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

namespace ProjectM.Client
{
    /// <summary>
    /// Client-only twin-stick input gather. Samples the Input System once per frame (WASD /
    /// left-stick -&gt; Move, right-stick -&gt; Aim) and writes <see cref="PlayerInput"/> on the
    /// locally-owned player ghost (filtered to <see cref="GhostOwnerIsLocal"/>). Runs in
    /// <see cref="GhostInputSystemGroup"/> — NOT the prediction loop — so devices are read once per
    /// frame, never re-read during rollback. Implemented as a non-Burst <see cref="ISystem"/>
    /// because it reads the managed Input System.
    /// <para>
    /// NOTE: the Input System device types are fully qualified rather than imported via
    /// <c>using UnityEngine.InputSystem;</c> on purpose — that namespace also defines a
    /// <c>PlayerInput</c> type which would collide with <see cref="ProjectM.Simulation.PlayerInput"/>
    /// and make the Entities source generator bind <c>RefRW&lt;PlayerInput&gt;</c> to the managed
    /// class (a spurious CS8377 "must be unmanaged").
    /// </para>
    /// </summary>
    [UpdateInGroup(typeof(GhostInputSystemGroup))]
    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation)]
    public partial struct PlayerInputGatherSystem : ISystem
    {
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<PlayerInput>();
        }

        public void OnUpdate(ref SystemState state)
        {
            float2 move = float2.zero;
            float2 aim = float2.zero;

            var keyboard = UnityEngine.InputSystem.Keyboard.current;
            if (keyboard != null)
            {
                if (keyboard.wKey.isPressed) move.y += 1f;
                if (keyboard.sKey.isPressed) move.y -= 1f;
                if (keyboard.dKey.isPressed) move.x += 1f;
                if (keyboard.aKey.isPressed) move.x -= 1f;
            }

            var gamepad = UnityEngine.InputSystem.Gamepad.current;
            if (gamepad != null)
            {
                float2 leftStick = gamepad.leftStick.ReadValue();
                if (math.lengthsq(leftStick) > math.lengthsq(move))
                    move = leftStick;

                aim = gamepad.rightStick.ReadValue();
            }

            // Right-stick deadzone: a resting stick yields zero Aim so PlayerAimSystem falls back to
            // the movement heading (controller-first directional aim).
            if (math.lengthsq(aim) < 0.04f)
                aim = float2.zero;

            foreach (var input in SystemAPI.Query<RefRW<PlayerInput>>().WithAll<GhostOwnerIsLocal>())
            {
                input.ValueRW.Move = move;
                input.ValueRW.Aim = aim;
            }
        }
    }
}