using System;
using Godot;
using System.Collections.Generic;
using AceFieldNewHorizon.Scripts.Entities;
using AceFieldNewHorizon.Scripts.Tiles;

namespace AceFieldNewHorizon.Scripts.System;

public partial class NaturalResourceGenerator : Node2D
{
    public const string ChunkTrackerGroupName = "NrgTrackingTarget";

    [Export] public GridManager Grid { get; set; }
    [Export] public BuildingRegistry Registry { get; set; }

    [Export] public int ChunkSize = 16;
    [Export] public int LoadDistance = 2; // Number of chunks to load in each direction
    [Export] public float StoneDensity = 0.1f;
    [Export] public float IronDensity = 0.03f;
    [Export] public int MinStoneVeinSize = 1;
    [Export] public int MaxStoneVeinSize = 5;
    [Export] public int MinIronVeinSize = 1;
    [Export] public int MaxIronVeinSize = 3;
    [Export] public int Seed;

    private const string LogPrefix = "[NaturalGeneration]";

    private RandomNumberGenerator _rng;
    private readonly Dictionary<Vector2I, ChunkData> _loadedChunks = new();
    private Vector2I _lastPlayerChunk = new(-1000, -1000);

    private Player _player;

    public override void _Ready()
    {
        _rng = new RandomNumberGenerator();
        _rng.Seed = (ulong)(Seed != 0 ? Seed : (int)GD.Randi());
    }

    public override void _Process(double delta)
    {
        _player = GetTree().GetFirstNodeInGroup(ChunkTrackerGroupName) as Player;
        if (_player != null)
        {
            UpdatePlayerPosition(_player.GlobalPosition);
        }
        else
        {
            GD.PrintErr($"{LogPrefix} Player not found in group: {ChunkTrackerGroupName}");
        }
    }

    public void UpdatePlayerPosition(Vector2 playerPosition)
    {
        var playerChunk = WorldToChunkCoords(playerPosition);
        if (playerChunk == _lastPlayerChunk) return;
        _lastPlayerChunk = playerChunk;

        // Unload chunks outside load distance
        var chunksToRemove = new List<Vector2I>();
        foreach (var chunkPos in _loadedChunks.Keys)
        {
            if (Mathf.Abs(chunkPos.X - playerChunk.X) > LoadDistance ||
                Mathf.Abs(chunkPos.Y - playerChunk.Y) > LoadDistance)
            {
                chunksToRemove.Add(chunkPos);
            }
        }

        foreach (var chunkPos in chunksToRemove)
        {
            UnloadChunk(chunkPos);
        }

        // Load chunks around player
        for (int x = -LoadDistance; x <= LoadDistance; x++)
        {
            for (int y = -LoadDistance; y <= LoadDistance; y++)
            {
                var chunkPos = new Vector2I(playerChunk.X + x, playerChunk.Y + y);
                if (!_loadedChunks.ContainsKey(chunkPos))
                {
                    GenerateChunk(chunkPos);
                }
            }
        }
    }

    private void GenerateChunk(Vector2I chunkPos)
    {
        GD.Print($"{LogPrefix} Generating chunk at {chunkPos}");
        var chunkData = new ChunkData();
        var chunkWorldPos = ChunkToWorldCoords(chunkPos);

        // First, place ground tiles
        for (int x = 0; x < ChunkSize; x++)
        {
            for (int y = 0; y < ChunkSize; y++)
            {
                var cell = new Vector2I(chunkWorldPos.X + x, chunkWorldPos.Y + y);
                if (!PlaceTile("ground", cell))
                {
                    GD.PrintErr($"{LogPrefix} Failed to place ground at {cell}");
                }
            }
        }

        // Then generate stone veins
        var stoneVeins = 0;
        for (var x = 0; x < ChunkSize; x++)
        {
            for (var y = 0; y < ChunkSize; y++)
            {
                var cell = new Vector2I(chunkWorldPos.X + x, chunkWorldPos.Y + y);
                if (_rng.Randf() < StoneDensity)
                {
                    var veinSize = _rng.RandiRange(MinStoneVeinSize, MaxStoneVeinSize);
                    GD.Print($"{LogPrefix} Attempting to place stone vein at {cell} with size {veinSize}");
                    PlaceVein(cell, "stone", veinSize, chunkData.StoneTiles);
                    stoneVeins++;
                }
            }
        }

        GD.Print($"{LogPrefix} Placed {stoneVeins} stone veins in chunk {chunkPos}");

        // Generate iron veins within stone
        int ironVeins = 0;
        foreach (var stoneCell in new List<Vector2I>(chunkData.StoneTiles))
        {
            if (_rng.Randf() < IronDensity)
            {
                var veinSize = _rng.RandiRange(MinIronVeinSize, MaxIronVeinSize);
                GD.Print($"{LogPrefix} Attempting to place iron vein at {stoneCell} with size {veinSize}");
                PlaceVein(stoneCell, "ore_iron", veinSize, chunkData.IronTiles);
                ironVeins++;
            }
        }

        GD.Print($"{LogPrefix} Placed {ironVeins} iron veins in chunk {chunkPos}");

