using Data.SeaHavenIndustries.Enums;
using SeaHaven.Services.Exceptions;

namespace SeaHaven.Services.Helpers
{
    /// <summary>
    /// SH-169 manual transition guard for the board lifecycleStatus PATCH.
    /// Incomplete and Scheduled are derived by the server; a direct request may only
    /// restate what derivation already produces, never forge a new automatic state.
    /// Past Due is a read-model overlay (<see cref="WorkOrderDerivedFields.IsPastDue(System.DateTime?, LifecycleStatus?, System.DateTime?)"/>),
    /// not a <see cref="LifecycleStatus"/> value, so it cannot be requested at all.
    /// </summary>
    public static class WorkOrderBoardPatchLifecycleRules
    {
        public const string AutomaticStatusCode = "AutomaticLifecycleStatus";

        public static bool IsAutomaticStatus(LifecycleStatus status)
            => status == LifecycleStatus.Incomplete || status == LifecycleStatus.Scheduled;

        public static void EnsureRequestAllowed(
            LifecycleStatus? current,
            LifecycleStatus requested,
            DateTime? scheduledDate,
            bool? scheduleWeekOnly)
        {
            if (!IsAutomaticStatus(requested))
                return;

            if (requested == LifecycleStatus.Scheduled
                && !WorkOrderBoardMutationRules.HasConcreteSchedule(scheduledDate, scheduleWeekOnly))
            {
                throw new WorkOrderBoardValidationException(
                    "ScheduledRequiresDate",
                    "Scheduled requires a concrete scheduledDate when scheduleWeekOnly is not true.");
            }

            // why: the board client restates the derived status after a schedule patch; that is a no-op, not a forge.
            if (current == requested)
                return;

            if (requested == LifecycleStatus.Scheduled
                && WorkOrderBoardMutationRules.ShouldPromoteToScheduled(current, scheduledDate, scheduleWeekOnly))
            {
                return;
            }

            throw new WorkOrderBoardValidationException(
                AutomaticStatusCode,
                $"{LifecycleStatusMapper.ToFeLabel(requested)} is set automatically and cannot be selected manually.");
        }
    }
}