#!/usr/bin/env python3
"""Regression tests for the locked 50-stock sampling protocol."""

from __future__ import annotations

import sys
import unittest
from pathlib import Path

import pandas as pd


ROOT = Path(__file__).resolve().parents[3]
SCRIPT_DIR = ROOT / "experiments/tbd_revision/scripts"
sys.path.insert(0, str(SCRIPT_DIR))

from make_ashare_50_stock_config import select_representative_stocks  # noqa: E402


class SamplingProtocolTests(unittest.TestCase):
    def test_selection_is_invariant_to_label_balance(self) -> None:
        rows = []
        bins = ("low", "mid", "high")
        for index in range(18):
            rows.append(
                {
                    "stock": f"stock_{index:02d}",
                    "board": "SZSE Main",
                    "liquidity_bin": bins[index % 3],
                    "volatility_bin": bins[(index // 3) % 3],
                    "spread_bin": bins[(index // 9) % 3],
                    "label_down_ratio": 0.2,
                    "label_flat_ratio": 0.6,
                    "label_up_ratio": 0.2,
                    "label_imbalance": 0.6,
                    "label_imbalance_bin": "mid",
                }
            )
        eligible = pd.DataFrame(rows)
        anchors = {"stock_00"}

        selected_a, _, _ = select_representative_stocks(
            eligible,
            target_size=9,
            seed=2026,
            anchors=anchors,
            board_allocation="proportional",
        )

        perturbed = eligible.copy()
        perturbed["label_down_ratio"] = [index / 100 for index in range(18)]
        perturbed["label_flat_ratio"] = [1.0 - index / 100 for index in range(18)]
        perturbed["label_up_ratio"] = 0.0
        perturbed["label_imbalance"] = perturbed[
            ["label_down_ratio", "label_flat_ratio", "label_up_ratio"]
        ].max(axis=1)
        perturbed["label_imbalance_bin"] = [
            bins[(index * 2) % 3] for index in range(18)
        ]
        selected_b, _, _ = select_representative_stocks(
            perturbed,
            target_size=9,
            seed=2026,
            anchors=anchors,
            board_allocation="proportional",
        )

        self.assertEqual(
            list(selected_a["stock"]),
            list(selected_b["stock"]),
        )
        self.assertEqual(
            list(selected_a["selection_order"]),
            list(selected_b["selection_order"]),
        )


if __name__ == "__main__":
    unittest.main()