// Copyright © 2020 Paddy Xu
// 
// This file is part of QuickLook program.
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;
using System.Windows;
using System.Xml;
using ImageMagick;

namespace QuickLook.Plugin.ImageViewer
{
    public class MetaProvider
    {
        private readonly SortedDictionary<string, (string, string)> _cache =
            new SortedDictionary<string, (string, string)>(); // [key, [label, value]]

        private readonly string _path;

        public MetaProvider(string path)
        {
            _path = path;

            GetExif();
        }

        public SortedDictionary<string, (string, string)> GetExif()
        {
            if (_cache.Count != 0)
                return _cache;

            var exif = NativeMethods.GetExif(_path);
            if (string.IsNullOrEmpty(exif))
                return _cache;

            var xml = new XmlDocument();
            xml.LoadXml(exif);
            var iter = xml.SelectNodes("/Exif/child::node()")?.GetEnumerator();
            while (iter != null && iter.MoveNext())
            {
                if (!(iter.Current is XmlNode node))
                    continue;

                var key = node.Name;
                var label = node.Attributes?["Label"]?.InnerText;
                var value = node.InnerText;

                _cache.Add(key, (label, value));
            }

            return _cache;
        }

        public byte[] GetThumbnail()
        {
            return NativeMethods.GetThumbnail(_path) ?? new byte[0];
        }

        public Size GetSize()
        {
            _cache.TryGetValue("_.Size.Width", out var w_);
            _cache.TryGetValue("_.Size.Height", out var h_);

            if (int.TryParse(w_.Item2, out var w) && int.TryParse(h_.Item2, out var h))
                return new Size(w, h);

            // fallback

            using (var mi = new MagickImage())
            {
                mi.Ping(_path);
                w = mi.Width;
                h = mi.Height;
            }

            return w + h == 0 ? new Size(800, 600) : new Size(w, h);
        }

        public Orientation GetOrientation()
        {
            return (Orientation) NativeMethods.GetOrientation(_path);
        }
    }

    internal static class NativeMethods
    {
        private static readonly bool Is64 = Environment.Is64BitProcess;

        public static string GetExif(string file)
        {
            try
            {
                var len = Is64 ? GetExif_64(file, null) : GetExif_32(file, null);
                if (len <= 0)
                    return string.Empty;

                var sb = new StringBuilder(len + 1);
                var _ = Is64 ? GetExif_64(file, sb) : GetExif_32(file, sb);

                return sb.ToString();
            }
            catch (Exception e)
            {
                Debug.WriteLine(e);
                return string.Empty;
            }
        }

        public static byte[] GetThumbnail(string file)
        {
            try
            {
                var len = Is64 ? GetThumbnail_64(file, null) : GetThumbnail_32(file, null);
                if (len <= 0)
                    return null;

                var buffer = new byte[len];
                var _ = Is64 ? GetThumbnail_64(file, buffer) : GetThumbnail_32(file, buffer);

                return buffer;
            }
            catch (Exception e)
            {
                Debug.WriteLine(e);
                return null;
            }
        }

        public static int GetOrientation(string file)
        {
            try
            {
                return Is64 ? GetOrientation_64(file) : GetOrientation_32(file);
            }
            catch (Exception e)
            {
                Debug.WriteLine(e);
                return 0;
            }
        }

        [DllImport("exiv2-ql-32.dll", EntryPoint = "GetExif", CallingConvention = CallingConvention.Cdecl)]
        private static extern int GetExif_32([MarshalAs(UnmanagedType.LPWStr)] string file,
            [MarshalAs(UnmanagedType.LPStr)] StringBuilder sb);

        [DllImport("exiv2-ql-32.dll", EntryPoint = "GetThumbnail", CallingConvention = CallingConvention.Cdecl)]
        private static extern int GetThumbnail_32([MarshalAs(UnmanagedType.LPWStr)] string file,
            [MarshalAs(UnmanagedType.LPArray)] byte[] buffer);

        [DllImport("exiv2-ql-32.dll", EntryPoint = "GetOrientation", CallingConvention = CallingConvention.Cdecl)]
        private static extern int GetOrientation_32([MarshalAs(UnmanagedType.LPWStr)] string file);

        [DllImport("exiv2-ql-64.dll", EntryPoint = "GetExif", CallingConvention = CallingConvention.Cdecl)]
        private static extern int GetExif_64([MarshalAs(UnmanagedType.LPWStr)] string file,
            [MarshalAs(UnmanagedType.LPStr)] StringBuilder sb);

        [DllImport("exiv2-ql-64.dll", EntryPoint = "GetThumbnail", CallingConvention = CallingConvention.Cdecl)]
        private static extern int GetThumbnail_64([MarshalAs(UnmanagedType.LPWStr)] string file,
            [MarshalAs(UnmanagedType.LPArray)] byte[] buffer);

        [DllImport("exiv2-ql-64.dll", EntryPoint = "GetOrientation", CallingConvention = CallingConvention.Cdecl)]
        private static extern int GetOrientation_64([MarshalAs(UnmanagedType.LPWStr)] string file);
    }

    public enum Orientation
    {
        Undefined = 0,
        TopLeft = 1,
        TopRight = 2,
        BottomRight = 3,
        BottomLeft = 4,
        LeftTop = 5,
        RightTop = 6,
        RightBottom = 7,
        LeftBottom = 8
    }
}