using System.Net;
using WebDav;

namespace ServiceLib.Handler;

public sealed class WebDavHandler
{
    private static readonly Lazy<WebDavHandler> _instance = new(() => new());
    public static WebDavHandler Instance => _instance.Value;

    private readonly Config? _config;
    private WebDavClient? _client;
    private string? _lastDescription;
    private string _webDir = Global.AppName + "_backup";
    private readonly string _webFileName = "backup.zip";
    private readonly string _tag = "WebDav--";

    public WebDavHandler()
    {
        _config = AppHandler.Instance.Config;
    }

    private async Task<bool> GetClient()
    {
        try
        {
            if (_config.WebDavItem.Url.IsNullOrEmpty()
            || _config.WebDavItem.UserName.IsNullOrEmpty()
            || _config.WebDavItem.Password.IsNullOrEmpty())
            {
                throw new ArgumentException("webdav parameter error or null");
            }
            if (_client != null)
            {
                _client?.Dispose();
                _client = null;
            }
            if (_config.WebDavItem.DirName.IsNullOrEmpty())
            {
                _webDir = Global.AppName + "_backup";
            }
            else
            {
                _webDir = _config.WebDavItem.DirName.TrimEx();
            }

            var clientParams = new WebDavClientParams
            {
                BaseAddress = new Uri(_config.WebDavItem.Url),
                Credentials = new NetworkCredential(_config.WebDavItem.UserName, _config.WebDavItem.Password)
            };
            _client = new WebDavClient(clientParams);
        }
        catch (Exception ex)
        {
            SaveLog(ex);
            return false;
        }
        return await Task.FromResult(true);
    }

    private async Task<bool> TryCreateDir()
    {
        if (_client is null)
        {
            return false;
        }
        try
        {
            var result2 = await _client.Mkcol(_webDir);
            if (result2.IsSuccessful)
            {
                return true;
            }
            SaveLog(result2.Description);
        }
        catch (Exception ex)
        {
            SaveLog(ex);
        }
        return false;
    }

    private void SaveLog(string desc)
    {
        _lastDescription = desc;
        Logging.SaveLog(_tag + desc);
    }

    private void SaveLog(Exception ex)
    {
        _lastDescription = ex.Message;
        Logging.SaveLog(_tag, ex);
    }

    public async Task<bool> CheckConnection()
    {
        if (await GetClient() == false)
        {
            return false;
        }
        await TryCreateDir();

        try
        {
            var testName = "readme_test";
            var myContent = new StringContent(testName);
            var result = await _client.PutFile($"{_webDir}/{testName}", myContent);
            if (result.IsSuccessful)
            {
                await _client.Delete($"{_webDir}/{testName}");
                return true;
            }
            else
            {
                SaveLog(result.Description);
            }
        }
        catch (Exception ex)
        {
            SaveLog(ex);
        }
        return false;
    }

    public async Task<bool> PutFile(string fileName)
    {
        if (await GetClient() == false)
        {
            return false;
        }
        await TryCreateDir();

        try
        {
            await using var fs = File.OpenRead(fileName);
            var result = await _client.PutFile($"{_webDir}/{_webFileName}", fs); // upload a resource
            if (result.IsSuccessful)
            {
                return true;
            }

            SaveLog(result.Description);
        }
        catch (Exception ex)
        {
            SaveLog(ex);
        }
        return false;
    }

    public async Task<bool> GetRawFile(string fileName)
    {
        if (await GetClient() == false)
        {
            return false;
        }
        await TryCreateDir();

        try
        {
            var response = await _client.GetRawFile($"{_webDir}/{_webFileName}");
            if (!response.IsSuccessful)
            {
                SaveLog(response.Description);
                return false;
            }

            await using var outputFileStream = new FileStream(fileName, FileMode.Create);
            await response.Stream.CopyToAsync(outputFileStream);
            return true;
        }
        catch (Exception ex)
        {
            SaveLog(ex);
        }
        return false;
    }

    public string GetLastError() => _lastDescription ?? string.Empty;
}