using System;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace FastGithub.DnscryptProxy
{
    /// <summary>
    /// DnscryptProxy服务
    /// </summary>
    sealed class DnscryptProxyService
    {
        private const string name = "dnscrypt-proxy";
        private readonly FastGithubConfig fastGithubConfig;

        /// <summary>
        /// 获取相关进程
        /// </summary>
        public Process? Process { get; private set; }

        /// <summary>
        /// 获取服务控制状态
        /// </summary>
        public ControllState ControllState { get; private set; } = ControllState.None;

        /// <summary>
        /// DnscryptProxy服务
        /// </summary>
        /// <param name="fastGithubConfig"></param>
        public DnscryptProxyService(FastGithubConfig fastGithubConfig)
        {
            this.fastGithubConfig = fastGithubConfig;
        }

        /// <summary>
        /// 启动dnscrypt-proxy
        /// </summary>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task StartAsync(CancellationToken cancellationToken)
        {
            this.ControllState = ControllState.Started;

            var tomlPath = $"{name}.toml";
            await TomlUtil.SetListensAsync(tomlPath, this.fastGithubConfig.PureDns, cancellationToken);

            foreach (var process in Process.GetProcessesByName(name))
            {
                process.Kill();
            }

            if (OperatingSystem.IsWindows())
            {
                StartDnscryptProxy("-service uninstall")?.WaitForExit();
                StartDnscryptProxy("-service install")?.WaitForExit();
                StartDnscryptProxy("-service start")?.WaitForExit();
                this.Process = Process.GetProcessesByName(name).FirstOrDefault(item => item.SessionId == 0);
            }
            else
            {
                this.Process = StartDnscryptProxy(string.Empty);
            }
        }


        /// <summary>
        /// 停止dnscrypt-proxy
        /// </summary>
        public void Stop()
        {
            this.ControllState = ControllState.Stopped;

            if (OperatingSystem.IsWindows())
            {
                StartDnscryptProxy("-service stop")?.WaitForExit();
                StartDnscryptProxy("-service uninstall")?.WaitForExit();
            }

            if (this.Process != null && this.Process.HasExited == false)
            {
                this.Process.Kill();
            }
        }

        /// <summary>
        /// 启动DnscryptProxy进程
        /// </summary>
        /// <param name="arguments"></param> 
        private static Process? StartDnscryptProxy(string arguments)
        {
            return Process.Start(new ProcessStartInfo
            {
                FileName = OperatingSystem.IsWindows() ? $"{name}.exe" : name,
                Arguments = arguments,
                UseShellExecute = true,
                CreateNoWindow = true,
                WindowStyle = ProcessWindowStyle.Hidden
            });
        }

        /// <summary>
        /// 转换为字符串
        /// </summary>
        /// <returns></returns>
        public override string ToString()
        {
            return name;
        }
    }
}