using System.Text.Json;
using ComplianceBLL.Adapter;
using ComplianceDAL.CustomCode.AdapterConfig;
using ComplianceDAL.DTO.GSTReturn;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.Resource.GB5Solution;
using GB5Shared.Validation;
using Microsoft.Extensions.Logging;

namespace ComplianceBLL.GSTValidate;

public class GSTValidateBLL : IGSTValidateBLL
{
    private readonly IAdapterConfigDAL _adapterConfigDal;
    private readonly IComplianceAdapterFactory _adapterFactory;
    private readonly IValidation _validation;
    private readonly ILogger<GSTValidateBLL> _logger;

    public GSTValidateBLL(
        IAdapterConfigDAL adapterConfigDal,
        IComplianceAdapterFactory adapterFactory,
        IValidation validation,
        ILogger<GSTValidateBLL> logger)
    {
        _adapterConfigDal = adapterConfigDal;
        _adapterFactory   = adapterFactory;
        _validation       = validation;
        _logger           = logger;
    }

    // Ported from GB4's GSTCafeServiceBLL.GetOTPRequest: step 1 of the OTP+auth-token flow every
    // GST Returns call requires. Builds the initial GSTHeaderDTO from the resolved AdapterConfigDTO
    // (Username/StateCode) — the FE has nothing more than the GSTIN at this point.
    public async Task<string> RequestOTPAsync(string gstin, string returnPeriod, LoginDTO login, CancellationToken ct)
    {
        try
        {
            await _validation.NotEmpty(gstin, nameof(gstin));

            var adapterConfig = await _adapterConfigDal.GetAdapterConfigByGSTIN(gstin, "GST_INDIA", login, ct).ConfigureAwait(false);
            if (adapterConfig is null)
                return JsonSerializer.Serialize(new { success = false, message = ComplianceResource.AdapterConfigNotFound });

            var header = new GSTHeaderDTO
            {
                GSTIN        = gstin,
                UserName     = adapterConfig.GSTNUserId,
                StateCode    = adapterConfig.StateCode,
                ReturnPeriod = returnPeriod
            };

            var adapter = _adapterFactory.GetAdapter(adapterConfig);
            var result  = await adapter.RequestOTPAsync(header, adapterConfig, ct).ConfigureAwait(false);

            if (!result.IsSuccess)
                return JsonSerializer.Serialize(new { success = false, message = ComplianceResource.PortalError, errorMessage = result.ErrorMessage });

            // FE must echo this back as the appKey param on GetAuthTokenAsync — GSTN's Authentication
            // API spec reuses the same app-key across the OTP-request and auth-token-exchange calls.
            return JsonSerializer.Serialize(new { success = true, message = "OTP sent. Enter it to authenticate.", appKey = result.AppKey });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "GST Validate: RequestOTPAsync failed for GSTIN {GSTIN}", gstin);
            throw;
        }
    }

    // Ported from GB4's GSTCafeServiceBLL.GetAuthToken: step 2 — exchanges the OTP for auth_token/sek.
    // Returns the full GSTHeaderDTO (GSTIN/UserName/StateCode/AuthToken/Sek) so the FE can replay it
    // wholesale as the GSTHeader request header on every subsequent Submit/File/Sync/Fetch call.
    public async Task<string> GetAuthTokenAsync(string gstin, string otp, string appKey, string returnPeriod, LoginDTO login, CancellationToken ct)
    {
        try
        {
            await _validation.NotEmpty(gstin, nameof(gstin));
            await _validation.NotEmpty(otp, nameof(otp));
            await _validation.NotEmpty(appKey, nameof(appKey));

            var adapterConfig = await _adapterConfigDal.GetAdapterConfigByGSTIN(gstin, "GST_INDIA", login, ct).ConfigureAwait(false);
            if (adapterConfig is null)
                return JsonSerializer.Serialize(new { success = false, message = ComplianceResource.AdapterConfigNotFound });

            var header = new GSTHeaderDTO
            {
                GSTIN        = gstin,
                UserName     = adapterConfig.GSTNUserId,
                StateCode    = adapterConfig.StateCode,
                ReturnPeriod = returnPeriod,
                AppKey       = appKey
            };

            var adapter = _adapterFactory.GetAdapter(adapterConfig);
            var result  = await adapter.GetAuthTokenAsync(otp, header, adapterConfig, ct).ConfigureAwait(false);

            if (!result.IsSuccess)
                return JsonSerializer.Serialize(new { success = false, message = ComplianceResource.PortalError, errorMessage = result.ErrorMessage });

            header.AuthToken = result.AuthToken;
            header.Sek       = result.Sek;

            return JsonSerializer.Serialize(new { success = true, header });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "GST Validate: GetAuthTokenAsync failed for GSTIN {GSTIN}", gstin);
            throw;
        }
    }
}