using System.Collections.Generic;
using UnityEngine;
using FishNet.Object;
using Ashwild.Inventory;
using Ashwild.Player;

namespace Ashwild.Crafting
{
    /// <summary>
    /// The local player's craft-discovery knowledge: the set of items it has ever acquired.
    /// A recipe is only revealed (and only craftable) once its ingredients have been discovered,
    /// so the player uncovers crafts by gathering resources rather than seeing the whole catalog
    /// at once. Discovery is triggered the first time an item enters the inventory — pickups,
    /// harvest drops AND craft results all count, which lets crafting chains reveal step by step.
    ///
    /// This is owner-only local state: each player keeps its own knowledge, and it is never
    /// replicated over the wire (no one else needs to read it). It mirrors PlayerInventory's
    /// singleton pattern purely for reliable owner gating — set the Instance for the owning
    /// client in OnStartNetwork, and gate the component off on remotes via ownerOnlyBehaviours.
    /// </summary>
    [DisallowMultipleComponent]
    public class CraftDiscovery : NetworkBehaviour
    {
        #region Singleton

        /// <summary>
        /// The local player's discovery knowledge (set only on the owning client).
        /// </summary>
        public static CraftDiscovery Instance { get; private set; }

        #endregion

        #region State

        private readonly HashSet<ItemData> discovered = new HashSet<ItemData>();

        #endregion

        #region Network Lifecycle

        /// <summary>
        /// Registers the singleton on the owning client only (before LocalPlayerSpawned fires).
        /// </summary>
        public override void OnStartNetwork()
        {
            base.OnStartNetwork();
            if (base.Owner.IsLocalClient) Instance = this;
        }

        /// <summary>
        /// Clears the singleton when this player leaves the network.
        /// </summary>
        public override void OnStopNetwork()
        {
            base.OnStopNetwork();
            if (Instance == this) Instance = null;
        }

        #endregion

        #region Unity Lifecycle

        /// <summary>
        /// Starts tracking every item the local player acquires.
        /// </summary>
        private void OnEnable()
        {
            PlayerEvents.ItemAdded += HandleItemAdded;
        }

        /// <summary>
        /// Stops tracking — mirrors OnEnable exactly.
        /// </summary>
        private void OnDisable()
        {
            PlayerEvents.ItemAdded -= HandleItemAdded;
        }

        #endregion

        #region Event Handlers

        /// <summary>
        /// Marks an acquired item as discovered. Transfers count too — pulling an item a co-op partner
        /// left in a chest is a genuine first acquisition and must unlock its recipes, even though the
        /// HUD stays silent about it. Guarded to the owning instance so a remote puppet that briefly
        /// subscribed before being gated off can never drive discovery on the wrong copy.
        /// </summary>
        private void HandleItemAdded(ItemData item, int quantity, bool isTransfer)
        {
            if (Instance != this) return;
            Discover(item);
        }

        #endregion

        #region Public API

        /// <summary>
        /// Whether the local player has ever acquired this item (and therefore knows it).
        /// </summary>
        public bool IsDiscovered(ItemData item) => item != null && discovered.Contains(item);

        #endregion

        #region Internal Helpers

        /// <summary>
        /// Adds an item to the discovered set the first time it is seen and announces it on the bus
        /// so the crafting view can reveal any recipe the item unlocks.
        /// </summary>
        private void Discover(ItemData item)
        {
            if (item == null) return;
            if (discovered.Add(item))
                PlayerEvents.RaiseItemDiscovered(item);
        }

        #endregion
    }
}