using System;
using System.Collections.Generic;
using System.Globalization;
using System.Reflection;
using System.IO;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Web.Hosting;
using ICSharpCode.SharpZipLib.Zip;
using Umbraco.Core.Configuration;
using Umbraco.Core.Logging;

namespace Umbraco.Core.IO
{
	public static class IOHelper
    {
        private static string _rootDir = "";

        // static compiled regex for faster performance
        private readonly static Regex ResolveUrlPattern = new Regex("(=[\"\']?)(\\W?\\~(?:.(?![\"\']?\\s+(?:\\S+)=|[>\"\']))+.)[\"\']?", RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace);

        public static char DirSepChar
        {
            get
            {
                return Path.DirectorySeparatorChar;
            }
        }

	    internal static void UnZip(string zipFilePath, string unPackDirectory, bool deleteZipFile)
	    {
	        // Unzip
	        string tempDir = unPackDirectory;
	        Directory.CreateDirectory(tempDir);

            //TODO: Get rid of SharpZipLib library
	        using (ZipInputStream s = new ZipInputStream(File.OpenRead(zipFilePath)))
	        {
                ZipEntry theEntry;
                while ((theEntry = s.GetNextEntry()) != null)
                {
                    string directoryName = Path.GetDirectoryName(theEntry.Name);
                    string fileName = Path.GetFileName(theEntry.Name);

                    if (fileName != String.Empty)
                    {
                        FileStream streamWriter = File.Create(tempDir + Path.DirectorySeparatorChar + fileName);

                        int size = 2048;
                        byte[] data = new byte[2048];
                        while (true)
                        {
                            size = s.Read(data, 0, data.Length);
                            if (size > 0)
                            {
                                streamWriter.Write(data, 0, size);
                            }
                            else
                            {
                                break;
                            }
                        }

                        streamWriter.Close();

                    }
                }

                // Clean up
                s.Close();
                if (deleteZipFile)
                    File.Delete(zipFilePath);
            }
	    }

	    //helper to try and match the old path to a new virtual one
        public static string FindFile(string virtualPath)
        {
            string retval = virtualPath;

            if (virtualPath.StartsWith("~"))
                retval = virtualPath.Replace("~", SystemDirectories.Root);

            if (virtualPath.StartsWith("/") && virtualPath.StartsWith(SystemDirectories.Root) == false)
                retval = SystemDirectories.Root + "/" + virtualPath.TrimStart('/');

            return retval;
        }

        //Replaces tildes with the root dir
        public static string ResolveUrl(string virtualPath)
        {
             if (virtualPath.StartsWith("~"))
                return virtualPath.Replace("~", SystemDirectories.Root).Replace("//", "/");
            else if (Uri.IsWellFormedUriString(virtualPath, UriKind.Absolute))
                return virtualPath;
            else
                return VirtualPathUtility.ToAbsolute(virtualPath, SystemDirectories.Root);
        }

        public static Attempt<string> TryResolveUrl(string virtualPath)
        {
            try
            {
                if (virtualPath.StartsWith("~"))
                    return Attempt.Succeed(virtualPath.Replace("~", SystemDirectories.Root).Replace("//", "/"));
                if (Uri.IsWellFormedUriString(virtualPath, UriKind.Absolute))
                    return Attempt.Succeed(virtualPath);
                return Attempt.Succeed(VirtualPathUtility.ToAbsolute(virtualPath, SystemDirectories.Root));
            }
            catch (Exception ex)
            {
                return Attempt.Fail(virtualPath, ex);
            }
        }

        public static string MapPath(string path, bool useHttpContext)
        {
            // Check if the path is already mapped
            if ((path.Length >= 2 && path[1] == Path.VolumeSeparatorChar)
                || path.StartsWith(@"\\")) //UNC Paths start with "\\". If the site is running off a network drive mapped paths will look like "\\Whatever\Boo\Bar"
            {
                return path;
            }
			// Check that we even have an HttpContext! otherwise things will fail anyways
			// http://umbraco.codeplex.com/workitem/30946

            if (useHttpContext && HttpContext.Current != null)
            {
                //string retval;
                if (String.IsNullOrEmpty(path) == false && (path.StartsWith("~") || path.StartsWith(SystemDirectories.Root)))
                    return HostingEnvironment.MapPath(path);
                else
                    return HostingEnvironment.MapPath("~/" + path.TrimStart('/'));
            }

        	var root = GetRootDirectorySafe();
        	var newPath = path.TrimStart('~', '/').Replace('/', IOHelper.DirSepChar);
        	var retval = root + IOHelper.DirSepChar.ToString(CultureInfo.InvariantCulture) + newPath;

        	return retval;
        }

        public static string MapPath(string path)
        {
            return MapPath(path, true);
        }

