using GenHTTP.Api.Content;
using GenHTTP.Api.Infrastructure;
using GenHTTP.Api.Protocol;
using GenHTTP.Engine;
using GenHTTP.Modules.Practices;
using InABox.API;
using InABox.Core;
using NPOI.SS.Formula.Functions;
using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Linq;
using System.Net;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;
using System.Timers;
using Timer = System.Timers.Timer;

namespace PRSServices;

public abstract class Handler<TProperties> : IHandler
{
    public IHandler Parent { get; set; }

    public abstract void Init(TProperties properties);

    public abstract ValueTask<IResponse?> HandleAsync(IRequest request);

    public ValueTask PrepareAsync()
    {
        return new ValueTask();
    }

    public IEnumerable<ContentElement> GetContent(IRequest request)
    {
        return Enumerable.Empty<ContentElement>();
    }
}

public class HandlerBuilder<THandler, TProperties> : IHandlerBuilder<HandlerBuilder<THandler, TProperties>> 
    where THandler : Handler<TProperties>, new()
{
    private readonly List<IConcernBuilder> _Concerns = new();

    public HandlerBuilder(TProperties properties)
    {
        Properties = properties;
    }

    private TProperties Properties;

    public HandlerBuilder<THandler, TProperties> Add(IConcernBuilder concern)
    {
        _Concerns.Add(concern);
        return this;
    }

    public IHandler Build(IHandler parent)
    {
        return Concerns.Chain(parent, _Concerns, p => {
            var handler = new THandler { Parent = p };
            handler.Init(Properties);
            return handler;
        });
    }
}

public class Listener<THandler, TProperties> 
    where THandler : Handler<TProperties>, new()
    where TProperties : notnull
{
    private CertificateManager CertificateManager;

    private ushort Port;

    private IServerHost host;
    private TProperties Properties;

    public Listener(TProperties properties)
    {
        CertificateManager = new CertificateManager();
        CertificateManager.UpdateCertificate += CertificateManager_UpdateCertificate;
        CertificateManager.CertificateExpiring += CertificateManager_CertificateExpiring;
        CertificateManager.CertificateExpired += CertificateManager_CertificateExpired;

        Init(properties);
    }

    private void CertificateManager_CertificateExpired()
    {
        Logger.Send(LogType.Information, "", "Expiry of certificate reached; restarting HTTPS listener...");
        Restart();
    }

    private void CertificateManager_CertificateExpiring(DateTime expiry)
    {
        string message;
        if (expiry.Date == DateTime.Now.Date)
        {
            message = $"HTTPS Certificate will expire today at {expiry.TimeOfDay:hh\\:mm}";
        }
        else
        {
            message = $"HTTPS Certificate will expire in {(expiry - DateTime.Now).Days} at {expiry:dd/MM/yyyy hh:mm}";
        }
        Logger.Send(LogType.Information, "", message);
    }

    private void CertificateManager_UpdateCertificate(X509Certificate2 certificate)
    {
        Logger.Send(LogType.Information, "", "HTTPS Certificate with greater expiry date found; restarting HTTPS listener...");
        Restart();
    }

    [MemberNotNull("host", "Properties")]
    public void Init(TProperties properties)
    {
        Properties = properties;
        host = Host.Create()
            .Console()
            .Handler(new HandlerBuilder<THandler, TProperties>(properties))
            .Defaults();
    }

    private void InitCertificate(ushort port, X509Certificate2 certificate)
    {
        host.Bind(IPAddress.Any, port, certificate);
    }

    public void InitPort(ushort port)
    {
        Port = port;
        host.Bind(IPAddress.Any, port);
    }

    public void InitHTTPS(ushort port, string certificateFile)
    {
        Port = port;

        CertificateManager.SetFile(certificateFile);
        var status = CertificateManager.GetCertificate(out var certificate);
        switch (status)
        {
            case CertificateStatus.Valid:
                var names = certificate!.GetNameInfo(X509NameType.DnsName, false);
                Logger.Send(LogType.Information, "", $"Certificate valid for {names}");
                InitCertificate(port, certificate);
                break;
            case CertificateStatus.Expired:
                Logger.Send(LogType.Error, "", "HTTPS Certificate has expired, using HTTP instead");
                InitPort(port);
                break;
            case CertificateStatus.NotFound:
                InitPort(port);
                break;
            case CertificateStatus.Error:
                Logger.Send(LogType.Error, "", "Error validating HTTPS Certificate, using HTTP instead");
                InitPort(port);
                break;
        }
    }

    public void Start()
    {
        host.Start();
    }

    public void Stop()
    {
        host.Stop();
        CertificateManager.Stop();
    }
    private void Restart()
    {
        Clear();
        Init(Properties);

        if(CertificateManager.CertificateFile != null)
        {
            InitHTTPS(Port, CertificateManager.CertificateFile);
        }
        else
        {
            InitPort(Port);
        }
        Start();
    }

    /// <summary>
    /// Clears certificate and host information, and stops the listener.
    /// </summary>
    private void Clear()
    {
        host?.Stop();
        CertificateManager.Clear();
    }
}