using System;
using System.Collections.Generic;
using UnityEngine;
using Zeitsand.Service.Interfaces;

namespace Zeitsand.Service.Core
{
	//
	// Simple generic service locator with added lifetime managment
    // Ment for core services like Persistance or other no monobehavior services
	// Services need to implement the IService interface for initialization and shutdown (enforced)
	// Services should be registered with their interfaces, so they can be replaced with stubs for testing if needed
    // Parameters should be passed via constructor while instancing the class
    //
    public static class Services
    {
        private static readonly Dictionary<Type, object> ServiceMap = new();
        private static readonly List<object> ServiceOrder = new();

        public static void Register<T>(T service)
        {
            if (service is IService)
            {
                ServiceMap.Add(typeof(T), service);
                ServiceOrder.Add(service);
                Debug.Log("Service registered: " + typeof(T));
            }
            else
            {
                Debug.LogError(
                    $"Service {service.GetType()} is not an IService. " +
                    "This is not allowed. Please implement the IService interface."
                );
            }
        }

		// should be called from the bootstrap ( after registering all services
        public static void Initialize()
        {
			// initialize in order of registration
            foreach(IService service in ServiceOrder)
                service.Initialize();
        }
    
		// should be called from bootstrap in onApplicationQuit
        public static void Shutdown()
        {
			// shutdown in reverse order of registration
            for (int i = ServiceOrder.Count - 1; i >= 0; i--)
            {
                if (ServiceOrder[i] is IService service)
                {
                    service.Shutdown();
                }
            }
        
            // Clear the service map and order list.
            ServiceMap.Clear();
            ServiceOrder.Clear();
        }

        public static T Get<T>() => (T)ServiceMap[typeof(T)];
    }
}