using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text;

namespace Capnpc.Csharp.MsBuild.Generation
{
    public static class FileSystemHelper
    {
        public static void CopyFileToFolder(string filePath, string folderName)
        {
            File.Copy(filePath, Path.Combine(folderName, Path.GetFileName(filePath)));
        }

        public static string GetRelativePath(string path, string basePath)
        {
            path = Path.GetFullPath(path);
            basePath = Path.GetFullPath(basePath);
            if (String.Equals(path, basePath, StringComparison.OrdinalIgnoreCase))
                return "."; // the "this folder"

            if (path.StartsWith(basePath + Path.DirectorySeparatorChar, StringComparison.OrdinalIgnoreCase))
                return path.Substring(basePath.Length + 1);

            //handle different drives
            string pathRoot = Path.GetPathRoot(path);
            if (!String.Equals(pathRoot, Path.GetPathRoot(basePath), StringComparison.OrdinalIgnoreCase))
                return path;

            //handle ".." pathes
            string[] pathParts = path.Substring(pathRoot.Length).Split(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
            string[] basePathParts = basePath.Substring(pathRoot.Length).Split(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);

            int commonFolderCount = 0;
            while (commonFolderCount < pathParts.Length && commonFolderCount < basePathParts.Length &&
                   String.Equals(pathParts[commonFolderCount], basePathParts[commonFolderCount], StringComparison.OrdinalIgnoreCase))
                commonFolderCount++;

            StringBuilder result = new StringBuilder();
            for (int i = 0; i < basePathParts.Length - commonFolderCount; i++)
            {
                result.Append("..");
                result.Append(Path.DirectorySeparatorChar);
            }

            if (pathParts.Length - commonFolderCount == 0)
                return result.ToString().TrimEnd(Path.DirectorySeparatorChar);

            result.Append(String.Join(Path.DirectorySeparatorChar.ToString(), pathParts, commonFolderCount, pathParts.Length - commonFolderCount));
            return result.ToString();
        }

        // This method accepts two strings the represent two files to 
        // compare. A return value of true indicates that the contents of the files
        // are the same. A return value of any other value indicates that the 
        // files are not the same.
        public static bool FileCompare(string filePath1, string filePath2)
        {
            int file1byte;
            int file2byte;

            // Determine if the same file was referenced two times.
            if (String.Equals(filePath1, filePath2, StringComparison.CurrentCultureIgnoreCase))
            {
                // Return true to indicate that the files are the same.
                return true;
            }

            // Open the two files.
            using (FileStream fs1 = new FileStream(filePath1, FileMode.Open, FileAccess.Read))
            using (FileStream fs2 = new FileStream(filePath2, FileMode.Open, FileAccess.Read))
            {
                // Check the file sizes. If they are not the same, the files 
                // are not the same.
                if (fs1.Length != fs2.Length)
                {
                    // Return false to indicate files are different
                    return false;
                }

                // Read and compare a byte from each file until either a
                // non-matching set of bytes is found or until the end of
                // file1 is reached.
                do
                {
                    // Read one byte from each file.
                    file1byte = fs1.ReadByte();
                    file2byte = fs2.ReadByte();
                } while ((file1byte == file2byte) && (file1byte != -1));
            }

            // Return the success of the comparison. "file1byte" is 
            // equal to "file2byte" at this point only if the files are 
            // the same.
            return ((file1byte - file2byte) == 0);
        }

        public static void CopyDirectory(string sourcePath, string destPath, bool cleanDestination = true)
        {
            if (cleanDestination)
                EnsureEmptyFolder(destPath);
            else
            {
                if (!Directory.Exists(destPath))
                {
                    Directory.CreateDirectory(destPath);
                }
            }

            foreach (string file in Directory.GetFiles(sourcePath))
            {
                var fileName = Path.GetFileName(file);
                Debug.Assert(fileName != null);
                string dest = Path.Combine(destPath, fileName);
                File.Copy(file, dest, true);
                File.SetAttributes(dest, File.GetAttributes(dest) & (~FileAttributes.ReadOnly));
            }

            foreach (string folder in Directory.GetDirectories(sourcePath))
            {
                var folderName = Path.GetFileName(folder);
                Debug.Assert(folderName != null);
                string dest = Path.Combine(destPath, folderName);
                CopyDirectory(folder, dest);
            }
        }

        public static void EnsureEmptyFolder(string folderName)
        {
            folderName = Path.GetFullPath(folderName);

            if (!Directory.Exists(folderName))
            {
                Directory.CreateDirectory(folderName);
                return;
            }

            DeleteFolderContent(folderName);
        }

        public static void EnsureFolderOfFile(string filePath)
        {
            string directory = Path.GetDirectoryName(filePath);
            if (directory != null && !Directory.Exists(directory))
                Directory.CreateDirectory(directory);
        }


        private static void Retry(int number, Action action)
        {
            try
            {
                action();
            }
            catch (UnauthorizedAccessException)
            {
                var i = number - 1;

                if (i == 0)
                    throw;

                Retry(i, action);
            }
        }

        public static void DeleteFolderContent(string folderName)
        {
            foreach (string file in Directory.GetFiles(folderName))
            {
                try
                {
                    Retry(5, () => File.Delete(file));
                }
                catch (Exception ex)
                {
                    throw new Exception("Unable to delete file: " + file, ex);
                }
            }

            foreach (string folder in Directory.GetDirectories(folderName))
            {
                try
                {
                    Retry(5, () => Directory.Delete(folder, true));
                }
                catch (Exception ex)
                {
                    throw new Exception("Unable to delete folder: " + folder, ex);
                }
            }
        }

        public static void DeleteFolder(string path)
        {
            if (!Directory.Exists(path))
                return;

            DeleteFolderContent(path);

            Retry(5, () => Directory.Delete(path, true));
        }
    }
}