using System;
using System.Collections.Generic;
using System.Linq;
using Cysharp.Threading.Tasks;
using Enums;
using Models.Interfaces;
using Presenter;
using ScriptableObjects;
using Services.Interfaces;
using Structs;
using UnityEngine;
using Utils;
using VContainer.Unity;
using Views;
using Object = UnityEngine.Object;

namespace Services {
    public class GameBoardService : IGameBoardService, ITickable, IDisposable {
        #region Inject
        private readonly GameVariables gameVariables;
        
        private readonly IGameBoard gameBoard;
        private readonly IObjectPool<GemView> objectPool;
        
        private readonly IMatchService matchService;
        private readonly IBombService bombService;
        private readonly IScoreService scoreService;
        
        private readonly ScorePresenter scorePresenter;
        private readonly AudioPresenter audioPresenter;
        
        private readonly Transform gemsHolder;
        private readonly Transform backgroundHolder;
        #endregion
        
        #region Variables
        private readonly List<GemPresenter> gemPresenters = new List<GemPresenter>();
        private GameState currentState = GameState.Move;
        #endregion
        
        public GameBoardService(
                GameVariables gameVariables, 
                IGameBoard gameBoard, 
                IObjectPool<GemView> objectPool, 
                IMatchService matchService,
                IBombService bombService, 
                IScoreService scoreService, 
                ScorePresenter scorePresenter, 
                AudioPresenter audioPresenter,
                Transform gemsHolder,
                Transform backgroundHolder) {
            this.gameVariables = gameVariables;
            this.gameBoard = gameBoard;
            this.objectPool = objectPool;
            this.matchService = matchService;
            this.bombService = bombService;
            this.scoreService = scoreService;
            this.scorePresenter = scorePresenter;
            this.audioPresenter = audioPresenter;
            this.gemsHolder = gemsHolder;
            this.backgroundHolder = backgroundHolder;
        }
        
        public void Tick() {
            foreach (GemPresenter gemPresenter in gemPresenters) {
                gemPresenter.Tick(this.gameVariables.gemSpeed);
            }

            this.scorePresenter.Tick(this.gameVariables.scoreSpeed);
        }
        
        //Instantiates background tiles and calls SpawnGems
        //Uses MatchService.MatchesAt to avoid matching Gems
        public void Setup() {
            for (int x = 0; x < this.gameBoard.Width; x++)
                for (int y = 0; y < this.gameBoard.Height; y++)
                {
                    Vector2 position = new Vector2(x, y);
                    SpawnBackgroundTile(position);

                    int iterations = 0;
                    int gemToUse = -1;
                    do {
                        gemToUse = RandomUtils.RandomGemTypeAsInt();
                        iterations++;
                    } while (this.matchService.MatchesAt(position.ToVector2Int(), (GemType)gemToUse) && iterations < 100);
                    
                    SpawnGem(position.ToVector2Int(), (GemType)gemToUse);
                }
            
            this.currentState = GameState.Move;
        }

        private void SpawnBackgroundTile(Vector2 position) {
            GameObject backgroundTile = Object.Instantiate(this.gameVariables.bgTilePrefabs, position, Quaternion.identity);
            backgroundTile.transform.SetParent(this.backgroundHolder);
            backgroundTile.name = "BG Tile - " + position.x + ", " + position.y;
        }

        //Uses the ObjectPool to spawn a gem at the given position
        private void SpawnGem(Vector2Int position, GemType gemType, bool isBomb = false) {
            if (isBomb) {
                DestroyMatchedGems(position);
            }
            
            GemView gemView = this.objectPool.Get(isBomb ? GemType.Bomb : gemType, position, isBomb ? 0 : this.gameVariables.dropHeight);
            gemView.name = "Gem - " + position.x + ", " + position.y + ' ' + gemType;
            
            GemTypeValues gemValue = GemUtils.GetGemValues(gemType, this.gameVariables.gemsPrefabs);
            Gem gem = new Gem(isBomb ? GemType.Bomb : gemType, position, gemValue, gemType);
            gemView.Bind(gem, gemValue, isBomb: isBomb);

            this.gemPresenters.Add(new GemPresenter(gem, gemView));
            this.gameBoard.SetGemAt(position, gem);
        }
        
