using LCU.Library.Internal.IncentiveApiModels.Entities;
using LCU.API.Internal.Operations.IncentiveApiLib.Repositories;
using LCU.Library.Internal.IncentiveApiModels.Enums;
using LCU.Library.Internal.IncentiveApiModels.Common;

namespace LCU.API.Internal.Operations.IncentiveApi.Services;

public class GapInsuranceActivityService : IGapInsuranceActivityService
{
    private readonly IActivityDetailService _activityDetailService;
    private readonly IActivityRepository _activityRepository;
    private readonly IActivityService _activityService;
    private readonly IUnitOfWork _unitOfWork;

    public GapInsuranceActivityService(
        IActivityDetailService activityDetailService,
        IActivityRepository activityRepository,
        IActivityService activityService,
        IUnitOfWork unitOfWork
    )
    {
        _activityDetailService = activityDetailService;
        _activityRepository = activityRepository;
        _activityService = activityService;
        _unitOfWork = unitOfWork;
    }

    public async Task<int> MatchOrRemoveGapAccessories(MonthRange monthRange = null)
    {
        var updateCount = 0;
        monthRange ??= new MonthRange(DateTime.UtcNow.AddMonths(-3), DateTime.UtcNow);
        var gapEligibleActivities = await _activityRepository.FindGapInsuranceEligible(monthRange);

        if (!gapEligibleActivities.Any())
        {
            return updateCount;
        }

        var matchedGapEligibleActivities = gapEligibleActivities.Where(x => x.HasActiveGapAccessory()).ToList();
        var matchedGapAccessoryActivities = await GetMatchingGapAccessoryActivities(matchedGapEligibleActivities);
        matchedGapEligibleActivities = await ValidateMatchedActivityAccessories(matchedGapEligibleActivities, matchedGapAccessoryActivities);

        var unmatchedGapEligibleActivities = gapEligibleActivities.Except(matchedGapEligibleActivities).ToList();
        var gapActivities = await _activityRepository.GetFilteredActivities(monthRange, Product.GAPInsurance, ActivityState.Accepted);

        foreach (var activity in unmatchedGapEligibleActivities)
        {
            try
            {
                updateCount += await TryMatchGapEligibleActivityWithAccessory(activity, gapActivities) != null ? 2 : 0;
            }
            catch (Exception error)
            {
                Log.Error(error, $"MatchOrRemoveGapAccessories failed processing Activity Id: {activity.Id}");
            }
        }

        return updateCount;
    }

    private async Task<Activity?> TryMatchGapEligibleActivityWithAccessory(Activity gapEligibleActivity, List<Activity> gapActivities)
    {
        if (gapActivities.Count <= 0)
        {
            return null;
        }

        var matchingGapAccessories = gapActivities
            .Where(x => x.Detail.AccountNumber.Equals(gapEligibleActivity.Detail.AccountNumber, StringComparison.CurrentCultureIgnoreCase))
            .ToList();

        if (matchingGapAccessories.Count <= 0)
        {
            return null;
        }

        if (matchingGapAccessories.Count > 1)
        {
            throw new Exception(
                $"Multiple matching GAP Accessory Activities found for Activity Id: {gapEligibleActivity.Id} using AccountNumber: {gapEligibleActivity.Detail.AccountNumber}");
        }

        var matchedAccessoryActivity = matchingGapAccessories.First();
        return await MatchGapAccessory(gapEligibleActivity, matchedAccessoryActivity);
    }

    private async Task<Activity> MatchGapAccessory(Activity parentActivity, Activity accessoryActivity)
    {
        var addedDateTime = accessoryActivity.Accepted.Date.AddHours(12);

        await ApplyMatchedChangeUpdates(parentActivity, accessoryActivity, addedDateTime);
        await ApplyMatchedChangeUpdates(accessoryActivity, parentActivity, addedDateTime);
        await _unitOfWork.CompleteAsync();

        return parentActivity;
    }

    private async Task ApplyMatchedChangeUpdates(Activity targetActivity, Activity linkedActivity, DateTime addedDateTime)
    {
        targetActivity.Detail.GapInsuranceAddDate = addedDateTime;
        targetActivity.MatchingGapInsuranceActivityId = linkedActivity.Id;
        await _activityDetailService.SaveActivityDetailUpdate(new ActivityDetailUpdate
        {
            ActivityDetailId = targetActivity.Detail.Id,
            Note = $"GapInsuranceAddDate has changed from NULL to {addedDateTime}"
        });

        if (targetActivity.Detail.GapInsuranceRemoveDate != null)
        {
            targetActivity.Detail.GapInsuranceRemoveDate = null;
            await _activityDetailService.SaveActivityDetailUpdate(new ActivityDetailUpdate
            {
                ActivityDetailId = targetActivity.Detail.Id,
                Note = $"GapInsuranceRemoveDate has changed from {targetActivity.Detail.GapInsuranceRemoveDate} to NULL"
            });
        }

        await _activityService.ApplyStateChange(new ActivityStateChange
        {
            ActivityId = targetActivity.Id,
            ActivityMatchId = linkedActivity.Id,
            Note = $"Matched {linkedActivity.Product} Activity Id: {linkedActivity.Id} Added",
            State = targetActivity.State
        }, false);
    }

