/*
 *                     GNU AFFERO GENERAL PUBLIC LICENSE
 *                       Version 3, 19 November 2007
 *  Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
 *  Everyone is permitted to copy and distribute verbatim copies
 *  of this license document, but changing it is not allowed.
 */

using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Linq;

namespace UVtools.Core.Extensions
{
    public static class ZipArchiveExtensions
    {
        /// <summary>
        /// Used to specify what our overwrite policy
        /// is for files we are extracting.
        /// </summary>
        public enum Overwrite
        {
            Always,
            IfNewer,
            Never
        }

        /// <summary>
        /// Used to identify what we will do if we are
        /// trying to create a zip file and it already
        /// exists.
        /// </summary>
        public enum ArchiveAction
        {
            Merge,
            Replace,
            Error,
            Ignore
        }

        /// <summary>
        /// Unzips the specified file to the given folder in a safe
        /// manner.  This plans for missing paths and existing files
        /// and handles them gracefully.
        /// </summary>
        /// <param name="sourceArchiveFileName">
        /// The name of the zip file to be extracted
        /// </param>
        /// <param name="destinationDirectoryName">
        /// The directory to extract the zip file to
        /// </param>
        /// <param name="overwriteMethod">
        /// Specifies how we are going to handle an existing file.
        /// The default is IfNewer.
        /// </param>
        public static void ImprovedExtractToDirectory(string sourceArchiveFileName, string destinationDirectoryName, Overwrite overwriteMethod = Overwrite.IfNewer)
        {
            //Opens the zip file up to be read
            using var archive = ZipFile.OpenRead(sourceArchiveFileName);
            archive.ImprovedExtractToDirectory(sourceArchiveFileName, destinationDirectoryName, overwriteMethod);
        }

        /// <summary>
        /// Unzips the specified file to the given folder in a safe
        /// manner.  This plans for missing paths and existing files
        /// and handles them gracefully.
        /// </summary>
        /// <param name="sourceArchiveFileName">
        /// The name of the zip file to be extracted
        /// </param>
        /// <param name="destinationDirectoryName">
        /// The directory to extract the zip file to
        /// </param>
        /// <param name="overwriteMethod">
        /// Specifies how we are going to handle an existing file.
        /// The default is IfNewer.
        /// </param>
        public static void ImprovedExtractToDirectory(this ZipArchive archive, string sourceArchiveFileName, string destinationDirectoryName, Overwrite overwriteMethod = Overwrite.IfNewer)
        {
            //Loops through each file in the zip file
            foreach (var file in archive.Entries)
            {
                file.ImprovedExtractToFile(destinationDirectoryName, overwriteMethod);
            }
        }

        /// <summary>
        /// Safely extracts a single file from a zip file
        /// </summary>
        /// <param name="file">
        /// The zip entry we are pulling the file from
        /// </param>
        /// <param name="destinationPath">
        /// The root of where the file is going
        /// </param>
        /// <param name="overwriteMethod">
        /// Specifies how we are going to handle an existing file.
        /// The default is Overwrite.IfNewer.
        /// </param>
        public static void ImprovedExtractToFile(this ZipArchiveEntry file, string destinationPath, Overwrite overwriteMethod = Overwrite.IfNewer)
        {
            //Gets the complete path for the destination file, including any
            //relative paths that were in the zip file
            string destinationFileName = Path.Combine(destinationPath, file.FullName);

            //Gets just the new path, minus the file name so we can create the
            //directory if it does not exist
            string destinationFilePath = Path.GetDirectoryName(destinationFileName);

            //Creates the directory (if it doesn't exist) for the new path
            Directory.CreateDirectory(destinationFilePath);

            //Determines what to do with the file based upon the
            //method of overwriting chosen
            switch (overwriteMethod)
            {
                case Overwrite.Always:
                    //Just put the file in and overwrite anything that is found
                    file.ExtractToFile(destinationFileName, true);
                    break;
                case Overwrite.IfNewer:
                    //Checks to see if the file exists, and if so, if it should
                    //be overwritten
                    if (!File.Exists(destinationFileName) || File.GetLastWriteTime(destinationFileName) < file.LastWriteTime)
                    {
                        //Either the file didn't exist or this file is newer, so
                        //we will extract it and overwrite any existing file
                        file.ExtractToFile(destinationFileName, true);
                    }
                    break;
                case Overwrite.Never:
                    //Put the file in if it is new but ignores the 
                    //file if it already exists
                    if (!File.Exists(destinationFileName))
                    {
                        file.ExtractToFile(destinationFileName);
                    }
                    break;
            }
        }

        /// <summary>
        /// Allows you to add files to an archive, whether the archive
        /// already exists or not
        /// </summary>
        /// <param name="archiveFullName">
        /// The name of the archive to you want to add your files to
        /// </param>
        /// <param name="files">
        /// A set of file names that are to be added
        /// </param>
        /// <param name="action">
        /// Specifies how we are going to handle an existing archive
        /// </param>
        /// <param name="compression">
        /// Specifies what type of compression to use - defaults to Optimal
        /// </param>
        public static void AddToArchive(string archiveFullName,
                                        List<string> files,
                                        ArchiveAction action = ArchiveAction.Replace,
                                        Overwrite fileOverwrite = Overwrite.IfNewer,
                                        CompressionLevel compression = CompressionLevel.Optimal)
        {
            //Identifies the mode we will be using - the default is Create
            ZipArchiveMode mode = ZipArchiveMode.Create;

            //Determines if the zip file even exists
            bool archiveExists = File.Exists(archiveFullName);

