//#define LOG

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text;
using AptGames;
using TerrorSquid.BulletSystem;
using UnityEngine;
using TerrorSquid.Entities;
using UnityEngine.AddressableAssets;
using UnityEngine.ResourceManagement.AsyncOperations;
using UnityEngine.SceneManagement;
using Debug = UnityEngine.Debug;

namespace TerrorSquid.ExplosionSystem {

    public static class Explosions {

        private static readonly Dictionary<int, int> current   = new Dictionary<int, int>();
        private static readonly Dictionary<int, int> lengths   = new Dictionary<int, int>();
        private static readonly Dictionary<int, int> offsetMap = new Dictionary<int, int>();

        private static float[]     radius;
        private static Explosion[] instances;
        private static bool[]      active;
        private static Transform[] transforms;
        private static int[]       explosionHashes;
        private static int[]       offsets;
        private static int[]       counts;
        private static int         totalBullets;

        public static void Init(BulletPatternSequence sequence) {
            totalBullets = sequence.GetTotalBullets();

            instances     = new Explosion[totalBullets];
            transforms    = new Transform[totalBullets];
            radius        = new float[totalBullets];
            active        = new bool[totalBullets];
        }

        public static int GetLength(int hash) {
            return lengths[hash];
        }

        #if DEV
        public static string GetStatus() {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < explosionHashes.Length; ++i) {
                int explHash = explosionHashes[i];
                int cur      = current[explHash];
                sb.AppendLine($"ID {explHash} cur: {cur}");
            }
            return sb.ToString();
        }
        #endif
        
        public static void Spawn(int explosionHash, Vector3 pos, Quaternion rotLocalSphere) {
            int typeIndex = Array.IndexOf(explosionHashes, explosionHash);
            #if DEV
            if (typeIndex < 0) {
                throw new Exception($"Cannot find explosion hash {explosionHash} in list of hashes");
            }
            #endif
            
            #if DEV
            if (typeIndex >= offsets.Length) {
                throw new Exception($"Type index {typeIndex} for hash {explosionHash} is greater than the length of offsets array");
            }

            if (!current.ContainsKey(explosionHash)) {
                throw new Exception($"Current dictionary does not contain a key for hash {explosionHash}");
            }
            #endif

            int offset = offsets[typeIndex];
            int cur = current[explosionHash];
            int instanceIndex = offset + cur;
            
            #if DEV
            if (instanceIndex >= instances.Length || instanceIndex < 0) {
                throw new Exception($"Instance index {instanceIndex} is out of range of instances array");
            }
            #endif
            
            transforms[instanceIndex].SetPositionAndRotation(pos, rotLocalSphere);
            instances[instanceIndex].Play();
            
            active[instanceIndex] = true;
            counts[typeIndex] = counts[typeIndex] + 1;

            int len = lengths[explosionHash];
            for (int i = cur + 1; i < len; ++i) {
                if (!active[offset + i]) {
                    current[explosionHash] = i;
                    break;
                }
            }
            
            Log($"Spawn"+
                $", hash: {explosionHash}"+
                $", typeIndex: {typeIndex}"+
                $", offset: {offset}"+
                $", instanceIndex: {instanceIndex}"+
                $", current: {current[explosionHash]}"+
                $", count: {counts[typeIndex]}");
        }

        public static void Pause() {
            int len = explosionHashes.Length;

            for (int h = 0; h < len; ++h) {
                int offset = offsets[h];
                int count  = counts[h];

                for (int i = offset; i < offset + count; ++i) {
                    instances[i].Pause();
                }
            }
        }

        public static void Resume() {
            int len = explosionHashes.Length;

            for (int h = 0; h < len; ++h) {
                int offset = offsets[h];
                int count  = counts[h];

                for (int i = offset; i < offset + count; ++i) {
                    instances[i].Resume();
                }
            }
        }

        private static void Despawn(int instanceIndex) {
            int seqIndex = GetSequenceIndex(instanceIndex);

            instances[instanceIndex].Stop();
            transforms[instanceIndex].localPosition = Vector3.zero;
            active[instanceIndex] = false;

            int explosionHash = explosionHashes[seqIndex];
            if (instanceIndex < current[explosionHash]) {
                current[explosionHash] = instanceIndex;
            }
            
            counts[seqIndex] = counts[seqIndex] - 1;
            
