using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Xml;
using iTextSharp.text.pdf;
using PDFPatcher.Common;
using PDFPatcher.Model;

namespace PDFPatcher.Processor
{
	internal sealed class DocInfoExporter(PdfReader reader, ExporterOptions options)
	{
		const string SimpleBookmarkPageNumLeader = " ………… ";
		const int OpenDocWorkload = 10;
		const int BookmarkWorkload = 30;

		readonly PdfReader _reader = reader;
		readonly ExporterOptions _options = options;
		readonly PdfContentExport _contentExport = new PdfContentExport(options);
		readonly PdfActionExporter _actionExport = new PdfActionExporter(options.UnitConverter);
		Dictionary<int, int> _pageReferenceMapper;
		Dictionary<string, PdfObject> _namedDestinations;

		public FilePath BinaryStreamPath {
			get => _contentExport.BinaryStreamPath;
			set => _contentExport.BinaryStreamPath = value;
		}

		Dictionary<int, int> PageReferenceMapper => _pageReferenceMapper ??= _reader.GetPageRefMapper();

		static internal XmlWriterSettings GetWriterSettings() {
			return new XmlWriterSettings() {
				Encoding = AppContext.Exporter.GetEncoding(),
				Indent = true,
				IndentChars = "\t",
				CheckCharacters = false
			};
		}

		internal int EstimateWorkload() {
			var n = _reader.NumberOfPages;
			var load = OpenDocWorkload;
			if (_options.ExportCatalog) {
				load += n / 100;
			}
			if (_options.ExportBookmarks) {
				load += BookmarkWorkload;
			}
			if (_options.ExtractPageLinks) {
				load += n;
			}
			if (_options.ExtractPageContent) {
				load += PageRangeCollection.Parse(_options.ExtractPageRange, 1, n, true).TotalPages;
			}
			if (_options.ExtractPageSettings) {
				load += n;
			}
			return load;
		}

		internal static GeneralInfo RewriteDocInfoWithEncoding(PdfReader pdf, Encoding encoding) {
			try {
				return RewriteDocInfoWithEncoding(pdf.Trailer.GetAsDict(PdfName.INFO), encoding);
			}
			catch (IOException) {
				// 忽略错误的元数据
				return new GeneralInfo();
			}
		}

		internal static GeneralInfo RewriteDocInfoWithEncoding(PdfDictionary info, Encoding encoding) {
			var r = new GeneralInfo();
			if (info == null || info.Length == 0) {
				return r;
			}
			var dump = new PdfDictionary();
			string t;
			PdfName n;
			PdfString s;
			foreach (var item in info) {
				s = item.Value as PdfString;
				if (s == null) {
					continue;
				}
				n = item.Key;
				t = s.Decode(encoding);
				if (PdfName.TITLE.Equals(n)) {
					r.Title = t;
				}
				else if (PdfName.AUTHOR.Equals(n)) {
					r.Author = t;
				}
				else if (PdfName.SUBJECT.Equals(n)) {
					r.Subject = t;
				}
				else if (PdfName.KEYWORDS.Equals(n)) {
					r.Keywords = t;
				}
				else if (PdfName.CREATOR.Equals(n)) {
					r.Creator = t;
				}
				else if (PdfName.PRODUCER.Equals(n)) {
					r.Producer = t;
				}
				dump.Put(n, t);
			}
			if (encoding != null) {
				info.Merge(dump);
			}
			dump = null;
			return r;
		}

		internal static void WriteDocumentInfoAttributes(XmlWriter w, string sourcePath, int numberOfPages) {
			w.WriteAttributeString(Constants.Info.ProductName, System.Windows.Forms.Application.ProductName);
			w.WriteAttributeString(Constants.Info.ProductVersion, Constants.InfoDocVersion);
			w.WriteAttributeString(Constants.Info.ExportDate, DateTime.Now.ToString("yyyy年MM月dd日 HH:mm:ss"));
			//w.WriteAttributeString (Constants.Info.DocumentName, Path.GetFileNameWithoutExtension (sourceFile));
			w.WriteAttributeString(Constants.Info.DocumentPath, sourcePath);
			w.WriteAttributeString(Constants.Info.PageNumber, numberOfPages.ToText());
		}

