using System.Globalization;
using System.Net.Mail;
using System.Text;
using GeradoresService.Core;
using GeradoresService.Data;

namespace GeradoresService.Generators.Contactos;

public sealed class EmailGenerator : GeneratorBase
{
    public override string Id => "email";
    public override string Name => "Email";
    public override string Category => Categories.Contactos;
    public override string Description => "Endereço de email fictício. Por omissão usa domínios reservados para testes (example.com).";
    public override bool HasChecksum => false;

    public override IReadOnlyList<GeneratorOption> Options =>
    [
        Option("dominio", "Domínio", "teste",
            ("teste", "Reservado para testes (example.com)"),
            ("realista", "Realista (gmail.com, sapo.pt…)")),
    ];

    public override GeneratedItem Generate(GeneratorContext context)
    {
        var first = context.Random.Next(2) == 0 ? context.Pick(PtData.MaleNames) : context.Pick(PtData.FemaleNames);
        return new GeneratedItem(Build(first, context.Pick(PtData.Surnames), context, context.Option(Options[0]) == "realista"));
    }

    public static string Build(string firstName, string surname, GeneratorContext context, bool realistic = false)
    {
        var domains = realistic ? PtData.RealisticEmailDomains : PtData.SafeEmailDomains;
        var separator = context.Pick([".", "_", ""]);
        var suffix = context.Random.Next(3) == 0 ? context.Random.Next(1, 100).ToString() : "";
        return $"{Slug(firstName)}{separator}{Slug(surname)}{suffix}@{context.Pick(domains)}";
    }

    private static string Slug(string s)
    {
        var sb = new StringBuilder();
        foreach (var c in s.Normalize(NormalizationForm.FormD))
            if (CharUnicodeInfo.GetUnicodeCategory(c) != UnicodeCategory.NonSpacingMark && char.IsLetterOrDigit(c))
                sb.Append(char.ToLowerInvariant(c));
        return sb.ToString();
    }

    public override ValidationResult Validate(string value)
    {
        var v = value.Trim();
        var at = v.LastIndexOf('@');
        if (at <= 0 || at == v.Length - 1 || !v[(at + 1)..].Contains('.') || v.Any(char.IsWhiteSpace)
            || !MailAddress.TryCreate(v, out var address) || address.Address != v)
            return ValidationResult.WrongFormat("Não é um endereço de email válido.");
        return ValidationResult.Valid(v.ToLowerInvariant(), "Formato de email válido.");
    }
}