using System;
using System.Collections.Generic;
using System.IO;

namespace JD.Core
{
    public class TempFileManager : IDisposable
    {
        private readonly Dictionary<string, string> _tempFiles;
        private int _untaggedIndex;

        static TempFileManager()
        {
            Instance = new TempFileManager();
        }

        public static TempFileManager Instance { get; }

        private TempFileManager()
        {
            _tempFiles = new Dictionary<string, string>();
            _untaggedIndex = 0;
        }

        public void Dispose()
        {
            foreach (var file in _tempFiles)
            {
                File.Delete(file.Value);
            }
        }

        public FileStream CreateAndOpenFile(string tag = null, string path = null, string subFolder = null, string fileNameWithoutExt = null, string extension = "")
        {
            if (String.IsNullOrEmpty(tag))
                tag = GetUntaggedIdentifier();
            if (path == null || !Directory.Exists(path))
                path = Path.GetTempPath();
            if (!path.EndsWith("\\"))
                path += "\\";

            Directory.CreateDirectory(path);
            if (subFolder != null)
            {
                if (!subFolder.EndsWith("\\"))
                    subFolder += "\\";
                path += subFolder;
                Directory.CreateDirectory(path);
            }

            var forceNewFileCreation = true;
            if (fileNameWithoutExt == null)
            {
                forceNewFileCreation = false;
                fileNameWithoutExt = Guid.NewGuid().ToString();
                while (File.Exists(path + fileNameWithoutExt + extension))
                {
                    fileNameWithoutExt = Guid.NewGuid().ToString();
                }
            }

            return CreateAndOpenFile(tag, path, fileNameWithoutExt, extension, forceNewFileCreation, 0);
        }

        private FileStream CreateAndOpenFile(string tag, string basePath, string fileNameWithoutExt, string extension, bool forceNewFileCreation, int shifter)
        {
            var path = basePath + fileNameWithoutExt;
            if (shifter != 0)
                path += $"_{shifter}";

            path += extension;
            
            if (_tempFiles.ContainsKey(tag))
            {
                try
                {
                    if (_tempFiles[tag] == path)
                        return OpenFile(tag, FileMode.Create, FileAccess.ReadWrite);
                    else
                        return null;
                }
                catch (Exception)
                {
                    return null;
                }
            }

            try
            {
                var fileMode = forceNewFileCreation ? FileMode.Create : FileMode.CreateNew;
                var fileStream = new FileStream(path, fileMode, FileAccess.ReadWrite);
                _tempFiles.Add(tag, path);
                return fileStream;
            }
            catch (Exception)
            {
                if (shifter > 10)
                    return null;
                return CreateAndOpenFile(tag, basePath, fileNameWithoutExt, extension, forceNewFileCreation, ++shifter);
            }
        }

        public FileStream OpenFile(string tag, FileMode fileMode, FileAccess fileAccess)
        {
            try
            {
                if (!_tempFiles.ContainsKey(tag))
                    return null;

                return new FileStream(_tempFiles[tag], fileMode, fileAccess);
            }
            catch (Exception)
            {
                return null;
            }
        }

        public string GetFileName(string tag)
        {
            if (!_tempFiles.ContainsKey(tag))
                return null;

            return _tempFiles[tag];
        }

        private string GetUntaggedIdentifier()
        {
            return $"_Untagged{_untaggedIndex++}";
        }
    }
}