using System.Security.Claims;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using ZB.MOM.WW.MxGateway.Server.Sessions;

namespace ZB.MOM.WW.MxGateway.Server.Dashboard;

public sealed class DashboardSessionAdminService(
    ISessionManager sessionManager,
    IHttpContextAccessor httpContextAccessor,
    ILogger<DashboardSessionAdminService>? logger = null) : IDashboardSessionAdminService
{
    private const string UnauthorizedMessage = "Sign in as an Admin to close sessions or kill workers.";
    private const string KillReason = "dashboard-admin-kill";

    private readonly ILogger<DashboardSessionAdminService> _logger =
        logger ?? NullLogger<DashboardSessionAdminService>.Instance;

    public bool CanManage(ClaimsPrincipal user)
    {
        ArgumentNullException.ThrowIfNull(user);

        return user.Identity?.IsAuthenticated == true
            && user.IsInRole(DashboardRoles.Admin);
    }

    public async Task<DashboardSessionAdminResult> CloseSessionAsync(
        ClaimsPrincipal user,
        string sessionId,
        CancellationToken cancellationToken)
    {
        if (!CanManage(user))
        {
            return DashboardSessionAdminResult.Fail(UnauthorizedMessage);
        }

        if (string.IsNullOrWhiteSpace(sessionId))
        {
            return DashboardSessionAdminResult.Fail("Session id is required.");
        }

        string actor = ResolveActor(user);
        try
        {
            SessionCloseResult result = await sessionManager
                .CloseSessionAsync(sessionId, cancellationToken)
                .ConfigureAwait(false);

            _logger.LogInformation(
                "Dashboard admin {Actor} closed session {SessionId} from {RemoteAddress}; alreadyClosed={AlreadyClosed}.",
                actor,
                sessionId,
                ResolveRemoteAddress(),
                result.AlreadyClosed);

            return DashboardSessionAdminResult.Success(
                result.AlreadyClosed
                    ? $"Session {sessionId} was already closed."
                    : $"Session {sessionId} closed.");
        }
        catch (SessionManagerException exception) when (exception.ErrorCode == SessionManagerErrorCode.SessionNotFound)
        {
            return DashboardSessionAdminResult.Fail($"Session {sessionId} was not found.");
        }
        catch (SessionManagerException exception)
        {
            _logger.LogWarning(
                exception,
                "Dashboard admin {Actor} close failed for session {SessionId}.",
                actor,
                sessionId);
            return DashboardSessionAdminResult.Fail(
                $"Close failed: {exception.Message}");
        }
    }

    public async Task<DashboardSessionAdminResult> KillWorkerAsync(
        ClaimsPrincipal user,
        string sessionId,
        CancellationToken cancellationToken)
    {
        if (!CanManage(user))
        {
            return DashboardSessionAdminResult.Fail(UnauthorizedMessage);
        }

        if (string.IsNullOrWhiteSpace(sessionId))
        {
            return DashboardSessionAdminResult.Fail("Session id is required.");
        }

        string actor = ResolveActor(user);
        try
        {
            SessionCloseResult result = await sessionManager
                .KillWorkerAsync(sessionId, KillReason, cancellationToken)
                .ConfigureAwait(false);

            _logger.LogInformation(
                "Dashboard admin {Actor} killed worker for session {SessionId} from {RemoteAddress}; alreadyClosed={AlreadyClosed}.",
                actor,
                sessionId,
                ResolveRemoteAddress(),
                result.AlreadyClosed);

            return DashboardSessionAdminResult.Success(
                result.AlreadyClosed
                    ? $"Session {sessionId} was already closed."
                    : $"Worker for session {sessionId} killed.");
        }
        catch (SessionManagerException exception) when (exception.ErrorCode == SessionManagerErrorCode.SessionNotFound)
        {
            return DashboardSessionAdminResult.Fail($"Session {sessionId} was not found.");
        }
        catch (SessionManagerException exception)
        {
            _logger.LogWarning(
                exception,
                "Dashboard admin {Actor} kill failed for session {SessionId}.",
                actor,
                sessionId);
            return DashboardSessionAdminResult.Fail(
                $"Kill failed: {exception.Message}");
        }
    }

    private static string ResolveActor(ClaimsPrincipal user)
    {
        return user.Identity?.Name ?? "<unknown>";
    }

    private string? ResolveRemoteAddress()
    {
        return httpContextAccessor.HttpContext?.Connection.RemoteIpAddress?.ToString();
    }
}