using System.IO.Compression;
using System.Text.RegularExpressions;

namespace PepLib
{
    public static class ZipHelper
    {
        /// <summary>
        /// Returns the files that match the specified pattern.
        /// </summary>
        /// <param name="file">Input zip file.</param>
        /// <param name="pattern">Pattern to match.</param>
        /// <param name="names">Names of the files that match the pattern.</param>
        /// <param name="streams">Data of the files that match the pattern.</param>
        /// <returns></returns>
        public static int ExtractByPattern(string file, string pattern, out string[] names, out Stream[] streams)
        {
            var nameList = new List<string>();
            var streamList = new List<Stream>();

            using (var fileStream = new FileStream(file, FileMode.Open, FileAccess.Read))
            using (var zip = new ZipArchive(fileStream, ZipArchiveMode.Read))
            {
                foreach (var entry in zip.Entries)
                {
                    if (!Regex.IsMatch(entry.FullName, pattern))
                        continue;

                    nameList.Add(entry.FullName);

                    var memstream = new MemoryStream();
                    using var entryStream = entry.Open();
                    entryStream.CopyTo(memstream);
                    memstream.Seek(0, SeekOrigin.Begin);
                    streamList.Add(memstream);
                }
            }

            names = nameList.ToArray();
            streams = streamList.ToArray();

            return streams.Length;
        }

        /// <summary>
        /// Returns the first file found that matches the specified file extension.
        /// </summary>
        /// <param name="file">Input zip file.</param>
        /// <param name="extension">Extension to match.</param>
        /// <param name="name">The name of the file that matches the file extension.</param>
        /// <param name="stream">The data of the file that matches the file extension.</param>
        /// <returns></returns>
        public static bool ExtractByExtension(string file, string extension, out string name, out Stream stream)
        {
            using (var fileStream = new FileStream(file, FileMode.Open, FileAccess.Read))
            using (var zip = new ZipArchive(fileStream, ZipArchiveMode.Read))
            {
                foreach (var entry in zip.Entries)
                {
                    if (Path.GetExtension(entry.FullName) != extension)
                        continue;

                    var memstream = new MemoryStream();
                    using var entryStream = entry.Open();
                    entryStream.CopyTo(memstream);
                    memstream.Seek(0, SeekOrigin.Begin);

                    stream = memstream;
                    name = entry.FullName;

                    return true;
                }
            }

            stream = null;
            name = null;

            return false;
        }
    }
}