"""Python 3.10+; validate a CSV header before creating dictionaries."""
import csv
import io
import unittest


def checked_rows(text, required):
    reader = csv.reader(io.StringIO(text, newline=""), strict=True)
    header = next(reader, None)
    if header is None or not header or any(not name for name in header):
        raise ValueError("missing or empty header")
    if len(header) != len(set(header)):
        raise ValueError("duplicate header")
    if not set(required) <= set(header):
        raise ValueError("required columns missing")
    result = []
    for row in reader:
        if len(row) != len(header):
            raise ValueError(f"wrong field count near physical line {reader.line_num}")
        result.append(dict(zip(header, row)))
    return result


class HeaderTests(unittest.TestCase):
    def test_reordered_columns_and_quoted_data(self):
        text = 'note,id\n"a,b",007\n'
        self.assertEqual(checked_rows(text, {"id"}), [{"note": "a,b", "id": "007"}])

    def test_bad_headers_and_widths(self):
        for text in ("", "id,id\n1,2\n", "id,\n1,2\n", "name\nAda\n", "id,name\n1\n", "id,name\n1,Ada,extra\n"):
            with self.subTest(text=text), self.assertRaises(ValueError):
                checked_rows(text, {"id"})


if __name__ == "__main__":
    unittest.main()