using GeradoresService.Core;

namespace GeradoresService.Generators.Financeiro;

/// <summary>
/// IBAN português: PT + 2 dígitos de controlo ISO 7064 (MOD 97-10) + NIB.
/// A validação aceita IBAN de qualquer país (verifica comprimento conhecido e MOD 97).
/// </summary>
public sealed class IbanGenerator : NibGenerator
{
    private static readonly Dictionary<string, int> Lengths = new()
    {
        ["PT"] = 25, ["ES"] = 24, ["FR"] = 27, ["DE"] = 22, ["IT"] = 27, ["GB"] = 22, ["IE"] = 22,
        ["NL"] = 18, ["BE"] = 16, ["LU"] = 20, ["CH"] = 21, ["AT"] = 20, ["DK"] = 18, ["FI"] = 18,
        ["SE"] = 24, ["NO"] = 15, ["PL"] = 28, ["CZ"] = 24, ["GR"] = 27, ["HR"] = 21, ["RO"] = 24,
        ["MT"] = 31, ["CY"] = 28, ["SK"] = 24, ["SI"] = 19, ["HU"] = 28, ["BG"] = 22, ["EE"] = 20,
        ["LT"] = 20, ["LV"] = 21, ["IS"] = 26, ["LI"] = 21, ["MC"] = 27, ["SM"] = 27, ["BR"] = 29,
    };

    public override string Id => "iban";
    public override string Name => "IBAN";
    public override string Description => "IBAN português (PT50 + NIB). Valida IBAN de qualquer país.";

    public override IReadOnlyList<GeneratorOption> Options =>
    [
        .. base.Options,
        Option("formato", "Formato", "espacos", ("espacos", "PT50 0000 0000 …"), ("compacto", "PT500000…")),
    ];

    public override GeneratedItem Generate(GeneratorContext context)
    {
        var iban = FromBban("PT", BuildNib(context));
        return new GeneratedItem(context.Option(Options[1]) == "compacto" ? iban : Format(iban));
    }

    public static string FromBban(string country, string bban)
    {
        var check = 98 - Checksums.Mod97(Checksums.LettersToDigits(bban + country) + "00");
        return $"{country}{check:D2}{bban}";
    }

    public static string Format(string iban) =>
        string.Join(' ', iban.Chunk(4).Select(c => new string(c)));

    public override ValidationResult Validate(string value)
    {
        var iban = Checksums.Clean(value).ToUpperInvariant();
        if (iban.Length < 15 || iban.Length > 34
            || !char.IsAsciiLetter(iban[0]) || !char.IsAsciiLetter(iban[1])
            || !char.IsAsciiDigit(iban[2]) || !char.IsAsciiDigit(iban[3])
            || !iban.All(char.IsAsciiLetterOrDigit))
            return ValidationResult.WrongFormat("Um IBAN tem código de país (2 letras), 2 dígitos de controlo e o BBAN.");

        var country = iban[..2];
        if (Lengths.TryGetValue(country, out var expectedLength) && iban.Length != expectedLength)
            return ValidationResult.WrongFormat($"Um IBAN {country} tem {expectedLength} caracteres (tem {iban.Length}).");

        var rearranged = Checksums.LettersToDigits(iban[4..] + iban[..4]);
        if (Checksums.Mod97(rearranged) != 1)
        {
            var expected = FromBban(country, iban[4..])[2..4];
            return ValidationResult.BadChecksum(
                $"Dígitos de controlo do IBAN inválidos: esperado {expected}, encontrado {iban[2..4]}.",
                ["Controlo: ISO 7064 MOD 97-10"]);
        }

        if (country == "PT")
        {
            var nibResult = ValidateNib(iban[4..], "IBAN");
            return nibResult with { Normalized = nibResult.IsValid ? Format(iban) : null };
        }

        return ValidationResult.Valid(Format(iban), $"IBAN válido ({country}).", ["Controlo: ISO 7064 MOD 97-10"]);
    }
}