using Data.SeaHavenIndustries;
using Data.SeaHavenIndustries.Enums;

namespace SeaHaven.Services.Helpers
{
    public static class WorkOrderDerivedFields
    {
        /// <summary>
        /// Past due overlay from Schedule On — never a WorkOrderType. Matches SHOC board design (SH-185).
        /// Changing Due Date alone must never trigger or clear it.
        /// </summary>
        public static bool IsPastDue(WorkOrder workOrder, DateOnly? asOf = null)
        {
            var today = asOf ?? DateOnly.FromDateTime(DateTime.UtcNow);
            if (workOrder.ScheduledDate == null)
                return false;

            if (LifecycleStatusMapper.IsTerminal(workOrder.LifecycleStatus))
                return false;

            return DateOnly.FromDateTime(workOrder.ScheduledDate.Value.Date) < today;
        }

        /// <summary>
        /// Board read-model past-due check against ScheduledDate. Compares UTC calendar dates;
        /// business/location timezone support is planned for a later phase.
        /// </summary>
        public static bool IsPastDue(
            DateTime? scheduledDate,
            LifecycleStatus? lifecycleStatus,
            DateTime? utcNow = null)
        {
            if (!scheduledDate.HasValue)
                return false;

            if (LifecycleStatusMapper.IsTerminal(lifecycleStatus))
                return false;

            var today = (utcNow ?? DateTime.UtcNow).Date;
            return scheduledDate.Value.Date < today;
        }

        /// <summary>
        /// Sets initial lifecycle on create. New WOs start Incomplete unless auto-scheduled.
        /// </summary>
        public static void SetInitialLifecycleStatus(WorkOrder workOrder)
        {
            workOrder.LifecycleStatus ??= LifecycleStatus.Incomplete;
            ApplyAutoScheduleIfEligible(workOrder);
        }

        /// <summary>
        /// Promote Incomplete/Pending to Scheduled, or demote Scheduled to Pending, from Schedule On.
        /// Assignee is not required. Week-only is not a concrete date.
        /// </summary>
        public static List<WorkOrderBoardFieldMutations.BoardFieldChange> ApplyLifecycleFromSchedule(WorkOrder workOrder)
        {
            var changes = new List<WorkOrderBoardFieldMutations.BoardFieldChange>();
            LifecycleStatus? next = null;
            if (WorkOrderBoardMutationRules.ShouldPromoteToScheduled(
                    workOrder.LifecycleStatus,
                    workOrder.ScheduledDate,
                    workOrder.ScheduleWeekOnly))
            {
                next = LifecycleStatus.Scheduled;
            }
            else if (WorkOrderBoardMutationRules.ShouldDemoteFromScheduled(
                         workOrder.LifecycleStatus,
                         workOrder.ScheduledDate,
                         workOrder.ScheduleWeekOnly))
            {
                next = LifecycleStatus.Pending;
            }

            if (next == null || workOrder.LifecycleStatus == next)
                return changes;

            var old = workOrder.LifecycleStatus?.ToString();
            workOrder.LifecycleStatus = next;
            workOrder.Status = GetLifecycleStatusLabel(next);
            changes.Add(WorkOrderBoardFieldMutations.BoardFieldChange.StatusChanged(
                "LifecycleStatus",
                old,
                next.Value.ToString()));
            return changes;
        }

        /// <summary>
        /// Applies schedule-driven lifecycle (promote or demote). True when the row becomes Scheduled.
        /// </summary>
        public static bool ApplyAutoScheduleIfEligible(WorkOrder workOrder)
        {
            var before = workOrder.LifecycleStatus;
            ApplyLifecycleFromSchedule(workOrder);
            return before != LifecycleStatus.Scheduled
                   && workOrder.LifecycleStatus == LifecycleStatus.Scheduled;
        }

        /// <summary>
        /// Maps scheduled date to Mon–Fri board column. Phase 1 uses the stored
        /// date's day-of-week (UTC); timezone-aware grouping is planned for a later phase.
        /// </summary>
        public static string? GetDayGroup(DateTime? scheduledDate)
        {
            if (!scheduledDate.HasValue)
                return null;

            return scheduledDate.Value.DayOfWeek switch
            {
                DayOfWeek.Monday => "monday",
                DayOfWeek.Tuesday => "tuesday",
                DayOfWeek.Wednesday => "wednesday",
                DayOfWeek.Thursday => "thursday",
                DayOfWeek.Friday => "friday",
                _ => null
            };
        }

        public static string? FormatApptTime(DateTime? start, DateTime? end)
        {
            if (!start.HasValue)
                return null;

            if (end.HasValue)
                return $"{start.Value:HH:mm} – {end.Value:HH:mm}";

            return start.Value.ToString("HH:mm");
        }

        public static string GetLifecycleStatusLabel(LifecycleStatus? status)
            => status.HasValue ? LifecycleStatusMapper.ToFeLabel(status.Value) : "";
    }
}