using System.Net;
using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;
using System.Globalization;
using Catalog.Communication.Abstractions;
using Catalog.Communication.Models;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

namespace Catalog.Communication;

public sealed class RaceUploadCommunicationClient : IRaceUploadCommunicationClient
{
    private const string AdminMenuPath = "admin/menu/Menu4.abl";
    private const string PublicLogonPath = "Logon.abl";
    private const string UsersPath = "Users.abl";
    private const string Foto2Path = "Foto2.abl";
    private const string ThumbnailPath = "foto";
    private const string OriginalPath = "fotoOriginali";

    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web)
    {
        PropertyNameCaseInsensitive = true,
    };

    private readonly HttpClient _httpClient;
    private readonly ILogger<RaceUploadCommunicationClient> _logger;
    private readonly IOptions<CatalogCommunicationOptions> _options;

    public RaceUploadCommunicationClient(
        HttpClient httpClient,
        IOptions<CatalogCommunicationOptions> options,
        ILogger<RaceUploadCommunicationClient> logger)
    {
        _httpClient = httpClient;
        _options = options;
        _logger = logger;
    }

    public Task<RawEndpointResponse> LoginAdminAsync(AdminLoginRequest request, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(request);

        var formFields = new Dictionary<string, string?>
        {
            ["login"] = request.Login,
            ["pwd"] = request.Password,
            ["cmdIU"] = request.Command,
        };

        return PostFormAsync(AdminMenuPath, formFields, "admin-login", cancellationToken);
    }

    public Task<RawEndpointResponse> LogoutAdminAsync(CancellationToken cancellationToken = default)
    {
        var formFields = new Dictionary<string, string?>
        {
            ["cmdIU"] = "login",
        };

        return PostFormAsync(AdminMenuPath, formFields, "admin-logout", cancellationToken);
    }

    public Task<UploadImageResponse?> UploadRaceImageAsync(RaceImageUploadRequest request, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(request);

        return PostMultipartAndParseUploadAsync<UploadImageResponse>(
            GetAdminPagePath("Gara"),
            "gara-upload-image",
            request.FileStream,
            request.FileName,
            request.FormFieldName,
            request.ContentType,
            static fields =>
            {
                fields["cmd"] = "loadImg";
            },
            new Dictionary<string, string?>
            {
                ["id"] = request.Id.ToString(System.Globalization.CultureInfo.InvariantCulture),
                ["codImage"] = request.CodImage.ToString(System.Globalization.CultureInfo.InvariantCulture),
                ["totImgNumber"] = request.TotImgNumber?.ToString(System.Globalization.CultureInfo.InvariantCulture),
            },
            cancellationToken);
    }

    public Task<UploadImageResponse?> RemoveRaceImageAsync(RaceImageRemoveRequest request, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(request);

        var fields = new Dictionary<string, string?>
        {
            ["cmd"] = "removeImg",
            ["id"] = request.Id.ToString(System.Globalization.CultureInfo.InvariantCulture),
            ["codImage"] = request.CodImage.ToString(System.Globalization.CultureInfo.InvariantCulture),
            ["totImgNumber"] = request.TotImgNumber?.ToString(System.Globalization.CultureInfo.InvariantCulture),
        };

        return PostFormAndParseUploadAsync<UploadImageResponse>(GetAdminPagePath("Gara"), fields, "gara-remove-image", cancellationToken);
    }

    public Task<UploadFileResponse?> UploadRaceFileAsync(RaceFileUploadRequest request, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(request);

        return PostMultipartAndParseUploadAsync<UploadFileResponse>(
            GetAdminPagePath("Gara"),
            "gara-upload-file",
            request.FileStream,
            request.FileName,
            request.FormFieldName,
            request.ContentType,
            static fields =>
            {
                fields["cmd"] = "saveFile";
            },
            new Dictionary<string, string?>
            {
                ["codFile"] = request.CodFile?.ToString(System.Globalization.CultureInfo.InvariantCulture),
                ["id"] = request.Id?.ToString(System.Globalization.CultureInfo.InvariantCulture),
            },
            cancellationToken);
    }

    public Task<RawEndpointResponse> SaveRaceAsync(RaceSaveRequest request, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(request);

