using SilkroadBot.Navigation.Interfaces;

namespace SilkroadBot.Navigation.Models;

/// <summary>
/// File-based map data provider. Loads navigation grids from disk.
/// </summary>
public class FileMapDataProvider : IMapDataProvider
{
    private readonly string _dataDirectory;
    private readonly Dictionary<short, RegionNavData> _cache = new();
    private readonly HashSet<short> _availableRegions = new();

    public FileMapDataProvider(string dataDirectory)
    {
        _dataDirectory = dataDirectory;
        ScanAvailableRegions();
    }

    public async Task<RegionNavData?> LoadRegionAsync(short regionId)
    {
        if (_cache.TryGetValue(regionId, out var cached))
            return cached;

        var filePath = Path.Combine(_dataDirectory, $"region_{regionId}.nav");
        if (!File.Exists(filePath))
        {
            // Generate a default passable region for testing
            return GenerateDefaultRegion(regionId);
        }

        var data = await LoadFromFileAsync(filePath, regionId);
        if (data != null)
            _cache[regionId] = data;
        return data;
    }

    public bool HasRegion(short regionId) => _availableRegions.Contains(regionId);

    public IReadOnlyList<short> GetAvailableRegions() => _availableRegions.ToList();

    private void ScanAvailableRegions()
    {
        if (!Directory.Exists(_dataDirectory))
        {
            Directory.CreateDirectory(_dataDirectory);
            return;
        }

        foreach (var file in Directory.GetFiles(_dataDirectory, "region_*.nav"))
        {
            var name = Path.GetFileNameWithoutExtension(file);
            if (short.TryParse(name.Replace("region_", ""), out var id))
                _availableRegions.Add(id);
        }
    }

    private static async Task<RegionNavData?> LoadFromFileAsync(string path, short regionId)
    {
        try
        {
            var bytes = await File.ReadAllBytesAsync(path);
            if (bytes.Length < 8) return null;

            int width = BitConverter.ToInt32(bytes, 0);
            int height = BitConverter.ToInt32(bytes, 4);
            
            var grid = new byte[width, height];
            int offset = 8;
            
            for (int x = 0; x < width && offset < bytes.Length; x++)
                for (int y = 0; y < height && offset < bytes.Length; y++)
                    grid[x, y] = bytes[offset++];

            return new RegionNavData
            {
                RegionId = regionId,
                Width = width * 10, // Scale to game units
                Height = height * 10,
                WalkabilityGrid = grid
            };
        }
        catch
        {
            return null;
        }
    }

    private static RegionNavData GenerateDefaultRegion(short regionId)
    {
        const int size = 128;
        var grid = new byte[size, size];
        
        // Default: everything is walkable
        for (int x = 0; x < size; x++)
            for (int y = 0; y < size; y++)
                grid[x, y] = 1;

        return new RegionNavData
        {
            RegionId = regionId,
            Width = size * 10,
            Height = size * 10,
            WalkabilityGrid = grid
        };
    }
}

/// <summary>
/// Navigation service implementation combining pathfinding with map data.
/// </summary>
public class NavigationService : Plugins.SDK.Interfaces.INavigationService
{
    private readonly Interfaces.IPathfindingAlgorithm _pathfinder;

    public NavigationService(Interfaces.IPathfindingAlgorithm pathfinder)
    {
        _pathfinder = pathfinder;
    }

    public async Task<IReadOnlyList<Domain.Models.WorldPosition>> FindPathAsync(
        Domain.Models.WorldPosition from, 
        Domain.Models.WorldPosition to, 
        CancellationToken ct = default)
    {
        var result = await _pathfinder.FindPathAsync(from, to);
        return result.Success ? result.Waypoints : Array.Empty<Domain.Models.WorldPosition>();
    }

    public bool IsWalkable(Domain.Models.WorldPosition position)
        => _pathfinder.IsPositionWalkable(position);

    public Domain.Models.WorldPosition GetNearestWalkable(Domain.Models.WorldPosition position)
        => _pathfinder.GetNearestWalkablePosition(position);
}