using System.Collections.Generic;
using ProjectM.Simulation;
using Unity.Collections;
using Unity.Entities;
using UnityEngine;

namespace ProjectM.Authoring
{
    /// <summary>
    /// Bakes the designer-authored item definitions into a single ItemDatabase blob singleton (immutable,
    /// shared, Burst-fast), mirroring AbilityDatabaseAuthoring. Place ONE in the gameplay subscene; it streams
    /// identically into the client and server worlds (config, not replicated). DependsOn each definition so a
    /// value change re-bakes the blob. Runtime lookup is ID-keyed (ItemDatabaseBlob.TryGetItem), so the list
    /// order here does not matter and inserting an item never renumbers existing ids.
    /// </summary>
    public class ItemDatabaseAuthoring : MonoBehaviour
    {
        [Tooltip("All item definitions in the game (resources + tools/gear). Looked up at runtime by ItemId.")]
        public List<ItemDefinition> Items = new List<ItemDefinition>();

        private class DatabaseBaker : Baker<ItemDatabaseAuthoring>
        {
            public override void Bake(ItemDatabaseAuthoring authoring)
            {
                var entity = GetEntity(TransformUsageFlags.None);

                int count = authoring.Items != null ? authoring.Items.Count : 0;

                var builder = new BlobBuilder(Allocator.Temp);
                ref var root = ref builder.ConstructRoot<ItemDatabaseBlob>();
                var arr = builder.Allocate(ref root.Items, count);
                for (int i = 0; i < count; i++)
                {
                    var def = authoring.Items[i];
                    if (def == null) { arr[i] = default; continue; }
                    DependsOn(def);
                    arr[i] = new ItemDefBlob
                    {
                        ItemId = (ushort)def.ItemId,
                        Category = def.Category,
                        Tier = def.Tier,
                        StackMax = def.StackMax,
                        EquipSlot = def.EquipSlot,
                        GrantedAbilityId = def.GrantedAbilityId,
                        Mod0 = ModAt(def, 0),
                        Mod1 = ModAt(def, 1),
                        Mod2 = ModAt(def, 2),
                        Mod3 = ModAt(def, 3),
                        Name = def.DisplayName,
                    };
                }

                var blob = builder.CreateBlobAssetReference<ItemDatabaseBlob>(Allocator.Persistent);
                builder.Dispose();
                AddBlobAsset(ref blob, out _);
                AddComponent(entity, new ItemDatabase { Value = blob });

                static ItemModSpec ModAt(ItemDefinition def, int i)
                {
                    if (def.Mods != null && i < def.Mods.Count)
                    {
                        var m = def.Mods[i];
                        return new ItemModSpec { Target = m.Target, Op = m.Op, Value = m.Value };
                    }
                    return new ItemModSpec { Target = 255 };
                }
            }
        }
    }
}