        //use a tilde character instead of the complete path
		internal static string ReturnPath(string settingsKey, string standardPath, bool useTilde)
        {
            string retval = ConfigurationManager.AppSettings[settingsKey];

            if (String.IsNullOrEmpty(retval))
                retval = standardPath;

            return retval.TrimEnd('/');
        }

        internal static string ReturnPath(string settingsKey, string standardPath)
        {
            return ReturnPath(settingsKey, standardPath, false);

        }

        /// <summary>
        /// Verifies that the current filepath matches a directory where the user is allowed to edit a file.
        /// </summary>
        /// <param name="filePath">The filepath to validate.</param>
        /// <param name="validDir">The valid directory.</param>
        /// <returns>A value indicating whether the filepath is valid.</returns>
        internal static bool VerifyEditPath(string filePath, string validDir)
        {
            return VerifyEditPath(filePath, new[] { validDir });
        }

        /// <summary>
        /// Validates that the current filepath matches a directory where the user is allowed to edit a file.
        /// </summary>
        /// <param name="filePath">The filepath to validate.</param>
        /// <param name="validDir">The valid directory.</param>
        /// <returns>True, if the filepath is valid, else an exception is thrown.</returns>
        /// <exception cref="FileSecurityException">The filepath is invalid.</exception>
        internal static bool ValidateEditPath(string filePath, string validDir)
        {
            if (VerifyEditPath(filePath, validDir) == false)
                throw new FileSecurityException(String.Format("The filepath '{0}' is not within an allowed directory for this type of files", filePath.Replace(MapPath(SystemDirectories.Root), "")));
            return true;
        }

        /// <summary>
        /// Verifies that the current filepath matches one of several directories where the user is allowed to edit a file.
        /// </summary>
        /// <param name="filePath">The filepath to validate.</param>
        /// <param name="validDirs">The valid directories.</param>
        /// <returns>A value indicating whether the filepath is valid.</returns>
        internal static bool VerifyEditPath(string filePath, IEnumerable<string> validDirs)
        {
            // this is called from ScriptRepository, PartialViewRepository, etc.
            // filePath is the fullPath (rooted, filesystem path, can be trusted)
            // validDirs are virtual paths (eg ~/Views)
            //
            // except that for templates, filePath actually is a virtual path

            //TODO
            // what's below is dirty, there are too many ways to get the root dir, etc.
            // not going to fix everything today

            var mappedRoot = MapPath(SystemDirectories.Root);
            if (filePath.StartsWith(mappedRoot) == false)
                filePath = MapPath(filePath);

            // yes we can (see above)
            //// don't trust what we get, it may contain relative segments
            //filePath = Path.GetFullPath(filePath);

            foreach (var dir in validDirs)
            {
                var validDir = dir;
                if (validDir.StartsWith(mappedRoot) == false)
                    validDir = MapPath(validDir);

                if (PathStartsWith(filePath, validDir, Path.DirectorySeparatorChar))
                    return true;
            }

            return false;
        }

        /// <summary>
        /// Verifies that the current filepath has one of several authorized extensions.
        /// </summary>
        /// <param name="filePath">The filepath to validate.</param>
        /// <param name="validFileExtensions">The valid extensions.</param>
        /// <returns>A value indicating whether the filepath is valid.</returns>
        internal static bool VerifyFileExtension(string filePath, List<string> validFileExtensions)
        {
            var ext = Path.GetExtension(filePath);
            return ext != null && validFileExtensions.Contains(ext.TrimStart('.'));
        }

        /// <summary>
        /// Validates that the current filepath has one of several authorized extensions.
        /// </summary>
        /// <param name="filePath">The filepath to validate.</param>
        /// <param name="validFileExtensions">The valid extensions.</param>
        /// <returns>True, if the filepath is valid, else an exception is thrown.</returns>
        /// <exception cref="FileSecurityException">The filepath is invalid.</exception>
        internal static bool ValidateFileExtension(string filePath, List<string> validFileExtensions)
        {
            if (VerifyFileExtension(filePath, validFileExtensions) == false)
                throw new FileSecurityException(String.Format("The extension for the current file '{0}' is not of an allowed type for this editor. This is typically controlled from either the installed MacroEngines or based on configuration in /config/umbracoSettings.config", filePath.Replace(MapPath(SystemDirectories.Root), "")));
            return true;
        }

        public static bool PathStartsWith(string path, string root, char separator)
        {
            // either it is identical to root,
            // or it is root + separator + anything

            if (path.StartsWith(root, StringComparison.OrdinalIgnoreCase) == false) return false;
            if (path.Length == root.Length) return true;
            if (path.Length < root.Length) return false;
            return path[root.Length] == separator;
        }

