using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.AddressableAssets;

namespace Jovian.EncounterSystem {
    /// <summary>
    /// Central lookup cache mapping <see cref="EncounterDefinition.internalId"/> to its owning
    /// <see cref="IEncounter"/> across one or more <see cref="EncountersCollection"/> assets.
    /// In editor the registry auto-populates via an asset postprocessor; at runtime call
    /// <see cref="PopulateEncounters"/> explicitly after load.
    /// </summary>
    [CreateAssetMenu(fileName = "EncounterRegistry", menuName = "Jovian/Encounter System/Encounter Registry")]
    public class EncounterRegistry : ScriptableObject {
        /// <summary>Collections whose encounters should be indexed.</summary>
        public EncountersCollection[] encounterCollections = Array.Empty<EncountersCollection>();

        private readonly Dictionary<string, IEncounter> encounters = new();

        /// <summary>The live id → encounter map.</summary>
        public Dictionary<string, IEncounter> GetEncounters() => encounters;

        /// <summary>Add an encounter to the cache if its id isn't already present.</summary>
        public void RegisterEncounter(IEncounter encounter) {
            encounters?.TryAdd(encounter?.EncounterDefinition?.internalId, encounter);
        }

        /// <summary>Remove an encounter from the cache by its id.</summary>
        public void UnregisterEncounter(IEncounter encounter) {
            encounters.Remove(encounter.EncounterDefinition.internalId);
        }

        /// <summary>Clear the cache. Call before a full re-population to avoid stale entries.</summary>
        public void ClearEncounters() {
            encounters.Clear();
        }

        /// <summary>Walk <see cref="encounterCollections"/> and register every encounter found.
        /// Call <see cref="ClearEncounters"/> first if you need a clean state.</summary>
        public void PopulateEncounters() {
            foreach(var collection in encounterCollections) {
                foreach(var encounter in collection.encounterTables) {
                    foreach(var encounterInstance in encounter.encounters) {
                        RegisterEncounter(encounterInstance);
                    }
                }
            }
        }
    }

#if UNITY_EDITOR
    /// <summary>
    /// Editor-time hook that keeps an <see cref="EncounterRegistry"/> asset (located via Addressables
    /// key <c>"EncounterRegistry"</c>) in sync with asset edits: clears and repopulates on any asset
    /// import/move/delete.
    /// </summary>
    public class EncounterRegister : UnityEditor.AssetPostprocessor {
        private static EncounterRegistry registryCache;

        private static void OnPostprocessAllAssets(string[] importedAssets, string[] deletedAssets, string[] movedAssets, string[] movedFromAssetPaths) {
            registryCache ??= Addressables.LoadAssetAsync<EncounterRegistry>("EncounterRegistry").WaitForCompletion();
            registryCache.ClearEncounters();
            registryCache.PopulateEncounters();
        }
    }
#endif
}