////////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   PathUtils.sg
//
//  Note:
//

using System;
using System.Text;
using System.Threading;
using Microsoft.Singularity;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.FileSystem;
using Microsoft.Singularity.V1.Services;

namespace FileSystem.Utils
{
    public class PathUtils
    {
        const char DirectorySeparatorChar = '/';
    
        internal static string FileFromPath(string! filePath)
        {
            string dirPath, fileName;
            SplitPath(filePath, out dirPath, out fileName);
            return fileName;
        }

        // Splits a file path into its directory and filename
        // components
        internal static void SplitPath(string! filePath,
                                       out string dirPath,
                                       out string fileName)
        {
            dirPath = String.Empty;
            fileName = String.Empty;

            string[]! parts = filePath.Split(DirectorySeparatorChar);
            if ((parts == null) || (parts.Length <= 1)) {
                // Not even a leading slash? Bah!
                return;
            }

            fileName = (!)parts[parts.Length-1];

            // The directory path is the full path minus
            // the trailing leaf part
            // need to special case Directory Service root. Need to return "/" as dirPath
            int len = (filePath.Length - fileName.Length - 1) > 0? filePath.Length - fileName.Length - 1 : 1; 
            dirPath = filePath.Substring(0, len);
        }


        /// <remarks> Sanitize path string.  This method removes
        /// trailing separators and repeat sequences of
        /// separators.  </remarks>
        public static string! ToPath(string! p)
        {
            int length = p.Length;

            if (p.Length > 0 && p.Length - 1 == DirectorySeparatorChar) {
                length = p.LastIndexOf(DirectorySeparatorChar);
            }

            StringBuilder sb = new StringBuilder(length);

            bool multi = false;
            for (int i = 0; i < length; i++) {
                if (p[i] == DirectorySeparatorChar) {
                    if (multi) {
                        continue;
                    }
                    else {
                        sb.Append(p[i]);
                        multi = true;
                    }
                }
                else {
                    sb.Append(p[i]);
                    multi = false;
                }
            }
            return sb.ToString();
        }
    }
}