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

namespace BrewMonster.Scripts
{
    public static class DebugCmdHistoryStore
    {
        private const string ResourcesJsonPathNoExt = "DebugCmdHistory";
        private const string PlayerPrefsJsonKey = "DebugCmdHistory_v1";
        private const string PlayerPrefsInitedKey = "DebugCmdHistory_inited_v1";
        private const int MaxEntries = 200;

        [Serializable]
        public class Entry
        {
            public int header;
            public int param;
            public bool hasParam;
            public string describe;
            public long lastUsedUtcTicks;

            public string KeyString => hasParam ? $"{header}:{param}" : $"{header}:";
        }

        [Serializable]
        private class EntryListWrapper
        {
            public List<Entry> items = new List<Entry>();
        }

        public static List<Entry> Load()
        {
#if UNITY_EDITOR
            return LoadFromEditorJsonFile();
#else
            // Runtime: first-run seed from Resources into PlayerPrefs, then keep using PlayerPrefs.
            if (!IsInited())
            {
                var seed = LoadFromResources();
                SaveToPlayerPrefs(seed);
                SetInited();
                return seed;
            }

            return LoadFromPlayerPrefs();
#endif
        }

        public static void Save(List<Entry> entries)
        {
#if UNITY_EDITOR
            SaveToEditorJsonFile(entries);
#else
            SaveToPlayerPrefs(entries);
#endif
        }

        public static bool Upsert(List<Entry> entries, int header, int param, bool hasParam, string describe)
        {
            if (entries == null)
                throw new ArgumentNullException(nameof(entries));

            describe = (describe ?? string.Empty).Trim();

            int idx = FindIndex(entries, header, param, hasParam);
            if (idx >= 0)
            {
                var e = entries[idx];
                bool changed = false;

                // Overwrite describe whenever it differs (supports updating from empty -> non-empty).
                if (!string.Equals((e.describe ?? string.Empty).Trim(), describe, StringComparison.Ordinal))
                {
                    e.describe = describe;
                    changed = true;
                }

                e.lastUsedUtcTicks = DateTime.UtcNow.Ticks;
                if (idx != 0)
                {
                    entries.RemoveAt(idx);
                    entries.Insert(0, e);
                    changed = true;
                }
                else if (!changed)
                {
                    // still considered "used"; keep order
                }

                return changed;
            }
            else
            {
                var e = new Entry
                {
                    header = header,
                    param = param,
                    hasParam = hasParam,
                    describe = describe,
                    lastUsedUtcTicks = DateTime.UtcNow.Ticks
                };
                entries.Insert(0, e);

                if (entries.Count > MaxEntries)
                    entries.RemoveRange(MaxEntries, entries.Count - MaxEntries);

                return true;
            }
        }

        public static void Clear()
        {
#if UNITY_EDITOR
            try
            {
                var path = GetEditorJsonAbsolutePath();
                if (File.Exists(path))
                    File.Delete(path);
            }
            catch (Exception ex)
            {
                Debug.LogWarning($"[DebugCmdHistoryStore] Clear (editor json) failed: {ex.Message}");
            }
#else
            PlayerPrefs.DeleteKey(PlayerPrefsJsonKey);
            PlayerPrefs.DeleteKey(PlayerPrefsInitedKey);
            PlayerPrefs.Save();
#endif
        }

        public static bool Remove(List<Entry> entries, int header, int param, bool hasParam)
        {
            if (entries == null)
                throw new ArgumentNullException(nameof(entries));

            int idx = FindIndex(entries, header, param, hasParam);
            if (idx < 0)
                return false;

            entries.RemoveAt(idx);
            return true;
        }

        private static string GetEditorJsonAbsolutePath()
        {
            // Keep it under Assets/Resources so it can be included as a TextAsset for runtime seeding.
            return Path.Combine(Application.dataPath, "Resources", $"{ResourcesJsonPathNoExt}.json");
        }

        private static List<Entry> LoadFromEditorJsonFile()
        {
            try
            {
                var path = GetEditorJsonAbsolutePath();
                if (!File.Exists(path))
                    return LoadFromResources(); // fallback if file not created yet

                var json = File.ReadAllText(path);
                if (string.IsNullOrWhiteSpace(json))
                    return new List<Entry>();

                var wrapper = JsonUtility.FromJson<EntryListWrapper>(json);
                if (wrapper == null || wrapper.items == null)
                    return new List<Entry>();

                wrapper.items.RemoveAll(e => e == null);
                return wrapper.items;
            }
            catch
            {
                return new List<Entry>();
            }
        }

        private static void SaveToEditorJsonFile(List<Entry> entries)
        {
            try
            {
                var wrapper = new EntryListWrapper { items = entries ?? new List<Entry>() };
                string json = JsonUtility.ToJson(wrapper, prettyPrint: true);

                var path = GetEditorJsonAbsolutePath();
                var dir = Path.GetDirectoryName(path);
                if (!string.IsNullOrWhiteSpace(dir) && !Directory.Exists(dir))
                    Directory.CreateDirectory(dir);

                File.WriteAllText(path, json);

#if UNITY_EDITOR
                UnityEditor.AssetDatabase.Refresh();
#endif
            }
            catch (Exception ex)
            {
                Debug.LogWarning($"[DebugCmdHistoryStore] Save (editor json) failed: {ex.Message}");
            }
        }

        private static List<Entry> LoadFromResources()
        {
            try
            {
                var asset = Resources.Load<TextAsset>(ResourcesJsonPathNoExt);
                if (asset == null || string.IsNullOrWhiteSpace(asset.text))
                    return new List<Entry>();

                var wrapper = JsonUtility.FromJson<EntryListWrapper>(asset.text);
                if (wrapper == null || wrapper.items == null)
                    return new List<Entry>();

                wrapper.items.RemoveAll(e => e == null);
                return wrapper.items;
            }
            catch
            {
                return new List<Entry>();
            }
        }

        private static List<Entry> LoadFromPlayerPrefs()
        {
            string json = PlayerPrefs.GetString(PlayerPrefsJsonKey, string.Empty);
            if (string.IsNullOrWhiteSpace(json))
                return new List<Entry>();

            try
            {
                var wrapper = JsonUtility.FromJson<EntryListWrapper>(json);
                if (wrapper == null || wrapper.items == null)
                    return new List<Entry>();

                wrapper.items.RemoveAll(e => e == null);
                return wrapper.items;
            }
            catch
            {
                return new List<Entry>();
            }
        }

        private static void SaveToPlayerPrefs(List<Entry> entries)
        {
            try
            {
                var wrapper = new EntryListWrapper { items = entries ?? new List<Entry>() };
                string json = JsonUtility.ToJson(wrapper);
                PlayerPrefs.SetString(PlayerPrefsJsonKey, json);
                PlayerPrefs.Save();
            }
            catch (Exception ex)
            {
                Debug.LogWarning($"[DebugCmdHistoryStore] Save failed: {ex.Message}");
            }
        }

        private static bool IsInited() => PlayerPrefs.GetInt(PlayerPrefsInitedKey, 0) == 1;
        private static void SetInited()
        {
            PlayerPrefs.SetInt(PlayerPrefsInitedKey, 1);
            PlayerPrefs.Save();
        }

        private static int FindIndex(List<Entry> entries, int header, int param, bool hasParam)
        {
            for (int i = 0; i < entries.Count; i++)
            {
                var e = entries[i];
                if (e == null) continue;
                if (e.header != header) continue;
                if (e.hasParam != hasParam) continue;
                if (hasParam && e.param != param) continue;
                return i;
            }
            return -1;
        }
    }
}