        var formFields = new Dictionary<string, string?>
        {
            ["cmd"] = "asq",
            ["act"] = "save",
            ["id_gara"] = request.IdGara.ToString(CultureInfo.InvariantCulture),
            ["descrizione"] = request.Description,
            ["dataGaraInizio"] = request.StartDate.ToString("dd/MM/yyyy", CultureInfo.InvariantCulture),
            ["dataGaraFine"] = (request.EndDate ?? request.StartDate).ToString("dd/MM/yyyy", CultureInfo.InvariantCulture),
            ["id_tipoGara"] = request.TipoGaraId.ToString(CultureInfo.InvariantCulture),
            ["flgEventoInLinea"] = request.EventoInLinea.ToString(CultureInfo.InvariantCulture),
            ["flgTipoIndex"] = request.TipoIndicizzazione.ToString(CultureInfo.InvariantCulture),
            ["flgFree"] = request.FreeEvent.ToString(CultureInfo.InvariantCulture),
            ["pathBase"] = request.PathBase,
            ["localita"] = request.Localita,
            ["codGara"] = request.CodGara?.ToString(CultureInfo.InvariantCulture),
        };

        return PostFormAsync(GetAdminPagePath("Gara"), formFields, "gara-save", cancellationToken);
    }

    public Task<RawEndpointResponse> CreateRacePointsAsync(long raceId, CancellationToken cancellationToken = default)
    {
        var formFields = new Dictionary<string, string?>
        {
            ["cmd"] = "creaPuntiFoto",
            ["id_gara"] = raceId.ToString(CultureInfo.InvariantCulture),
        };

        return PostFormAsync(GetAdminPagePath("Gara"), formFields, "gara-create-points", cancellationToken);
    }

    public Task<RawEndpointResponse> IndexRacePointAsync(long pointId, CancellationToken cancellationToken = default)
    {
        var formFields = new Dictionary<string, string?>
        {
            ["cmd"] = "indexFoto",
            ["id_puntoFotoIdx"] = pointId.ToString(CultureInfo.InvariantCulture),
        };

        return PostFormAsync(GetAdminPagePath("Gara"), formFields, "gara-index-point", cancellationToken);
    }

    public Task<RawEndpointResponse> GetRaceDetailAsync(long raceId, CancellationToken cancellationToken = default)
    {
        var formFields = new Dictionary<string, string?>
        {
            ["cmd"] = "search",
            ["id_gara"] = raceId.ToString(CultureInfo.InvariantCulture),
        };

        return PostFormAsync(GetAdminPagePath("Gara"), formFields, "gara-detail", cancellationToken);
    }

    public async Task<RawEndpointResponse> UploadFileToReceiverAsync(ReceiveFileUploadRequest request, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(request);
        ArgumentException.ThrowIfNullOrWhiteSpace(request.FileName);
        ArgumentException.ThrowIfNullOrWhiteSpace(request.DestinationPath);
        ArgumentNullException.ThrowIfNull(request.FileStream);

        var payload = await ReadAllBytesAsync(request.FileStream, cancellationToken).ConfigureAwait(false);
        var query = new Dictionary<string, string?>
        {
            ["name"] = request.FileName,
            ["path"] = request.DestinationPath,
            ["overwriteRemoteFile"] = request.OverwriteRemoteFile ? "true" : "false",
            ["bs"] = request.BufferSize?.ToString(CultureInfo.InvariantCulture),
        };

        var path = AppendQuery(GetReceiveFilePath(), query);

        return await ExecuteWithResilienceAsync(
            () =>
            {
                var byteContent = new ByteArrayContent(payload);
                byteContent.Headers.ContentType = new MediaTypeHeaderValue(request.ContentType ?? "application/octet-stream");

                return new HttpRequestMessage(HttpMethod.Post, path)
                {
                    Content = byteContent,
                };
            },
            ToRawResponseAsync,
            "receiver-upload",
            cancellationToken).ConfigureAwait(false);
    }

    public Task<RawEndpointResponse> ExecuteGaraCommandAsync(IReadOnlyDictionary<string, string?> formFields, CancellationToken cancellationToken = default)
    {
        return PostFormAsync(GetAdminPagePath("Gara"), formFields, "gara-command", cancellationToken);
    }

    public Task<RawEndpointResponse> ExecuteAdminPhotoCommandAsync(AdminPhotoEndpoint endpoint, IReadOnlyDictionary<string, string?> formFields, CancellationToken cancellationToken = default)
    {
        var path = endpoint switch
        {
            AdminPhotoEndpoint.Foto => GetAdminPagePath("Foto"),
            AdminPhotoEndpoint.TipoGara => GetAdminPagePath("TipoGara"),
            AdminPhotoEndpoint.LogFoto => GetAdminPagePath("LogFoto"),
            _ => throw new ArgumentOutOfRangeException(nameof(endpoint), endpoint, "Unsupported endpoint."),
        };

