using NUnit.Framework;
using ProjectM.Simulation;
using Unity.Collections;
using Unity.Entities;

namespace ProjectM.Tests
{
    /// <summary>
    /// Regression guard for the Phase 1 inline-mod design: <see cref="ItemDatabaseBlob.TryGetItem"/> returns the
    /// def BY VALUE, so the inline <see cref="ItemModSpec"/> slots must survive that copy. (A nested BlobArray of
    /// mods would corrupt its relative-offset pointer on this copy and read empty — the blocker the inline layout
    /// avoids.) Looks up the SECOND item by id and reads a non-zero mod value: an index-1 lookup + a non-zero read
    /// is exactly what would expose an offset corruption that a length-only check on item 0 could miss.
    /// </summary>
    public class ItemDatabaseBlobTests
    {
        [Test]
        public void TryGetItem_RoundTrips_Inline_Mods_For_Second_Item()
        {
            var builder = new BlobBuilder(Allocator.Temp);
            ref var root = ref builder.ConstructRoot<ItemDatabaseBlob>();
            var arr = builder.Allocate(ref root.Items, 2);
            arr[0] = new ItemDefBlob { ItemId = 100, EquipSlot = EquipSlotId.Weapon };
            arr[1] = new ItemDefBlob
            {
                ItemId = 101,
                EquipSlot = EquipSlotId.Armor,
                Mod0 = new ItemModSpec { Target = (byte)StatTarget.MoveSpeed, Op = (byte)ModOp.PercentAdd, Value = 0.25f },
                Mod1 = new ItemModSpec { Target = (byte)StatTarget.Damage, Op = (byte)ModOp.Flat, Value = 7f },
                Mod2 = new ItemModSpec { Target = 255 },
                Mod3 = new ItemModSpec { Target = 255 },
            };
            var blob = builder.CreateBlobAssetReference<ItemDatabaseBlob>(Allocator.Persistent);
            builder.Dispose();

            try
            {
                ref var db = ref blob.Value;
                Assert.IsTrue(db.TryGetItem(101, out var def), "Second item resolves by id.");
                Assert.AreEqual(EquipSlotId.Armor, def.EquipSlot);

                var m0 = def.GetMod(0);
                Assert.AreEqual((byte)StatTarget.MoveSpeed, m0.Target, "Inline Mod0 target survives the by-value copy.");
                Assert.AreEqual(0.25f, m0.Value, 1e-4f, "Inline Mod0 value survives the by-value copy (would read 0 under a nested-blob corruption).");

                var m1 = def.GetMod(1);
                Assert.AreEqual((byte)StatTarget.Damage, m1.Target);
                Assert.AreEqual(7f, m1.Value, 1e-4f);

                Assert.AreEqual(255, def.GetMod(2).Target, "Unused inline slots stay 255.");
            }
            finally { blob.Dispose(); }
        }
    }
}