using System.ComponentModel;
using CounterStrikeSharp.API.Core;

namespace GroupVerifyApi;

/// <summary>What GroupVerify itself implements behind the API. Not for other plugins.</summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public interface IGroupVerifyBackend
{
    /// <summary>See <see cref="IGroupVerifyApi.IsActive"/>.</summary>
    bool IsActive { get; }

    /// <summary>See <see cref="IGroupVerifyApi.GetStatus"/>.</summary>
    VerifyStatus GetStatus(ulong steamId64);
}

/// <summary>
/// The one API object, living in this shared assembly so it outlives GroupVerify reloads: CSS keeps
/// the first capability supplier registered forever, and subscribers keep their handlers here.
/// GroupVerify attaches its backend on load and detaches it on unload. Not for other plugins.
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public sealed class GroupVerifyBridge : IGroupVerifyApi
{
    /// <summary>The instance GroupVerify registers as the capability.</summary>
    public static GroupVerifyBridge Instance { get; } = new();

    private IGroupVerifyBackend? _backend;

    private GroupVerifyBridge()
    {
    }

    /// <inheritdoc />
    public event Action<CCSPlayerController, VerifyStatus>? OnVerifiedChanged;

    /// <inheritdoc />
    public bool IsActive => _backend?.IsActive ?? false;

    /// <inheritdoc />
    public bool IsVerified(CCSPlayerController player)
    {
        if (player is not { IsValid: true, IsBot: false, IsHLTV: false })
            return false;
        var steamId = player.AuthorizedSteamID?.SteamId64;
        return steamId != null && IsVerified(steamId.Value);
    }

    /// <inheritdoc />
    public bool IsVerified(ulong steamId64) => GetStatus(steamId64).Verified;

    /// <inheritdoc />
    public VerifyStatus GetStatus(ulong steamId64) =>
        _backend is { IsActive: true } backend ? backend.GetStatus(steamId64) : default;

    /// <summary>Called by GroupVerify on load.</summary>
    public void Attach(IGroupVerifyBackend backend) => _backend = backend;

    /// <summary>Called by GroupVerify on unload; ignored if a newer backend has attached since.</summary>
    public void Detach(IGroupVerifyBackend backend)
    {
        if (ReferenceEquals(_backend, backend))
            _backend = null;
    }

    /// <summary>
    /// Called by GroupVerify on the game thread. Each handler runs on its own, so one that throws
    /// doesn't stop the others; the exceptions are returned for GroupVerify to log.
    /// </summary>
    public List<Exception> RaiseVerifiedChanged(CCSPlayerController player, VerifyStatus status)
    {
        var errors = new List<Exception>();
        foreach (var handler in OnVerifiedChanged?.GetInvocationList() ?? [])
        {
            try
            {
                ((Action<CCSPlayerController, VerifyStatus>)handler)(player, status);
            }
            catch (Exception ex)
            {
                errors.Add(ex);
            }
        }
        return errors;
    }
}