        /// <summary>
        /// Returns the path to the root of the application, by getting the path to where the assembly where this
        /// method is included is present, then traversing until it's past the /bin directory. Ie. this makes it work
        /// even if the assembly is in a /bin/debug or /bin/release folder
        /// </summary>
        /// <returns></returns>
        internal static string GetRootDirectorySafe()
        {
            if (String.IsNullOrEmpty(_rootDir) == false)
            {
                return _rootDir;
            }

			var codeBase = Assembly.GetExecutingAssembly().CodeBase;
			var uri = new Uri(codeBase);
			var path = uri.LocalPath;
        	var baseDirectory = Path.GetDirectoryName(path);
            if (String.IsNullOrEmpty(baseDirectory))
                throw new Exception("No root directory could be resolved. Please ensure that your Umbraco solution is correctly configured.");

            _rootDir = baseDirectory.Contains("bin")
                           ? baseDirectory.Substring(0, baseDirectory.LastIndexOf("bin", StringComparison.OrdinalIgnoreCase) - 1)
                           : baseDirectory;

            return _rootDir;
        }

        internal static string GetRootDirectoryBinFolder()
        {
            string binFolder = String.Empty;
            if (String.IsNullOrEmpty(_rootDir))
            {
                binFolder = Assembly.GetExecutingAssembly().GetAssemblyFile().Directory.FullName;
                return binFolder;
            }

            binFolder = Path.Combine(GetRootDirectorySafe(), "bin");

#if DEBUG
            var debugFolder = Path.Combine(binFolder, "debug");
            if (Directory.Exists(debugFolder))
                return debugFolder;
#endif
            var releaseFolder = Path.Combine(binFolder, "release");
            if (Directory.Exists(releaseFolder))
                return releaseFolder;

            if (Directory.Exists(binFolder))
                return binFolder;

            return _rootDir;
        }

        /// <summary>
        /// Allows you to overwrite RootDirectory, which would otherwise be resolved
        /// automatically upon application start.
        /// </summary>
        /// <remarks>The supplied path should be the absolute path to the root of the umbraco site.</remarks>
        /// <param name="rootPath"></param>
        internal static void SetRootDirectory(string rootPath)
	    {
            _rootDir = rootPath;
	    }

        /// <summary>
        /// Check to see if filename passed has any special chars in it and strips them to create a safe filename.  Used to overcome an issue when Umbraco is used in IE in an intranet environment.
        /// </summary>
        /// <param name="filePath">The filename passed to the file handler from the upload field.</param>
        /// <returns>A safe filename without any path specific chars.</returns>
        internal static string SafeFileName(string filePath)
        {
            // use string extensions
            return filePath.ToSafeFileName();
        }

	    public static void EnsurePathExists(string path)
	    {
	        var absolutePath = MapPath(path);
	        if (Directory.Exists(absolutePath) == false)
	            Directory.CreateDirectory(absolutePath);
	    }

	    public static void EnsureFileExists(string path, string contents)
	    {
	        var absolutePath = IOHelper.MapPath(path);
	        if (File.Exists(absolutePath)) return;

	        using (var writer = File.CreateText(absolutePath))
	        {
	            writer.Write(contents);
	        }
	    }

        /// <summary>
        /// Deletes all files passed in.
        /// </summary>
        /// <param name="files"></param>
        /// <param name="onError"></param>
        /// <returns></returns>
        internal static bool DeleteFiles(IEnumerable<string> files, Action<string, Exception> onError = null)
        {
            //ensure duplicates are removed
            files = files.Distinct();

            var allsuccess = true;

            var fs = FileSystemProviderManager.Current.GetFileSystemProvider<MediaFileSystem>();
            Parallel.ForEach(files, file =>
            {
                try
                {
                    if (file.IsNullOrWhiteSpace()) return;

                    var relativeFilePath = fs.GetRelativePath(file);
                    if (fs.FileExists(relativeFilePath) == false) return;

                    var parentDirectory = Path.GetDirectoryName(relativeFilePath);

                    // don't want to delete the media folder if not using directories.
                    if (UmbracoConfig.For.UmbracoSettings().Content.UploadAllowDirectories && parentDirectory != fs.GetRelativePath("/"))
                    {
                        //issue U4-771: if there is a parent directory the recursive parameter should be true
                        fs.DeleteDirectory(parentDirectory, String.IsNullOrEmpty(parentDirectory) == false);
                    }
                    else
                    {
                        fs.DeleteFile(file, true);
                    }
                }
                catch (Exception e)
                {
                    onError?.Invoke(file, e);
                    allsuccess = false;
                }
            });

            return allsuccess;
        }
    }
}