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

namespace BrewMonster.Scripts
{
    public static class DebugCmdHistoryStore
    {
        private const string PlayerPrefsKey = "DebugCmdHistory_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()
        {
            string json = PlayerPrefs.GetString(PlayerPrefsKey, 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>();
            }
        }

        public static void Save(List<Entry> entries)
        {
            var wrapper = new EntryListWrapper { items = entries ?? new List<Entry>() };
            string json = JsonUtility.ToJson(wrapper);
            PlayerPrefs.SetString(PlayerPrefsKey, json);
            PlayerPrefs.Save();
        }

        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()
        {
            PlayerPrefs.DeleteKey(PlayerPrefsKey);
            PlayerPrefs.Save();
        }

        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 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;
        }
    }
}