using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Net;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Threading;
using System.Threading.Tasks;
using ReactiveUI.Fody.Helpers;
using Wabbajack.Compression.Zip;
using Wabbajack.Downloaders.Http;
using Wabbajack.DTOs;
using Wabbajack.DTOs.DownloadStates;
using Wabbajack.DTOs.Logins;
using Wabbajack.Networking.Http.Interfaces;
using Wabbajack.Networking.NexusApi;
using Wabbajack.Paths;
using Wabbajack.Paths.IO;

namespace Wabbajack.Launcher.ViewModels;

public class MainWindowViewModel : ViewModelBase
{
    private readonly WebClient _client = new();
    private readonly List<string> _errors = new();

    private (Version Version, long Size, Func<Task<Uri>> Uri) _version;
    public Uri GITHUB_REPO = new("https://api.github.com/repos/wabbajack-tools/wabbajack/releases");
    private readonly NexusApi _nexusApi;
    private readonly HttpDownloader _downloader;
    private readonly ITokenProvider<NexusApiState> _tokenProvider;

    public MainWindowViewModel(NexusApi nexusApi, HttpDownloader downloader, ITokenProvider<NexusApiState> tokenProvider)
    {
        _nexusApi = nexusApi;
        Status = "Checking for new versions";
        _downloader = downloader;
        _tokenProvider = tokenProvider;
        var tsk = CheckForUpdates();
    }

    [Reactive] public string Status { get; set; }

    private async Task CheckForUpdates()
    {
        _client.Headers.Add("user-agent", "Wabbajack Launcher");
        Status = "Selecting Release";

        try
        {

            if (_tokenProvider.HaveToken())
            {
                _version = await GetNexusReleases(CancellationToken.None);
            }

            if (_version == default)
            {
                _version = await GetGithubRelease(CancellationToken.None);
            }


        }
        catch (Exception ex)
        {
            _errors.Add(ex.Message);
            await FinishAndExit();
        }

        if (_version == default)
        {
            _errors.Add("Unable to find releases");
            await FinishAndExit();
        }

        Status = "Looking for Updates";

        var baseFolder = KnownFolders.CurrentDirectory.Combine(_version.Version.ToString());

        if (baseFolder.Combine("Wabbajack.exe").FileExists()) await FinishAndExit();

        Status = $"Getting download Uri for {_version.Version}";
        var uri = await _version.Uri();

        var wc = new WebClient();
        wc.DownloadProgressChanged += UpdateProgress;
        Status = $"Downloading {_version.Version} ...";
        byte[] data;
        try
        {
            data = await wc.DownloadDataTaskAsync(uri);
        }
        catch (Exception ex)
        {
            _errors.Add(ex.Message);
            // Something went wrong so fallback to original URL
            try
            {
                data = await wc.DownloadDataTaskAsync(uri);
            }
            catch (Exception ex2)
            {
                _errors.Add(ex2.Message);
                await FinishAndExit();
                throw; // avoid unsigned variable 'data'
            }
        }

        try
        {
            using var zip = new ZipArchive(new MemoryStream(data), ZipArchiveMode.Read);
            foreach (var entry in zip.Entries)
            {
                Status = $"Extracting: {entry.Name}";
                var outPath = baseFolder.Combine(entry.FullName.ToRelativePath());
                if (!outPath.Parent.DirectoryExists())
                    outPath.Parent.CreateDirectory();

                if (entry.FullName.EndsWith("/") || entry.FullName.EndsWith("\\"))
                    continue;
                await using var o = entry.Open();
                await using var of = outPath.Open(FileMode.Create, FileAccess.Write, FileShare.None);
                await o.CopyToAsync(of);
            }
        }
        catch (Exception ex)
        {
            _errors.Add(ex.Message);
        }
        finally
        {
            await FinishAndExit();
        }
    }

    private async Task FinishAndExit()
    {
        try
        {
            Status = "Launching...";
            var wjFolder = KnownFolders.CurrentDirectory.EnumerateDirectories()
                .OrderByDescending(v =>
                    Version.TryParse(v.FileName.ToString(), out var ver) ? ver : new Version(0, 0, 0, 0))
                .FirstOrDefault();