		internal void ExportDocument(XmlWriter w) {
			Tracker.IncrementProgress(OpenDocWorkload);
			if (_options.UnitConverter.UnitFactor != 1) {
				w.WriteStartElement(Constants.Units.ThisName);
				w.WriteAttributeString(Constants.Units.Unit, _options.UnitConverter.Unit);
				w.WriteEndElement();
			}
			if (_options.ExportDocProperties) {
				Tracker.TraceMessage("导出文档信息。");
				RewriteDocInfoWithEncoding(_reader, AppContext.Encodings.DocInfoEncoding);
				ExportDocumentInfo(w);
			}
			if (_options.ExportViewerPreferences) {
				Tracker.TraceMessage("导出阅读器设置。");
				ExportViewerPreferences(w);
			}
			if (_options.ExportBookmarks || _options.ExtractPageLinks) {
				if (_options.ConsolidateNamedDestinations) {
					_reader.ConsolidateNamedDestinations();
				}
				if (_options.ExportBookmarks) {
					Tracker.TraceMessage("导出书签。");
					w.WriteStartElement(Constants.DocumentBookmark);
					ExportBookmarks(OutlineManager.GetBookmark(_reader, _options.UnitConverter), w);
					w.WriteEndElement();
					Tracker.IncrementProgress(BookmarkWorkload);
				}
				if (_options.ExtractPageLinks) {
					Tracker.TraceMessage("导出页面连接。");
					ExtractPageLinks(w);
				}
				if (_options.ConsolidateNamedDestinations == false) {
					Tracker.TraceMessage("导出命名目标。");
					ExportNamedDestinations(w);
				}
			}
			if (_options.ExtractPageSettings) {
				Tracker.TraceMessage("导出页面设置。");
				w.WriteStartElement(Constants.Content.PageSettings.ThisName);
				ExtractPageSettings(w);
				w.WriteEndElement();
			}
			if (_options.ExportCatalog) {
				_contentExport.ExportTrailer(w, _reader);
			}
			if (_options.ExtractPageContent) {
				_contentExport.ExportContents(w, _reader);
			}
			Tracker.TraceMessage("完成导出任务。");
		}

		internal void ExportDocumentInfo(XmlWriter w) {
			var info = _reader.Catalog;
			w.WriteStartElement(Constants.Info.ThisName);
			if (info.Contains(PdfName.VERSION))
				w.WriteAttributeString(Constants.Version, PdfHelper.GetPdfNameString(info.GetAsName(PdfName.VERSION)));
			info = _reader.Trailer.GetAsDict(PdfName.INFO);
			if (info?.Length > 0) {
				string key, val;
				foreach (var item in info) {
					key = PdfName.DecodeName(item.Key.ToString());
					val = item.Value.IsString() ? ((PdfString)item.Value).Decode(null) : item.Value.ToString();
					switch (key) {
						case "Title": key = Constants.Info.Title; break;
						case "Author": key = Constants.Info.Author; break;
						case "Subject": key = Constants.Info.Subject; break;
						case "Keywords": key = Constants.Info.Keywords; break;
						case "Creator": key = Constants.Info.Creator; break;
						case "Producer": key = Constants.Info.Producer; break;
						case "CreationDate":
							key = Constants.Info.CreationDate;
							goto case "//DecodeDate";
						case "ModDate":
							key = Constants.Info.ModDate;
							goto case "//DecodeDate";
						case "//DecodeDate":
							try {
								val = PdfDate.Decode(val).ToString("yyyy年MM月dd日 HH:mm:ss");
							}
							catch (Exception) {
								continue;
							}
							break;
					}
					w.WriteAttributeString(XmlConvert.EncodeLocalName(key), PdfHelper.GetValidXmlString(val));
				}
				if (_reader.Metadata?.Length > 0) {
					w.WriteStartElement(Constants.Info.MetaData);
					using (MemoryStream ms = new MemoryStream(_reader.Metadata)) {
						var d = new XmlDocument();
						d.Load(ms);
						d.DocumentElement?.WriteContentTo(w);
					}
					w.WriteEndElement();
				}
			}
			w.WriteEndElement();

