from decimal import Decimal
from pathlib import Path

import pytest
import yaml

from synthgen.__main__ import main
from synthgen.config import Config, ConfigError, dump_config, load_config
from synthgen.rng import rng_for

EXAMPLE = Path(__file__).resolve().parent.parent / "examples" / "default.yaml"


def test_defaults():
    assert load_config(None, []) == Config()


def test_example_matches_defaults():
    assert load_config(EXAMPLE, []) == Config()


def test_yaml_and_set_override(tmp_path):
    path = tmp_path / "cfg.yaml"
    path.write_text("group_size: 7\n", encoding="utf-8")
    assert load_config(path, []).group_size == 7
    assert load_config(path, ["group_size=9"]).group_size == 9
    assert load_config(None, ["vgo_mismatch_share=0.25"]).vgo_mismatch_share == Decimal("0.25")


def test_dump_roundtrip(tmp_path):
    cfg = Config(group_size=12, prefix="DEMO2", vgo_mismatch_share=Decimal("0.25"))
    path = tmp_path / "dump.yaml"
    path.write_text(dump_config(cfg), encoding="utf-8")
    assert load_config(path, []) == cfg
    keys = list(yaml.safe_load(dump_config(cfg)))
    assert keys == [
        "group_size", "prefix", "periods", "start", "osv_counterparties_mean",
        "no_inn_companies", "vgo_mismatch_share", "seed", "out",
    ]


@pytest.mark.parametrize(
    "override",
    [
        "group_size=1",
        "group_size=41",
        "periods=0",
        "periods=13",
        "start=2025-Q5",
        "start=2019-Q4",
        "prefix=A",
        "prefix=A B",
        "prefix=ABCDEFGHIJKLM",
        "osv_counterparties_mean=151",
        "no_inn_companies=6",
        "vgo_mismatch_share=1.5",
        "unknown=1",
    ],
)
def test_validation(override):
    with pytest.raises(ConfigError):
        load_config(None, [override])


def test_unknown_key_in_yaml(tmp_path):
    path = tmp_path / "cfg.yaml"
    path.write_text("unknown: 1\n", encoding="utf-8")
    with pytest.raises(ConfigError):
        load_config(path, [])


def test_cli_bad_config_exit_2(capsys):
    assert main(["--set", "group_size=1"]) == 2
    assert capsys.readouterr().err != ""


def test_cli_writes_actual_config(tmp_path):
    out = tmp_path / "res"
    assert main(["--set", "group_size=7", "--set", "periods=1", "--set", "osv_counterparties_mean=2", "--out", str(out)]) == 0
    assert "group_size: 7" in (out / "config.yaml").read_text(encoding="utf-8")


def test_rng_for_stable():
    assert rng_for(1, "a").random() == rng_for(1, "a").random()
    assert rng_for(1, "a").random() != rng_for(1, "b").random()
    assert rng_for(1, "a").random() != rng_for(2, "a").random()