using System.Collections.Generic;
using System.IO;
using LLM.Editor.Data;
using LLM.Editor.Helper;
using UnityEditor;
using UnityEngine;

namespace LLM.Editor.Core
{
    /// <summary>
    /// Handles all file I/O for the session cache.
    /// Manages to create new sessions, reading/writing chat logs, and persisting the command queue.
    /// </summary>
    public static class SessionManager
    {
        private static readonly string _sessionCacheRoot;
        private static string _currentSessionId;

        private const string SESSION_ID_KEY = "MCP_CurrentSessionID";
        private const string QUEUE_FILE = "queue.json";
        private const string CHAT_LOG_FILE = "chat_log.json";

        // Helper class for serializing a list to JSON
        [System.Serializable] private class CommandListWrapper { public List<CommandData> commands; }
        [System.Serializable] private class ChatLogWrapper { public List<ChatEntry> history; }

        static SessionManager()
        {
            _sessionCacheRoot = Path.Combine(Application.persistentDataPath, "LLMCache");
            Directory.CreateDirectory(_sessionCacheRoot);
            _currentSessionId = SessionState.GetString(SESSION_ID_KEY, null);
            Debug.Log($"[SessionManager] Initialized. Current Session: {_currentSessionId}");
        }

        public static string GetCurrentSessionId() => _currentSessionId;

        public static bool HasActiveSession() => !string.IsNullOrEmpty(_currentSessionId) && Directory.Exists(Path.Combine(_sessionCacheRoot, _currentSessionId));

        public static void StartNewSession()
        {
            _currentSessionId = $"session_{System.DateTime.Now:yyyyMMddHHmmss}";
            SessionState.SetString(SESSION_ID_KEY, _currentSessionId);
            Directory.CreateDirectory(Path.Combine(_sessionCacheRoot, _currentSessionId));
            Debug.Log($"[SessionManager] Started new session: {_currentSessionId}");
        }

        public static void EndSession()
        {
            _currentSessionId = null;
            SessionState.EraseString(SESSION_ID_KEY);
            Debug.Log("[SessionManager] Ended session.");
        }

        public static void SaveCommandQueue(List<CommandData> queue)
        {
            if (!HasActiveSession())
            {
                Debug.LogError("[SessionManager] Cannot save queue, no active session.");
                return;
            }

            var wrapper = new CommandListWrapper { commands = queue };
            var json = wrapper.ToJson();
            var path = Path.Combine(_sessionCacheRoot, _currentSessionId, QUEUE_FILE);
            File.WriteAllText(path, json);
            Debug.Log($"[SessionManager] Saved {queue.Count} command(s) to queue.");
        }

        public static List<CommandData> LoadCommandQueue()
        {
            if (!HasActiveSession()) return new List<CommandData>();

            var path = Path.Combine(_sessionCacheRoot, _currentSessionId, QUEUE_FILE);
            if (!File.Exists(path)) return new List<CommandData>();

            var json = File.ReadAllText(path);
            var wrapper = json.FromJson<CommandListWrapper>();
            Debug.Log($"[SessionManager] Loaded {wrapper.commands.Count} command(s) from queue.");
            return wrapper.commands ?? new List<CommandData>();
        }

        public static void SaveChatHistory(List<ChatEntry> history)
        {
            if (!HasActiveSession()) return;
            var wrapper = new ChatLogWrapper { history = history };
            var json = wrapper.ToJson();
            var path = Path.Combine(_sessionCacheRoot, _currentSessionId, CHAT_LOG_FILE);
            File.WriteAllText(path, json);
        }

        public static List<ChatEntry> LoadChatHistory()
        {
            if (!HasActiveSession()) return new List<ChatEntry>();
            var path = Path.Combine(_sessionCacheRoot, _currentSessionId, CHAT_LOG_FILE);
            if (!File.Exists(path)) return new List<ChatEntry>();
            var json = File.ReadAllText(path);
            var wrapper = json.FromJson<ChatLogWrapper>();
            return wrapper?.history ?? new List<ChatEntry>();
        }
    }
}