		}

		internal static void WriteDocumentInfoAttributes(TextWriter w, string sourcePath, int numberOfPages) {
			w.WriteLine("#版本=" + Constants.InfoDocVersion);
			w.WriteLine("#" + Constants.Info.DocumentPath + "=" + sourcePath);
			w.WriteLine("#页数=" + numberOfPages);
			w.WriteLine();
		}

		internal void ExportDocument(TextWriter w) {
			var i = RewriteDocInfoWithEncoding(_reader, AppContext.Encodings.DocInfoEncoding);
			OutlineManager.WriteSimpleBookmarkInstruction(w, Constants.Info.Title, PdfHelper.GetValidXmlString(i.Title));
			OutlineManager.WriteSimpleBookmarkInstruction(w, Constants.Info.Author, PdfHelper.GetValidXmlString(i.Author));
			OutlineManager.WriteSimpleBookmarkInstruction(w, Constants.Info.Subject, PdfHelper.GetValidXmlString(i.Subject));
			OutlineManager.WriteSimpleBookmarkInstruction(w, Constants.Info.Keywords, PdfHelper.GetValidXmlString(i.Keywords));
			OutlineManager.WriteSimpleBookmarkInstruction(w, Constants.Info.Creator, PdfHelper.GetValidXmlString(i.Creator));
			OutlineManager.WriteSimpleBookmarkInstruction(w, Constants.Info.Producer, PdfHelper.GetValidXmlString(i.Producer));
		}

		internal void ExportViewerPreferences(XmlWriter w) {
			var catalog = _reader.Catalog;
			if (catalog.Contains(PdfName.VIEWERPREFERENCES) || catalog.Contains(PdfName.PAGELAYOUT) || catalog.Contains(PdfName.PAGEMODE)) {
				w.WriteStartElement(Constants.ViewerPreferences);
				if (catalog.Contains(PdfName.PAGELAYOUT)) {
					w.WriteAttributeString(Constants.PageLayout,
						ValueHelper.MapValue(catalog.GetAsName(PdfName.PAGELAYOUT), Constants.PageLayoutType.PdfNames,
						Constants.PageLayoutType.Names));
				}
				if (catalog.Contains(PdfName.PAGEMODE)) {
					w.WriteAttributeString(Constants.PageMode,
						ValueHelper.MapValue(catalog.GetAsName(PdfName.PAGEMODE), Constants.PageModes.PdfNames,
						Constants.PageModes.Names));
				}
				if (catalog.Contains(PdfName.VIEWERPREFERENCES)) {
					ExportViewerPreferences(catalog.GetAsDict(PdfName.VIEWERPREFERENCES), w);
				}
				w.WriteEndElement();
			}

			if (!catalog.Contains(PdfName.PAGELABELS)) {
				return;
			}

			var labels = ExtractPageLabels(catalog.GetAsDict(PdfName.PAGELABELS));
			if (labels.Count > 0) {
				w.WriteStartElement(Constants.PageLabels);
				foreach (var item in labels) {
					w.WriteStartElement(Constants.PageLabelsAttributes.Style);
					w.WriteAttributeString(Constants.PageLabelsAttributes.PageNumber, item.PageNumber.ToText());
					if (item.StartPage != 0) {
						w.WriteAttributeString(Constants.PageLabelsAttributes.StartPage, item.StartPage.ToText());
					}
					if (String.IsNullOrEmpty(item.Prefix) == false) {
						w.WriteAttributeString(Constants.PageLabelsAttributes.Prefix, item.Prefix);
					}
					if (String.IsNullOrEmpty(item.Style) == false) {
						w.WriteAttributeString(Constants.PageLabelsAttributes.Style,
							ValueHelper.MapValue(item.Style[0],
								Constants.PageLabelStyles.PdfValues,
								Constants.PageLabelStyles.Names,
								item.Style)
						);
					}
					w.WriteEndElement();
				}
				w.WriteEndElement();
			}
		}

