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

namespace Jovian.EncounterSystem {
    /// <summary>One dialog line — an id/text pair in a <see cref="DialogLineLibrary"/>.</summary>
    [Serializable]
    public class DialogLine {
        /// <summary>Stable key referenced by <see cref="DialogLineRef"/> (e.g. "common.farewell").</summary>
        public string id;

        /// <summary>The actual text shown to the player.</summary>
        [TextArea(2, 6)]
        public string text;
    }

    /// <summary>
    /// Single-asset registry of reusable dialog lines. One library file holds many lines; dialog
    /// options reference them by id via <see cref="DialogLineRef"/>. Split into multiple libraries
    /// (e.g. CommonLines, TownDialogue) only when a single file becomes unwieldy.
    /// </summary>
    [CreateAssetMenu(fileName = "DialogLineLibrary", menuName = "Jovian/Encounter System/Dialog Line Library", order = 4)]
    public class DialogLineLibrary : ScriptableObject {
        /// <summary>All lines in the library.</summary>
        public List<DialogLine> lines = new();

        private Dictionary<string, string> cache;

        /// <summary>Return the text for <paramref name="id"/>, or <c>null</c> if not found.</summary>
        public string Resolve(string id) {
            if(string.IsNullOrEmpty(id)) {
                return null;
            }

            EnsureCache();
            return cache.TryGetValue(id, out var text) ? text : null;
        }

        /// <summary>Force the next <see cref="Resolve"/> call to rebuild the id → text cache.
        /// Called automatically from <c>OnValidate</c> after inspector edits.</summary>
        public void InvalidateCache() {
            cache = null;
        }

        private void EnsureCache() {
            if(cache != null) {
                return;
            }

            cache = new Dictionary<string, string>();
            if(lines == null) {
                return;
            }

            foreach(var line in lines) {
                if(line != null && !string.IsNullOrEmpty(line.id)) {
                    cache[line.id] = line.text;
                }
            }
        }

#if UNITY_EDITOR
        private void OnValidate() {
            InvalidateCache();
        }
#endif
    }
}