        return PostFormAsync(path, formFields, $"photo-admin-{endpoint}", cancellationToken);
    }

    public Task<RawEndpointResponse> ExecutePublicLogonAsync(IReadOnlyDictionary<string, string?> formFields, CancellationToken cancellationToken = default)
    {
        return PostFormAsync(PublicLogonPath, formFields, "public-logon", cancellationToken);
    }

    public Task<RawEndpointResponse> ExecuteUsersAsync(HttpMethod method, IReadOnlyDictionary<string, string?>? formFields = null, CancellationToken cancellationToken = default)
    {
        return SendCommandAsync(method, UsersPath, formFields, "public-users", cancellationToken);
    }

    public Task<RawEndpointResponse> ExecuteFoto2Async(HttpMethod method, IReadOnlyDictionary<string, string?>? formFields = null, CancellationToken cancellationToken = default)
    {
        return SendCommandAsync(method, Foto2Path, formFields, "public-foto2", cancellationToken);
    }

    public Task<MediaFileResponse> DownloadThumbnailAsync(string filename, long? idFoto = null, CancellationToken cancellationToken = default)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(filename);
        return DownloadFileAsync(ThumbnailPath, filename, idFoto, "media-thumbnail", cancellationToken);
    }

    public Task<MediaFileResponse> DownloadOriginalAsync(string filename, long? idFoto = null, CancellationToken cancellationToken = default)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(filename);
        return DownloadFileAsync(OriginalPath, filename, idFoto, "media-original", cancellationToken);
    }

    private Task<RawEndpointResponse> SendCommandAsync(HttpMethod method, string path, IReadOnlyDictionary<string, string?>? formFields, string operationName, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(method);

        if (method == HttpMethod.Get)
        {
            var relativePath = AppendQuery(path, formFields);
            return GetAsync(relativePath, operationName, cancellationToken);
        }

        if (method == HttpMethod.Post)
        {
            return PostFormAsync(path, formFields ?? new Dictionary<string, string?>(), operationName, cancellationToken);
        }

        throw new NotSupportedException($"Only GET and POST are supported. Requested method: {method}.");
    }

    private Task<RawEndpointResponse> GetAsync(string relativePath, string operationName, CancellationToken cancellationToken)
    {
        return ExecuteWithResilienceAsync(
            () => new HttpRequestMessage(HttpMethod.Get, relativePath),
            ToRawResponseAsync,
            operationName,
            cancellationToken);
    }

    private Task<RawEndpointResponse> PostFormAsync(string relativePath, IReadOnlyDictionary<string, string?> formFields, string operationName, CancellationToken cancellationToken)
    {
        return ExecuteWithResilienceAsync(
            () =>
            {
                var request = new HttpRequestMessage(HttpMethod.Post, relativePath)
                {
                    Content = BuildFormContent(formFields),
                };

                return request;
            },
            ToRawResponseAsync,
            operationName,
            cancellationToken);
    }

    private Task<TUpload?> PostFormAndParseUploadAsync<TUpload>(string relativePath, IReadOnlyDictionary<string, string?> formFields, string operationName, CancellationToken cancellationToken)
    {
        return ExecuteWithResilienceAsync(
            () =>
            {
                var request = new HttpRequestMessage(HttpMethod.Post, relativePath)
                {
                    Content = BuildFormContent(formFields),
                };

                return request;
            },
            async (response, token) =>
            {
                var raw = await ToRawResponseAsync(response, token).ConfigureAwait(false);
                return ParseSingleItemArray<TUpload>(raw.Body);
            },
            operationName,
            cancellationToken);
    }

    private async Task<TUpload?> PostMultipartAndParseUploadAsync<TUpload>(
        string relativePath,
        string operationName,
        Stream fileStream,
        string fileName,
        string formFieldName,
        string? contentType,
        Action<Dictionary<string, string?>> configureRequiredFields,
        IReadOnlyDictionary<string, string?> optionalFields,
        CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(fileStream);
        ArgumentException.ThrowIfNullOrWhiteSpace(fileName);
        ArgumentException.ThrowIfNullOrWhiteSpace(formFieldName);

        var payload = await ReadAllBytesAsync(fileStream, cancellationToken).ConfigureAwait(false);

        return await ExecuteWithResilienceAsync(
            () =>
            {
                var multipart = new MultipartFormDataContent();
                var fields = new Dictionary<string, string?>();
                configureRequiredFields(fields);

