using System.Collections.Generic;
using Unity.Collections;
using Unity.Entities;

namespace ProjectM.Simulation
{
    /// <summary>
    /// Scans a server world for PLAYER-built structures (<see cref="PlacedStructure"/> + <see cref="RuntimePlacedTag"/>)
    /// into the flat SaveData v2 arrays — the SINGLE shared scan used by BOTH the autosave (SaveWriteSystem) and the
    /// quit-to-menu save (WorldLauncher), so the two paths can never drift (only RuntimePlacedTag structures are saved;
    /// anything baked into the subscene is the subscene's source of truth, not the save's). Cooldowns are stored as
    /// REMAINING ticks (epoch-independent). Managed (List/array) — runs only on a save, never in the hot loop.
    /// </summary>
    public static class SaveStructureScan
    {
        public static void Collect(EntityManager em, uint nowTick, out StructureSave[] structures, out StructureIoRow[] io)
        {
            var structs = new List<StructureSave>();
            var ioRows = new List<StructureIoRow>();

            using var q = em.CreateEntityQuery(
                ComponentType.ReadOnly<PlacedStructure>(),
                ComponentType.ReadOnly<RuntimePlacedTag>());
            using var entities = q.ToEntityArray(Allocator.Temp);

            for (int k = 0; k < entities.Length; k++)
            {
                var e = entities[k];
                var ps = em.GetComponentData<PlacedStructure>(e);
                int idx = structs.Count;

                var row = new StructureSave
                {
                    Type = ps.Type,
                    CellX = ps.Cell.x,
                    CellZ = ps.Cell.y,
                    RemainingTicks = ProductionMath.RemainingTicks(ps.NextTick, nowTick),
                };

                if (em.HasComponent<Conveyor>(e))
                    row.Direction = em.GetComponentData<Conveyor>(e).Direction;

                if (em.HasComponent<ConveyorItem>(e) && em.IsComponentEnabled<ConveyorItem>(e))
                {
                    var item = em.GetComponentData<ConveyorItem>(e);
                    row.ConveyorResId = item.ResourceId;
                    row.ConveyorCount = item.Count;
                }

                structs.Add(row);

                if (em.HasBuffer<MachineInput>(e))
                {
                    var buf = em.GetBuffer<MachineInput>(e, true);
                    for (int i = 0; i < buf.Length; i++)
                        ioRows.Add(new StructureIoRow { StructureIndex = idx, Slot = 0, ResourceId = buf[i].ResourceId, Count = buf[i].Count });
                }
                if (em.HasBuffer<MachineOutput>(e))
                {
                    var buf = em.GetBuffer<MachineOutput>(e, true);
                    for (int i = 0; i < buf.Length; i++)
                        ioRows.Add(new StructureIoRow { StructureIndex = idx, Slot = 1, ResourceId = buf[i].ResourceId, Count = buf[i].Count });
                }
            }

            structures = structs.ToArray();
            io = ioRows.ToArray();
        }
    }
}