook(tmp_path / "prices.xlsx", half_hourly, hourly)


def test_trailing_blank_rows_are_dropped(tmp_path):
    path = synthetic_day(tmp_path, trailing_blanks=24)
    prices = load_prices(path, expected_days=1)
    assert len(prices) == 48


def test_hourly_prices_are_broadcast_onto_half_hours(tmp_path):
    prices = load_prices(synthetic_day(tmp_path), expected_days=1)

    # Each hourly price covers exactly two consecutive half-hours.
    assert prices["market_2_price"].iloc[0] == 100.0
    assert prices["market_2_price"].iloc[1] == 100.0
    assert prices["market_2_price"].iloc[2] == 101.0
    assert prices["market_2_price"].iloc[47] == 123.0

    pairs = prices["market_2_price"].to_numpy().reshape(-1, 2)
    assert np.array_equal(pairs[:, 0], pairs[:, 1])

    # Market 1 is untouched, and hour_index groups half-hours in twos.
    assert prices["market_1_price"].tolist() == [float(i) for i in range(48)]
    assert prices["hour_index"].tolist() == [i // 2 for i in range(48)]


def test_row_count_mismatch_is_an_error_not_a_guess(tmp_path):
    half_hourly = [
        (pd.Timestamp("2018-01-01") + pd.Timedelta(minutes=30 * i), 1.0)
        for i in range(47)  # one short
    ]
    hourly = [
        (pd.Timestamp("2018-01-01") + pd.Timedelta(hours=h), 1.0) for h in range(24)
    ]
    path = write_workbook(tmp_path / "short.xlsx", half_hourly, hourly)

    with pytest.raises(ValueError, match="expected 48 rows"):
        load_prices(path, expected_days=1)


def test_index_is_rebuilt_regularly_despite_clock_change_labels(tmp_path, caplog):
    """Duplicated 02:00 labels are logged and replaced by a regular index."""
    stamps = [
        pd.Timestamp("2018-03-25") + pd.Timedelta(minutes=30 * i) for i in range(48)
    ]
    # Reproduce the spring-forward labelling: 01:00/01:30 skipped, 02:00/02:30 twice.
    stamps[2] = pd.Timestamp("2018-03-25 02:00")
    stamps[3] = pd.Timestamp("2018-03-25 02:30")

    half_hourly = [(ts, 10.0) for ts in stamps]
    hourly = [
        (pd.Timestamp("2018-03-25") + pd.Timedelta(hours=h), 20.0) for h in range(24)
    ]
    path = write_workbook(tmp_path / "clocks.xlsx", half_hourly, hourly)

    with caplog.at_level("INFO"):
        prices = load_prices(path, expected_days=1)

    assert "do not match a regular half-hourly index" in caplog.text
    expected = pd.date_range("2018-01-01", periods=48, freq="30min")
    assert prices.index.equals(expected)
    assert not prices.index.duplicated().any()


def test_slice_whole_days_includes_the_whole_end_day(tmp_path):
    half_hourly = [
        (pd.Timestamp("2018-01-01") + pd.Timedelta(minutes=30 * i), float(i))
        for i in range(96)
    ]
    hourly = [
        (pd.Timestamp("2018-01-01") + pd.Timedelta(hours=h), 1.0) for h in range(48)
    ]
    prices = load_prices(write_workbook(tmp_path / "two.xlsx", half_hourly, hourly),
                         expected_days=2)

    first_day = slice_whole_days(prices, "2018-01-01", "2018-01-01")
    assert len(first_day) == 48
    assert first_day.index[-1] == pd.Timestamp("2018-01-01 23:30")

    # hour_index is re-based so a slice can be optimised standalone.
    assert first_day["hour_index"].iloc[0] == 0
    second_day = slice_whole_days(prices, "2018-01-02", "2018-01-02")
    assert second_day["hour_index"].iloc[0] == 0


def test_build_markets_sets_the_commitment_block_lengths(tmp_path):
    prices = load_prices(synthetic_day(tmp_path), expected_days=1)
    market_1, market_2 = build_markets(prices)

    assert market_1.name == MARKET_1 and market_1.block_half_hours == 1
    assert market_2.name == MARKET_2 and market_2.block_half_hours == 2
    assert market_2.block_of(0) == market_2.block_of(1) == 0
    assert market_2.block_of(2) == 1


@requires_data
def test_real_workbook_loads_with_the_expected_shape():
    prices = load_prices(PRICE_FILE)

    assert len(prices) == 1096 * 48
    assert prices.index[0] == pd.Timestamp("2018-01-01 00:00")
    assert prices.index[-1] == pd.Timestamp("2020-12-31 23:30")
    assert prices.index.is_monotonic_increasing
    assert not prices.index.duplicated().any()
    assert prices.notna().all().all()

    pairs = prices["market_2_price"].to_numpy().reshape(-1, 2)
    assert np.array_equal(pairs[:, 0], pairs[:, 1])


@requires_data
def test_spec_reads_losses_as_efficiencies():
    """Attachment 1 quotes losses; the model must store 1 - loss."""
    spec = BatterySpec.from_excel(SPEC_FILE)

    assert spec.max_charge_mw == 2.0
    assert spec.max_discharge_mw == 2.0
    assert spec.capacity_mwh == 4.0
    assert spec.charge_efficiency == pytest.approx(0.95)
    assert spec.discharge_efficiency == pytest.approx(0.95)
    assert spec.round_trip_efficiency == pytest.approx(0.9025)
    assert spec.lifetime_years == 10.0
    assert spec.lifetime_cycles == 5000.0
    assert spec.degradation_fraction_per_cycle == pytest.approx(1e-5)
    assert spec.capex_gbp == 500_000.0
    assert spec.fixed_opex_gbp_per_year == 5_000.0