using System.Text;

namespace AIAssistantModule.Infrastructure.Helpers
{
    public class FileAccessHelper
    {
        private static readonly Encoding DefaultEncoding = new UTF8Encoding(false);

        public async Task<string> ReadFileAsync(string filePath, CancellationToken cancellationToken = default)
        {
            if (string.IsNullOrWhiteSpace(filePath))
                throw new ArgumentException("File path cannot be null or empty.", nameof(filePath));

            if (!File.Exists(filePath))
                throw new FileNotFoundException("File not found.", filePath);

            return await File.ReadAllTextAsync(filePath, DefaultEncoding, cancellationToken);
        }

        public async Task WriteFileAsync(
            string filePath,
            string content,
            bool backup = true,
            CancellationToken cancellationToken = default)
        {
            if (string.IsNullOrWhiteSpace(filePath))
                throw new ArgumentException("File path cannot be null or empty.", nameof(filePath));

            if (content is null)
                throw new ArgumentNullException(nameof(content));

            var directory = Path.GetDirectoryName(filePath);

            if (!string.IsNullOrWhiteSpace(directory) && !Directory.Exists(directory))
            {
                Directory.CreateDirectory(directory);
            }

            if (backup && File.Exists(filePath))
            {
                BackupFile(filePath);
            }

            await File.WriteAllTextAsync(filePath, content, DefaultEncoding, cancellationToken);
        }

        private void BackupFile(string filePath)
        {
            var timestamp = DateTime.UtcNow.ToString("yyyyMMddHHmmssfff");
            var backupPath = $"{filePath}.bak_{timestamp}";

            File.Copy(filePath, backupPath, overwrite: false);
        }
    }
}