using Data.SeaHavenIndustries;
using Data.SeaHavenIndustries.Enums;
using Microsoft.EntityFrameworkCore;

namespace SeaHaven.DataServices.Helpers
{
    /// <summary>
    /// The single rule and write for "a work order that becomes Canceled cancels its pending
    /// uplifts in the same action". Every path that can cancel a work order (board update,
    /// the cancel endpoint, CRM webhook and reconciliation) asks <see cref="Applies"/> and
    /// stages the cancellation into its own unit of work, so the uplift change and its own
    /// audit row commit, or roll back, with the work order's status change.
    /// </summary>
    public static class PendingUpliftCancellation
    {
        public const string AuditAction = "uplift_cancel";
        public const string CancelledStatus = "Withdrawn";

        private static readonly string[] PendingStatuses = { "Pending", "ChangesRequested" };

        /// <summary>True when a lifecycle change moves a work order into Canceled.</summary>
        public static bool Applies(LifecycleStatus? before, LifecycleStatus? after)
            => before != LifecycleStatus.Canceled && after == LifecycleStatus.Canceled;

        /// <summary>
        /// Uplift requests that belong to a work order: on a live dispatch that the work
        /// order owns or is linked to.
        /// </summary>
        internal static IQueryable<DispatchUpliftRequest> ForWorkOrder(ApplicationDbContext context, int workOrderId)
            => context.DispatchUpliftRequests.Where(u =>
                (u.IsDeleted == null || u.IsDeleted == false)
                && u.Dispatch != null
                && (u.Dispatch.IsDeleted == null || u.Dispatch.IsDeleted == false)
                && (
                    u.Dispatch.WorkOrderId == workOrderId
                    || u.Dispatch.DispatchWorkOrders!.Any(link => link.WorkOrderId == workOrderId)));

        /// <summary>
        /// Stages (does not save) the cancellation of every pending uplift on the work order,
        /// with one audit row per uplift. Returns how many uplifts were cancelled.
        /// </summary>
        internal static async Task<int> StageAsync(
            ApplicationDbContext context,
            int workOrderId,
            string? actorId,
            string actorType,
            DateTime now,
            CancellationToken cancellationToken)
        {
            var pending = await ForWorkOrder(context, workOrderId)
                .Include(u => u.Dispatch)
                .Where(u => PendingStatuses.Contains(u.Status))
                .ToListAsync(cancellationToken);

            foreach (var request in pending)
            {
                var previous = request.Status;
                request.Status = CancelledStatus;
                request.DecidedAt = now;
                request.DecidedByUserId = actorId;
                request.LastModificationTime = now;

                context.WorkOrderAuditLogs.Add(new WorkOrderAuditLog
                {
                    WorkOrderId = workOrderId,
                    UserId = actorId,
                    FieldName = $"Dispatch {request.Dispatch!.DispatchNumber} Uplift",
                    OldValue = previous,
                    NewValue = CancelledStatus,
                    Action = AuditAction,
                    ActorType = actorType,
                    CreatedAt = now,
                });
            }

            return pending.Count;
        }
    }
}