using Arch.Core;
using HSchool.Ai;
using HSchool.People;

namespace HSchool.Simulation;

/// <summary>
/// Sick people seek the medical office; FIFO corridor wait; nurse tend while co-located.
/// Only the school worker thread mutates <see cref="School.NurseVisits"/>.
/// </summary>
internal static class NurseCareSystem
{
    private static readonly QueryDescription PresenceQuery =
        new QueryDescription().WithAll<PersonIdentity, Presence, PersonActivity, Intent>();

    public static bool IsVisiting(School school, string personId) =>
        school.NurseVisits.Any(row => row.PersonId.Equals(personId, StringComparison.Ordinal));

    public static bool TryDutyRoom(School school, string personId, out string roomId)
    {
        roomId = null!;
        var ticket = school.NurseVisits.FirstOrDefault(row =>
            row.PersonId.Equals(personId, StringComparison.Ordinal));
        if (ticket is null || school.Map is null)
        {
            return false;
        }

        var office = NurseCare.OfficeNodeId(school.Map);
        var wait = NurseCare.WaitNodeId(school.Map, office);
        if (office is null || wait is null)
        {
            return false;
        }

        roomId = ticket.Admitted ? office : wait;
        return true;
    }

    public static byte ResolvePresencePhase(School school, string personId)
    {
        var ticket = school.NurseVisits.FirstOrDefault(row =>
            row.PersonId.Equals(personId, StringComparison.Ordinal));
        if (ticket is null)
        {
            return NurseCare.PresenceNone;
        }

        var walking = false;
        var caring = false;
        string? nodeId = null;
        school.World.Query(
            in PresenceQuery,
            (ref PersonIdentity identity, ref Presence presence, ref PersonActivity activity, ref Intent _) =>
            {
                if (!identity.Id.Equals(personId, StringComparison.Ordinal))
                {
                    return;
                }

                nodeId = presence.NodeId;
                walking = presence.Path.Length > 0 || presence.RemainingMinutes > 0
                    || (presence.DestinationId is not null
                        && !presence.DestinationId.Equals(presence.NodeId, StringComparison.Ordinal));
                caring = activity.IsActive && ActivitySystem.IsNurseCare(activity.ActionId);
            });

        if (caring)
        {
            return NurseCare.PresenceCare;
        }

        if (walking)
        {
            return NurseCare.PresenceGoing;
        }

        var office = NurseCare.OfficeNodeId(school.Map!);
        if (ticket.Admitted
            && office is not null
            && nodeId is not null
            && nodeId.Equals(office, StringComparison.Ordinal))
        {
            return NurseCare.PresenceCare;
        }

        return NurseCare.PresenceWaiting;
    }

    public static string? PresenceActionId(byte phase) => phase switch
    {
        NurseCare.PresenceGoing => NurseCare.GoingAction,
        NurseCare.PresenceWaiting => NurseCare.WaitingAction,
        NurseCare.PresenceCare => NurseCare.CareAction,
        _ => null,
    };

    public static void ClearAll(School school)
    {
        if (school.NurseVisits.Count == 0)
        {
            return;
        }

        var ids = school.NurseVisits.Select(row => row.PersonId).ToArray();
        school.NurseVisits.Clear();
        foreach (var id in ids)
        {
            PresenceSystem.Enqueue(school, id);
        }
    }

    public static void Apply(School school, double gameMinutes)
    {
        if (school.Roster is null || school.Map is null || school.Catalog is null)
        {
            return;
        }

        if (!NurseCare.CanStart(school.Roster, school.Map))
        {
            ClearAll(school);
            return;
        }

        EnqueueNeedingCare(school);
        DropRecovered(school);
        AdmitHead(school);
        ApplyTend(school, gameMinutes);
        TryStartCareActivity(school);
    }

    private static void EnqueueNeedingCare(School school)
    {
        var catalog = school.Catalog!;
        var now = school.Clock.Time;
        foreach (var person in school.Roster!.People.OrderBy(row => row.Id, StringComparer.Ordinal))
        {
            if (IsVisiting(school, person.Id))
            {
                continue;
            }

            if (DiseaseEffects.ConditionNeedingNurse(person, catalog, now) is null)
            {
                continue;
            }

            // Pupils and staff on campus can seek care; parents off-roster roles skip.
            if (!person.IsStudent && !person.IsStaff)
            {
                continue;
            }

            school.NurseVisits.Add(new NurseVisitTicket(person.Id, school.NextNurseVisitOrder++, admitted: false));
            PresenceSystem.Enqueue(school, person.Id);
        }
    }

    private static void DropRecovered(School school)
    {
        var catalog = school.Catalog!;
        var now = school.Clock.Time;
        for (var i = school.NurseVisits.Count - 1; i >= 0; i--)
        {
            var ticket = school.NurseVisits[i];
            var person = school.Roster!.People.FirstOrDefault(row =>
                row.Id.Equals(ticket.PersonId, StringComparison.Ordinal));
            if (person is not null
                && DiseaseEffects.ConditionNeedingNurse(person, catalog, now) is not null)
            {
                continue;
            }

            school.NurseVisits.RemoveAt(i);
            PresenceSystem.Enqueue(school, ticket.PersonId);
        }
    }

    private static void AdmitHead(School school)
    {
        if (school.NurseVisits.Any(row => row.Admitted))
        {
            return;
        }

