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using System.Collections.Generic;
using System.IO;
using NGit;
using NGit.Api;
using NGit.Api.Errors;
using NGit.Dircache;
using NGit.Treewalk;
using NGit.Treewalk.Filter;
using Sharpen;

namespace NGit.Api
{
	/// <summary>
	/// A class used to execute a
	/// <code>Rm</code>
	/// command. It has setters for all
	/// supported options and arguments of this command and a
	/// <see cref="Call()">Call()</see>
	/// method
	/// to finally execute the command. Each instance of this class should only be
	/// used for one invocation of the command (means: one call to
	/// <see cref="Call()">Call()</see>
	/// )
	/// </summary>
	/// <seealso><a href="http://www.kernel.org/pub/software/scm/git/docs/git-rm.html"
	/// *      >Git documentation about Rm</a></seealso>
	public class RmCommand : GitCommand<DirCache>
	{
		private ICollection<string> filepatterns;

		/// <param name="repo"></param>
		protected internal RmCommand(Repository repo) : base(repo)
		{
			filepatterns = new List<string>();
		}

		/// <param name="filepattern">File to remove.</param>
		/// <returns>
		/// 
		/// <code>this</code>
		/// </returns>
		public virtual NGit.Api.RmCommand AddFilepattern(string filepattern)
		{
			CheckCallable();
			filepatterns.AddItem(filepattern);
			return this;
		}

		/// <summary>
		/// Executes the
		/// <code>Rm</code>
		/// command. Each instance of this class should only
		/// be used for one invocation of the command. Don't call this method twice
		/// on an instance.
		/// </summary>
		/// <returns>the DirCache after Rm</returns>
		/// <exception cref="NGit.Api.Errors.NoFilepatternException"></exception>
		public override DirCache Call()
		{
			if (filepatterns.IsEmpty())
			{
				throw new NoFilepatternException(JGitText.Get().atLeastOnePatternIsRequired);
			}
			CheckCallable();
			DirCache dc = null;
			try
			{
				dc = repo.LockDirCache();
				DirCacheBuilder builder = dc.Builder();
				TreeWalk tw = new TreeWalk(repo);
				tw.Reset();
				// drop the first empty tree, which we do not need here
				tw.Recursive = true;
				tw.Filter = PathFilterGroup.CreateFromStrings(filepatterns);
				tw.AddTree(new DirCacheBuildIterator(builder));
				while (tw.Next())
				{
					FilePath path = new FilePath(repo.WorkTree, tw.PathString);
					FileMode mode = tw.GetFileMode(0);
					if (mode.GetObjectType() == Constants.OBJ_BLOB)
					{
						// Deleting a blob is simply a matter of removing
						// the file or symlink named by the tree entry.
						Delete(path);
					}
				}
				builder.Commit();
				SetCallable(false);
			}
			catch (IOException e)
			{
				throw new JGitInternalException(JGitText.Get().exceptionCaughtDuringExecutionOfRmCommand
					, e);
			}
			finally
			{
				if (dc != null)
				{
					dc.Unlock();
				}
			}
			return dc;
		}

		private void Delete(FilePath p)
		{
			while (p != null && !p.Equals(repo.WorkTree) && p.Delete())
			{
				p = p.GetParentFile();
			}
		}
	}
}
