using System.Text.Json;
using System.Text.Json.Serialization;

namespace VoiceCat.Core;

public enum ServerAuthentication { Guest, Account }

public sealed record ServerProfile(Guid Id, string Host, ushort Port, ServerAuthentication Authentication, string? Username, string? Nickname)
{
    public static ServerProfile Create(string host, ushort port, ServerAuthentication authentication, string? username = null, string? nickname = null, Guid? id = null)
    {
        host = host.Trim(); username = Normalize(username); nickname = Normalize(nickname);
        if (host.Length == 0) throw new ArgumentException("Server host is required.", nameof(host));
        if (port == 0) throw new ArgumentOutOfRangeException(nameof(port));
        if (authentication == ServerAuthentication.Account && username is null) throw new ArgumentException("Username is required for account authentication.", nameof(username));
        return new(id.GetValueOrDefault(Guid.NewGuid()), host, port, authentication,
            authentication == ServerAuthentication.Account ? username : null,
            authentication == ServerAuthentication.Guest ? nickname : null);
    }

    [JsonIgnore]
    public string DisplayName => Authentication == ServerAuthentication.Account
        ? $"{Username}@{Host}:{Port}"
        : $"{Host}:{Port} (Guest{(Nickname is null ? "" : $": {Nickname}")})";

    internal bool IsValid => Id != Guid.Empty && !string.IsNullOrWhiteSpace(Host) && Port != 0 &&
        (Authentication == ServerAuthentication.Guest || !string.IsNullOrWhiteSpace(Username));

    private static string? Normalize(string? value) => string.IsNullOrWhiteSpace(value) ? null : value.Trim();
}

public sealed class ServerProfileStore(string path)
{
    private static readonly JsonSerializerOptions Json = new()
    {
        Converters = { new JsonStringEnumConverter() },
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        WriteIndented = true
    };

    public IReadOnlyList<ServerProfile> Load()
    {
        try
        {
            if (!File.Exists(path)) return [];
            return (JsonSerializer.Deserialize<ServerProfile[]>(File.ReadAllBytes(path), Json) ?? [])
                .Where(profile => profile.IsValid).ToArray();
        }
        catch (Exception exception) when (exception is IOException or UnauthorizedAccessException or JsonException) { return []; }
    }

    public void Save(IEnumerable<ServerProfile> profiles)
    {
        ArgumentNullException.ThrowIfNull(profiles);
        ServerProfile[] valid = profiles.Where(profile => profile is not null && profile.IsValid).ToArray();
        string fullPath = Path.GetFullPath(path);
        Directory.CreateDirectory(Path.GetDirectoryName(fullPath)!);
        string temporary = fullPath + "." + Guid.NewGuid().ToString("N") + ".tmp";
        try
        {
            File.WriteAllBytes(temporary, JsonSerializer.SerializeToUtf8Bytes(valid, Json));
            File.Move(temporary, fullPath, true);
        }
        finally { if (File.Exists(temporary)) File.Delete(temporary); }
    }
}