		private static List<PageLabel> ExtractPageLabels(PdfDictionary labels) {
			var a = new List<PageLabel>();
			var ls = labels.GetAsArray(PdfName.NUMS);
			if (ls == null) {
				return new List<PageLabel>();
			}
			for (int i = 0; i < ls.Size; i++) {
				var l = new PageLabel {
					PageNumber = ls.GetAsNumber(i++).IntValue + 1
				};
				var label = ls.GetAsDict(i);
				if (label.Contains(PdfName.ST)) {
					l.StartPage = label.GetAsNumber(PdfName.ST).IntValue;
				}
				if (label.Contains(PdfName.P)) {
					l.Prefix = label.GetAsString(PdfName.P).ToUnicodeString();
				}
				if (label.Contains(PdfName.S)) {
					l.Style = PdfHelper.GetPdfNameString(label.GetAsName(PdfName.S));
				}
				a.Add(l);
				l = null;
			}
			return a;
		}

		internal void ExtractPageSettings(XmlWriter w) {
			int n = _reader.NumberOfPages;
			PageSettings active = null, current;
			int fromP = 1, toP;
			for (int i = 1; i <= n; i++) {
				Tracker.IncrementProgress(1);
				current = PageSettings.FromReader(_reader, i, _options.UnitConverter);
				if (PageSettings.HavingSameDimension(active, current) && i != n) {
					continue;
				}
				if (i == 1) {
					active = current;
					if (n > i) {
						continue;
					}
				}
				toP = i == n ? n : i - 1;
				active.PageRange = (fromP != toP) ? String.Concat(fromP.ToText(), '-', toP.ToText()) : toP.ToText();
				w.WriteStartElement(Constants.Content.Page);
				active.WriteXml(w);
				w.WriteEndElement();
				fromP = i;
				active = current;
			}
		}

		private static void ExportViewerPreferences(PdfDictionary preferences, XmlWriter w) {
			foreach (var item in preferences) {
				if (item.Key.Equals(PdfName.TYPE)) {
					continue;
				}
				var itemName = ValueHelper.MapValue(item.Key, Constants.ViewerPreferencesType.PdfNames, Constants.ViewerPreferencesType.Names, PdfName.DecodeName(item.Key.ToString()));
				if (item.Value is PdfName nv) {
					if (PdfName.DIRECTION.Equals(item.Key)) {
						w.WriteAttributeString(Constants.ViewerPreferencesType.Direction,
							ValueHelper.MapValue(nv, Constants.ViewerPreferencesType.DirectionType.PdfNames,
							Constants.ViewerPreferencesType.DirectionType.Names));
					}
					else {
						w.WriteAttributeString(itemName, PdfHelper.GetPdfFriendlyName(nv));
					}
				}
				else if (item.Value.IsBoolean()) {
					w.WriteAttributeString(
						itemName,
						((PdfBoolean)item.Value).BooleanValue ? Constants.Boolean.True : Constants.Boolean.False
						);
				}
				else {
					w.WriteAttributeString(itemName, item.Value.ToString());
				}
			}
		}

		internal void ExportNamedDestinations(XmlWriter w) {
			var nds = LoadNamedDestinations();
			if (nds != null && nds.Count > 0) {
				w.WriteStartElement(Constants.NamedDestination);
				foreach (var item in nds) {
					w.WriteStartElement("位置");
					w.WriteAttributeString(Constants.DestinationAttributes.Name, StringHelper.ReplaceControlAndBomCharacters(item.Key));
					_actionExport.ExportGotoAction(item.Value as PdfObject, nds, w, PageReferenceMapper);
					w.WriteEndElement();
				}
				w.WriteEndElement();
			}
		}

		Dictionary<string, PdfObject> LoadNamedDestinations() {
			return _namedDestinations ??= _reader.GetNamedDestinations();
		}

		internal void ExportBookmarks(XmlElement bookmarks, TextWriter w, int level, bool isOpen) {
			if (bookmarks == null || bookmarks.HasChildNodes == false) {
				return;
			}
			var childBookmarks = bookmarks.SelectNodes(Constants.Bookmark);
			if (childBookmarks == null || childBookmarks.Count == 0) {
				return;
			}
			string title, page;
			bool open;
			foreach (XmlElement item in childBookmarks) {
				title = item.GetAttribute(Constants.BookmarkAttributes.Title);
				page = item.GetAttribute(Constants.DestinationAttributes.Page);
				open = item.GetAttribute(Constants.BookmarkAttributes.Open) == Constants.Boolean.True;

