using Fitness_core_BE.DTOs.TimeBankCard;
using Fitness_core_BE.Helpers;
using Fitness_core_BE.Infra.UoW;
using Fitness_core_BE.Interfaces;
using Fitness_core_BE.Interfaces.Services;
using Fitness_core_BE.Models;
using System.Text.Json;

namespace Fitness_core_BE.Services
{
    public class TimeBankCardService : ITimeBankCardService
    {
        private readonly ITimeBankCardRepository _timeBankCardRepository;
        private readonly IUnitOfWork _uow;
        private readonly UserRoleHelper _userRoleHelper;

        public TimeBankCardService(ITimeBankCardRepository timeBankCardRepository, IUnitOfWork uow, UserRoleHelper userRoleHelper)
        {
            _timeBankCardRepository = timeBankCardRepository;
            _uow = uow;
            _userRoleHelper = userRoleHelper;
        }

        public async Task<object> IssueCard(object payload, HttpContext httpContext)
        {
            await _uow.BeginAsync();
            try
            {
                var data = DeserializePayload.Deserialize(payload);
                var rfidTagId = data["rfidTagId"].GetString() ?? throw new ArgumentException("rfidTagId is required");
                var totalMinutes = data["totalMinutesPurchased"].GetInt32();
                if (totalMinutes < 1) throw new ArgumentException("totalMinutesPurchased must be at least 1");

                if (await _timeBankCardRepository.GetByRfidTagId(rfidTagId) != null)
                    throw new ArgumentException("This RFID tag already has an active time-bank card");

                var clientId = await _userRoleHelper.GetClientId(DataExtractor.GetUserIdFromContext(httpContext));

                var card = new TimeBankCard
                {
                    FKClientId = clientId,
                    RfidTagId = rfidTagId,
                    TotalMinutesPurchased = totalMinutes,
                    MinutesRemaining = totalMinutes,
                    AmountPaid = data.ContainsKey("amountPaid") ? data["amountPaid"].GetDecimal() : 0m,
                    FKCustomerId = data.ContainsKey("customerId") && data["customerId"].ValueKind != JsonValueKind.Null
                        ? Guid.Parse(data["customerId"].GetString()!)
                        : null,
                    ExpiresAt = data.ContainsKey("expiresAt") && data["expiresAt"].ValueKind != JsonValueKind.Null
                        ? DateTime.Parse(data["expiresAt"].GetString()!).ToUniversalTime()
                        : null
                };

                var result = await _timeBankCardRepository.CreateTimeBankCard(card);
                await _uow.CommitAsync();

                return MapToDto(result);
            }
            catch
            {
                await _uow.RollbackAsync();
                throw;
            }
        }

        public async Task<object> Swipe(object payload)
        {
            await _uow.BeginAsync();
            try
            {
                var data = DeserializePayload.Deserialize(payload);
                var rfidTagId = data["rfidTagId"].GetString() ?? throw new ArgumentException("rfidTagId is required");
                var facilityId = Guid.Parse(data["facilityId"].GetString()!);

                var card = await _timeBankCardRepository.GetByRfidTagId(rfidTagId)
                    ?? throw new KeyNotFoundException("No active time-bank card found for this RFID tag");

                if (card.ExpiresAt.HasValue && card.ExpiresAt.Value < DateTime.UtcNow)
                    throw new ArgumentException("This card has expired");

                int? minutesDeducted = null;

                if (!card.ActiveSessionStartedAt.HasValue)
                {
                    // Tap-in: just open the session. Reject outright if there's no balance left
                    // at all, so a spent card doesn't get to "start the clock" on a visit it
                    // can never pay for.
                    if (card.MinutesRemaining < 1)
                        throw new ArgumentException("This card has no time remaining");

                    card.ActiveSessionStartedAt = DateTime.UtcNow;
                    card.ActiveSessionFacilityId = facilityId;
                }
                else
                {
                    // Tap-out: bill for actual elapsed time, rounded up to the next whole minute
                    // (a 61-second visit still costs 2 minutes, not 1) -- capped at whatever
                    // balance remains rather than letting a forgotten tap-out run the balance
                    // negative.
                    var elapsed = DateTime.UtcNow - card.ActiveSessionStartedAt.Value;
                    var elapsedMinutes = Math.Max(1, (int)Math.Ceiling(elapsed.TotalMinutes));
                    minutesDeducted = Math.Min(elapsedMinutes, card.MinutesRemaining);

                    card.MinutesRemaining -= minutesDeducted.Value;

                    await _timeBankCardRepository.AddUsageLog(new TimeBankCardUsageLog
                    {
                        FKTimeBankCardId = card.TimeBankCardId,
                        FKClientId = card.FKClientId,
                        FKFacilityId = card.ActiveSessionFacilityId ?? facilityId,
                        MinutesDeducted = minutesDeducted.Value,
                        MinutesRemainingAfter = card.MinutesRemaining
                    });

                    card.ActiveSessionStartedAt = null;
                    card.ActiveSessionFacilityId = null;
                }

                await _uow.CommitAsync();
                return MapToDto(card, minutesDeducted);
            }
            catch
            {
                await _uow.RollbackAsync();
                throw;
            }
        }

        public async Task<object> GetBalance(object payload)
        {
            var data = DeserializePayload.Deserialize(payload);
            var rfidTagId = data["rfidTagId"].GetString() ?? throw new ArgumentException("rfidTagId is required");

            var card = await _timeBankCardRepository.GetByRfidTagId(rfidTagId)
                ?? throw new KeyNotFoundException("No active time-bank card found for this RFID tag");

            return MapToDto(card);
        }

        public async Task<object> GetMyCards(object payload, HttpContext httpContext)
        {
            var cusId = await _userRoleHelper.GetCusId(DataExtractor.GetUserIdFromContext(httpContext));
            var cards = await _timeBankCardRepository.GetByCustomerId(cusId);
            return cards.Select(c => MapToDto(c)).ToList();
        }

        private static TimeBankCardDto MapToDto(TimeBankCard card, int? minutesDeductedThisSwipe = null) => new()
        {
            TimeBankCardId = card.TimeBankCardId,
            RfidTagId = card.RfidTagId,
            CustomerId = card.FKCustomerId,
            TotalMinutesPurchased = card.TotalMinutesPurchased,
            MinutesRemaining = card.MinutesRemaining,
            AmountPaid = card.AmountPaid,
            PurchasedAt = card.PurchasedAt,
            ExpiresAt = card.ExpiresAt,
            IsActive = card.IsActive,
            SessionOpen = card.ActiveSessionStartedAt.HasValue,
            SessionStartedAt = card.ActiveSessionStartedAt,
            SessionFacilityName = card.ActiveSessionFacility?.Name,
            MinutesDeductedThisSwipe = minutesDeductedThisSwipe
        };
    }
}