"""Tests für CSV-Parser Foundation (Issue #21)."""

import pytest

from csv_parser.core import (
    decode_raw_bytes,
    sniff_delimiter,
    parse_csv_sample,
    column_signature,
    headers_signature_match_score,
    get_csv_import_limits,
)
from csv_parser.type_converter import convert_value, build_row_after_mapping


def test_decode_bom_utf8():
    raw = "\ufeffa;b;c\n1;2;3".encode("utf-8-sig")
    t = decode_raw_bytes(raw)
    assert not t.startswith("\ufeff")
    assert "a;b;c" in t


def test_sniff_delimiter():
    assert sniff_delimiter("a;b;c;d") == ";"
    assert sniff_delimiter("a,b,c") == ","


def test_parse_csv_sample_header():
    text = "Date;kcal\n2024-01-01;2000\n"
    headers, rows, delim = parse_csv_sample(text, delimiter=";", max_data_rows=3)
    assert headers == ["Date", "kcal"]
    assert delim == ";"
    assert rows[0]["Date"] == "2024-01-01"
    assert rows[0]["kcal"] == "2000"


def test_column_signature_sorted_unique():
    sig = column_signature(["B", "a", "a"])
    assert sig == ["a", "b"]


def test_jaccard():
    s1 = column_signature(["Date", "Calories"])
    s2 = column_signature(["Date", "Calories", "Fat"])
    assert headers_signature_match_score(s1, s2) == pytest.approx(2 / 3)


def test_get_csv_import_limits_default():
    assert get_csv_import_limits(None)["max_rows_per_file"] == 50_000


def test_convert_date_and_kcal_factor():
    d = convert_value("15.01.2024", "date", {"type": "date", "format": "dd.mm.yyyy"})
    assert d.year == 2024 and d.month == 1 and d.day == 15

    k = convert_value("8000", "kcal", {"type": "float", "conversion_factor": 0.239, "decimal_separator": "."})
    assert abs(k - 8000 * 0.239) < 0.01


def test_build_row_after_mapping():
    csv_row = {"Datum": "01.01.2024", "kj": "4200"}
    fm = {"Datum": "date", "kj": "kcal"}
    tc = {
        "date": {"type": "date", "format": "dd.mm.yyyy"},
        "kcal": {"type": "float", "conversion_factor": 0.239, "decimal_separator": "."},
    }
    out = build_row_after_mapping(csv_row, fm, tc)
    assert out["date"].month == 1
    assert out["kcal"] is not None