mql5/Experts/_Architecture/State/StateManager.mqh

//+------------------------------------------------------------------+
//|                                               StateManager.mqh   |
//|                                  Copyright 2025, MetaQuotes Ltd. |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2025, MetaQuotes Ltd."
#property link      "https://www.mql5.com"
#property version   "1.00"

#include "IState.mqh"
#include <Arrays\List.mqh>

//+------------------------------------------------------------------+
//| State manager – holds named states and can save/load all        |
//+------------------------------------------------------------------+
class StateManager
{
private:
   struct StateEntry
   {
      string   name;
      IState*  state;
   };

   StateEntry        m_entries[];
   int               m_count;

public:
   StateManager() : m_count(0) {}
   ~StateManager()
   {
      // States are owned externally, do not delete here.
   }

   // Register a state object under a unique name
   void AddState(string name, IState* state)
   {
      int size = ArraySize(m_entries);
      ArrayResize(m_entries, size + 1);
      m_entries[size].name  = name;
      m_entries[size].state = state;
      m_count = size + 1;
   }

   // Save all states into a single JSON object
   JSON::Object* SaveAll()
   {
      JSON::Object* root = new JSON::Object();
      for(int i = 0; i < m_count; i++)
      {
         JSON::Object* stateObj = m_entries[i].state.Save();
         if(stateObj != NULL)
            root.setProperty(m_entries[i].name, stateObj);
      }
      return root;
   }

   // Load all states from a JSON object
   bool LoadAll(const JSON::Object* root)
   {
      if(root == NULL) return false;

      for(int i = 0; i < m_count; i++)
      {
         JSON::Object* stateObj = root.getObject(m_entries[i].name);
         if(stateObj == NULL) continue; // skip missing
         m_entries[i].state.Load(stateObj);
      }
      return true;
   }

   // Write the JSON representation to a file
   bool SaveToFile(string filename)
   {
      JSON::Object* root = SaveAll();
      if(root == NULL) return false;

      string jsonStr = root.toString();
      delete root;

      int handle = FileOpen(filename, FILE_WRITE|FILE_TXT|FILE_ANSI);
      if(handle == INVALID_HANDLE) return false;

      FileWriteString(handle, jsonStr);
      FileClose(handle);
      return true;
   }

   // Read JSON from file and load states
   bool LoadFromFile(string filename)
   {
      int handle = FileOpen(filename, FILE_READ|FILE_TXT|FILE_ANSI);
      if(handle == INVALID_HANDLE) return false;

      string jsonStr = "";
      while(!FileIsEnding(handle))
         jsonStr += FileReadString(handle, 0);

      FileClose(handle);

      JSON::Object* root = new JSON::Object(jsonStr);
      bool result = LoadAll(root);
      delete root;
      return result;
   }
};
//+------------------------------------------------------------------+