            var filename = wjFolder.Combine("Wabbajack.exe");
            await CreateBatchFile(filename);
            var info = new ProcessStartInfo
            {
                FileName = filename.ToString(),
                Arguments = string.Join(" ",
                    Environment.GetCommandLineArgs().Skip(1).Select(s => s.Contains(' ') ? '\"' + s + '\"' : s)),
                WorkingDirectory = wjFolder.ToString()
            };
            Process.Start(info);
        }
        catch (Exception)
        {
            if (_errors.Count == 0)
            {
                Status = "Failed: Unknown error";
                await Task.Delay(10000);
            }

            foreach (var error in _errors)
            {
                Status = "Failed: " + error;
                await Task.Delay(10000);
            }
        }
        finally
        {
            Environment.Exit(0);
        }
    }

    private async Task CreateBatchFile(AbsolutePath filename)
    {
        filename = filename.Parent.Combine("wabbajack-cli.exe");
        var data = $"\"{filename}\" %*";
        var file = Path.Combine(Directory.GetCurrentDirectory(), "wabbajack-cli.bat");
        if (File.Exists(file) && await File.ReadAllTextAsync(file) == data) return;
        await File.WriteAllTextAsync(file, data);
    }

    private void UpdateProgress(object sender, DownloadProgressChangedEventArgs e)
    {
        Status = $"Downloading {_version.Version} ({e.ProgressPercentage}%)...";
    }

    private async Task<(Version Version, long Size, Func<Task<Uri>> Uri)> GetGithubRelease(CancellationToken token)
    {
        var releases = await GetGithubReleases();
        
        
        var version = releases.Select(r =>
        {
            if (r.Tag.Split(".").Length == 4 && Version.TryParse(r.Tag, out var v))
                return (v, r);
            return (new Version(0, 0, 0, 0), r);
        })
            .OrderByDescending(r => r.Item1)
            .FirstOrDefault();
        
        var asset = version.r.Assets.FirstOrDefault(a => a.Name == version.Item1 + ".zip");
        if (asset == null)
        {
            Status = $"Error, no asset found for Github Release {version.r}";
            return default;
        }

        return (version.Item1, asset.Size, async () => asset!.BrowserDownloadUrl);
    }
    
    private async Task<Release[]> GetGithubReleases()
    {
        Status = "Checking GitHub Repository";
        var data = await _client.DownloadStringTaskAsync(GITHUB_REPO);
        Status = "Parsing Response";
        return JsonSerializer.Deserialize<Release[]>(data)!;
    }
    
    private async Task<(Version Version, long Size, Func<Task<Uri>> uri)> GetNexusReleases(CancellationToken token)
    {
        Status = "Checking Nexus for updates";
        if (!await _nexusApi.IsPremium(token))
            return default;
        
        var data = await _nexusApi.ModFiles("site", 403, token);
        Status = "Parsing Response";
        //return JsonSerializer.Deserialize<Release[]>(data)!;

        var found = data.info.Files.Where(f => f.CategoryId == 5)
            .Where(f => f.Name.EndsWith(".zip"))
            .Select(f => Version.TryParse(f.Name[..^4], out var version) ? (version, f.SizeInBytes ?? f.Size,  f.FileId) : default)
            .FirstOrDefault(f => f != default);
        if (found == default) return default;

        return (found.version, found.Item2, async () =>
        {
            var link = await _nexusApi.DownloadLink("site", 403, found.FileId, token);

            return link.info.First().URI;
        });
    }


    private class Release
    {
        [JsonPropertyName("tag_name")] public string Tag { get; set; }

        [JsonPropertyName("assets")] public Asset[] Assets { get; set; }
    }

    private class Asset
    {
        [JsonPropertyName("browser_download_url")]
        public Uri BrowserDownloadUrl { get; set; }

        [JsonPropertyName("name")] public string Name { get; set; }

        
        [JsonPropertyName("size")] public long Size { get; set; }
    }
}