using System.Threading.Tasks;
using UnityEngine;

namespace Bootstrap
{
    /// <summary>
    /// Settings for the custom boot process
    /// </summary>
    public class CustomBootSettings : ScriptableObject
    {
        /// <summary>
        /// A list of prefabs which should be loaded during boot
        /// </summary>
        public GameObject[] BootPrefabs;
        
        /// <summary>
        /// Internal references to instances of the prefabs from <see cref="BootPrefabs"/>
        /// </summary>
        private GameObject[] Instances;

        /// <summary>
        /// Runtime container object which acts as the parent for any BootPrefab instances
        /// </summary>
        private GameObject RuntimeContainer;
        
        /// <summary>
        /// Initialise the boot settings object asynchronously, loading each prefab in <see cref="BootPrefabs"/>
        /// </summary>
        public async Task Initialise()
        {
            RuntimeContainer = new GameObject($"{name}_Container");
            DontDestroyOnLoad(RuntimeContainer);
            Instances = new GameObject[BootPrefabs.Length];
            
            // Calculate total prefabs for progress tracking
            int totalPrefabs = BootPrefabs.Length;
            float progressPerPrefab = totalPrefabs > 0 ? 1f / totalPrefabs : 1f;
            float currentProgress = 0f;
            
            for (var i = 0; i < BootPrefabs.Length; i++)
            {
                if (!BootPrefabs[i]) 
                {
                    // Report incremental progress even for null prefabs
                    currentProgress = (i + 1) * progressPerPrefab;
                    CustomBoot.UpdateProgress(currentProgress);
                    continue;
                }
                
                var instance = GameObject.InstantiateAsync(BootPrefabs[i], RuntimeContainer.transform);
                while (!instance.isDone)
                {
                    // Report partial progress while waiting
                    float progressInStep = instance.progress * progressPerPrefab;
                    float overallProgress = i * progressPerPrefab + progressInStep;
                    CustomBoot.UpdateProgress(overallProgress);
                    await Task.Yield();
                }

                Instances[i] = instance.Result[0];
                
                // Report completion of this step
                currentProgress = (i + 1) * progressPerPrefab;
                CustomBoot.UpdateProgress(currentProgress);
            }
        }
        
        /// <summary>
        /// Initialise the boot settings object synchronously, loading each prefab in <see cref="BootPrefabs"/>
        /// </summary>
        public void InitialiseSync()
        {
            RuntimeContainer = new GameObject($"{name}_Container");
            if (Application.isPlaying)
            {
                DontDestroyOnLoad(RuntimeContainer);
            }

            Instances = new GameObject[BootPrefabs.Length];
            
            // Calculate total prefabs for progress tracking
            int totalPrefabs = BootPrefabs.Length;
            float progressPerPrefab = totalPrefabs > 0 ? 1f / totalPrefabs : 1f;
            float currentProgress = 0f;
            
            for (var i = 0; i < BootPrefabs.Length; i++)
            {
                if (!BootPrefabs[i])
                {
                    // Report incremental progress even for null prefabs
                    currentProgress = (i + 1) * progressPerPrefab;
                    CustomBoot.UpdateProgress(currentProgress);
                    continue;
                }
                
                var instance = GameObject.Instantiate(BootPrefabs[i], RuntimeContainer.transform);
                Instances[i] = instance;
                
                // Report completion of this step
                currentProgress = (i + 1) * progressPerPrefab;
                CustomBoot.UpdateProgress(currentProgress);
            }
        }

        /// <summary>
        /// Destroy all loaded instances referenced by <see cref="Instances"/>
        /// </summary>
        public void Cleanup()
        {
            foreach (var t in Instances)
            {
                if (t)
                {
                    if (Application.isPlaying)
                    {
                        GameObject.Destroy(t);
                    }
                    else
                    {
                        GameObject.DestroyImmediate(t);
                    }
                    
                }
            }

            Instances = null;

            if (Application.isPlaying)
            {
                GameObject.Destroy(RuntimeContainer);
            }
            else
            {
                GameObject.DestroyImmediate(RuntimeContainer);
            }
        }
    }
}