using System.Collections.Generic;
using System.Net.Http;
using System.Text.Json;
using System.Text.Json.Serialization;
using CMSMicroservice.Application.Common.Interfaces;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

namespace CMSMicroservice.Infrastructure.Services.Payment;

/// <summary>
/// درگاه پرداخت بیست‌کارت (20Card IPG Merchant API).
/// مبلغ ورودی به تومان است. درخواست‌ها به‌صورت multipart/form-data ارسال می‌شوند.
/// </summary>
public class TwentyCardPaymentService : IPaymentGatewayService
{
    private readonly HttpClient _httpClient;
    private readonly ILogger<TwentyCardPaymentService> _logger;
    private readonly string _terminalId;
    private readonly string _terminalUsername;
    private readonly string _terminalPassword;
    private readonly string _defaultEmail;

    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        PropertyNameCaseInsensitive = true,
        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
    };

    public TwentyCardPaymentService(
        HttpClient httpClient,
        IConfiguration configuration,
        ILogger<TwentyCardPaymentService> logger)
    {
        _httpClient = httpClient;
        _logger = logger;

        var baseUrl = configuration["TwentyCard:BaseUrl"]
            ?? throw new InvalidOperationException("TwentyCard:BaseUrl is not configured.");
        _terminalId = configuration["TwentyCard:TerminalId"]
            ?? throw new InvalidOperationException("TwentyCard:TerminalId is not configured.");
        _terminalUsername = configuration["TwentyCard:TerminalUsername"]
            ?? throw new InvalidOperationException("TwentyCard:TerminalUsername is not configured.");
        _terminalPassword = configuration["TwentyCard:TerminalPassword"]
            ?? throw new InvalidOperationException("TwentyCard:TerminalPassword is not configured.");
        _defaultEmail = configuration["TwentyCard:DefaultEmail"] ?? "info@kbs2.ir";

        _httpClient.BaseAddress = new Uri(baseUrl.TrimEnd('/') + "/");
        if (!_httpClient.DefaultRequestHeaders.Contains("Accept"))
            _httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Accept", "application/json");
        _logger.LogInformation("TwentyCard payment service initialized. BaseUrl={BaseUrl}", baseUrl);
    }

    public async Task<PaymentInitiateResult> InitiatePaymentAsync(
        PaymentRequest request,
        CancellationToken cancellationToken = default)
    {
        try
        {
            // ۲۰کارت amount را به ریال می‌گیرد (تومان × ۱۰)
            var amountRial = ((long)request.Amount) * 10L;
            var amount = amountRial.ToString();
            var payerName = string.IsNullOrWhiteSpace(request.Name)
                ? (string.IsNullOrWhiteSpace(request.Mobile) ? "کاربر" : request.Mobile)
                : request.Name.Trim();
            var invoice = string.IsNullOrWhiteSpace(request.Invoice)
                ? request.UserId.ToString()
                : request.Invoice;

            using var content = BuildForm(new Dictionary<string, string>
            {
                ["terminal_id"] = _terminalId,
                ["terminal_username"] = _terminalUsername,
                ["terminal_password"] = _terminalPassword,
                ["amount"] = amount,
                ["name"] = payerName,
                ["mobile"] = request.Mobile ?? string.Empty,
                ["invoice"] = invoice,
                ["callback"] = request.CallbackUrl,
                ["description"] = request.Description ?? string.Empty,
                // بدون email درگاه ۲۰کارت به‌جای validation، HTTP 500 برمی‌گرداند
                ["email"] = ResolveEmail(request.Email)
            });

            if (!string.IsNullOrWhiteSpace(request.NationalId))
                AddFormField(content, "national_id", request.NationalId);

            _logger.LogInformation(
                "TwentyCard payment request: Amount={AmountToman} Toman ({AmountRial} Rial), User={UserId}, Invoice={Invoice}",
                (long)request.Amount, amountRial, request.UserId, invoice);

            var response = await _httpClient.PostAsync("api/pgw/merchant/request", content, cancellationToken);
            var responseBody = await response.Content.ReadAsStringAsync(cancellationToken);

            if (!response.IsSuccessStatusCode)
            {
                _logger.LogError(
                    "TwentyCard HTTP error on request: StatusCode={StatusCode}, Body={Body}",
                    (int)response.StatusCode, responseBody);

                return new PaymentInitiateResult
                {
                    IsSuccess = false,
                    ErrorMessage = $"خطای ارتباط با درگاه ۲۰کارت (HTTP {(int)response.StatusCode})"
                };
            }

            var result = JsonSerializer.Deserialize<TwentyCardRequestResponse>(responseBody, JsonOptions);
            var authority = result?.Data?.Authority;
            var redirectUrl = result?.Data?.RedirectUrl;

            if (string.IsNullOrWhiteSpace(authority) || string.IsNullOrWhiteSpace(redirectUrl))
            {
                _logger.LogError("TwentyCard request failed. Body={Body}", responseBody);
                return new PaymentInitiateResult
                {
                    IsSuccess = false,
                    ErrorMessage = result?.Message
                        ?? result?.Error?.Message
                        ?? "ایجاد تراکنش ۲۰کارت ناموفق بود"
                };
            }

