#if SKIA
using FastReport.Fonts;
using SkiaSharp;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Text;
using System.IO;
using System.Runtime.InteropServices;

namespace FastReport
{
    public static partial class FontManager
    {
        // do not remove
        private static readonly CharacterMatcher characterMatcher = new();
        private static readonly FontFamilyMatcher1 fontFamilyMatcher1 = new();

        // Note to future implementors:
        // this might be added to gdi/uniscribe as well, but it produces not-so-good results,
        // because we cannot apply this to text measure phase, only to pdf render phase.
        private static List<FontFallback> FallbackFonts { get; } = new();

        /// <summary>
        /// Adds a new fallback font.
        /// </summary>
        /// <param name="fontName">The font name, e.g. "Noto Sans CJK JP".</param>
        /// <remarks>
        /// Fallback font is used to display characters that not present in the original font. It is often used for CJK.
        /// For example, you may add "Noto Sans CJK JP" fallback. User defined fallback fonts will then be checked first.
        /// </remarks>
        public static void AddFallbackFont(string fontName)
        {
            FallbackFonts.Add(new(fontName));
        }

        /// <summary>
        /// Removes specified fallback font.
        /// </summary>
        /// <param name="fontName">The font name.</param>
        public static void RemoveFallbackFont(string fontName)
        {
            for (int i = 0; i < FallbackFonts.Count; i++)
            {
                if (FallbackFonts[i].Name == fontName)
                {
                    FallbackFonts.RemoveAt(i);
                    i--;
                }
            }
        }

        /// <summary>
        /// Clears all fallback fonts.
        /// </summary>
        public static void ClearFallbackFonts()
        {
            FallbackFonts.Clear();
        }

        private static void AddFontInternal(byte[] buffer, PrivateFontCollection collection)
        {
            var ms = new MemoryStream(buffer);

            using (FontStream fs = new FontStream(ms))
            {
                var list = TrueTypeCollection.CreateFonts(fs); 

                for (int ttcIndex = 0; ttcIndex < list.Count; ttcIndex++)
                {
                    var ttf = list[ttcIndex];
                    collection.AddFont(buffer, ttf.Family, ttcIndex);
                }
            }
        }

        /// <summary>
        /// Adds a font from a memory buffer.
        /// </summary>
        /// <param name="buffer">The buffer containing font data.</param>
        public static void AddFont(byte[] buffer)
        {
            AddFontInternal(buffer, PrivateFontCollection);
        }

        /// <summary>
        /// Adds a font contained in system memory.
        /// </summary>
        /// <param name="memory">The memory address of the font to add.</param>
        /// <param name="length">The memory length of the font to add.</param>
        public static void AddFont(IntPtr memory, int length)
        {
            byte[] buffer = new byte[length];
            Marshal.Copy(memory, buffer, 0, length);
            AddFont(buffer);
        }

        /// <summary>
        /// Adds a font from a stream.
        /// </summary>
        /// <param name="stream">The stream containing font data.</param>
        public static void AddFont(Stream stream)
        {
            var ms = new MemoryStream();
            stream.CopyTo(ms);
            AddFont(ms.ToArray());
        }

        /// <summary>
        /// Adds a font from a file.
        /// </summary>
        /// <param name="fileName">The name of the font file.</param>
        /// <returns>true if file exists, otherwise false.</returns>
        public static bool AddFont(string fileName)
        {
            if (File.Exists(fileName))
            {
                AddFont(File.ReadAllBytes(fileName));
                return true;
            }
            else
            {
                Debug.WriteLine($"Font file not found {fileName}");
            }
            return false;
        }

        /// <summary>
        /// Adds a font from a file to a temporary font list.
        /// </summary>
        /// <param name="fileName">The name of the font file.</param>
        /// <returns>true if file exists, otherwise false.</returns>
        public static bool AddTempFont(string fileName)
        {
            if (File.Exists(fileName))
            {
                TemporaryFontCollection ??= new PrivateFontCollection();
                AddFontInternal(File.ReadAllBytes(fileName), TemporaryFontCollection);
                return true;
            }
            else
            {
                Debug.WriteLine($"Font file not found {fileName}");
            }
            return false;
        }

        /// <summary>
        /// Adds a font from a stream to a temporary font list.
        /// </summary>
        /// <param name="stream">The stream containing font data.</param>
        public static void AddTempFont(Stream stream)
        {
            TemporaryFontCollection ??= new PrivateFontCollection();
            var ms = new MemoryStream();
            stream.CopyTo(ms);
            AddFontInternal(ms.ToArray(), TemporaryFontCollection);
        }

        /// <summary>
        /// Clears temporary fonts.
        /// </summary>
        public static void ClearTempFonts()
        {
            var collection = TemporaryFontCollection;
            TemporaryFontCollection = null;
            collection?.Dispose();
        }

        // Defines a font fallback item.
        private class FontFallback
        {
            private FontFamily _family;

            public string Name { get; }
            
            // The font family, if found. May be null.
            public FontFamily FontFamily => _family ?? FindFontFamily(Name, SearchScope.NonInstalled);

            public FontFallback(string name)
            {
                Name = name;
                // do initial search in installed fonts. Other collections should be checked later.
                _family = FindFontFamily(name, SearchScope.Installed);
            }
        }

        // used by the font fallback code from RichTextKit to find a typeface that contains a given character
        private class CharacterMatcher : Topten.RichTextKit.ICharacterMatcher
        {
            private readonly Topten.RichTextKit.ICharacterMatcher oldCharacterMatcher;

            public CharacterMatcher()
            {
                oldCharacterMatcher = Topten.RichTextKit.FontFallback.CharacterMatcher;
                Topten.RichTextKit.FontFallback.CharacterMatcher = this;
            }

            public SKTypeface MatchCharacter(string familyName, int weight, int width, SKFontStyleSlant slant, string[] bcp47, int character)
            {
                // check user defined fallbacks first
                foreach (var ff in FallbackFonts)
                {
                    var tf = ff.FontFamily?.GetTypeface(weight, width, slant);
                    if (tf != null && tf.ContainsGlyph(character))
                    {
                        return tf;
                    }
                }

                // check private fonts
                if (TemporaryFontCollection != null)
                {
                    foreach (var f in TemporaryFontCollection.Families)
                    {
                        var tf = f.GetTypeface(weight, width, slant);
                        if (tf.ContainsGlyph(character))
                        {
                            return tf;
                        }
                    }
                }

                foreach (var f in PrivateFontCollection.Families)
                {
                    var tf = f.GetTypeface(weight, width, slant);
                    if (tf.ContainsGlyph(character))
                    {
                        return tf;
                    }
                }

                // do default check
                return oldCharacterMatcher?.MatchCharacter(familyName, weight, width, slant, bcp47, character);
            }
        }

        // used in the FontFamily to look up family name in all font collections
        private class FontFamilyMatcher1 : FontFamily.IFontFamilyMatcher
        {
            public FontFamilyMatcher1()
            {
                FontFamily.FontFamilyMatcher = this;
            }

            public FontFamily GetFontFamilyOrDefault(string name) => 
                FontManager.GetFontFamilyOrDefault(name);

            public FontFamily GetFontFamilyForTypeface(SKTypeface typeface, FontStyle style)
            {
                var family = TemporaryFontCollection?.Find(typeface, style);
                family ??= PrivateFontCollection.Find(typeface, style);
                family ??= InstalledFontCollection.Find(typeface, style);
                return family;
            }
        }
    }
}
#endif