        //Listens to InputService OnSwapRequest
        public async UniTask<bool> TrySwap(Vector2Int from, Vector2Int to) {
            if (this.currentState != GameState.Move) 
                return false;
            
            if (!GemUtils.IsInBounds(from, this.gameBoard) || !GemUtils.IsInBounds(to, this.gameBoard)) 
                return false;
            
            if (!AreAdjacentCardinal(from, to)) 
                return false;
            
            this.currentState = GameState.Wait;

            ApplySwap(from, to);

            await UniTask.Delay(600);
            this.bombService.SetLastSwap(from, to);
            this.bombService.ClearPendingBombs();
            this.matchService.FindAllMatches();
            this.bombService.DetectBombSpawnFromLastSwap(this.matchService.CurrentMatches);
            
            if (this.matchService.CurrentMatches.Count == 0) {
                ApplySwap(to, from);
                await UniTask.Delay(600);
                this.currentState = GameState.Move;
                return false;
            }
            
            List<Vector2Int> protectedPositions = ApplyPendingBombSpawns();
            await DestroyMatchesAsync(protectedPositions);
            this.currentState = GameState.Move;
            return true;
        }
        
        private void ApplySwap(Vector2Int from, Vector2Int to) {
            Gem fromGem = this.gameBoard.GetGemAt(from);
            Gem toGem = this.gameBoard.GetGemAt(to);
            // swap their stored positions
            fromGem.SetPosition(to);
            toGem.SetPosition(from);

            // update grid
            this.gameBoard.SetGemAt(from, toGem);
            this.gameBoard.SetGemAt(to, fromGem);
        }
        
        private List<Vector2Int> ApplyPendingBombSpawns() {
            List<Vector2Int> positions = new List<Vector2Int>();
            BombSpawnRequest? bombSpawnRequest = this.bombService.PendingBombSpawn;
            
            if (bombSpawnRequest != null) {
                BombSpawnRequest bombRequest = this.bombService.PendingBombSpawn.GetValueOrDefault();
                positions.Add(bombRequest.Position);
                SpawnGem(bombRequest.Position, bombRequest.Color, isBomb: true);
            }

            this.bombService.ClearPendingBombs();
            return positions;
        }
        
        private async UniTask DestroyMatchesAsync(List<Vector2Int> protectedPositions) {
            List<Vector2Int> matchPositions = new List<Vector2Int>(this.matchService.CurrentMatches.Count);
            for (int i = 0; i < this.matchService.CurrentMatches.Count; i++) {
                Gem match = this.matchService.CurrentMatches[i];
                if (match == null) continue;

                Vector2Int pos = match.Position;
                if (protectedPositions != null && protectedPositions.Contains(pos))
                    continue;

                matchPositions.Add(pos);
            }

            IReadOnlyList<Vector2Int> bombCandidates = matchPositions.Distinct().ToList();

            List<Vector2Int> initialBombs = new List<Vector2Int>();
            foreach (Vector2Int p in bombCandidates) {
                if (!GemUtils.IsInBounds(p, this.gameBoard)) continue;

                if (protectedPositions != null && protectedPositions.Contains(p))
                    continue;

                Gem gem = this.gameBoard.GetGemAt(p);
                if (gem is { Type: GemType.Bomb })
                    initialBombs.Add(p);
            }
            initialBombs = initialBombs.Distinct().ToList();

            // If a bomb is part of the match, do NOT destroy matching pieces immediately.
            // Let the bomb's manhattan-distance explosion destroy them in sequence.
            if (initialBombs.Count > 0) {
                await this.bombService.DetonateChainAsync(
                    initialBombs,
                    DestroyAtAsync,
                    this.gameBoard);

                await MoveGemsDown();
                return;
            }

            bool willBreakAnyNonBombGem = matchPositions.Select(pos => this.gameBoard.GetGemAt(pos)).Where(gem => gem != null).Any(gem => gem.Type != GemType.Bomb);

            if (willBreakAnyNonBombGem)
                this.audioPresenter.OnMatch(this.gameVariables.matchSfx);

            foreach (Vector2Int pos in matchPositions.Distinct().ToList()) {
                Gem gem = this.gameBoard.GetGemAt(pos);
                if (gem == null) continue;
                if (gem.Type == GemType.Bomb) continue;