    private async Task<List<Activity>> ValidateMatchedActivityAccessories(List<Activity> matchedActivities, List<Activity> accessoryActivities)
    {
        var accessoryRemovedActivities = new List<Activity>();
        foreach (var parentActivity in matchedActivities)
        {
            try
            {
                var accessoryActivity = accessoryActivities.FirstOrDefault(x => x.MatchingGapInsuranceActivityId == parentActivity.Id) == null
                    ? await _activityRepository.GetActivityById(parentActivity.MatchingGapInsuranceActivityId)
                    : accessoryActivities.FirstOrDefault(x => x.MatchingGapInsuranceActivityId == parentActivity.Id);

                if (accessoryActivity == null && parentActivity.Detail.GapInsuranceRemoveDate == null)
                {
                    accessoryRemovedActivities.Add(await RemoveMissingGapAccessory(parentActivity));
                    continue;
                }

                if (parentActivity?.State == ActivityState.Accepted && accessoryActivity?.State == ActivityState.Accepted)
                {
                    continue;
                }

                accessoryRemovedActivities.Add(await RemoveGapAccessory(parentActivity, accessoryActivity));
            }
            catch (Exception ex)
            {
                var parentActivityId = parentActivity != null ? parentActivity.Id.ToString() : "NULL";
                Log.Error(ex, $"Failed to validate matched GAP accessory for Activity Id:{parentActivityId}");
            }
        }

        Log.Information($"Removed GAP Accessory From {accessoryRemovedActivities.Count} Activities");

        return matchedActivities.Except(accessoryRemovedActivities).ToList();
    }

    private async Task<Activity> RemoveGapAccessory(Activity parentActivity, Activity accessoryActivity)
    {
        var removedDate = await DetermineRemovedDate(parentActivity, accessoryActivity);

        await ApplyRemovalChangeUpdates(parentActivity, accessoryActivity, removedDate);
        await ApplyRemovalChangeUpdates(accessoryActivity, parentActivity, removedDate);
        await _unitOfWork.CompleteAsync();
        return parentActivity.State == ActivityState.Accepted ? parentActivity : null;
    }

    private async Task ApplyRemovalChangeUpdates(Activity targetActivity, Activity linkedActivity, DateTime removedDateTime)
    {
        targetActivity.Detail.GapInsuranceRemoveDate = removedDateTime;
        targetActivity.MatchingGapInsuranceActivityId = 0;
        await _activityDetailService.SaveActivityDetailUpdate(new ActivityDetailUpdate
        {
            ActivityDetailId = targetActivity.Detail.Id,
            Note = $"GapInsuranceRemoveDate has changed from NULL to {removedDateTime}"
        });
        await _activityService.ApplyStateChange(new ActivityStateChange
        {
            ActivityId = targetActivity.Id,
            ActivityMatchId = linkedActivity.Id,
            Note = $"Matched {linkedActivity.Product} Activity Id: {linkedActivity.Id} Removed",
            State = targetActivity.State
        }, false);
    }

    private static async Task<DateTime> DetermineRemovedDate(Activity parentActivity, Activity accessoryActivity)
    {
        if (parentActivity.State == ActivityState.Accepted && accessoryActivity.State != ActivityState.Accepted)
        {
            return await Task.FromResult(accessoryActivity.Accepted.Date.AddHours(12));
        }

        if (parentActivity.State != ActivityState.Accepted && accessoryActivity.State == ActivityState.Accepted)
        {
            return await Task.FromResult(parentActivity.Accepted.Date.AddHours(12));
        }

        return await Task.FromResult(parentActivity.LastUpdated <= accessoryActivity.LastUpdated
            ? parentActivity.Accepted.Date.AddHours(12)
            : accessoryActivity.Accepted.Date.AddHours(12));
    }

    private async Task<Activity?> RemoveMissingGapAccessory(Activity activity)
    {
        Log.Warning($"Unable To Find GAP Accessory Activity Id: {activity.MatchingGapInsuranceActivityId}, Removing GAP Accessory From Activity Id: {activity.Id}");
        var removeDate = DateTime.Now.Date.AddHours(12);
        activity.MatchingGapInsuranceActivityId = 0;
        activity.Detail.GapInsuranceRemoveDate = removeDate;
        await _activityDetailService.SaveActivityDetailUpdate(new ActivityDetailUpdate
        {
            ActivityDetailId = activity.Detail.Id,
            Note = $"GapInsuranceRemoveDate has changed from NULL to {removeDate}"
        });
        var activityStateChange = new ActivityStateChange
        {
            ActivityId = activity.Id,
            Note = $"{Product.GAPInsurance} Accessory Activity Removed, Accessory Activity Not Found",
            State = activity.State
        };
   
        await _activityService.ApplyStateChange(activityStateChange);
        return activity.State == ActivityState.Accepted ? activity : null;
    }

    private async Task<List<Activity>> GetMatchingGapAccessoryActivities(IReadOnlyCollection<Activity> matchedActivities)
    {
        if (!matchedActivities.Any())
        {
            return new List<Activity>();
        }

        var ids = matchedActivities
            .Select(activity => activity.MatchingGapInsuranceActivityId)
            .ToList();

        return await _activityRepository.FindById(ids);
    }
}