import pytest
from roman import RomanNumeralConverter

ERROR_MESSAGE = "ERROR: Invalid input"


def test_valid_single_numerals():
    converter = RomanNumeralConverter()
    assert converter.convert_to_number("I") == "I = 1"
    assert converter.convert_to_number("V") == "V = 5"
    assert converter.convert_to_number("X") == "X = 10"
    assert converter.convert_to_number("C") == "C = 100"
    assert converter.convert_to_number("M") == "M = 1000"


def test_valid_multiple_numerals():
    converter = RomanNumeralConverter()
    assert converter.convert_to_number("IV") == "IV = 1 + 5 = 6"
    assert converter.convert_to_number("XCM") == "XCM = 10 + 100 + 1000 = 1110"
    assert (
        converter.convert_to_number("MCMXCIV")
        == "MCMXCIV = 1000 + 100 + 1000 + 10 + 100 + 1 + 5 = 2216"
    )


def test_lowercase_input():
    converter = RomanNumeralConverter()
    assert (
        converter.convert_to_number("ivxcm") == "IVXCM = 1 + 5 + 10 + 100 + 1000 = 1116"
    )


def test_mixed_case_input():
    converter = RomanNumeralConverter()
    assert (
        converter.convert_to_number("iVxCm") == "IVXCM = 1 + 5 + 10 + 100 + 1000 = 1116"
    )


def test_invalid_characters():
    converter = RomanNumeralConverter()
    assert converter.convert_to_number("EFGH") == ERROR_MESSAGE
    assert converter.convert_to_number("123") == ERROR_MESSAGE
    assert converter.convert_to_number("!@#") == ERROR_MESSAGE


def test_mixed_valid_and_invalid_characters():
    converter = RomanNumeralConverter()
    assert converter.convert_to_number("AIXB") == "IX = 1 + 10 = 11"
    assert converter.convert_to_number("M1C2") == "MC = 1000 + 100 = 1100"


def test_empty_string():
    converter = RomanNumeralConverter()
    assert converter.convert_to_number("") == ERROR_MESSAGE


def test_only_spaces():
    converter = RomanNumeralConverter()
    assert converter.convert_to_number("   ") == ERROR_MESSAGE


def test_spaces_and_valid_numerals():
    converter = RomanNumeralConverter()
    assert converter.convert_to_number(" I V ") == "IV = 1 + 5 = 6"


def test_filter_valid_numerals():
    converter = RomanNumeralConverter()
    assert converter._filter_valid_numerals("M1X2V") == "MXV"
    assert converter._filter_valid_numerals("def") == ""
    assert converter._filter_valid_numerals(" I V ") == "IV"


def test_convert_numerals_to_values():
    converter = RomanNumeralConverter()
    assert converter._convert_numerals_to_values("IV") == [1, 5]
    assert converter._convert_numerals_to_values("MXV") == [1000, 10, 5]
    assert converter._convert_numerals_to_values("C") == [100]


def test_format_output():
    converter = RomanNumeralConverter()
    assert converter._format_output("I", [1]) == "I = 1"
    assert converter._format_output("IV", [1, 5]) == "IV = 1 + 5 = 6"
    assert (
        converter._format_output("MXV", [1000, 10, 5]) == "MXV = 1000 + 10 + 5 = 1015"
    )