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

namespace ComplianceBLL.GSTReturn;

public class GSTReturnBLL : IGSTReturnBLL
{
    private readonly IGSTReturnDAL _dal;
    private readonly IComplianceArtifactDAL _artifactDal;
    private readonly IAdapterConfigDAL _adapterConfigDal;
    private readonly IComplianceAdapterFactory _adapterFactory;
    private readonly IValidation _validation;
    private readonly ILogger<GSTReturnBLL> _logger;

    public GSTReturnBLL(
        IGSTReturnDAL dal,
        IComplianceArtifactDAL artifactDal,
        IAdapterConfigDAL adapterConfigDal,
        IComplianceAdapterFactory adapterFactory,
        IValidation validation,
        ILogger<GSTReturnBLL> logger)
    {
        _dal              = dal;
        _artifactDal      = artifactDal;
        _adapterConfigDal = adapterConfigDal;
        _adapterFactory   = adapterFactory;
        _validation       = validation;
        _logger           = logger;
    }

    public async Task<string> GetReturnStatusAsync(GetReturnStatusRequestDTO request, LoginDTO login, CancellationToken ct)
    {
        await _validation.NotEmpty(request.GSTIN, nameof(request.GSTIN));
        await _validation.NotEmpty(request.ReturnPeriod, nameof(request.ReturnPeriod));

        var (year, month) = ParseReturnPeriodYearMonth(request.ReturnPeriod);
        var period = await _dal.GetCompliancePeriodAsync(
            request.Framework, request.GSTIN, request.ReturnType, year, month, login, ct).ConfigureAwait(false);

        return JsonSerializer.Serialize(period);
    }

    public async Task<string> GetReturnStatusListAsync(ReturnStatusListFilterDTO filter, LoginDTO login, CancellationToken ct)
    {
        var list = await _dal.GetPeriodListAsync(filter, login, ct).ConfigureAwait(false);
        return JsonSerializer.Serialize(list);
    }

    public async Task<string> SyncReturnStatusFromPortalAsync(SyncReturnStatusRequestDTO request, GSTHeaderDTO header, LoginDTO login, CancellationToken ct)
    {
        await _validation.NotEmpty(request.GSTIN, nameof(request.GSTIN));
        await _validation.NotEmpty(request.ReturnPeriod, nameof(request.ReturnPeriod));

        if (string.IsNullOrEmpty(header?.AuthToken) || string.IsNullOrEmpty(header.Sek))
            return JsonSerializer.Serialize(new { success = false, message = "Please request OTP and authenticate before syncing return status." });

        header.ReturnPeriod = request.ReturnPeriod;

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

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

        if (!result.IsSuccess)
        {
            _logger.LogWarning("SyncReturnStatus failed for GSTIN {GSTIN} Period {Period}: {Error}",
                request.GSTIN, request.ReturnPeriod, result.ErrorMessage);
            return JsonSerializer.Serialize(new { success = false, message = ComplianceResource.PortalError, errorMessage = result.ErrorMessage });
        }

        // Parse portal response and update local period status
        var (year, month) = ParseReturnPeriodYearMonth(request.ReturnPeriod);
        var portalStatus  = ExtractStatusFromPortalResponse(result.RawResponse, request.ReturnType);

        await _dal.UpdatePeriodStatusAsync(
            "GST_INDIA", request.GSTIN, request.ReturnType, year, month,
            portalStatus.status, portalStatus.ackNumber, portalStatus.confirmationNumber,
            login.UserId, login, ct).ConfigureAwait(false);

        _logger.LogInformation("Synced return status: GSTIN={GSTIN} Period={Period} Status={Status}",
            request.GSTIN, request.ReturnPeriod, portalStatus.status);

        return JsonSerializer.Serialize(new { success = true, status = portalStatus.status, ackNumber = portalStatus.ackNumber });
    }

    public async Task<string> GetGSTR3BDataAsync(string gstin, string returnPeriod, LoginDTO login, CancellationToken ct)
    {
        await _validation.NotEmpty(gstin, nameof(gstin));
        await _validation.NotEmpty(returnPeriod, nameof(returnPeriod));

        var raw = await _dal.GetGSTR3BOutwardSectionAsync(gstin, returnPeriod, login, ct).ConfigureAwait(false);
        if (raw is null)
            return JsonSerializer.Serialize(new { success = false, message = "No outward data found for this period. Run SyncGSTOutward first." });

        var section31 = new GSTR3BSection31DTO
        {
            TaxableValueA = raw.TaxableValueA,
            IGSTAmountA   = raw.IGSTAmountA - raw.CDNRIGSTAmount,
            CGSTAmountA   = raw.CGSTAmountA - raw.CDNRCGSTAmount,
            SGSTAmountA   = raw.SGSTAmountA - raw.CDNRSGSTAmount,
            CessAmountA   = raw.CessAmountA,
            TaxableValueB = raw.TaxableValueB,
            IGSTAmountB   = raw.IGSTAmountB,
            CessAmountB   = raw.CessAmountB,
            TaxableValueC = raw.TaxableValueC,
            CDNRIGSTAmount = raw.CDNRIGSTAmount,
            CDNRCGSTAmount = raw.CDNRCGSTAmount,
            CDNRSGSTAmount = raw.CDNRSGSTAmount
        };