                foreach (var field in fields)
                {
                    if (string.IsNullOrWhiteSpace(field.Value))
                    {
                        continue;
                    }

                    multipart.Add(new StringContent(field.Value, Encoding.UTF8), field.Key);
                }

                foreach (var field in optionalFields)
                {
                    if (string.IsNullOrWhiteSpace(field.Value))
                    {
                        continue;
                    }

                    multipart.Add(new StringContent(field.Value, Encoding.UTF8), field.Key);
                }

                var fileContent = new ByteArrayContent(payload);
                fileContent.Headers.ContentType = new MediaTypeHeaderValue(contentType ?? "application/octet-stream");
                multipart.Add(fileContent, formFieldName, fileName);

                return new HttpRequestMessage(HttpMethod.Post, relativePath)
                {
                    Content = multipart,
                };
            },
            async (response, token) =>
            {
                var raw = await ToRawResponseAsync(response, token).ConfigureAwait(false);
                return ParseSingleItemArray<TUpload>(raw.Body);
            },
            operationName,
            cancellationToken).ConfigureAwait(false);
    }

    private Task<MediaFileResponse> DownloadFileAsync(string basePath, string filename, long? idFoto, string operationName, CancellationToken cancellationToken)
    {
        var escapedFileName = Uri.EscapeDataString(filename);
        var relativePath = idFoto.HasValue
            ? $"{basePath}/{escapedFileName}?id_foto={idFoto.Value.ToString(System.Globalization.CultureInfo.InvariantCulture)}"
            : $"{basePath}/{escapedFileName}";

        return ExecuteWithResilienceAsync(
            () => new HttpRequestMessage(HttpMethod.Get, relativePath),
            async (response, token) =>
            {
                var content = await response.Content.ReadAsByteArrayAsync(token).ConfigureAwait(false);
                return new MediaFileResponse
                {
                    StatusCode = response.StatusCode,
                    Content = content,
                    ContentType = response.Content.Headers.ContentType?.MediaType,
                    FileName = response.Content.Headers.ContentDisposition?.FileNameStar ?? response.Content.Headers.ContentDisposition?.FileName,
                    Headers = BuildHeaders(response),
                };
            },
            operationName,
            cancellationToken);
    }

    private async Task<TResponse> ExecuteWithResilienceAsync<TResponse>(
        Func<HttpRequestMessage> requestFactory,
        Func<HttpResponseMessage, CancellationToken, Task<TResponse>> responseFactory,
        string operationName,
        CancellationToken cancellationToken)
    {
        var options = _options.Value;
        Exception? lastException = null;

        for (var attempt = 0; attempt <= options.RetryCount; attempt++)
        {
            using var request = requestFactory();
            using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
            timeoutCts.CancelAfter(options.RequestTimeout);

            HttpResponseMessage? response = null;

            try
            {
                response = await _httpClient
                    .SendAsync(request, HttpCompletionOption.ResponseHeadersRead, timeoutCts.Token)
                    .ConfigureAwait(false);

                if (IsRetryableStatusCode(response.StatusCode) && attempt < options.RetryCount)
                {
                    _logger.LogWarning(
                        "Operation {OperationName} received retryable status code {StatusCode} at attempt {Attempt}/{MaxAttempts}.",
                        operationName,
                        (int)response.StatusCode,
                        attempt + 1,
                        options.RetryCount + 1);

                    await DelayBeforeRetryAsync(options, attempt, cancellationToken).ConfigureAwait(false);
                    continue;
                }

                return await responseFactory(response, cancellationToken).ConfigureAwait(false);
            }
            catch (OperationCanceledException ex) when (!cancellationToken.IsCancellationRequested)
            {
                lastException = ex;

                if (attempt < options.RetryCount)
                {
                    _logger.LogWarning(ex, "Operation {OperationName} timed out at attempt {Attempt}/{MaxAttempts}.", operationName, attempt + 1, options.RetryCount + 1);
                    await DelayBeforeRetryAsync(options, attempt, cancellationToken).ConfigureAwait(false);
                    continue;
                }

                _logger.LogError(ex, "Operation {OperationName} timed out after {MaxAttempts} attempts.", operationName, options.RetryCount + 1);
                throw;
            }
            catch (HttpRequestException ex)
            {
                lastException = ex;

                if (attempt < options.RetryCount)
                {
                    _logger.LogWarning(ex, "Operation {OperationName} failed with transient HTTP error at attempt {Attempt}/{MaxAttempts}.", operationName, attempt + 1, options.RetryCount + 1);
                    await DelayBeforeRetryAsync(options, attempt, cancellationToken).ConfigureAwait(false);
                    continue;
                }