            //Figures out what to do based upon our specified overwrite method
            switch (action)
            {
                case ArchiveAction.Merge:
                    //Sets the mode to update if the file exists, otherwise
                    //the default of Create is fine
                    if (archiveExists)
                    {
                        mode = ZipArchiveMode.Update;
                    }
                    break;
                case ArchiveAction.Replace:
                    //Deletes the file if it exists.  Either way, the default
                    //mode of Create is fine
                    if (archiveExists)
                    {
                        File.Delete(archiveFullName);
                    }
                    break;
                case ArchiveAction.Error:
                    //Throws an error if the file exists
                    if (archiveExists)
                    {
                        throw new IOException(String.Format("The zip file {0} already exists.", archiveFullName));
                    }
                    break;
                case ArchiveAction.Ignore:
                    //Closes the method silently and does nothing
                    if (archiveExists)
                    {
                        return;
                    }
                    break;
            }

            //Opens the zip file in the mode we specified
            using ZipArchive zipFile = ZipFile.Open(archiveFullName, mode);
            //This is a bit of a hack and should be refactored - I am
            //doing a similar foreach loop for both modes, but for Create
            //I am doing very little work while Update gets a lot of
            //code.  This also does not handle any other mode (of
            //which there currently wouldn't be one since we don't
            //use Read here).
            if (mode == ZipArchiveMode.Create)
            {
                foreach (string file in files)
                {
                    //Adds the file to the archive
                    zipFile.CreateEntryFromFile(file, Path.GetFileName(file), compression);
                }
            }
            else
            {
                foreach (string file in files)
                {
                    var fileInZip = (from f in zipFile.Entries
                        where f.Name == Path.GetFileName(file)
                        select f).FirstOrDefault();

                    switch (fileOverwrite)
                    {
                        case Overwrite.Always:
                            //Deletes the file if it is found
                            if (fileInZip != null)
                            {
                                fileInZip.Delete();
                            }

                            //Adds the file to the archive
                            zipFile.CreateEntryFromFile(file, Path.GetFileName(file), compression);

                            break;
                        case Overwrite.IfNewer:
                            //This is a bit trickier - we only delete the file if it is
                            //newer, but if it is newer or if the file isn't already in
                            //the zip file, we will write it to the zip file
                            if (fileInZip != null)
                            {
                                //Deletes the file only if it is older than our file.
                                //Note that the file will be ignored if the existing file
                                //in the archive is newer.
                                if (fileInZip.LastWriteTime < File.GetLastWriteTime(file))
                                {
                                    fileInZip.Delete();

                                    //Adds the file to the archive
                                    zipFile.CreateEntryFromFile(file, Path.GetFileName(file), compression);
                                }
                            }
                            else
                            {
                                //The file wasn't already in the zip file so add it to the archive
                                zipFile.CreateEntryFromFile(file, Path.GetFileName(file), compression);
                            }
                            break;
                        case Overwrite.Never:
                            //Don't do anything - this is a decision that you need to
                            //consider, however, since this will mean that no file will
                            //be written.  You could write a second copy to the zip with
                            //the same name (not sure that is wise, however).
                            break;
                    }
                }
            }
        }

        /// <summary>
        /// Get or put a file into archive
        /// </summary>
        /// <param name="input"><see cref="ZipArchive"/></param>
        /// <param name="filename">Filename to create</param>
        /// <returns>Created <see cref="ZipArchiveEntry"/></returns>
        public static ZipArchiveEntry GetPutFile(this ZipArchive input, string filename)
        {
            return input.GetEntry(filename) ?? input.CreateEntry(filename);
        }

        /// <summary>
        /// Create or update a file into archive and write content to it
        /// </summary>
        /// <param name="input"><see cref="ZipArchive"/></param>
        /// <param name="filename">Filename to create</param>
        /// <param name="content">Content to write</param>
        /// <param name="checkExists"></param>
        /// <returns>Created <see cref="ZipArchiveEntry"/></returns>
        public static ZipArchiveEntry PutFileContent(this ZipArchive input, string filename, string content, ZipArchiveMode mode)
        {
            ZipArchiveEntry entry;
            if (mode == ZipArchiveMode.Update)
            {
                entry = input.GetEntry(filename) ?? input.CreateEntry(filename);
            }
            else
            {
                entry = input.CreateEntry(filename);
            }

            if (string.IsNullOrEmpty(content)) return entry;
            using var stream = entry.Open();
            if (mode == ZipArchiveMode.Update) stream.SetLength(0);
            using TextWriter tw = new StreamWriter(stream);
            tw.Write(content);
            tw.Close();

            return entry;
        }

        /// <summary>
        /// Create or update a file into archive and write content to it
        /// </summary>
        /// <param name="input"><see cref="ZipArchive"/></param>
        /// <param name="filename">Filename to create</param>
        /// <param name="content">Content to write</param>
        /// <returns>Created <see cref="ZipArchiveEntry"/></returns>
        public static ZipArchiveEntry PutFileContent(this ZipArchive input, string filename, byte[] content, ZipArchiveMode mode)
        {
            ZipArchiveEntry entry;
            if (mode == ZipArchiveMode.Update)
            {
                entry = input.GetEntry(filename) ?? input.CreateEntry(filename);
            }
            else
            {
                entry = input.CreateEntry(filename);
            }

            if (content is null) return entry;
            using var stream = entry.Open();
            if (mode == ZipArchiveMode.Update) stream.SetLength(0);
            stream.Write(content, 0, content.Length);
            stream.Close();
            return entry;
        }
    }
}