using System;

namespace HavenSoft.Gen3Hex.Model {
   public interface IFileSystem {
      string CopyText { get; set; }

      /// <summary>
      /// Have the filesystem ask the user for a new name for a file.
      /// If no extensionOptions are provided, the user may specify any extension.
      /// Otherwise, the returned name will end with one of the extensionOptions.
      /// </summary>
      /// <param name="currentName">
      /// The current name of the file, which may be either relative or absolute, including extension.
      /// This parameter may be empty, but not null.
      /// </param>
      /// <param name="extensionOptions">
      /// A set of extensions, such as 'txt', 'gba', or 'png'. Should not start with a dot.
      /// The set may be empty, but not null.
      /// </param>
      /// <returns>
      /// The new name if provided, or null if the operation was canceled by the user.
      /// </returns>
      string RequestNewName(string currentName, params string[] extensionOptions);

      /// <summary>
      /// Have the filesystem ask the user for an existing file.
      /// If no extensionOptions are provided, the user may specify any existing file.
      /// </summary>
      /// <param name="extensionOptions">
      /// A set of extensions, such as 'txt', 'gba', or 'png'. Should not start with a dot.
      /// The set may be empty, but not null.
      /// </param>
      /// <returns>
      /// If the user chooses a file, that file is loaded and returned.
      /// If the user cancels or selects an unreadable file, returns null.
      /// </returns>
      LoadedFile OpenFile(params string[] extensionOptions);

      /// <summary>
      /// Have the filesystem open a specific file.
      /// </summary>
      /// <returns>
      /// If the file exists, it is loaded and returned.
      /// If it doesn't exist, returns null.
      /// </returns>
      LoadedFile LoadFile(string fileName);

      /// <summary>
      /// When a file changes, the filesystem will call all listeners for that file.
      /// </summary>
      void AddListenerToFile(string fileName, Action<IFileSystem> listener);

      void RemoveAllListenersForFile(string fileName);

      /// <summary>
      /// Saves the file without prompting the user for permission.
      /// </summary>
      /// <returns>
      /// true if it was possible to save, false if there was an error.
      /// In the case of false, the file system would have already dealt with the error.
      /// The return value is just so the program can know if it was written or not.
      /// </returns>
      bool Save(LoadedFile file);

      /// <summary>
      /// should prompt the user if they want to save and then save
      /// </summary>
      /// <returns>
      /// true if the user wanted to save the file and it was written successfully
      /// false if the user decided not to save the file
      /// null if there was any error or if the operation was canceled by the user.
      /// the FileSystem object will handle the error and potentially notify the user,
      /// the result is only so the program can know if it was written or not.
      /// </returns>
      bool? TrySavePrompt(LoadedFile file);
   }
}