using Microsoft.Extensions.Logging;

namespace GSS2.Core;

public class ImageStorageService
{
    private readonly ILogger<ImageStorageService> _logger;
    private readonly DirectoryInfo _rootDirectory;

    public ImageStorageService(ILogger<ImageStorageService> logger, DirectoryInfo rootDirectory)
    {
        _logger = logger;
        _logger.LogInformation("Инициализация");

        _rootDirectory = rootDirectory;
        if (!_rootDirectory.Exists)
        {
            _rootDirectory.Create();
            _logger.LogInformation("Создана директория: {}", _rootDirectory.FullName);
        }

        _logger.LogInformation("Инициализировано");
    }

    public async Task<string> SaveAsync(Stream fileStream, string extension, string subDirectory, CancellationToken cancellationToken = default)
    {
        var fileName = GenerateFileName(extension);
        var fullPath = GetFullPath(fileName, subDirectory);
        System.Diagnostics.Debug.Assert(fullPath is not null);

        var directory = Path.GetDirectoryName(fullPath)!;
        Directory.CreateDirectory(directory);

        await using var file = new FileStream(
            fullPath,
            FileMode.CreateNew,
            FileAccess.Write,
            FileShare.None,
            81920,
            useAsync: true);

        await fileStream.CopyToAsync(file, cancellationToken);

        _logger.LogInformation("Файл сохранён: {}", fileName);

        return fileName;
    }

    public Stream OpenRead(string fileName, string? subDirectory = null)
    {
        var fullPath = GetFullPath(fileName, subDirectory);
        if (fullPath is null)
            throw new FileNotFoundException(null, fullPath);
        return new FileStream(fullPath, FileMode.Open, FileAccess.Read, FileShare.Read);
    }

    public bool Delete(string fileName, string? subDirectory = null)
    {
        var fullPath = GetFullPath(fileName, subDirectory);
        if (fullPath is null)
            throw new FileNotFoundException(null, fullPath);

        if (!File.Exists(fullPath))
            return false;

        File.Delete(fullPath);
        _logger.LogInformation("Файл удалён: {}", fileName);

        var parentDirectory = Directory.GetParent(fullPath);
        if (parentDirectory?.GetFiles().Count() == 0)
        {
            parentDirectory.Delete();
            _logger.LogInformation("Удалена пустая директория: {}", parentDirectory.Name);
        }

        return true;
    }

    private string GenerateFileName(string extension)
    {
        var guid = Guid.NewGuid().ToString("N");
        return $"{guid}{extension}";
    }

    public string? GetFullPath(string fileName, string? subDirectory = null)
    {
        if (fileName.Count() < 4)
            return null;

        var level1 = fileName.Substring(0, 2);
        var level2 = fileName.Substring(2, 2);

        if (subDirectory is not null)
            return Path.Combine(_rootDirectory.FullName, subDirectory, level1, level2, fileName);

        return ListFiles()
            .FirstOrDefault(f => Path.GetFileName(f) == fileName);
    }

    public List<string> ListFiles(string? subDirectory = null)
    {
        if (subDirectory is not null)
            return Directory.GetDirectories(Path.Join(_rootDirectory.FullName, subDirectory))
                .SelectMany(Directory.GetDirectories)
                .SelectMany(Directory.GetFiles)
                .ToList();

        return Directory.GetDirectories(_rootDirectory.FullName)
            .Select(Path.GetFileName)
            .SelectMany(ListFiles)
            .ToList();
    }
}