global using System;
using System.Collections.Concurrent;
using System.IO;
using System.Linq;
using System.Text.Json;
using DTLib.Demystifier;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using ParadoxSaveParser.Lib;

namespace ParadoxSaveParser.WebAPI;

public enum SaveFileProcessingStatus
{
    Initialized, Uploading, Parsing, SavingResults, Done, Error
}

public enum Game
{
    Unknown, EU4
}

public class SaveFileMetadata
{
    public required string id { get; init; }
    public required Game game { get; init; }
    public required SaveFileProcessingStatus status { get; set; }

    public string? errorMesage { get; set; }
    
    private static readonly JsonSerializerOptions _jsonOptions = new() { WriteIndented = true };
    public void SaveToFile()
    {
        using var metaFile = File.Open(PathHelper.GetMetaFilePath(id), FileMode.CreateNew, FileAccess.Write);
        JsonSerializer.Serialize(metaFile, this, _jsonOptions);
    }
}

public static class PathHelper
{
    
    public const string DATA_DIR = "data";
    public static string SAVES_DIR = Path.Join(DATA_DIR, "saves");
    public static string GetMetaFilePath(string save_id) => Path.Join(SAVES_DIR, save_id + ".meta.json");
    public static string GetEU4SaveFilePath(string save_id) => Path.Join(SAVES_DIR, save_id + ".eu4");
}

public class Program
{
    private static ConcurrentDictionary<string, SaveFileMetadata> _saveMetadataStorage = new();
    private static WebApplication _app = null!;
    
    public static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);
        _app = builder.Build();

        foreach (var metaFilePath in Directory.GetFiles(PathHelper.SAVES_DIR, "*.meta.json", SearchOption.TopDirectoryOnly))
        {
            using var metaFile = File.Open(metaFilePath, FileMode.Open, FileAccess.Read);
            var meta = JsonSerializer.Deserialize<SaveFileMetadata>(metaFile) ?? throw new NullReferenceException(metaFilePath);
            if (meta.status != SaveFileProcessingStatus.Done)
            {
                _app.Logger.Log(LogLevel.Warning, "metadata file '{metaFilePath}' status has invalid status {status}", metaFilePath, meta.status);
            }

            if(!_saveMetadataStorage.TryAdd(meta.id, meta))
                throw new Exception("Guid collision!");
        }
        
        _app.UseHttpsRedirection();
        _app.MapPost("/parse/eu4", (HttpContext httpContext) =>
        {
            var remoteFile = httpContext.Request.Form.Files.FirstOrDefault();
            if(remoteFile is null || !remoteFile.FileName.EndsWith(".eu4"))
                throw new Exception($"Invalid file format: {remoteFile?.FileName}");
            
            string saveId = Guid.NewGuid().ToString();
            string metaFilePath = PathHelper.GetMetaFilePath(saveId);
            if (File.Exists(metaFilePath))
            {
                httpContext.Response.StatusCode = StatusCodes.Status500InternalServerError;
                throw new Exception($"Guid collision! file {metaFilePath} already exists.");
            }
            
            var meta = new SaveFileMetadata
            {
                id = saveId,
                game = Game.EU4,
                status = SaveFileProcessingStatus.Initialized,
            };
            if (!_saveMetadataStorage.TryAdd(saveId, meta))
            {
                throw new Exception($"Guid collision! Can't create metadata with id {saveId}");
            }

            BeginEU4SaveParse(remoteFile, meta);
            return meta;
        });
        
        _app.Run();
    }

    private static async void BeginEU4SaveParse(IFormFile remoteFile, SaveFileMetadata meta)
    {
        try
        {
            meta.status = SaveFileProcessingStatus.Uploading;
            string saveFilePath = PathHelper.GetEU4SaveFilePath(meta.id);
            await using var saveFile = File.Open(saveFilePath, FileMode.CreateNew, FileAccess.ReadWrite);
            await using (var remoteStream = remoteFile.OpenReadStream())
            {
                await remoteStream.CopyToAsync(saveFile);
            }

            meta.status = SaveFileProcessingStatus.Parsing;
            saveFile.Seek(0, SeekOrigin.Begin);
            var parser = new ParserEU4(saveFile);
            //var result = parser.Parse();
            meta.status = SaveFileProcessingStatus.SavingResults;
            // save
            meta.status = SaveFileProcessingStatus.Done;
        }
        catch (Exception ex)
        {
            meta.status = SaveFileProcessingStatus.Error;
            string errorMesage = ex.ToStringDemystified();
            _app.Logger.Log(LogLevel.Error, "EU4SaveParse Error: {errorMesage}", errorMesage);
        }
    }
}