using System.Linq;
using System.Text.RegularExpressions;
using NLog;
using NzbDrone.Common.Disk;
using NzbDrone.Common.EnvironmentInfo;

namespace NzbDrone.Mono.EnvironmentInfo.VersionAdapters
{
    public class MacOsVersionAdapter : IOsVersionAdapter
    {
        private const string PLIST_DIR = "/System/Library/CoreServices/";

        private static readonly Regex DarwinVersionRegex = new ("<key>ProductVersion<\\/key>\\s*<string>(?<version>1\\d\\.\\d{1,2}\\.?\\d{0,2}?)<\\/string>",
            RegexOptions.Compiled | RegexOptions.IgnoreCase);

        private readonly IDiskProvider _diskProvider;
        private readonly Logger _logger;

        public MacOsVersionAdapter(IDiskProvider diskProvider, Logger logger)
        {
            _diskProvider = diskProvider;
            _logger = logger;
        }

        public OsVersionModel Read()
        {
            var version = "10.0";

            if (!_diskProvider.FolderExists(PLIST_DIR))
            {
                _logger.Debug("Directory {0} doesn't exist", PLIST_DIR);
                return null;
            }

            var allFiles = _diskProvider.GetFiles(PLIST_DIR, false);

            var versionFile = allFiles.SingleOrDefault(c =>
                c.EndsWith("/SystemVersion.plist") ||
                c.EndsWith("/ServerVersion.plist"));

            if (string.IsNullOrWhiteSpace(versionFile))
            {
                _logger.Debug("Couldn't find version plist file in {0}", PLIST_DIR);
                return null;
            }

            var text = _diskProvider.ReadAllText(versionFile);
            var match = DarwinVersionRegex.Match(text);

            if (match.Success)
            {
                version = match.Groups["version"].Value;
            }

            var name = versionFile.Contains("Server") ? "macOS Server" : "macOS";

            return new OsVersionModel(name, version);
        }

        public bool Enabled => OsInfo.IsOsx;
    }
}