// Copyright 2014-2018 Dirk Lemstra (https://github.com/dlemstra/MagickViewer)
//
// Licensed under the ImageMagick License (the "License"); you may not use this file except in
// compliance with the License. You may obtain a copy of the License at
//
//   https://www.imagemagick.org/script/license.php
//
// Unless required by applicable law or agreed to in writing, software distributed under the
// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
// express or implied. See the License for the specific language governing permissions and
// limitations under the License.

using System;
using System.IO;
using System.Linq;
using ImageMagick;

namespace Orbit.Module.ViewModel
{
    class ImageIterator
    {
        public FileInfo Current
        {
            get;
            set;
        }

        internal FileInfo Next()
        {
            if (Current == null)
                return null;

            FileInfo[] files = GetSupportedFiles();
            if (files.Length == 1)
                return null;

            for (int i = 0; i < files.Length; i++)
            {
                if (IsCurrent(files[i]))
                {
                    i++;
                    if (i == files.Length)
                        i = 0;
                    return files[i];
                }
            }

            return null;
        }

        internal FileInfo Previous()
        {
            if (Current == null)
                return null;

            FileInfo[] files = GetSupportedFiles();
            if (files.Length == 1)
                return null;

            for (int i = files.Length - 1; i >= 0; i--)
            {
                if (IsCurrent(files[i]))
                {
                    i--;
                    if (i == -1)
                        i = files.Length - 1;
                    return files[i];
                }
            }

            return null;
        }

        private FileInfo[] GetSupportedFiles()
        {
            return (from file in Current.Directory.GetFiles()
                    where file.IsSupported()
                    select file).ToArray();
        }

        private bool IsCurrent(FileInfo file)
        {
            return Current.FullName.Equals(file.FullName, StringComparison.OrdinalIgnoreCase);
        }
    }

    public static class FileInfoExtensions
    {
        public static bool IsSupported(this FileInfo self)
        {
            if (self == null || string.IsNullOrEmpty(self.FullName))
                return false;

            if (self.Name.Length < 2)
                return false;

            if (string.IsNullOrEmpty(self.Extension))
                return false;

            if (!Enum.TryParse(self.Extension.Substring(1), true, out MagickFormat format))
                return false;

            return (from formatInfo in MagickNET.SupportedFormats
                    where formatInfo.IsReadable && formatInfo.Format == format
                    select formatInfo).Any();
        }
    }
}