using Distribution.Infra.Authorization;
using Distribution.Infra.UoW;

namespace Distribution.Features.Route;

public class RouteService(IRouteRepository repo, Region.IRegionRepository regionRepo, IUnitOfWork uow, ICurrentUserService currentUser, IScopeAccessService scopeAccess)
{
    private const int RouteManagerRoleLevel = 20;
    private const double DeviationThresholdMeters = 500;

    private async Task<bool> CanManageRouteAsync(Guid routeId)
    {
        if (currentUser.RoleLevel < RouteManagerRoleLevel || currentUser.UserId is null) return false;
        return await scopeAccess.HasRouteScopeAsync(currentUser.UserId.Value, routeId);
    }

    private static double DistanceMeters(decimal lat1, decimal lon1, decimal lat2, decimal lon2)
    {
        const double earthRadiusMeters = 6371000;
        var dLat = ToRadians((double)(lat2 - lat1));
        var dLon = ToRadians((double)(lon2 - lon1));
        var a = Math.Sin(dLat / 2) * Math.Sin(dLat / 2) +
                Math.Cos(ToRadians((double)lat1)) * Math.Cos(ToRadians((double)lat2)) *
                Math.Sin(dLon / 2) * Math.Sin(dLon / 2);
        var c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
        return earthRadiusMeters * c;
    }

    private static double ToRadians(double degrees) => degrees * Math.PI / 180;

    private static RouteResponse ToResponse(Models.Route route) =>
        new(route.Id, route.FK_RegionId, route.RouteName, route.StartPoint, route.EndPoint, route.Length, route.FK_OwnerUserId, route.IsActive, route.CreatedAt);

    private static RouteVisitResponse ToVisitResponse(Models.RouteVisitLog log) =>
        new(log.Id, log.FK_RouteId, log.FK_StoreId, log.FK_UserId, log.CheckInAt, log.IsDeviationFlagged, log.CheckOutAt);

    public async Task<List<RouteResponse>> GetAllAsync() =>
        (await repo.GetAllAsync())
            .Where(r => r.IsActive)
            .Select(r => new RouteResponse(r.Id, r.FK_RegionId, r.RouteName, r.StartPoint, r.EndPoint, r.Length, r.FK_OwnerUserId, r.IsActive, r.CreatedAt))
            .ToList();

    public async Task<RouteResponse?> GetByIdAsync(Guid id)
    {
        var route = await repo.GetByIdAsync(id);
        if (route is null || !route.IsActive) return null;
        return new RouteResponse(route.Id, route.FK_RegionId, route.RouteName, route.StartPoint, route.EndPoint, route.Length, route.FK_OwnerUserId, route.IsActive, route.CreatedAt);
    }

    public async Task<RouteResponse> CreateAsync(CreateRouteRequest request, CancellationToken ct = default)
    {
        var route = new Models.Route
        {
            FK_RegionId = request.RegionId,
            RouteName = request.RouteName,
            StartPoint = request.StartPoint,
            EndPoint = request.EndPoint,
            Length = request.Length
        };
        await uow.BeginAsync(ct);
        try
        {
            await repo.AddAsync(route);
            await uow.CommitAsync(ct);
        }
        catch
        {
            await uow.RollbackAsync(ct);
            throw;
        }
        return ToResponse(route);
    }

    public async Task<RouteResponse?> UpdateAsync(Guid id, UpdateRouteRequest request, CancellationToken ct = default)
    {
        var route = await repo.GetByIdAsync(id);
        if (route is null || !route.IsActive) return null;
        route.FK_RegionId = request.RegionId;
        route.RouteName = request.RouteName;
        route.StartPoint = request.StartPoint;
        route.EndPoint = request.EndPoint;
        route.Length = request.Length;
        await uow.BeginAsync(ct);
        try
        {
            repo.Update(route);
            await uow.CommitAsync(ct);
        }
        catch
        {
            await uow.RollbackAsync(ct);
            throw;
        }
        return ToResponse(route);
    }

    public async Task<RouteResponse?> AssignToRegionAsync(Guid id, AssignRouteToRegionRequest request, CancellationToken ct = default)
    {
        var route = await repo.GetByIdAsync(id);
        if (route is null || !route.IsActive) return null;

        var region = await regionRepo.GetByIdAsync(request.RegionId);
        if (region is null || !region.IsActive) return null;

        route.FK_RegionId = request.RegionId;
        await uow.BeginAsync(ct);
        try
        {
            repo.Update(route);
            await uow.CommitAsync(ct);
        }
        catch
        {
            await uow.RollbackAsync(ct);
            throw;
        }
        return ToResponse(route);
    }