        var head = school.NurseVisits.OrderBy(row => row.Order).FirstOrDefault();
        if (head is null)
        {
            return;
        }

        head.Admitted = true;
        PresenceSystem.Enqueue(school, head.PersonId);
    }

    private static void ApplyTend(School school, double gameMinutes)
    {
        if (gameMinutes <= 0)
        {
            return;
        }

        var nurseId = NurseCare.NurseId(school.Roster!);
        if (nurseId is null)
        {
            return;
        }

        var office = NurseCare.OfficeNodeId(school.Map!);
        if (office is null || !IsIdleOrCaringIn(school, nurseId, office))
        {
            return;
        }

        var nurse = school.Roster!.People.First(row => row.Id.Equals(nurseId, StringComparison.Ordinal));
        var medicine = LiveMedicine(school, nurseId) ?? NurseCare.MedicineOf(nurse);
        var scale = school.Catalog!.BehaviorRules?.NurseTendMedicineScale ?? 1f;
        var dayNumber = DateOnly.FromDateTime(school.Clock.Time).DayNumber;
        var changed = false;

        foreach (var ticket in school.NurseVisits.Where(row => row.Admitted).ToArray())
        {
            if (!IsInNode(school, ticket.PersonId, office))
            {
                continue;
            }

            var patient = school.Roster.People.FirstOrDefault(row =>
                row.Id.Equals(ticket.PersonId, StringComparison.Ordinal));
            if (patient is null)
            {
                continue;
            }

            if (DiseaseEffects.Tend(
                    patient,
                    school.PeopleSeed,
                    dayNumber,
                    gameMinutes,
                    school.Catalog,
                    medicine,
                    school.Clock.Time,
                    scale))
            {
                changed = true;
            }
        }

        if (changed)
        {
            school.RosterTalkDirty = true;
        }
    }

    private static void TryStartCareActivity(School school)
    {
        var admitted = school.NurseVisits.FirstOrDefault(row => row.Admitted);
        if (admitted is null || school.Catalog is null)
        {
            return;
        }

        var office = NurseCare.OfficeNodeId(school.Map!);
        if (office is null
            || !IsInNode(school, admitted.PersonId, office)
            || !school.Catalog.Actions.TryGetValue(NurseCare.CareAction, out var action)
            || action.Abstract)
        {
            return;
        }

        var minutes = action.Minutes > 0f ? action.Minutes : 5f;
        school.World.Query(
            in PresenceQuery,
            (ref PersonIdentity identity, ref Presence presence, ref PersonActivity activity, ref Intent intent) =>
            {
                if (!identity.Id.Equals(admitted.PersonId, StringComparison.Ordinal))
                {
                    return;
                }

                if (activity.IsActive || presence.Path.Length > 0 || presence.RemainingMinutes > 0)
                {
                    return;
                }

                if (presence.NodeId is null
                    || !presence.NodeId.Equals(office, StringComparison.Ordinal))
                {
                    return;
                }

                activity = new PersonActivity(NurseCare.CareAction, null, minutes);
                intent = Intent.None;
            });
    }

    private static bool IsInNode(School school, string personId, string nodeId)
    {
        var found = false;
        school.World.Query(
            in PresenceQuery,
            (ref PersonIdentity identity, ref Presence presence, ref PersonActivity _, ref Intent _) =>
            {
                if (identity.Id.Equals(personId, StringComparison.Ordinal)
                    && presence.NodeId is not null
                    && presence.NodeId.Equals(nodeId, StringComparison.Ordinal)
                    && presence.Path.Length == 0
                    && presence.RemainingMinutes <= 0)
                {
                    found = true;
                }
            });
        return found;
    }

    private static bool IsIdleOrCaringIn(School school, string personId, string nodeId)
    {
        var found = false;
        school.World.Query(
            in PresenceQuery,
            (ref PersonIdentity identity, ref Presence presence, ref PersonActivity activity, ref Intent _) =>
            {
                if (!identity.Id.Equals(personId, StringComparison.Ordinal))
                {
                    return;
                }

                if (presence.NodeId is null
                    || !presence.NodeId.Equals(nodeId, StringComparison.Ordinal)
                    || presence.Path.Length > 0
                    || presence.RemainingMinutes > 0)
                {
                    return;
                }

                // Nurse on MedicalDuty stands in the office; any active non-care action blocks tend.
                if (activity.IsActive && !ActivitySystem.IsNurseCare(activity.ActionId))
                {
                    return;
                }

                found = true;
            });
        return found;
    }

    private static float? LiveMedicine(School school, string personId)
    {
        float? found = null;
        var query = new QueryDescription().WithAll<PersonIdentity, PersonSkills>();
        school.World.Query(in query, (ref PersonIdentity identity, ref PersonSkills skills) =>
        {
            if (identity.Id.Equals(personId, StringComparison.Ordinal)
                && skills.Values.TryGetValue(NurseCare.MedicineSkill, out var level))
            {
                found = level;
            }
        });
        return found;
    }
}

/// <summary>One nurse-visit ticket. <see cref="Order"/> is FIFO; lower goes first.</summary>
internal sealed class NurseVisitTicket(string personId, int order, bool admitted)
{
    public string PersonId { get; } = personId;

    public int Order { get; } = order;

    public bool Admitted { get; set; } = admitted;
}