"""Tests for extract_categories.py - extracting unique categories from b4w CSV exports."""

import csv
import sys
from pathlib import Path

sys.path.insert(0, str(Path(__file__).parent.parent / "scripts"))

from scripts.initial_load.categories.extract_categories import extract_unique_categories


def write_csv(path: Path, categories: list[str]) -> None:
    with open(path, "w", encoding="utf-8") as f:
        writer = csv.DictWriter(f, fieldnames=["Id", "AcctId", "Category"])
        writer.writeheader()
        for i, category in enumerate(categories, 1):
            writer.writerow({"Id": str(i), "AcctId": "587713594", "Category": category})


def read_lines(path: Path) -> list[str]:
    return path.read_text(encoding="utf-8").splitlines()


def test_extract_unique_categories_basic(tmp_path):
    csv_file = tmp_path / "input.csv"
    output_file = tmp_path / "categories.txt"
    write_csv(csv_file, ["Girokonto:Lebenshaltung", "Girokonto:Sparen"])

    result = extract_unique_categories(str(csv_file), str(output_file))

    assert result == ["Girokonto:Lebenshaltung", "Girokonto:Sparen"]
    assert read_lines(output_file) == ["Girokonto:Lebenshaltung", "Girokonto:Sparen"]


def test_extract_unique_categories_no_duplicates(tmp_path):
    csv_file = tmp_path / "input.csv"
    output_file = tmp_path / "categories.txt"
    write_csv(
        csv_file,
        ["Girokonto:Lebenshaltung", "Girokonto:Sparen", "Girokonto:Lebenshaltung"],
    )

    extract_unique_categories(str(csv_file), str(output_file))

    assert len(read_lines(output_file)) == 2


def test_extract_unique_categories_output_format(tmp_path):
    csv_file = tmp_path / "input.csv"
    output_file = tmp_path / "categories.txt"
    write_csv(
        csv_file,
        ["Girokonto:Lebenshaltung", "Girokonto:Sparen", "Girokonto:Privat"],
    )

    extract_unique_categories(str(csv_file), str(output_file))

    lines = read_lines(output_file)
    assert len(lines) == 3
    # Plain list: no numbering prefix, no blank lines.
    assert all(line == line.strip() and not line[0].isdigit() for line in lines)


def test_extract_unique_categories_german_special_chars(tmp_path):
    csv_file = tmp_path / "input.csv"
    output_file = tmp_path / "categories.txt"
    write_csv(
        csv_file,
        ["Girokonto:Freizeit:Urlaub&Ausflüge", "Girokonto:Privat:Mitgliedsbeiträge"],
    )

    extract_unique_categories(str(csv_file), str(output_file))

    assert read_lines(output_file) == [
        "Girokonto:Freizeit:Urlaub&Ausflüge",
        "Girokonto:Privat:Mitgliedsbeiträge",
    ]


def test_extract_unique_categories_handles_empty_csv(tmp_path):
    csv_file = tmp_path / "input.csv"
    output_file = tmp_path / "categories.txt"
    csv_file.write_text("Id,AcctId,Category\n", encoding="utf-8")

    extract_unique_categories(str(csv_file), str(output_file))

    assert output_file.exists()
    assert read_lines(output_file) == []


def test_extract_unique_categories_handles_csv_with_all_empty_categories(tmp_path):
    csv_file = tmp_path / "input.csv"
    output_file = tmp_path / "categories.txt"
    csv_file.write_text(
        "Id,AcctId,Category\n1,587713594,\n2,587713594,\n3,587713594,\n",
        encoding="utf-8",
    )

    extract_unique_categories(str(csv_file), str(output_file))

    assert read_lines(output_file) == []


def test_extract_unique_categories_rerun_is_idempotent(tmp_path):
    csv_file = tmp_path / "input.csv"
    output_file = tmp_path / "categories.txt"
    write_csv(csv_file, ["Girokonto:Lebenshaltung", "Girokonto:Sparen"])

    extract_unique_categories(str(csv_file), str(output_file))
    first_run = read_lines(output_file)

    # A new category appears in the CSV on the second run.
    write_csv(
        csv_file, ["Girokonto:Lebenshaltung", "Girokonto:Sparen", "Girokonto:Privat"]
    )
    extract_unique_categories(str(csv_file), str(output_file))
    second_run = read_lines(output_file)

    # Existing entries are merged, not duplicated; list stays sorted and plain.
    assert second_run == [
        "Girokonto:Lebenshaltung",
        "Girokonto:Privat",
        "Girokonto:Sparen",
    ]
    assert first_run == ["Girokonto:Lebenshaltung", "Girokonto:Sparen"]