				if (open != isOpen && item.HasChildNodes) {
					OutlineManager.WriteSimpleBookmarkInstruction(w, "打开书签", open ? "是" : "否");
					isOpen = open;
				}
				if (String.IsNullOrEmpty(title) == false) {
					for (int i = 0; i < level; i++) {
						w.Write('\t');
					}
					w.Write(title.Replace('\n', ' ').Replace('\r', ' '));
					w.Write(SimpleBookmarkPageNumLeader);
					w.WriteLine(page);
				}

				if (childBookmarks != null) {
					level++;
					ExportBookmarks(item, w, level, isOpen);
					level--;
				}
			}
		}

		/// <summary>
		/// 导出 PDF 书签。
		/// </summary>
		/// <param name="bookmarks"></param>
		/// <param name="w"></param>
		internal void ExportBookmarks(XmlElement bookmarks, XmlWriter w) {
			if (bookmarks == null) {
				return;
			}
			foreach (XmlElement child in bookmarks.ChildNodes) {
				if (child == null) {
					continue;
				}
				w.WriteStartElement(Constants.Bookmark);
				foreach (XmlAttribute entry in child.Attributes) {
					var key = entry.Name as string;
					var value = entry.Value ?? String.Empty;
					switch (key) {
						case Constants.Coordinates.Bottom:
						case Constants.Coordinates.Left:
						case Constants.Coordinates.Top:
						case Constants.Coordinates.Right:
							if (String.IsNullOrEmpty(value) || value == "null") {
								continue;
							}
							goto default;
						case Constants.Coordinates.ScaleFactor:
							if (String.IsNullOrEmpty(value)) {
								continue;
							}
							goto default;
						case Constants.BookmarkAttributes.Title:
							w.WriteAttributeString(key, PdfHelper.GetValidXmlString(value));
							break;
						default:
							w.WriteAttributeString(key, value);
							break;
					}
				}
				if (child.ChildNodes.Count > 0) {
					ExportBookmarks(child, w);
				}
				w.WriteEndElement();
			}
		}

		/// <summary>
		/// 导出 PDF 文档页内连接。
		/// </summary>
		/// <param name="r"></param>
		/// <param name="w"></param>
		internal void ExtractPageLinks(XmlWriter w) {
			w.WriteStartElement(Constants.PageLink);
			int numPages = _reader.NumberOfPages;