                this.scoreService.ScoreCheck(gem.ScoreValue);
                DestroyMatchedGems(pos);
            }

            await this.bombService.DetonateChainAsync(
                initialBombs,
                DestroyAtAsync,
                this.gameBoard);

            await MoveGemsDown();
        }

        private UniTask DestroyAtAsync(Vector2Int pos) {
            Gem gem = this.gameBoard.GetGemAt(pos);
            if (gem == null)
                return UniTask.CompletedTask;
            
            if (gem.Type == GemType.Bomb)
                this.audioPresenter.OnBombExplosion(this.gameVariables.bombExplodeSfx);

            this.scoreService.ScoreCheck(gem.ScoreValue);
            DestroyMatchedGems(pos);
            return UniTask.CompletedTask;
        }

        private async UniTask MoveGemsDown() {
            await UniTask.Delay(50);

            int nullCounter = 0;
            for (int x = 0; x < this.gameBoard.Width; x++)
            {
                for (int y = 0; y < this.gameBoard.Height; y++)
                {
                    Gem currentGem = this.gameBoard.GetGemAt(new Vector2Int(x, y));
                    if (currentGem == null)
                    {
                        nullCounter++;
                    }
                    else if (nullCounter > 0)
                    {
                        currentGem.SetPosition(new Vector2Int(currentGem.Position.x, currentGem.Position.y - nullCounter));
                        this.gameBoard.SetGemAt(currentGem.Position, currentGem);
                        this.gameBoard.SetGemAt(new Vector2Int(x,y), null);
                    }
                }
                nullCounter = 0;
            }

            await FillBoard();
        }

        private async UniTask FillBoard() {
            await UniTask.Delay(250);
            RefillBoard();
            await UniTask.Delay(600);

            this.matchService.FindAllMatches();
            if (this.matchService.CurrentMatches.Count > 0) {
                await UniTask.Delay(600);

                // In cascades, there is no "creating slot" bomb protection.
                await DestroyMatchesAsync(new List<Vector2Int>());
            } else {
                await UniTask.Delay(250);
                this.currentState = GameState.Move;
            }
        }

        private void RefillBoard() {
            for (int x = 0; x < this.gameBoard.Width; x++)
            {
                for (int y = 0; y < this.gameBoard.Height; y++)
                {
                    Gem currentGem = this.gameBoard.GetGemAt(new Vector2Int(x,y));
                    if (currentGem == null) {
                        int gemToUse = RandomUtils.RandomGemTypeAsInt();

                        int iterations = 0;
                        while (this.matchService.MatchesAt(new Vector2Int(x, y), (GemType)gemToUse) && iterations < 100)
                        {
                            gemToUse = RandomUtils.RandomGemTypeAsInt();
                            iterations++;
                        }

                        SpawnGem(new Vector2Int(x, y), (GemType)gemToUse);
                    }
                }
            }
        }

        private void DestroyMatchedGems(Vector2Int position) {
            List<GemView> gemsViews = this.gemsHolder.GetComponentsInChildren<GemView>().ToList();
            Gem currentGem = this.gameBoard.GetGemAt(position);
            if (currentGem != null)
            {
                GemView gemView = gemsViews.FirstOrDefault(gv => gv.Gem == currentGem);
                if (gemView is null) {
                    return;
                }
                
                this.objectPool.Release(gemView);
                RemovePresenterFor(gemView);
                this.gameBoard.SetGemAt(position, null);
            }
        }
        
        #region Utils
        private void RemovePresenterFor(GemView gemView) {
            if (gemView is null) {
                return;
            }

            GemPresenter presenter = this.gemPresenters.FirstOrDefault(p => p.GemView == gemView);
            this.gemPresenters.Remove(presenter);
        }
        
        private static bool AreAdjacentCardinal(Vector2Int a, Vector2Int b) {
            Vector2Int d = b - a;
            return (Mathf.Abs(d.x) == 1 && d.y == 0) || (Mathf.Abs(d.y) == 1 && d.x == 0);
        }
        #endregion

        public void Dispose() {
            this.objectPool.Clear();
        }
    }
}