"""Config loading + validation tests (IMPLEMENTATION_PLAN §4.1)."""

from pathlib import Path

import pytest

from opcda_diagnozer.config import ConfigError, load_config

EXAMPLE = Path(__file__).resolve().parents[1] / "config.example.yaml"


def _write(tmp_path: Path, text: str) -> Path:
    p = tmp_path / "config.yaml"
    p.write_text(text, encoding="utf-8")
    return p


def test_example_config_loads() -> None:
    config = load_config(EXAMPLE)
    assert config.opc.server == "Matrikon.OPC.Simulation.1"
    assert config.opc.host is None  # host commented out -> local server
    assert len(config.tags) == 2
    assert config.tags[0].name == "Channel1.Device1.Counter"
    assert config.tags[0].expect_change is True
    assert config.tags[1].expect_change is False
    assert config.poll.interval_s == 1.0
    assert config.poll.timeout_ms == 5000
    assert config.latency.warn_ms == 1000
    assert config.report.eventlog.min_severity == "WARN"
    assert config.report.jsonl.dir == "C:/ProgramData/OPCDA-Diagnozer/logs"


def test_missing_file_is_actionable() -> None:
    with pytest.raises(ConfigError, match="not found"):
        load_config("no-such-config.yaml")


def test_missing_opc_section_is_actionable(tmp_path: Path) -> None:
    p = _write(tmp_path, "tags:\n  - name: t\n")
    with pytest.raises(ConfigError, match=r"opc: missing required key 'server'"):
        load_config(p)


def test_unknown_key_rejected(tmp_path: Path) -> None:
    p = _write(tmp_path, "opc:\n  server: X\n  typo_key: 1\ntags:\n  - name: t\n")
    with pytest.raises(ConfigError, match="typo_key"):
        load_config(p)


def test_unknown_top_level_section_rejected(tmp_path: Path) -> None:
    p = _write(tmp_path, "opc:\n  server: X\ntags:\n  - name: t\nnonsense: {}\n")
    with pytest.raises(ConfigError, match="nonsense"):
        load_config(p)


def test_empty_tags_rejected(tmp_path: Path) -> None:
    p = _write(tmp_path, "opc:\n  server: X\ntags: []\n")
    with pytest.raises(ConfigError, match="at least one tag"):
        load_config(p)


def test_duplicate_tags_rejected(tmp_path: Path) -> None:
    p = _write(tmp_path, "opc:\n  server: X\ntags:\n  - name: a\n  - name: a\n")
    with pytest.raises(ConfigError, match="duplicate"):
        load_config(p)


def test_latency_threshold_order_rejected(tmp_path: Path) -> None:
    p = _write(
        tmp_path,
        "opc:\n  server: X\ntags:\n  - name: t\n"
        "latency:\n  warn_ms: 5000\n  critical_ms: 1000\n",
    )
    with pytest.raises(ConfigError, match="warn_ms"):
        load_config(p)


def test_hard_hang_must_exceed_timeout(tmp_path: Path) -> None:
    p = _write(
        tmp_path,
        "opc:\n  server: X\ntags:\n  - name: t\n"
        "poll:\n  timeout_ms: 5000\n  hard_hang_s: 4\n",
    )
    with pytest.raises(ConfigError, match="hard_hang_s"):
        load_config(p)