			for (int i = 1; i <= numPages; i++) {
				var pageDic = _reader.GetPageNRelease(i);
				Tracker.IncrementProgress(1);
				var annots = (PdfArray)PdfReader.GetPdfObject(pageDic.Get(PdfName.ANNOTS));
				if (annots == null) {
					continue;
				}
				foreach (PdfObject item in annots.ArrayList) {
					if (item.IsNull()) {
						continue;
					}
					var annot = (PdfDictionary)PdfReader.GetPdfObjectRelease(item);
					if (PdfName.LINK.Equals(annot.Get(PdfName.SUBTYPE))) {
						w.WriteStartElement(Constants.PageLinkAttributes.Link);
						w.WriteAttributeString(Constants.PageLinkAttributes.PageNumber, i.ToText());
						var rect = annot.GetAsArray(PdfName.RECT);
						if (rect != null && rect.Size == 4) {
							var u = _options.UnitConverter;
							var p = new float[4];
							var k = 0;
							foreach (PdfNumber ri in rect.ArrayList) {
								if (ri == null) {
									break;
								}
								p[k] = u.FromPoint(ri.FloatValue);
								k++;
							}
							if (k == 4) {
								w.WriteAttributeString(Constants.Coordinates.Left, p[0].ToText());
								w.WriteAttributeString(Constants.Coordinates.Bottom, p[1].ToText());
								w.WriteAttributeString(Constants.Coordinates.Right, p[2].ToText());
								w.WriteAttributeString(Constants.Coordinates.Top, p[3].ToText());
							}
						}
						if (annot.Contains(PdfName.BORDER)) {
							w.WriteAttributeString(Constants.PageLinkAttributes.Border, PdfHelper.GetNumericArrayString(annot.GetAsArray(PdfName.BORDER), 1));
						}
						if (annot.Contains(PdfName.C)) {
							ExportColor(annot.GetAsArray(PdfName.C), w);
						}
						if (annot.Contains(PdfName.H)) {
							var style = PdfHelper.GetPdfNameString(annot.GetAsName(PdfName.H));
							style = ValueHelper.MapValue(style,
								["N", "I", "O", "P"],
								["无", "取反内容", "取反边框", "按下"],
								style
								);
							w.WriteAttributeString(Constants.PageLinkAttributes.Style, style);
						}
						if (annot.Contains(PdfName.QUADPOINTS)) {
							w.WriteAttributeString(Constants.PageLinkAttributes.QuadPoints, PdfHelper.GetNumericArrayString(annot.GetAsArray(PdfName.QUADPOINTS), _options.UnitConverter.UnitFactor));
						}
						if (annot.Contains(PdfName.CONTENTS)) {
							w.WriteAttributeString(Constants.PageLinkAttributes.Contents, annot.GetAsString(PdfName.CONTENTS).ToUnicodeString());
						}
						ExportLinkAction(annot, w);
						if (annot.Contains(PdfName.BS)) {
							w.WriteStartElement("边框样式");
							var bs = annot.GetAsDict(PdfName.BS);
							if (bs.Contains(PdfName.W)) {
								w.WriteAttributeString("宽度", bs.GetAsNumber(PdfName.W).FloatValue.ToText());
							}
							if (bs.Contains(PdfName.S)) {
								var style = PdfHelper.GetPdfNameString(bs.GetAsName(PdfName.S));
								style = ValueHelper.MapValue(style,
									["S", "U", "D", "B", "I"],
									["方框", "下划线", "虚线", "凸起", "凹陷"],
									style
									);
								w.WriteAttributeString("样式", style);
								if (PdfName.D.Equals(bs.GetAsName(PdfName.S)) && bs.Contains(PdfName.D)) {
									w.WriteAttributeString("线型", PdfHelper.GetArrayString(bs.GetAsArray(PdfName.D)));
								}
							}
							w.WriteEndElement();
						}
						w.WriteEndElement();
					}
				}
			}
			w.WriteEndElement();
		}

		internal static void ExportColor(PdfArray color, XmlWriter target) {
			if (color == null) {
				return;
			}
			switch (color.Size) {
				case 0:
					target.WriteAttributeString(Constants.Color, Constants.Colors.Transparent);
					break;
				case 1:
					target.WriteAttributeString(Constants.Colors.Gray, color.GetAsNumber(0).FloatValue.ToText());
					break;
				case 3:
					target.WriteAttributeString(Constants.Colors.Red, color.GetAsNumber(0).FloatValue.ToText());
					target.WriteAttributeString(Constants.Colors.Green, color.GetAsNumber(1).FloatValue.ToText());
					target.WriteAttributeString(Constants.Colors.Blue, color.GetAsNumber(2).FloatValue.ToText());
					break;
				case 4:
					target.WriteAttributeString(Constants.Colors.Cyan, color.GetAsNumber(0).FloatValue.ToText());
					target.WriteAttributeString(Constants.Colors.Magenta, color.GetAsNumber(1).FloatValue.ToText());
					target.WriteAttributeString(Constants.Colors.Yellow, color.GetAsNumber(2).FloatValue.ToText());
					target.WriteAttributeString(Constants.Colors.Black, color.GetAsNumber(3).FloatValue.ToText());
					break;
			}
		}

		/// <summary>
		/// 导出 PDF 文档的单个连接信息。
		/// </summary>
		/// <param name="link"></param>
		/// <param name="w"></param>
		void ExportLinkAction(PdfDictionary link, XmlWriter w) {
			var dest = PdfReader.GetPdfObjectRelease(link.Get(PdfName.DEST));
			var names = LoadNamedDestinations();
			w.WriteStartElement(Constants.PageLinkAttributes.LinkAction);

			if (dest != null) {
				_actionExport.ExportGotoAction(dest, names, w, PageReferenceMapper);
			}
			else {
				_actionExport.ExportAction((PdfDictionary)PdfReader.GetPdfObjectRelease(link.Get(PdfName.A)), names, PageReferenceMapper, w);
			}
			w.WriteEndElement();
		}
	}
}