using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Umbraco.Cms.Core.Configuration.Models;
using Umbraco.Cms.Core.Models;
using Umbraco.Cms.Core.PropertyEditors;
using Umbraco.Cms.Core.Strings;
using Umbraco.Extensions;

namespace Umbraco.Cms.Core.IO
{
    public sealed class MediaFileManager
    {
        private readonly IMediaPathScheme _mediaPathScheme;
        private readonly ILogger<MediaFileManager> _logger;
        private readonly IShortStringHelper _shortStringHelper;
        private readonly IServiceProvider _serviceProvider;
        private MediaUrlGeneratorCollection? _mediaUrlGenerators;

        public MediaFileManager(
            IFileSystem fileSystem,
            IMediaPathScheme mediaPathScheme,
            ILogger<MediaFileManager> logger,
            IShortStringHelper shortStringHelper,
            IServiceProvider serviceProvider)
        {
            _mediaPathScheme = mediaPathScheme;
            _logger = logger;
            _shortStringHelper = shortStringHelper;
            _serviceProvider = serviceProvider;
            FileSystem = fileSystem;
        }

        [Obsolete("Use the ctr that doesn't include unused parameters.")]
        public MediaFileManager(
            IFileSystem fileSystem,
            IMediaPathScheme mediaPathScheme,
            ILogger<MediaFileManager> logger,
            IShortStringHelper shortStringHelper,
            IServiceProvider serviceProvider,
            IOptions<ContentSettings> contentSettings)
            : this(fileSystem, mediaPathScheme, logger, shortStringHelper, serviceProvider)
        { }

        /// <summary>
        /// Gets the media filesystem.
        /// </summary>
        public IFileSystem FileSystem { get; }

        /// <summary>
        /// Delete media files.
        /// </summary>
        /// <param name="files">Files to delete (filesystem-relative paths).</param>
        public void DeleteMediaFiles(IEnumerable<string> files)
        {
            files = files.Distinct();

            // kinda try to keep things under control
            var options = new ParallelOptions { MaxDegreeOfParallelism = 20 };

            Parallel.ForEach(files, options, file =>
            {
                try
                {
                    if (file.IsNullOrWhiteSpace())
                    {
                        return;
                    }

                    if (FileSystem.FileExists(file) == false)
                    {
                        return;
                    }

                    FileSystem.DeleteFile(file);

                    var directory = _mediaPathScheme.GetDeleteDirectory(this, file);
                    if (!directory.IsNullOrWhiteSpace())
                    {
                        FileSystem.DeleteDirectory(directory!, true);
                    }
                }
                catch (Exception e)
                {
                    _logger.LogError(e, "Failed to delete media file '{File}'.", file);
                }
            });
        }

        #region Media Path

        /// <summary>
        /// Gets the file path of a media file.
        /// </summary>
        /// <param name="filename">The file name.</param>
        /// <param name="cuid">The unique identifier of the content/media owning the file.</param>
        /// <param name="puid">The unique identifier of the property type owning the file.</param>
        /// <returns>The filesystem-relative path to the media file.</returns>
        /// <remarks>With the old media path scheme, this CREATES a new media path each time it is invoked.</remarks>
        public string GetMediaPath(string? filename, Guid cuid, Guid puid)
        {
            filename = Path.GetFileName(filename);
            if (filename == null)
            {
                throw new ArgumentException("Cannot become a safe filename.", nameof(filename));
            }

            filename = _shortStringHelper.CleanStringForSafeFileName(filename.ToLowerInvariant());