        var netIGST = section31.IGSTAmountA + section31.IGSTAmountB;
        var netCGST = section31.CGSTAmountA;
        var netSGST = section31.SGSTAmountA;
        var netCess = section31.CessAmountA + section31.CessAmountB;

        var gstr3b = new GSTR3BDTO
        {
            GSTIN        = gstin,
            ReturnPeriod = returnPeriod,
            Section31    = section31,
            Summary      = new GSTR3BSummaryDTO
            {
                NetIGST          = netIGST,
                NetCGST          = netCGST,
                NetSGST          = netSGST,
                NetCess          = netCess,
                TotalTaxLiability = netIGST + netCGST + netSGST + netCess
            }
        };

        return JsonSerializer.Serialize(gstr3b);
    }

    public async Task<string> SubmitGSTR3BAsync(SubmitGSTR3BRequestDTO request, GSTHeaderDTO header, LoginDTO login, CancellationToken ct)
    {
        await _validation.NotEmpty(request.GSTIN, nameof(request.GSTIN));
        await _validation.NotEmpty(request.ReturnPeriod, nameof(request.ReturnPeriod));
        await _validation.NotEmpty(request.EVCOtp, nameof(request.EVCOtp));

        if (string.IsNullOrEmpty(header?.AuthToken) || string.IsNullOrEmpty(header.Sek))
            return JsonSerializer.Serialize(new { success = false, message = "Please request OTP and authenticate before submitting this return." });

        header.ReturnPeriod = request.ReturnPeriod;

        var gstr3bJson = await GetGSTR3BDataAsync(request.GSTIN, request.ReturnPeriod, login, ct).ConfigureAwait(false);

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

        var adapter = _adapterFactory.GetAdapter(adapterConfig);

        var saveResult = await adapter.SaveReturnAsync(
            "GSTR3B", gstr3bJson, header, adapterConfig, ct).ConfigureAwait(false);

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

        header.EvcOTP = request.EVCOtp;
        var fileResult = await adapter.FileReturnAsync(
            "GSTR3B", header, adapterConfig, ct).ConfigureAwait(false);

        await _artifactDal.SaveAudit(new ComplianceAuditDTO
        {
            Action          = "API_CALL",
            RequestPayload  = gstr3bJson,
            ResponsePayload = fileResult.RawResponse,
            PreviousState   = "NotStarted",
            NewState        = fileResult.IsSuccess ? "Filed" : "NotStarted",
            ProviderCode    = "GSTCafe",
            HttpStatusCode  = fileResult.HttpStatusCode,
            ReferenceNumber = fileResult.ReferenceId,
            ErrorMessage    = fileResult.ErrorMessage,
            AttemptNumber   = 1,
            UserId          = login.UserId
        }, login, ct).ConfigureAwait(false);

        if (!fileResult.IsSuccess)
        {
            _logger.LogWarning("SubmitGSTR3B filing failed for GSTIN {GSTIN} Period {Period}: {Error}",
                request.GSTIN, request.ReturnPeriod, fileResult.ErrorMessage);
            return JsonSerializer.Serialize(new { success = false, message = ComplianceResource.PortalError, errorMessage = fileResult.ErrorMessage });
        }

        var (year, month) = ParseReturnPeriodYearMonth(request.ReturnPeriod);
        await _dal.UpdatePeriodStatusAsync(
            "GST_INDIA", request.GSTIN, "GSTR3B", year, month,
            "Filed", string.Empty, fileResult.ReferenceId, login.UserId, login, ct).ConfigureAwait(false);

        _logger.LogInformation("GSTR-3B filed: GSTIN={GSTIN} Period={Period} AckNumber={AckNumber}",
            request.GSTIN, request.ReturnPeriod, fileResult.ReferenceId);

        return JsonSerializer.Serialize(new
        {
            success   = true,
            message   = ComplianceResource.ReturnFiled,
            ackNumber = fileResult.ReferenceId
        });
    }

    // ── Private helpers ───────────────────────────────────────────────────────

    private static (int year, int month) ParseReturnPeriodYearMonth(string returnPeriod)
    {
        var month = int.Parse(returnPeriod[..2]);
        var year  = int.Parse(returnPeriod[2..]);
        return (year, month);
    }

    private static (string status, string ackNumber, string confirmationNumber) ExtractStatusFromPortalResponse(
        string rawResponse, string returnType)
    {
        try
        {
            using var doc = JsonDocument.Parse(rawResponse);
            var root = doc.RootElement;

            var status      = root.TryGetProperty("status_cd", out var sc) ? sc.GetString() ?? "NotStarted" : "NotStarted";
            var ackNumber   = root.TryGetProperty("arn", out var arn)       ? arn.GetString() ?? string.Empty : string.Empty;
            var confirmNum  = root.TryGetProperty("confirm_no", out var cn) ? cn.GetString() ?? string.Empty : string.Empty;

            var localStatus = status switch
            {
                "P" or "Filed" => "Filed",
                "S" or "Submitted" => "Submitted",
                _ => "NotStarted"
            };

            return (localStatus, ackNumber, confirmNum);
        }
        catch
        {
            return ("NotStarted", string.Empty, string.Empty);
        }
    }
}