using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using NLog;
using NzbDrone.Common.EnvironmentInfo;
using NzbDrone.Common.Extensions;

namespace NzbDrone.Common.Disk
{
    public interface IFileSystemLookupService
    {
        FileSystemResult LookupContents(string query, bool includeFiles);
    }

    public class FileSystemLookupService : IFileSystemLookupService
    {
        private readonly IDiskProvider _diskProvider;
        private readonly Logger _logger;

        private readonly HashSet<string> _setToRemove = new HashSet<string>
                                                        {
                                                            //Windows
                                                            "boot",
                                                            "bootmgr",
                                                            "cache",
                                                            "msocache",
                                                            "recovery",
                                                            "$recycle.bin",
                                                            "recycler",
                                                            "system volume information",
                                                            "temporary internet files",
                                                            "windows",

                                                            //OS X
                                                            ".fseventd",
                                                            ".spotlight",
                                                            ".trashes",
                                                            ".vol",
                                                            "cachedmessages",
                                                            "caches",
                                                            "trash"
                                                        };

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

        public FileSystemResult LookupContents(string query, bool includeFiles)
        {
            var result = new FileSystemResult();

            if (query.IsNullOrWhiteSpace())
            {
                if (OsInfo.IsWindows)
                {
                    result.Directories = GetDrives();

                    return result;
                }

                query = "/";
            }

            var lastSeparatorIndex = query.LastIndexOf(Path.DirectorySeparatorChar);
            var path = query.Substring(0, lastSeparatorIndex + 1);

            if (lastSeparatorIndex != -1)
            {
                try
                {
                    result.Parent = GetParent(path);
                    result.Directories = GetDirectories(path);

                    if (includeFiles)
                    {
                        result.Files = GetFiles(path);
                    }
                }

                catch (DirectoryNotFoundException)
                {
                    return new FileSystemResult { Parent = GetParent(path) };
                }
                catch (ArgumentException)
                {
                    return new FileSystemResult();
                }
                catch (IOException)
                {
                    return new FileSystemResult { Parent = GetParent(path) };
                }
                catch (UnauthorizedAccessException)
                {
                    return new FileSystemResult { Parent = GetParent(path) };
                }
            }

            return result;
        }

        private List<FileSystemModel> GetDrives()
        {
            return _diskProvider.GetFixedDrives()
                                .Select(d => new FileSystemModel
                                             {
                                                 Type = FileSystemEntityType.Drive,
                                                 Name = d,
                                                 Path = d,
                                                 LastModified = null
                                             })
                                .ToList();
        }

        private List<FileSystemModel> GetDirectories(string path)
        {
            var directories = _diskProvider.GetDirectoryInfos(path)
                                           .Select(d => new FileSystemModel
                                                        {
                                                            Name = d.Name,
                                                            Path = GetDirectoryPath(d.FullName.GetActualCasing()),
                                                            LastModified = d.LastWriteTimeUtc,
                                                            Type = FileSystemEntityType.Folder
                                                        })
                                           .ToList();

            directories.RemoveAll(d => _setToRemove.Contains(d.Name.ToLowerInvariant()));

            return directories;
        }

        private List<FileSystemModel> GetFiles(string path)
        {
            return _diskProvider.GetFileInfos(path)
                                .Select(d => new FileSystemModel
                                             {
                                                 Name = d.Name,
                                                 Path = d.FullName.GetActualCasing(),
                                                 LastModified = d.LastWriteTimeUtc,
                                                 Extension = d.Extension,
                                                 Size = d.Length,
                                                 Type = FileSystemEntityType.File
                                             })
                                .ToList();
        }

        private string GetDirectoryPath(string path)
        {
            if (path.Last() != Path.DirectorySeparatorChar)
            {
                path += Path.DirectorySeparatorChar;
            }

            return path;
        }
        
        private string GetParent(string path)
        {
            var di = new DirectoryInfo(path);

            if (di.Parent != null)
            {
                var parent = di.Parent.FullName;

                if (parent.Last() != Path.DirectorySeparatorChar)
                {
                    parent += Path.DirectorySeparatorChar;
                }

                return parent;
            }

            if (!path.Equals("/"))
            {
                return String.Empty;
            }

            return null;
        }
    }
}