        _loadedChunks[chunkPos] = chunkData;
    }

    private void UnloadChunk(Vector2I chunkPos)
    {
        GD.Print($"{LogPrefix} Unloading chunk at {chunkPos}");
        if (!_loadedChunks.TryGetValue(chunkPos, out var chunkData)) return;

        // Remove all tiles in this chunk
        var chunkWorldPos = ChunkToWorldCoords(chunkPos);
        for (int x = 0; x < ChunkSize; x++)
        {
            for (int y = 0; y < ChunkSize; y++)
            {
                var cell = new Vector2I(chunkWorldPos.X + x, chunkWorldPos.Y + y);
                // Free a 1x1 area for each cell
                Grid.FreeArea(cell, Vector2I.One, 0f, GridLayer.Ground);
            }
        }

        _loadedChunks.Remove(chunkPos);
    }

    private Vector2I WorldToChunkCoords(Vector2 worldPos)
    {
        var cell = GridUtils.WorldToGrid(worldPos);
        return new Vector2I(
            (int)Mathf.Floor((float)cell.X / ChunkSize),
            (int)Mathf.Floor((float)cell.Y / ChunkSize)
        );
    }

    private Vector2I ChunkToWorldCoords(Vector2I chunkPos)
    {
        return new Vector2I(
            chunkPos.X * ChunkSize,
            chunkPos.Y * ChunkSize
        );
    }
    
    private bool IsInLoadedChunk(Vector2I cell)
    {
        // Check the chunk where the cell is located
        var chunkPos = new Vector2I(
            (int)Mathf.Floor((float)cell.X / ChunkSize),
            (int)Mathf.Floor((float)cell.Y / ChunkSize)
        );
    
        // Also check adjacent chunks since veins can cross chunk boundaries
        for (var dx = -1; dx <= 1; dx++)
        {
            for (var dy = -1; dy <= 1; dy++)
            {
                var checkPos = new Vector2I(chunkPos.X + dx, chunkPos.Y + dy);
                if (_loadedChunks.ContainsKey(checkPos))
                {
                    return true;
                }
            }
        }
    
        return false;
    }

    private void PlaceVein(Vector2I startCell, string tileType, int maxSize, List<Vector2I> tileList)
    {
        GD.Print($"{LogPrefix} Starting to place vein of type {tileType} at {startCell} with max size {maxSize}");

        var placed = new HashSet<Vector2I>();
        var queue = new Queue<Vector2I>();
        queue.Enqueue(startCell);

        int placedCount = 0;

        while (queue.Count > 0 && placedCount < maxSize)
        {
            var cell = queue.Dequeue();

            // Skip if already placed or out of bounds
            if (placed.Contains(cell))
            {
                GD.Print($"{LogPrefix} Skipping cell {cell} - already placed");
                continue;
            }
            if (!IsInLoadedChunk(cell))
            {
                GD.Print($"{LogPrefix} Skipping cell {cell} - out of bounds");
                continue;
            }
            
            // Try to place the tile
            if (PlaceTile(tileType, cell))
            {
                tileList.Add(cell);
                placed.Add(cell);
                placedCount++;
                GD.Print($"{LogPrefix} Successfully placed {tileType} at {cell} ({placedCount}/{maxSize})");

                // Add adjacent cells to queue
                var directions = new[] { Vector2I.Up, Vector2I.Right, Vector2I.Down, Vector2I.Left };
                foreach (var dir in directions)
                {
                    var newCell = cell + dir;
                    if (!placed.Contains(newCell))
                    {
                        queue.Enqueue(newCell);
                    }
                }
            }
            else
            {
                GD.Print($"{LogPrefix} Failed to place {tileType} at {cell}");
            }
        }

        GD.Print($"{LogPrefix} Finished placing vein - placed {placedCount}/{maxSize} {tileType} tiles");
    }

    private bool PlaceTile(string tileType, Vector2I cell)
    {
        try
        {
            // First, remove any existing tile at this position
            Grid.FreeArea(cell, Vector2I.One, 0f, GridLayer.Ground);
        
            var building = Registry.GetBuilding(tileType);
            if (building == null)
            {
                GD.PrintErr($"{LogPrefix} Building type not found in registry: {tileType}");
                return false;
            }

            var scene = building.Scene;
            if (scene == null)
            {
                GD.PrintErr($"{LogPrefix} Scene is null for building type: {tileType}");
                return false;
            }

            var instance = scene.Instantiate() as Node2D;
            if (instance == null)
            {
                GD.PrintErr($"{LogPrefix} Failed to instantiate scene for: {tileType}");
                return false;
            }

            instance.GlobalPosition = GridUtils.GridToWorld(cell);
            instance.ZIndex = (int)building.Layer;
            AddChild(instance);
            Grid.OccupyArea(cell, instance, building.Size, 0f, building.Layer);
            GD.Print($"{LogPrefix} Successfully placed {tileType} at {cell}");
            return true;
        }
        catch (Exception e)
        {
            GD.PrintErr($"{LogPrefix} Error placing {tileType} at {cell}: {e.Message}");
            return false;
        }
    }
}

public class ChunkData
{
    public List<Vector2I> StoneTiles { get; } = [];
    public List<Vector2I> IronTiles { get; } = [];
}