using ProjectM.Simulation;
using Unity.Entities;
using Unity.NetCode;

namespace ProjectM.Client
{
    /// <summary>
    /// Client-only sender for <see cref="EquipRequest"/> / <see cref="UnequipRequest"/> RPCs. One-off actions, so
    /// RPCs (not per-tick input); the server applies them authoritatively in
    /// <see cref="ProjectM.Server.EquipSystem"/>. Number keys 1-9 equip the Nth EQUIPPABLE item in the local bag
    /// (resources are skipped via the catalog); U unequips the weapon. Managed SystemBase because it reads the
    /// managed Input System; Input System types are fully qualified and <c>using UnityEngine.InputSystem;</c> is
    /// omitted (it defines a colliding PlayerInput type). An <c>#if UNITY_EDITOR</c> static hook drives the same
    /// path from execute_code for headless validation. The HUD click-to-equip (HudSystem) is the primary UX;
    /// these keys are the reachable fallback. Wire types are unconditional; only this send SYSTEM is gated.
    /// </summary>
    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation)]
    public partial class EquipSendSystem : SystemBase
    {
        struct PendingEquip { public bool Unequip; public ushort ItemId; public byte Slot; }

        static readonly System.Collections.Generic.Queue<PendingEquip> s_Pending =
            new System.Collections.Generic.Queue<PendingEquip>();

        /// <summary>EDITOR / execute_code hook: queue an equip of <paramref name="itemId"/> from the bag.</summary>
        public static void Equip(ushort itemId) =>
            s_Pending.Enqueue(new PendingEquip { Unequip = false, ItemId = itemId });

        /// <summary>EDITOR / execute_code hook: queue an unequip of <paramref name="slot"/> (an EquipSlotId).</summary>
        public static void Unequip(byte slot) =>
            s_Pending.Enqueue(new PendingEquip { Unequip = true, Slot = slot });

        protected override void OnCreate()
        {
            RequireForUpdate<NetworkId>();
        }

        protected override void OnUpdate()
        {
            if (!SystemAPI.TryGetSingletonEntity<NetworkId>(out var connection))
                return;

            var keyboard = UnityEngine.InputSystem.Keyboard.current;
            if (keyboard != null)
            {
                int n = NumberKeyPressed(keyboard);
                if (n >= 0)
                {
                    ushort itemId = NthEquippableBagItem(n);
                    if (itemId != 0) SendEquip(connection, itemId);
                }
                if (keyboard.uKey.wasPressedThisFrame)
                    SendUnequip(connection, EquipSlotId.Weapon);
            }

            while (s_Pending.Count > 0)
            {
                var p = s_Pending.Dequeue();
                if (p.Unequip) SendUnequip(connection, p.Slot);
                else SendEquip(connection, p.ItemId);
            }
        }

        static int NumberKeyPressed(UnityEngine.InputSystem.Keyboard kb)
        {
            if (kb.digit1Key.wasPressedThisFrame) return 0;
            if (kb.digit2Key.wasPressedThisFrame) return 1;
            if (kb.digit3Key.wasPressedThisFrame) return 2;
            if (kb.digit4Key.wasPressedThisFrame) return 3;
            if (kb.digit5Key.wasPressedThisFrame) return 4;
            if (kb.digit6Key.wasPressedThisFrame) return 5;
            if (kb.digit7Key.wasPressedThisFrame) return 6;
            if (kb.digit8Key.wasPressedThisFrame) return 7;
            if (kb.digit9Key.wasPressedThisFrame) return 8;
            return -1;
        }

        /// <summary>Resolve the Nth EQUIPPABLE distinct item in the local player's bag (skips resources via the catalog).</summary>
        ushort NthEquippableBagItem(int n)
        {
            bool haveDb = SystemAPI.TryGetSingleton<ItemDatabase>(out var db);
            foreach (var bag in SystemAPI.Query<DynamicBuffer<InventorySlot>>().WithAll<GhostOwnerIsLocal, PlayerTag>())
            {
                int idx = 0;
                for (int i = 0; i < bag.Length; i++)
                {
                    ushort id = bag[i].ItemId;
                    if (id == 0 || bag[i].Count <= 0) continue;
                    if (haveDb && db.Value.IsCreated)
                    {
                        ref var b = ref db.Value.Value;
                        if (!b.TryGetItem(id, out var def) || def.EquipSlot >= EquipSlotId.Count) continue;
                    }
                    if (idx == n) return id;
                    idx++;
                }
                break;
            }
            return 0;
        }

        void SendEquip(Entity connection, ushort itemId)
        {
            var req = EntityManager.CreateEntity();
            EntityManager.AddComponentData(req, new EquipRequest { ItemId = itemId });
            EntityManager.AddComponentData(req, new SendRpcCommandRequest { TargetConnection = connection });
        }

        void SendUnequip(Entity connection, byte slot)
        {
            var req = EntityManager.CreateEntity();
            EntityManager.AddComponentData(req, new UnequipRequest { Slot = slot });
            EntityManager.AddComponentData(req, new SendRpcCommandRequest { TargetConnection = connection });
        }
    }
}