                _logger.LogError(ex, "Operation {OperationName} failed with HTTP error after {MaxAttempts} attempts.", operationName, options.RetryCount + 1);
                throw;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Operation {OperationName} failed with unexpected error at attempt {Attempt}/{MaxAttempts}.", operationName, attempt + 1, options.RetryCount + 1);
                throw;
            }
            finally
            {
                response?.Dispose();
            }
        }

        throw new HttpRequestException($"Operation '{operationName}' failed after {options.RetryCount + 1} attempts.", lastException);
    }

    private static bool IsRetryableStatusCode(HttpStatusCode statusCode)
    {
        return statusCode is HttpStatusCode.RequestTimeout
            or HttpStatusCode.TooManyRequests
            or HttpStatusCode.BadGateway
            or HttpStatusCode.ServiceUnavailable
            or HttpStatusCode.GatewayTimeout
            or HttpStatusCode.InternalServerError;
    }

    private static async Task DelayBeforeRetryAsync(CatalogCommunicationOptions options, int attempt, CancellationToken cancellationToken)
    {
        var delay = TimeSpan.FromMilliseconds(options.RetryBaseDelay.TotalMilliseconds * Math.Pow(2, attempt));
        await Task.Delay(delay, cancellationToken).ConfigureAwait(false);
    }

    private static FormUrlEncodedContent BuildFormContent(IReadOnlyDictionary<string, string?> formFields)
    {
        var pairs = formFields
            .Where(kvp => !string.IsNullOrWhiteSpace(kvp.Value))
            .Select(kvp => new KeyValuePair<string, string>(kvp.Key, kvp.Value!));

        return new FormUrlEncodedContent(pairs);
    }

    private static string AppendQuery(string path, IReadOnlyDictionary<string, string?>? query)
    {
        if (query is null || query.Count == 0)
        {
            return path;
        }

        var encodedPairs = query
            .Where(kvp => !string.IsNullOrWhiteSpace(kvp.Value))
            .Select(kvp => $"{Uri.EscapeDataString(kvp.Key)}={Uri.EscapeDataString(kvp.Value!)}")
            .ToArray();

        if (encodedPairs.Length == 0)
        {
            return path;
        }

        var separator = path.Contains('?', StringComparison.Ordinal) ? "&" : "?";
        return string.Concat(path, separator, string.Join("&", encodedPairs));
    }

    private static async Task<RawEndpointResponse> ToRawResponseAsync(HttpResponseMessage response, CancellationToken cancellationToken)
    {
        var body = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);

        return new RawEndpointResponse
        {
            StatusCode = response.StatusCode,
            Body = body,
            Headers = BuildHeaders(response),
        };
    }

    private static IReadOnlyDictionary<string, IReadOnlyList<string>> BuildHeaders(HttpResponseMessage response)
    {
        var headers = new Dictionary<string, IReadOnlyList<string>>(StringComparer.OrdinalIgnoreCase);

        foreach (var header in response.Headers)
        {
            headers[header.Key] = header.Value.ToArray();
        }

        foreach (var header in response.Content.Headers)
        {
            headers[header.Key] = header.Value.ToArray();
        }

        return headers;
    }

    private static TUpload? ParseSingleItemArray<TUpload>(string json)
    {
        if (string.IsNullOrWhiteSpace(json))
        {
            return default;
        }

        var items = JsonSerializer.Deserialize<List<TUpload>>(json, JsonOptions);
        return items is { Count: > 0 } ? items[0] : default;
    }

    private static async Task<byte[]> ReadAllBytesAsync(Stream stream, CancellationToken cancellationToken)
    {
        if (stream.CanSeek)
        {
            stream.Position = 0;
        }

        using var memoryStream = new MemoryStream();
        await stream.CopyToAsync(memoryStream, cancellationToken).ConfigureAwait(false);
        return memoryStream.ToArray();
    }

    private string GetAdminPagePath(string pageName)
    {
        var basePath = _options.Value.AdminPageBasePath.Trim('/');
        return $"{basePath}/{pageName}.abl";
    }

    private string GetReceiveFilePath()
    {
        var value = _options.Value.ReceiveFilePath;
        if (string.IsNullOrWhiteSpace(value))
        {
            return "ReceiveFile.abl";
        }

        return value.Trim();
    }
}