using System;
using System.IO;
using System.IO.Compression;

namespace Alkami.Ops.Common.FileSystem
{
    public static class ZipHelpers
    {
        /// <summary>
        /// Unzip a path into a specific folder
        /// </summary>
        /// <param name="zipPath">Path of the file to unzip.</param>
        /// <param name="destinationDirectory">If null defaults to a new folder at current location with the Zip file's name.</param>
        public static void UnZip(string zipPath, string destinationDirectory = null)
        {
            if (!string.IsNullOrWhiteSpace(zipPath))
            {
                if (string.IsNullOrWhiteSpace(destinationDirectory))
                {
                    destinationDirectory = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location);
                    destinationDirectory = Path.Combine(destinationDirectory, Path.GetFileNameWithoutExtension(zipPath));
                }

                Directory.CreateDirectory(destinationDirectory);

                try
                {
                    using (var archive = ZipFile.OpenRead(zipPath))
                    {
                        archive.ExtractToDirectory(destinationDirectory);
                    }
                }
                catch (IOException ex)
                {
                    Console.Error.WriteLine("Exception occurred while extracting files.");

                    Console.Error.WriteLine(ex);
                }
            }
        }

        /// <summary>
        /// Unzips a single directory from inside a zip file.
        /// </summary>
        /// <param name="zipPath">Path of the file to unzip.</param>
        /// <param name="internalDirectory">Directory inside of zip file to be extracted. If null or nonexistent nothing will be extracted.</param>
        /// <param name="destinationDirectory">If null defaults to a new folder at current location with the Zip subfolder's name.</param>
        public static void UnZipSubDirectory(string internalDirectory, string zipPath, string destinationDirectory = null)
        {
            if (!string.IsNullOrWhiteSpace(zipPath))
            {
                if (string.IsNullOrWhiteSpace(destinationDirectory))
                {
                    destinationDirectory = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location);
                    destinationDirectory = Path.Combine(destinationDirectory, Path.GetFileNameWithoutExtension(zipPath));
                }

                Directory.CreateDirectory(destinationDirectory);

                try
                {
                    using (var archive = ZipFile.OpenRead(zipPath))
                    {
                        foreach (var entry in archive.Entries)
                        {
                            if (GetRootFolder(entry.FullName).IndexOf(internalDirectory, StringComparison.OrdinalIgnoreCase) >= 0)
                            {
                                ExtractEntry(entry, destinationDirectory, entry.FullName);
                            }
                        }
                    }
                }
                catch (IOException ex)
                {
                    Console.Error.WriteLine("Exception occurred while extracting files.");

                    Console.Error.WriteLine(ex);
                }
                catch (Exception ex)
                {
                    Console.Error.WriteLine("Unknown exception occurred while extracting files");

                    Console.Error.WriteLine(ex);

                    throw;
                }
            }
        }

        /// <summary>
        /// Recursively handle subfolders
        /// </summary>
        /// <param name="entry">Zip entry to extract</param>
        /// <param name="destinationDirectory">Desired destination directory. Is added to with each recursive loop as subdirectories are popped off of the entry</param>
        /// <param name="entryPath">Current entry path. Shorter every loop as we pop off directories and add them to the destinationDirectory parameter.</param>
        private static void ExtractEntry(ZipArchiveEntry entry, string destinationDirectory, string entryPath)
        {
            var targetIsDirectory = false;
            var topLevelDirectory = "";

            if (!string.IsNullOrWhiteSpace(entryPath) && !entryPath.Equals('/'))
            {
                topLevelDirectory = Path.GetDirectoryName(entryPath);
            }
            else
            {
                targetIsDirectory = true;
            }

            if (!string.IsNullOrEmpty(topLevelDirectory))
            {
                Directory.CreateDirectory(Path.Combine(destinationDirectory, topLevelDirectory));
                destinationDirectory = Path.Combine(destinationDirectory, topLevelDirectory);
                ExtractEntry(entry, destinationDirectory, Path.GetFileName(entryPath));
            }
            else
            {
                if (targetIsDirectory)
                {
                    Directory.CreateDirectory(destinationDirectory);
                }
                else
                {
                    entry.ExtractToFile(Path.Combine(destinationDirectory, entry.Name));
                }
            }
        }

        /// <summary>
        /// Cargo culted from https://stackoverflow.com/a/40124633/3691973
        /// </summary>
        /// <param name="path">Path to examine</param>
        /// <returns>Top level folder.</returns>
        private static string GetRootFolder(string path)
        {
            var root = Path.GetPathRoot(path);
            while (true)
            {
                var temp = Path.GetDirectoryName(path);
                if (temp != null && temp.Equals(root))
                    break;
                path = temp;
            }
            return path;
        }
    }
}