            return _mediaPathScheme.GetFilePath(this, cuid, puid, filename);
        }

        #endregion

        #region Associated Media Files

        /// <summary>
        /// Returns a stream (file) for a content item (or a null stream if there is no file).
        /// </summary>
        /// <param name="content"></param>
        /// <param name="mediaFilePath">The file path if a file was found</param>
        /// <param name="propertyTypeAlias"></param>
        /// <param name="variationContextAccessor"></param>
        /// <returns></returns>
        public Stream GetFile(
            IContentBase content,
            out string? mediaFilePath,
            string propertyTypeAlias = Constants.Conventions.Media.File,
            string? culture = null,
            string? segment = null)
        {
            // TODO: If collections were lazy we could just inject them
            if (_mediaUrlGenerators == null)
            {
                _mediaUrlGenerators = _serviceProvider.GetRequiredService<MediaUrlGeneratorCollection>();
            }

            if (!content.TryGetMediaPath(propertyTypeAlias, _mediaUrlGenerators!, out mediaFilePath, culture, segment))
            {
                return Stream.Null;
            }

            return FileSystem.OpenFile(mediaFilePath!);
        }

        /// <summary>
        /// Stores a media file associated to a property of a content item.
        /// </summary>
        /// <param name="content">The content item owning the media file.</param>
        /// <param name="propertyType">The property type owning the media file.</param>
        /// <param name="filename">The media file name.</param>
        /// <param name="filestream">A stream containing the media bytes.</param>
        /// <param name="oldpath">An optional filesystem-relative filepath to the previous media file.</param>
        /// <returns>The filesystem-relative filepath to the media file.</returns>
        /// <remarks>
        /// <para>The file is considered "owned" by the content/propertyType.</para>
        /// <para>If an <paramref name="oldpath"/> is provided then that file (and associated thumbnails if any) is deleted
        /// before the new file is saved, and depending on the media path scheme, the folder may be reused for the new file.</para>
        /// </remarks>
        public string StoreFile(IContentBase content, IPropertyType? propertyType, string filename, Stream filestream, string? oldpath)
        {
            if (content == null)
            {
                throw new ArgumentNullException(nameof(content));
            }

            if (propertyType == null)
            {
                throw new ArgumentNullException(nameof(propertyType));
            }

            if (filename == null)
            {
                throw new ArgumentNullException(nameof(filename));
            }

            if (string.IsNullOrWhiteSpace(filename))
            {
                throw new ArgumentException("Value can't be empty or consist only of white-space characters.", nameof(filename));
            }

            if (filestream == null)
            {
                throw new ArgumentNullException(nameof(filestream));
            }

            // clear the old file, if any
            if (string.IsNullOrWhiteSpace(oldpath) == false)
            {
                FileSystem.DeleteFile(oldpath!);
            }

            // get the filepath, store the data
            var filepath = GetMediaPath(filename, content.Key, propertyType.Key);
            FileSystem.AddFile(filepath, filestream);
            return filepath;
        }

        /// <summary>
        /// Copies a media file as a new media file, associated to a property of a content item.
        /// </summary>
        /// <param name="content">The content item owning the copy of the media file.</param>
        /// <param name="propertyType">The property type owning the copy of the media file.</param>
        /// <param name="sourcepath">The filesystem-relative path to the source media file.</param>
        /// <returns>The filesystem-relative path to the copy of the media file.</returns>
        public string? CopyFile(IContentBase content, IPropertyType propertyType, string sourcepath)
        {
            if (content == null)
            {
                throw new ArgumentNullException(nameof(content));
            }

            if (propertyType == null)
            {
                throw new ArgumentNullException(nameof(propertyType));
            }

            if (sourcepath == null)
            {
                throw new ArgumentNullException(nameof(sourcepath));
            }

            if (string.IsNullOrWhiteSpace(sourcepath))
            {
                throw new ArgumentException("Value can't be empty or consist only of white-space characters.", nameof(sourcepath));
            }

            // ensure we have a file to copy
            if (FileSystem.FileExists(sourcepath) == false)
            {
                return null;
            }

            // get the filepath
            var filename = Path.GetFileName(sourcepath);
            var filepath = GetMediaPath(filename, content.Key, propertyType.Key);
            FileSystem.CopyFile(sourcepath, filepath);
            return filepath;
        }

        #endregion
    }
}