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

namespace ProjectM.Server
{
    /// <summary>
    /// Host-only autosave writer. A managed <see cref="SystemBase"/> (file IO =&gt; NO Burst) that reacts to the
    /// <see cref="SaveRequest"/> flag the Bursted <c>CyclePhaseSystem</c> raises on the Siege-&gt;Calm checkpoint:
    /// reads the authoritative <see cref="GoalProgress"/> + shared resource ledger off the CycleDirector ghost,
    /// writes the JSON save (<see cref="SaveService"/>), then clears the flag. ServerSimulation-only, so a pure
    /// (Join) client never writes. Deliberately carries NO <c>[UpdateAfter(CyclePhaseSystem)]</c> (that would risk
    /// a sort-cycle); a one-tick-late autosave is irrelevant.
    /// </summary>
    [WorldSystemFilter(WorldSystemFilterFlags.ServerSimulation)]
    public partial class SaveWriteSystem : SystemBase
    {
        protected override void OnCreate()
        {
            RequireForUpdate<SaveRequest>();
            RequireForUpdate<NetworkTime>();
        }

        protected override void OnUpdate()
        {
            var dir = SystemAPI.GetSingletonEntity<SaveRequest>();
            var req = SystemAPI.GetComponent<SaveRequest>(dir);
            if (req.Pending == 0)
                return;

            req.Pending = 0;
            SystemAPI.SetComponent(dir, req);

            var goal = SystemAPI.HasComponent<GoalProgress>(dir)
                ? SystemAPI.GetComponent<GoalProgress>(dir)
                : default;

            // END-1: persist the Engine Core integrity (a wounded base stays wounded across save/quit).
            var core = SystemAPI.HasComponent<CoreIntegrity>(dir)
                ? SystemAPI.GetComponent<CoreIntegrity>(dir)
                : default;


            // The shared ledger lives on this same CycleDirector ghost (ResourceLedger-tagged StorageEntry buffer).
            var buffer = SystemAPI.GetBuffer<StorageEntry>(dir);
            var rows = new LedgerRow[buffer.Length];
            for (int i = 0; i < buffer.Length; i++)
                rows[i] = new LedgerRow { ItemId = buffer[i].ItemId, Count = buffer[i].Count };

            // M7: also persist player-built structures + their production tick-state / inventory (single shared scan).
            uint nowTick = SystemAPI.GetSingleton<NetworkTime>().ServerTick.TickIndexForValidTick;
            SaveStructureScan.Collect(EntityManager, nowTick, out var structures, out var structureIo);

            SaveService.Save(new SaveData
            {
                GoalCharge = goal.Charge,
                GoalTarget = goal.Target,
                CoreCurrent = core.Current,

                Ledger = rows,
                Structures = structures,
                StructureIo = structureIo,
                SavedAtMs = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(),
            });
        }
    }
}