    public async Task<bool> DeleteAsync(Guid id, CancellationToken ct = default)
    {
        var route = await repo.GetByIdAsync(id);
        if (route is null || !route.IsActive) return false;
        await uow.BeginAsync(ct);
        try
        {
            repo.Remove(route);
            await uow.CommitAsync(ct);
        }
        catch
        {
            await uow.RollbackAsync(ct);
            throw;
        }
        return true;
    }

    public async Task<RouteResponse?> AssignStoresToRouteAsync(Guid id, AssignStoresToRouteRequest request, CancellationToken ct = default)
    {
        var route = await repo.GetByIdAsync(id);
        if (route is null || !route.IsActive) return null;
        if (!await CanManageRouteAsync(id)) return null;

        var stores = await repo.GetStoresByIdsAsync(request.StoreIds);
        if (stores.Count != request.StoreIds.Distinct().Count()) return null;

        await uow.BeginAsync(ct);
        try
        {
            foreach (var store in stores)
            {
                store.FK_RouteId = id;
                repo.UpdateStore(store);
            }
            await uow.CommitAsync(ct);
        }
        catch
        {
            await uow.RollbackAsync(ct);
            throw;
        }
        return ToResponse(route);
    }

    public async Task<RouteResponse?> AssignOwnerAsync(Guid id, AssignRouteOwnerRequest request, CancellationToken ct = default)
    {
        var route = await repo.GetByIdAsync(id);
        if (route is null || !route.IsActive) return null;
        if (!await CanManageRouteAsync(id)) return null;

        var salesRep = await repo.GetActiveUserAsync(request.SalesRepId);
        if (salesRep is null) return null;

        route.FK_OwnerUserId = request.SalesRepId;
        await uow.BeginAsync(ct);
        try
        {
            repo.Update(route);
            await uow.CommitAsync(ct);
        }
        catch
        {
            await uow.RollbackAsync(ct);
            throw;
        }
        return ToResponse(route);
    }

    public async Task<RouteVisitResponse?> RecordCheckInAsync(Guid id, RecordCheckInRequest request, CancellationToken ct = default)
    {
        // TEMPORARY: currentUser.UserId is always unset due to the broken auth middleware
        // (testbug.md #28) — fall back to the explicitly supplied user, and skip the route-scope
        // check (which also depends on a resolved user) until that's fixed.
        var userId = currentUser.UserId ?? request.CheckedInByUserId
            ?? throw new InvalidOperationException("CheckedInByUserId is required while auth is unavailable");

        var route = await repo.GetByIdAsync(id);
        if (route is null || !route.IsActive) return null;

        var store = await repo.GetStoreByIdAsync(request.StoreId);
        if (store is null || !store.IsActive || store.FK_RouteId != id) return null;

        var distance = DistanceMeters(request.Latitude, request.Longitude, store.Latitude, store.Longitude);

        var log = new Models.RouteVisitLog
        {
            FK_RouteId = id,
            FK_StoreId = request.StoreId,
            FK_UserId = userId,
            CheckInAt = request.Timestamp ?? DateTime.Now,
            CheckInLatitude = request.Latitude,
            CheckInLongitude = request.Longitude,
            IsDeviationFlagged = distance > DeviationThresholdMeters
        };
        await uow.BeginAsync(ct);
        try
        {
            await repo.AddVisitLogAsync(log);
            await uow.CommitAsync(ct);
        }
        catch
        {
            await uow.RollbackAsync(ct);
            throw;
        }
        return ToVisitResponse(log);
    }

    public async Task<RouteVisitResponse?> RecordCheckOutAsync(Guid id, RecordCheckOutRequest request, CancellationToken ct = default)
    {
        // TEMPORARY: the route-scope check depends on the broken auth middleware
        // (testbug.md #28) — skipped for now, same as check-in.
        var route = await repo.GetByIdAsync(id);
        if (route is null || !route.IsActive) return null;

        var log = await repo.GetOpenVisitAsync(id, request.StoreId);
        if (log is null) return null;

        log.CheckOutAt = request.Timestamp ?? DateTime.Now;
        await uow.BeginAsync(ct);
        try
        {
            repo.UpdateVisitLog(log);
            await uow.CommitAsync(ct);
        }
        catch
        {
            await uow.RollbackAsync(ct);
            throw;
        }
        return ToVisitResponse(log);
    }
}