            return new PaymentInitiateResult
            {
                IsSuccess = true,
                RefId = authority,
                GatewayUrl = redirectUrl
            };
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "TwentyCard InitiatePayment failed");
            return new PaymentInitiateResult
            {
                IsSuccess = false,
                ErrorMessage = "خطا در ارتباط با درگاه ۲۰کارت"
            };
        }
    }

    public Task<PaymentVerificationResult> VerifyPaymentAsync(
        string refId,
        string verificationToken,
        CancellationToken cancellationToken = default)
        => throw new NotImplementedException("TwentyCard requires VerifyPaymentAsync with amount.");

    public async Task<PaymentVerificationResult> VerifyPaymentAsync(
        string refId,
        string verificationToken,
        decimal amountInToman,
        CancellationToken cancellationToken = default)
    {
        try
        {
            if (!string.Equals(verificationToken, "OK", StringComparison.OrdinalIgnoreCase))
            {
                return new PaymentVerificationResult
                {
                    IsSuccess = false,
                    RefId = refId,
                    Message = "پرداخت توسط کاربر لغو شد یا ناموفق بود",
                    VerificationCode = 0
                };
            }

            using var content = BuildForm(new Dictionary<string, string>
            {
                ["terminal_id"] = _terminalId,
                ["terminal_username"] = _terminalUsername,
                ["terminal_password"] = _terminalPassword,
                ["authority"] = refId,
                ["amount"] = (((long)amountInToman) * 10L).ToString()
            });

            var response = await _httpClient.PostAsync("api/pgw/merchant/verify", content, cancellationToken);
            var responseBody = await response.Content.ReadAsStringAsync(cancellationToken);

            _logger.LogInformation(
                "TwentyCard verify response: Authority={Authority}, StatusCode={StatusCode}, Body={Body}",
                refId, (int)response.StatusCode, responseBody);

            var result = JsonSerializer.Deserialize<TwentyCardVerifyResponse>(responseBody, JsonOptions);

            var paid = result?.Status?.Paid == true;
            var verified = result?.Status?.Verified == true;
            var noError = result?.Error != true;

            if (response.IsSuccessStatusCode && noError && paid && verified)
            {
                return new PaymentVerificationResult
                {
                    IsSuccess = true,
                    RefId = refId,
                    TrackingCode = refId,
                    Message = result?.Message ?? "تراکنش با موفقیت تایید شد",
                    VerificationCode = result?.Code ?? 200
                };
            }

            // Code 103 = already verified — treat as success for idempotency
            if (result?.Code == 103)
            {
                return new PaymentVerificationResult
                {
                    IsSuccess = true,
                    RefId = refId,
                    TrackingCode = refId,
                    Message = result.Message ?? "تراکنش قبلاً تایید شده است",
                    VerificationCode = 103
                };
            }

            return new PaymentVerificationResult
            {
                IsSuccess = false,
                RefId = refId,
                Message = result?.Message ?? "تایید تراکنش ۲۰کارت ناموفق بود",
                VerificationCode = result?.Code ?? (int)response.StatusCode
            };
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "TwentyCard VerifyPayment failed. Authority={Authority}", refId);
            return new PaymentVerificationResult
            {
                IsSuccess = false,
                RefId = refId,
                Message = "خطا در تایید تراکنش ۲۰کارت"
            };
        }
    }

    public Task<PayoutResult> ProcessPayoutAsync(
        PayoutRequest request,
        CancellationToken cancellationToken = default)
    {
        return Task.FromResult(new PayoutResult
        {
            IsSuccess = false,
            Message = "واریز از طریق درگاه ۲۰کارت پشتیبانی نمی‌شود"
        });
    }

    private static MultipartFormDataContent BuildForm(Dictionary<string, string> fields)
    {
        var form = new MultipartFormDataContent();
        foreach (var (key, value) in fields)
            AddFormField(form, key, value ?? string.Empty);
        return form;
    }

    /// <summary>
    /// شبیه curl --form: بدون Content-Type روی هر part ( بعضی بک‌اندهای PHP با charset=utf-8 می‌شکنند).
    /// </summary>
    private static void AddFormField(MultipartFormDataContent form, string name, string value)
    {
        var part = new StringContent(value ?? string.Empty);
        part.Headers.ContentType = null;
        form.Add(part, name);
    }

    private string ResolveEmail(string? email)
    {
        if (!string.IsNullOrWhiteSpace(email) && email.Contains('@', StringComparison.Ordinal))
            return email.Trim();
        return _defaultEmail;
    }

    private sealed class TwentyCardRequestResponse
    {
        public string? Message { get; set; }
        public TwentyCardRequestData? Data { get; set; }
        public TwentyCardErrorBody? Error { get; set; }
    }

    private sealed class TwentyCardErrorBody
    {
        public string? Code { get; set; }
        public string? Message { get; set; }
    }

    private sealed class TwentyCardRequestData
    {
        [JsonPropertyName("authority")]
        public string? Authority { get; set; }

        [JsonPropertyName("redirectUrl")]
        public string? RedirectUrl { get; set; }
    }

    private sealed class TwentyCardVerifyResponse
    {
        public bool Error { get; set; }
        public int Code { get; set; }
        public string? Message { get; set; }
        public TwentyCardVerifyStatus? Status { get; set; }
    }

    private sealed class TwentyCardVerifyStatus
    {
        public bool Paid { get; set; }
        public bool Verified { get; set; }
    }
}