using System.IO.Compression;
using System.Linq;
using System.Net;

namespace ParadoxSaveParser.WebAPI;

public partial class Program
{
    private static async Task<HttpStatusCode> UploadSaveHandler(HttpListenerContext ctx)
    {
        string? contentType = ctx.Request.Headers.GetValues("Content-Type")?.FirstOrDefault();
        if (contentType != "application/octet-stream")
            return await ReturnResponseError(ctx, new ErrorMessage(
                HttpStatusCode.BadRequest,
                $"Invalid request Content-Type: '{contentType}'"));

        string saveId = Guid.NewGuid().ToString();
        var metaFilePath = PathHelper.GetMetaFilePath(saveId);
        if (File.Exists(metaFilePath))
            return await ReturnResponseError(ctx, new ErrorMessage(
                HttpStatusCode.InternalServerError,
                $"Guid collision! file' {metaFilePath}' already exists."));

        var meta = new SaveFileMetadata
            { id = saveId, game = Game.EU4, status = SaveFileProcessingStatus.Initialized };
        if (!_saveMetadataStorage.TryAdd(saveId, meta))
            return await ReturnResponseError(ctx, new ErrorMessage(
                HttpStatusCode.InternalServerError,
                $"Guid collision! Can't create metadata with id {saveId}"));

        meta.status = SaveFileProcessingStatus.Uploading;
        var saveFilePath = PathHelper.GetSaveFilePath(meta.id);
        await using var saveFile = File.OpenWrite(saveFilePath);
        await using var remoteStream = ctx.Request.InputStream;
        await remoteStream.CopyToAsync(saveFile, _mainCancel.Token);
        meta.status = SaveFileProcessingStatus.Uploaded;

        return await ReturnResponseString(ctx, saveId);
    }

    private static ValueOrError<SaveFileMetadata> GetMetaFromRequestId(HttpListenerContext ctx,
        string requestParamName)
    {
        var idOrError = GetRequestQueryValue(ctx, requestParamName);
        if (idOrError.HasError)
            return idOrError.Error!;

        if (!_saveMetadataStorage.TryGetValue(idOrError.Value!, out var meta))
            return new ErrorMessage(HttpStatusCode.InternalServerError,
                $"Save with id {idOrError.Value} not found");

        return meta;
    }

    private static async Task<HttpStatusCode> GetSaveStatusHandler(HttpListenerContext ctx)
    {
        var metaOrError = GetMetaFromRequestId(ctx, "id");
        if (metaOrError.HasError)
            return await ReturnResponseError(ctx, metaOrError.Error!);

        return await ReturnResponseJson(ctx, metaOrError.Value!);
    }

    private static async Task<HttpStatusCode> ParseSaveEU4Handler(HttpListenerContext ctx)
    {
        var metaOrError = GetMetaFromRequestId(ctx, "id");
        if (metaOrError.HasError)
            return await ReturnResponseError(ctx, metaOrError.Error!);
        var meta = metaOrError.Value!;

        var searchQueryOrError = GetRequestQueryValue(ctx, "search");
        if (searchQueryOrError.HasError)
            return await ReturnResponseError(ctx, searchQueryOrError.Error!);
        string searchQuery = searchQueryOrError.Value!;

        try
        {
            string extractedGamestatePath = PathHelper.GetSaveFilePath(meta.id) + ".gamestate";
            using (var zipArchive = ZipFile.Open(PathHelper.GetSaveFilePath(meta.id).Str, ZipArchiveMode.Read))
            {
                var zipEntry = zipArchive.Entries.FirstOrDefault(e => e.Name == "gamestate");
                if (zipEntry is null)
                    return await ReturnResponseError(ctx, new ErrorMessage(
                        HttpStatusCode.BadRequest,
                        "Invalid save format: no 'gamestate' file found"));

                zipEntry.ExtractToFile(extractedGamestatePath, true);
            }

            var gamestateStream = File.OpenRead(extractedGamestatePath);

            meta.status = SaveFileProcessingStatus.Parsing;
            var se = SearchExpressionCompiler.Compile(searchQuery);
            var parser = new SaveParserEU4(gamestateStream, se);
            var result = parser.Parse();

            meta.status = SaveFileProcessingStatus.SavingResults;
            var resultFilePath = PathHelper.GetParsedSaveFilePath(meta.id);
            await using var resultFile = File.OpenWrite(resultFilePath);
            await JsonSerializer.SerializeAsync(resultFile, result, _saveSerializerOptions, _mainCancel.Token);
            meta.status = SaveFileProcessingStatus.Done;
            meta.SaveToFile();
        }
        catch (Exception ex)
        {
            string errorMesage = ex.ToStringDemystified();
            _loggerRoot.LogWarn(nameof(ParseSaveEU4Handler), errorMesage);
            return await ReturnResponseError(ctx, new ErrorMessage(HttpStatusCode.BadRequest, errorMesage));
        }
        finally
        {
            GC.Collect(GC.MaxGeneration, GCCollectionMode.Aggressive, true, true);
        }

        return await ReturnResponseJson(ctx, meta);
    }
}