# backend/ordnanceSurvey/tests/test_os_match.py
"""
Debug harness for Ordnance Survey address matching.

Mirrors backend/address2UPRN/tests/test_csv.py, but for the OS Places flow:
for each (User Input, Postcode) case it hits the live OS Places API, scores every
candidate address with AddressMatch.score (exactly as backend/ordnanceSurvey/main.py
does), and prints the full ranked breakdown so you can see *why* a match was or
wasn't found.

Run with -s to see the ranking:

    pytest backend/ordnanceSurvey/tests/test_os_match.py -s

Requires ORDNANCE_SURVEY_API_KEY to be set (config Settings / env); skipped otherwise.
"""

import csv
import os
import time
from pathlib import Path
from typing import Any, Optional

import pytest

from backend.ordnanceSurvey.helpers import (
    lookup_os_places,
    os_places_results_to_dataframe,
)
from backend.utils.addressMatch import AddressMatch

FIXTURE_PATH = Path(__file__).parent / "test_data.csv"

# Be polite to the live OS Places API between cases.
OS_THROTTLE_SECONDS = 1.0

# Handler treats best_score <= 0 as "no match" (see ordnanceSurvey/main.py).
MATCH_THRESHOLD = 0.0


@pytest.fixture(autouse=True)
def _throttle_os_requests():
    yield
    time.sleep(OS_THROTTLE_SECONDS)


def _api_key() -> Optional[str]:
    # Read straight from the environment so the debug harness doesn't depend on
    # the full Settings model loading cleanly. Falls back to Settings if unset.
    key = os.getenv("ORDNANCE_SURVEY_API_KEY")
    if not key:
        try:
            from backend.app.config import get_settings

            key = get_settings().ORDNANCE_SURVEY_API_KEY
        except Exception:
            key = None
    if not key or key == "changeme":
        return None
    return key


def load_test_cases():
    with open(FIXTURE_PATH, newline="", encoding="utf-8") as f:
        reader = csv.DictReader(f)
        return [
            pytest.param(
                row["User Input"],
                row["Postcode"],
                (row.get("Expected UPRN") or "").strip(),
                id=f'{row["User Input"]} [{row["Postcode"]}]',
            )
            for row in reader
        ]


def _scored_candidates(
    user_input: str, postcode: str, api_key: str
) -> list[dict[str, Any]]:
    """
    Fetch OS Places candidates for a postcode (bypassing the DB cache) and score
    every candidate ADDRESS exactly as ordnanceSurvey/main.py does. Returned
    ranked best-first.
    """
    response: dict[str, Any] = lookup_os_places(postcode, api_key)
    assert response.get("status") == 200, f"OS Places API failed: {response}"
    assert "data" in response, f"No data in OS Places response: {response}"

    candidates = os_places_results_to_dataframe(response["data"])
    records: list[dict[str, Any]] = candidates.to_dict("records")  # type: ignore[assignment]

    scored: list[dict[str, Any]] = []
    for rec in records:
        address = str(rec.get("ADDRESS", ""))
        scored.append(
            {
                "uprn": rec.get("UPRN", "?"),
                "address": address,
                "normalised": AddressMatch.normalise_address(address),
                "score": AddressMatch.score(user_input, address),
            }
        )
    scored.sort(key=lambda r: r["score"], reverse=True)
    return scored


def _print_debug(
    user_input: str, postcode: str, scored: list[dict[str, Any]]
) -> None:
    print(f"\n{'=' * 80}")
    print(f"User input : {user_input!r}")
    print(f"Normalised : {AddressMatch.normalise_address(user_input)!r}")
    print(f"Postcode   : {postcode!r}")
    print(f"Candidates : {len(scored)}")
    print(f"{'-' * 80}")
    if not scored:
        print("(no OS Places candidates returned for this postcode)")
        return
    for row in scored[:15]:
        print(f"  score={row['score']:.4f}  uprn={row['uprn']}")
        print(f"      ADDRESS    : {row['address']}")
        print(f"      normalised : {row['normalised']}")
    print(f"{'=' * 80}")


@pytest.mark.integration
@pytest.mark.parametrize("user_input,postcode,expected_uprn", load_test_cases())
def test_os_match_finds_candidate(
    user_input: str,
    postcode: str,
    expected_uprn: str,
):
    api_key = _api_key()
    if api_key is None:
        pytest.skip("ORDNANCE_SURVEY_API_KEY not set")

    scored = _scored_candidates(user_input, postcode, api_key)
    _print_debug(user_input, postcode, scored)

    best = scored[0] if scored else None
    best_score = float(best["score"]) if best is not None else 0.0

    # The handler records a match only when best_score > 0. This assertion is
    # the debug signal: when it fails, the printed ranking above shows why.
    assert best is not None and best_score > MATCH_THRESHOLD, (
        f"No OS match for {user_input!r} @ {postcode!r} "
        f"(best_score={best_score:.4f}). See ranking above."
    )

    if expected_uprn:
        assert str(best["uprn"]) == expected_uprn, (
            f"Best match UPRN {best['uprn']!r} != expected {expected_uprn!r}"
        )