            Log($"Despawn"+
                $", instanceIndex: {instanceIndex}"+
                $", current: {current[explosionHash]}"+
                $", count: {counts[seqIndex]}"+
                $", active: {active[instanceIndex]}");
        }

        public static void Update(float dt) {
            int len = explosionHashes.Length;

            for (int h = 0; h < len; ++h) {
                int hash = explosionHashes[h];
                int offset = offsets[h];
                int count = counts[h];
                int cur = count;

                for (int it = count; it > 0; --it) {
                    int i = it - 1;
                    int n = offset + i;
                    if (!instances[n].IsAlive()) {
                        Despawn(n);
                        cur = i;
                    }
                }

                current[hash] = cur;
            }
        }

        private static int GetSequenceIndex(int instanceIndex) {
            int index = 0;
            for (int i = 0; i < offsets.Length - 1; ++i) {
                if (offsets[i + 1] > instanceIndex) {
                    return index;
                }
                ++index;
            }
            return index;
        }

        public static void DespawnAll() {
            for (int i = 0; i < totalBullets; ++i) {
                instances[i].Stop();
                active[i] = false;
            }
            
            int hashes = explosionHashes.Length;
            for (int h = 0; h < hashes; ++h) {
                int hash = explosionHashes[h];
                current[hash] = 0;
            }
        }

        public static float GetRadiusByNameHash(int nameHash) {
            return radius[Array.IndexOf(explosionHashes, nameHash)];
        }

        public static IEnumerator Load(LoadState loadState, BulletPatternSequence sequence) {
            loadState.explosionsLoaded = 0;
            loadState.explosionsToLoad = sequence.GetTotalBullets();

            // Load assets by label
            AsyncOperationHandle<IList<GameObject>> handle = Addressables.LoadAssetsAsync<GameObject>("explosion", null);
            yield return handle;
            
            Dictionary<int, GameObject> prefabs = new Dictionary<int, GameObject>();
            for (int i = 0; i < handle.Result.Count; ++i) {
                prefabs.Add(HashUtils.Simple(handle.Result[i].name), handle.Result[i]);
            }

            int seqLen = sequence.Count;

            for (int i = 0; i < seqLen; ++i) {
                PatternConfig cfg = sequence.Get(i);
                int explosionHash = cfg.ExplosionHash;
                current[explosionHash] = 0;

                if (lengths.ContainsKey(explosionHash)) {
                    lengths[explosionHash] += cfg.MaxNum;
                } else {
                    lengths[explosionHash] = cfg.MaxNum;
                }
            }
            
            List<int> uniqueHashes = new List<int>();
            for (int i = 0; i < seqLen; ++i) {
                if (!uniqueHashes.Contains(sequence.Get(i).ExplosionHash)) {
                    uniqueHashes.Add(sequence.Get(i).ExplosionHash);
                }
            }

            explosionHashes = uniqueHashes.ToArray();
            offsets = new int[explosionHashes.Length];
            counts = new int[explosionHashes.Length];

            {
                int offset = 0;
                for (int i = 0; i < explosionHashes.Length; ++i) {
                    offsets[i] = offset;
                    offsetMap.Add(explosionHashes[i], offset);
                    offset += lengths[explosionHashes[i]];
                }
            }

            Scene sceneExplosions = SceneManager.CreateScene("Explosions");

            for (int i = 0; i < explosionHashes.Length; ++i) {
                int explosionHash = explosionHashes[i];
                int length = lengths[explosionHash];
                int offset = offsets[i];
                GameObject prefab = prefabs[explosionHash];

                for (int e = 0; e < length; ++e) {
                    int n = offset + e;
                    instances[n]                 = GameObject.Instantiate(prefab).GetComponent<Explosion>();
                    instances[n].gameObject.name = $"{prefab.name}_{e:0000}";
                    transforms[n]                = instances[n].transform;
                    radius[n]                    = instances[n].Radius;
                    SceneManager.MoveGameObjectToScene(instances[n].gameObject, sceneExplosions);
                    ++loadState.explosionsLoaded;
                    
                    if (n % CONST.INSTANTIATES_PER_FRAME == 0) {
                        yield return null;
                    }
                }
            }
        }

        [Conditional("LOG")]
        private static void Log(object msg) {
            Debug.Log(msg);
        }
    }
}